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  Subjects -> FORESTS AND FORESTRY (Total: 125 journals)
    - FORESTS AND FORESTRY (124 journals)
    - LUMBER AND WOOD (1 journals)

FORESTS AND FORESTRY (124 journals)                     

Showing 1 - 12 of 12 Journals sorted alphabetically
Acta Silvatica et Lignaria Hungarica     Open Access  
Advance in Forestry Research     Open Access   (Followers: 5)
Advances in Forestry Science     Open Access   (Followers: 3)
Agrociencia     Open Access   (Followers: 1)
Agroforestry Systems     Hybrid Journal   (Followers: 19)
Annals of Forest Research     Open Access   (Followers: 1)
Annals of Forest Science     Hybrid Journal   (Followers: 7)
Annals of Silvicultural Research     Open Access   (Followers: 1)
Appita Journal: Journal of the Technical Association of the Australian and New Zealand Pulp and Paper Industry     Full-text available via subscription   (Followers: 14)
Arboricultural Journal : The International Journal of Urban Forestry     Hybrid Journal   (Followers: 7)
Arboriculture and Urban Forestry     Partially Free   (Followers: 7)
Artvin Çoruh Üniversitesi Orman Fakültesi Dergisi / Artvin Coruh University Journal of Forestry Faculty     Open Access  
Asian Journal of Forestry     Open Access  
Australian Forest Grower     Full-text available via subscription   (Followers: 4)
Australian Forestry     Full-text available via subscription   (Followers: 2)
Balduinia     Open Access   (Followers: 1)
Banko Janakari     Open Access  
Bartın Orman Fakültesi Dergisi / Journal of Bartin Faculty of Forestry     Open Access  
Bosque     Open Access   (Followers: 2)
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Horticulture     Open Access  
Canadian Journal of Forest Research     Hybrid Journal   (Followers: 29)
Canadian Journal of Plant Science     Full-text available via subscription   (Followers: 12)
Central European Forestry Journal     Open Access   (Followers: 1)
Ciência Florestal     Open Access   (Followers: 3)
Ciencia forestal en México     Open Access  
Colombia Forestal     Open Access  
Current Forestry Reports     Hybrid Journal   (Followers: 1)
Dissertationes Forestales     Open Access  
Düzce Üniversitesi Ormancılık Dergisi     Open Access  
East African Agricultural and Forestry Journal     Hybrid Journal   (Followers: 2)
Eurasian Journal of Forest Science     Open Access  
European Journal of Forest Engineering     Open Access  
European Journal of Forest Research     Hybrid Journal   (Followers: 8)
Expert Opinion on Environmental Biology     Hybrid Journal   (Followers: 1)
Floresta e Ambiente     Open Access   (Followers: 1)
Folia Forestalia Polonica     Open Access  
Forest Ecology and Management     Hybrid Journal   (Followers: 58)
Forest Ecosystems     Open Access   (Followers: 1)
Forest Pathology     Hybrid Journal   (Followers: 1)
Forest Phytophthoras     Open Access   (Followers: 2)
Forest Policy and Economics     Hybrid Journal   (Followers: 22)
Forest Research     Open Access  
Forest Research Papers     Open Access   (Followers: 2)
Forest Science     Hybrid Journal   (Followers: 7)
Forest Science and Practice     Hybrid Journal   (Followers: 2)
Forest Science and Technology     Partially Free   (Followers: 1)
Forest Systems     Open Access   (Followers: 1)
Forest@ : Journal of Silviculture and Forest Ecology     Open Access   (Followers: 1)
Foresta Veracruzana     Open Access  
Forestry Chronicle     Full-text available via subscription   (Followers: 9)
Forestry Letters     Open Access   (Followers: 1)
Forestry Studies : Metsanduslikud Uurimused     Open Access  
Forestry: An International Journal of Forest Research     Hybrid Journal   (Followers: 16)
Forests     Open Access   (Followers: 2)
Forests, Trees and Livelihoods     Partially Free   (Followers: 4)
Ghana Journal of Forestry     Full-text available via subscription   (Followers: 2)
Holzforschung     Hybrid Journal   (Followers: 1)
iForest : Biogeosciences and Forestry     Open Access   (Followers: 3)
Indian Forester     Full-text available via subscription   (Followers: 3)
Indonesian Journal of Forestry Research     Open Access   (Followers: 3)
INNOTEC : Revista del Laboratorio Tecnológico del Uruguay     Open Access  
International Forestry Review     Full-text available via subscription   (Followers: 6)
International Journal of Agriculture and Forestry     Open Access   (Followers: 8)
International Journal of Agriculture, Forestry and Life Sciences     Open Access  
International Journal of Forest Engineering     Hybrid Journal   (Followers: 1)
International Journal of Forestry Research     Open Access   (Followers: 3)
Irish Journal of Agricultural and Food Research     Open Access   (Followers: 2)
Journal of Agriculture, Forestry and the Social Sciences     Full-text available via subscription   (Followers: 4)
Journal of Biodiversity Management & Forestry     Hybrid Journal   (Followers: 5)
Journal of Environmental Extension     Full-text available via subscription  
Journal of Forest and Livelihood     Open Access  
Journal of Forest Economics     Hybrid Journal   (Followers: 5)
Journal of Forest Research     Hybrid Journal   (Followers: 2)
Journal of Forestry     Hybrid Journal   (Followers: 14)
Journal of Forestry Research     Hybrid Journal   (Followers: 3)
Journal of Horticulture and Forestry     Open Access   (Followers: 5)
Journal of Natural Resources Policy Research     Hybrid Journal   (Followers: 10)
Journal of Research in Forestry, Wildlife and Environment     Open Access   (Followers: 4)
Journal of Sustainable Forestry     Hybrid Journal   (Followers: 6)
Journal of the Faculty of Forestry Istanbul University     Open Access  
Journal of Wood Chemistry and Technology     Hybrid Journal   (Followers: 10)
Journal of Wood Science     Hybrid Journal   (Followers: 5)
Jurnal Ilmu Kehutanan     Open Access   (Followers: 1)
Jurnal Manajemen Hutan Tropika     Open Access   (Followers: 1)
Jurnal Penelitian Kehutanan Wallacea     Open Access  
Jurnal Penelitian Sosial dan Ekonomi Kehutanan     Open Access  
Kastamonu University Journal of Forestry Faculty     Open Access  
La Calera     Open Access  
Landscapes     Hybrid Journal   (Followers: 15)
Lesnícky časopis     Open Access  
Maderas. Ciencia y tecnología     Open Access   (Followers: 1)
Mathematical and Computational Forestry & Natural-Resource Sciences     Free  
Media Konservasi     Open Access   (Followers: 1)
Natural Areas Journal     Full-text available via subscription   (Followers: 11)
New Forests     Hybrid Journal   (Followers: 2)
New Zealand Journal of Forestry Science     Open Access   (Followers: 2)
Open Journal of Forestry     Open Access   (Followers: 2)
Ormancılık Araştırma Dergisi / Turkish Journal of Forestry Research     Open Access  
Quebracho. Revista de Ciencias Forestales     Open Access  
Research Journal of Forestry     Open Access   (Followers: 2)
Revista Árvore     Open Access   (Followers: 2)
Revista Chapingo. Serie Ciencias Forestales y del Ambiente     Open Access  
Revista Cubana de Ciencias Forestales     Open Access  
Revista de Agricultura Neotropical     Open Access   (Followers: 1)
Revista Ecologia e Nutrição Florestal - ENFLO     Open Access  
Revista Forestal Mesoamericana Kurú     Open Access  
Revista Verde de Agroecologia e Desenvolvimento Sustentável     Open Access   (Followers: 2)
Revue forestière française     Full-text available via subscription   (Followers: 4)
Rural Sustainability Research     Open Access   (Followers: 3)
Rwanda Journal     Full-text available via subscription  
Scandinavian Journal of Forest Research     Hybrid Journal   (Followers: 5)
Science, Technology and Arts Research Journal     Open Access   (Followers: 1)
Silva Lusitana     Open Access  
Small-scale Forestry     Hybrid Journal   (Followers: 1)
Southern African Forestry Journal     Full-text available via subscription   (Followers: 1)
Southern Forests : a Journal of Forest Science     Hybrid Journal   (Followers: 4)
Tanzania Journal of Forestry and Nature Conservation     Full-text available via subscription   (Followers: 2)
Trees     Hybrid Journal   (Followers: 4)
Turkish Journal of Agriculture and Forestry     Open Access   (Followers: 1)
Turkish Journal of Forestry / Türkiye Ormancılık Dergisi     Open Access  
Urban Forestry & Urban Greening     Hybrid Journal   (Followers: 8)
Veld & Flora     Full-text available via subscription   (Followers: 1)
Wahana Forestra : Jurnal Kehutanan     Open Access  
Wood and Fiber Science     Full-text available via subscription   (Followers: 4)

           

Journal Cover Forests
  Journal Prestige (SJR): 0.63
  Citation Impact (citeScore): 16
  Number of Followers: 2  
    
  This is an Open Access Journal Open Access journal
   ISSN (Print) 1999-4907
   Published by MDPI Homepage  [202 journals]
  • Forests, Vol. 9, Pages 284: The Influence of Individual-Specific Plant
           Parameters and Species Composition on the Allergenic Potential of Urban
           Green Spaces

    • Authors: Susanne Jochner-Oette, Theresa Stitz, Johanna Jetschni, Paloma Cariñanos
      First page: 284
      Abstract: Green planning focusses on specific site requirements such as temperature tolerance or aesthetics as crucial criteria in the choice of plants. The allergenicity of plants, however, is often neglected. Cariñanos et al. (2014; Landscape and Urban Planning, 123: 134–144) developed the Urban Green Zone Allergenicity Index (IUGZA) that considers a variety of plant characteristics to calculate the allergenic potential of urban green spaces. Based on this index, we calculated an index for the individual-specific allergenic potential (IISA) that accounts for a varying foliage volume by accurate measurements of crown heights and surface areas occupied by each tree and only included mature individuals. The studied park, located in Eichstätt, Germany, has an area of 2.2 ha and consists of 231 trees. We investigated the influence of species composition using six planting scenarios and analysed the relationship between allergenic potential and species diversity using Shannon index. Only a small number of trees was female and therefore characterised as non-allergenic, 9% of the trees were classified as sources of main local allergens. The allergenic potential of the park based on literature values for crown height and surface was IUGZA = 0.173. Applying our own measurements resulted in IISA = 0.018. The scenarios indicated that replacing trees considered as sources of main local allergens has the strongest impact on the park’s allergenic potential. The IUGZA offers an easy way to assess the allergenic potential of a park by the use of a few calculations. The IISA reduces the high influence of the foliage volume but there are constraints in practicability and in speed of the analysis. Although our study revealed that a greater biodiversity was not necessarily linked to lower index values, urban green planning should focus on biodiversity for ameliorating the allergenic potential of parks.
      Citation: Forests
      PubDate: 2018-05-23
      DOI: 10.3390/f9060284
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 285: Effect of Topography on Persistent Fire
           Refugia of the Canadian Rocky Mountains

    • Authors: Marie-Pierre Rogeau, Quinn E. Barber, Marc-André Parisien
      First page: 285
      Abstract: Persistent fire refugia, which are forest stands that have survived multiple fires, play an important ecological role in the resilience of mountainous forest ecosystems following disturbances. The loss of numerous refugia patches to large, high-severity fires in recent years is prompting the need to better understand drivers of fire refugia endurance. We investigate the role of topographic features on fire refugia survivorship based on pre-1950 fire regime conditions. Mapped refugia patches (n = 557) covering 28% of the forested landscape were used to develop three predictive models based on patch size (all sizes, <30 ha, <10 ha), as a function of explanatory variables describing several components of topography. Five topographic variables consistently favoured persistent fire refugia occurrence, though the ranking of explanatory variable importance varied among patch-size models. For the all-refugia model, elevation (23.7%), proportion of non-fuel at a 5000-m scale (20.3%), solar radiation (14.6%), Topographic Position Index at a 2000-m scale (10.1%), and distance from rivers (10.1%) were the top variables. The models’ predictive abilities were high, but decreased with larger patch sizes. We conclude that many suitable areas are currently unoccupied by fire refugia; that random elements affect their survivorship; and that additional environmental factors not considered in this study may contribute to their persistence. With changing climate and fire-regime conditions, careful fire and forest management considerations will be needed to limit future losses of persistent fire refugia forests.
      Citation: Forests
      PubDate: 2018-05-23
      DOI: 10.3390/f9060285
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 286: Widespread Distribution of Trypodendron laeve
           in the Carpathian Mountains (Romania)

    • Authors: Nicolai Olenici, Mihai-Leonard Duduman, Gabriela Isaia, Miloš Knížek, Iuliana Vasian
      First page: 286
      Abstract: Trypodendron laeve Eggers, 1939 is a species of ambrosia beetle much less known than the other three Trypodendron species occurring in Europe. Its status (native or alien) in Central Europe has been a subject of debate over the past two decades. In Romania, the species was discovered in 2008 and the aim of the research presented in this paper was to investigate its distribution in the Carpathians, mainly at high altitudes (>800 m), in tree stands with Norway spruce (Picea abies [L.] H. Karst). Panel intercept traps baited with synthetic pheromone for Trypodendron lineatum (Olivier, 1795) were used in the spring of 2015, at 31 locations. Adults of T. laeve were caught in 20 of them. Additional observations were made within some studies using similar baits and T. laeve specimens were caught in eight locations. T. laeve was always trapped together with T. lineatum, and at some locations also together with T. domesticum (Linnaeus, 1758) and T. signatum (Fabricius, 1787). In all traps, fewer specimens of T. laeve were caught compared to T. lineatum. The species has a widespread distribution in the mountain regions, within forests composed of native tree species and generally located far away from commercial routes. There, it occurs together with other native species of the same taxonomic genus. It seems to be more abundant at high altitudes, but overall its populations are less abundant than those of T. lineatum.
      Citation: Forests
      PubDate: 2018-05-23
      DOI: 10.3390/f9060286
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 287: Comparison of Whole-Tree Wood Property Maps
           for 13- and 22-Year-Old Loblolly Pine

    • Authors: Laurence Schimleck, Finto Antony, Christian Mora, Joseph Dahlen
      First page: 287
      Abstract: Maps developed using Akima’s interpolation method were used to compare patterns of within-tree variation for Pinus taeda L. (loblolly pine) wood properties in plantation-grown trees aged 13 and 22 years. Air-dry density, microfibril angle (MFA) and modulus of elasticity (MOE) maps represented the average of 18 sampled trees in each age class. Near infrared (NIR) spectroscopy models calibrated using SilviScan provided data for the analysis. Zones of high density, low MFA and high MOE wood increased markedly in size in maps of the older trees. The proportion of wood meeting the visually graded No. 1 (11 GPa) and No. 2 (9.7 GPa) MOE design values for southern pine lumber increased from 44 to 74% and from 58 to 83% respectively demonstrating the impact of age on end-product quality. Air-dry density increased from pith to bark at all heights but lacked a significant trend vertically, while radial and longitudinal trends were observed for MFA and MOE. Changes were consistent with the asymptotic progression of properties associated with full maturity in older trees.
      Citation: Forests
      PubDate: 2018-05-24
      DOI: 10.3390/f9060287
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 288: Analysis of Nitrogen Utilization Capability
           during the Proliferation and Maturation Phases of Norway Spruce (Picea
           abies (L.) H.Karst.) Somatic Embryogenesis

    • Authors: Julia Dahrendorf, David Clapham, Ulrika Egertsdotter
      First page: 288
      Abstract: Somatic embryogenesis (SE) is a laboratory-based method that allows for cost-effective production of large numbers of clonal copies of plants, of particular interest for conifers where other clonal propagation methods are mostly unavailable. In this study, the effect of l-glutamine as an organic nitrogen source was evaluated for three contrasted media (containing NH4 + NO3 without glutamine, or glutamine + NO3, or glutamine without inorganic nitrogen) during proliferation and maturation of Norway spruce somatic embryos through analyses of activities of the key enzymes of nitrogen metabolism: nitrate reductase (NR), glutamine synthetase (GS) and arginase. A major change in nitrogen metabolism was indicated by the increased activity of GS from zero in the proliferation stage through maturation to high activity in somatic embryo-derived plantlets; furthermore, NR activity increased from zero at the proliferation stage to high activity in maturing embryos and somatic-embryo derived plantlets. In contrast, arginase activity was high at all stages. In accordance with the GS and NR data, proliferation was fastest on the glutamine media, the largest number of mature embryos developed on the glutamine medium without inorganic nitrogen, and the ammonium content of proliferating cultures was much higher than that of mature somatic embryos. The best developed embryos, judged by germination, were from the glutamine + NO3 medium. These insights into nitrogen utilization will help to improve culture medium composition.
      Citation: Forests
      PubDate: 2018-05-24
      DOI: 10.3390/f9060288
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 289: Kinetic Analysis of the Color of Larch Sapwood
           and Heartwood during Heat Treatment

    • Authors: Yanxia Wei, Peng Zhang, Yang Liu, Yao Chen, Jianmin Gao, Yongming Fan
      First page: 289
      Abstract: The kinetics of color changes in larch sapwood and heartwood during heat treatment were investigated in this study in order to determine if the process of color change that occurs in the surface of wood can be regulated. Wood samples were heated at 90, 110, 130, and 150 °C in an oven, vacuum, and in an oven subjected to saturated steam for 3, 6, 9, and 12 h each. The results of the color measurement showed that the values of L* (lightness) and ΔE* (total color difference) decreased and increased in both the sapwood and heartwood, respectively, with increasing temperature and treatment time. The three kinetic model approach, consisting of (i) the time-temperature superposition principle (TTSP); (ii) zero-order reaction model; and, (iii) first-order reaction model, was used to model the kinetics of color changes. The results indicated that the L* value of the sample (including heartwood and sapwood) was well fitted to the first-order reaction model (R2 = 0.9999). The Arrhenius activation energy was 14.2369 and 11.0984 kJ/mol for the sapwood and heartwood, respectively. The first-order reaction model also showed a better fit for the ΔE* values between sapwood and heartwood with higher R2 values than the other two methods. Therefore, the color changes of larch wood could successfully be analyzed using the first-order reaction model.
      Citation: Forests
      PubDate: 2018-05-24
      DOI: 10.3390/f9060289
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 290: Soil Chemical Attributes, Biometric
           Characteristics, and Concentrations of N and P in Leaves and Litter
           Affected by Fertilization and the Number of Sprouts per the Eucalyptus
           L’Hér. Strain in the Brazilian Cerrado

    • Authors: Natasha M. I. Godoi, Sabrina N. dos S. Araújo, Salatiér Buzetti, Rodolfo de N. Gazola, Thiago de S. Celestrino, Alexandre C. da Silva, Thiago A. R. Nogueira, Marcelo C. M. Teixeira Filho
      First page: 290
      Abstract: Given the lack of recommendations for the fertilization of Eucalyptus clones in the second production cycle, the effects of fertilizer rates and the number of sprouts per strain in terms of the soil chemical attributes, biometric characteristics, and the concentrations of N and P in the leaves and in the litter of Eucalyptus L’Hér. in the Brazilian Cerrado were evaluated. The experimental design was a randomized block with four replicates, arranged in a 2 × 4 factorial scheme: one or two sprouts per strain; four fertilizer rates (0, 50, 100, or 200% of 200 kg ha−1 of the formula 06-30-06 + 1.5% Cu + 1% Zn) applied immediately after sprout definition. The option of one sprout per strain yielded higher contents of organic matter (K, S, B, and Mn) in the 0.20–0.40-m layer, the leaf chlorophyll index, the diameter at breast height, and the height of the Eucalyptus 44 months after the definition of sprouts. However, N and P leaf concentrations and the wood volume did not differ as a function of the sprout numbers. The fertilizer dosage did not influence the wood volume, even in sandy soil with low fertility. Approximately 86% of the wood volume was obtained from the supply of soil and root nutrient reserves and 14% of this productivity is due to fertilization minerals. The adequate fertilization in the first cycle of the Eucalyptus supplies almost the entire nutritional demand of the forest in the second production cycle.
      Citation: Forests
      PubDate: 2018-05-24
      DOI: 10.3390/f9060290
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 291: Automatic Detection of Single Trees in
           Airborne Laser Scanning Data through Gradient Orientation Clustering

    • Authors: Tianyang Dong, Qizheng Zhou, Sibin Gao, Ying Shen
      First page: 291
      Abstract: Currently, existing methods for single-tree detection based on airborne laser scanning (ALS) data usually require some thresholds and parameters to be set manually. Manually setting threshold or parameters is laborious and time-consuming, and for dense forests, the high commission and omission rate make most existing single-tree detection techniques inefficient. As a solution to these problems, this paper proposed an automatic single-tree detection method in ALS data through gradient orientation clustering (GOC). In this method, the rasterized Canopy Height Model (CHM) was derived from ALS data using surface interpolation. Then, potential trees were assumed as approximate conical shapes and extracted based on the GOC. Finally, trees were identified from the potential trees based on the compactness of the crown shape. This method used the gradient orientation information of rasterized CHM, thus increasing the generalization of single-tree detection method. In order to verify the validity and practicability of the proposed method, twelve 1256 m2 circular study plots of different forest types were selected from the benchmark dataset (NEWFOR), and the results from nine different methods were presented and compared for these study plots. Among nine methods, the proposed method had the highest root mean square matching score (RMS_M = 43). Moreover, the proposed method had excellent detection (M > 47) in both single-layer coniferous and single-layered mixed stands.
      Citation: Forests
      PubDate: 2018-05-24
      DOI: 10.3390/f9060291
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 292: Models for Predicting Specific Gravity and
           Ring Width for Loblolly Pine from Intensively Managed Plantations, and
           Implications for Wood Utilization

    • Authors: Joseph Dahlen, David Auty, Thomas L. Eberhardt
      First page: 292
      Abstract: Loblolly pine (Pinus taeda L.) is increasingly grown on intensively managed plantations that yield high growth rates. Wood properties, including specific gravity (SG), change with cambial age, and thus intensively managed trees contain a high proportion of low density corewood when harvested because of reduced rotation lengths. This study was undertaken to develop models of ring-level properties (SG and width) in intensively managed loblolly pine plantations. Ninety-three trees from five stands aged from 24 to 33 years were harvested, and 490 disks were obtained from in between the 5.2-m logs that were cut, and at the merchantable top. The disks were cut into pith-to-bark radial strips that were scanned on an X-ray densitometer, and the resultant data analyzed using non-linear mixed-effects models. The fixed effects of the models, which included cambial age and for some models disk height and ring width, were able to explain 56, 46, 54, 16, and 46 percent of the within-tree variation for ring SG, ring width, latewood SG, earlywood SG, and latewood percent, respectively. To assess implications for wood utilization, a modeled tree was built by using height, diameter, and taper equations and these models were linked with the developed ring SG model to produce a tree properties map. The linked information was also used to generate tree and log SG and proportion of corewood values for different rotation ages. The results from this study are a step towards integrating wood quality models into growth-and-yield modeling systems that are important for loblolly pine plantation management.
      Citation: Forests
      PubDate: 2018-05-24
      DOI: 10.3390/f9060292
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 293: Planting Density and Site Effects on Stem
           Dimensions, Stand Productivity, Biomass Partitioning, Carbon Stocks and
           Soil Nutrient Supply in Hybrid Poplar Plantations

    • Authors: Benoit Truax, Julien Fortier, Daniel Gagnon, France Lambert
      First page: 293
      Abstract: In this study, planting density and site effects on hybrid poplar productivity and stem dimensions were evaluated on the mid-term and longer term (8 and 14 years) in southern Québec (Canada). We also evaluated the effects of planting density and site on biomass accumulation and carbon stocks in different plantation compartments, on biomass partitioning at the stand-level, on soil carbon stocks and on soil nutrient supply rate after 14 years. The experimental design consisted of three replicate poplar stands located along a site fertility gradient. Each stand contained six planting densities (ranging from 494 to 1975 trees/ha) and a single genotype (Populus canadensis × P. maximowiczii hybrid). Planting density had a large effect on stem dimensions, but a minor effect on stand volume, aboveground woody biomass production, and aboveground biomass carbon stocks. Site selection and tree survival were more important factors affecting these variables. At all sites, and independent of planting density, mean annual volume increments were also higher after 14 vs. 8 years. On fertile sites, strong correlations between area per tree at planting and biomass partitioning, carbon allocation belowground, soil nutrient supply rate and soil carbon stocks were observed. Aboveground, higher competition for light with increasing planting density resulted in an increase in the stem to branch ratio. Belowground, higher competition for soil resources with increasing planting density reduced soil macronutrient availability (except for potassium), which likely stimulated carbon allocation belowground and carbon accumulation in the soil. Over the longer-term, higher density plantations of poplars could provide greater benefits in terms of carbon storage belowground (soil and roots).
      Citation: Forests
      PubDate: 2018-05-25
      DOI: 10.3390/f9060293
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 294: Characterization of Phosphorus in a
           

    • Authors: Yo-Jin Shiau, Chung-Wen Pai, Jeng-Wei Tsai, Wen-Cheng Liu, Rita S. W. Yam, Shih-Chieh Chang, Sen-Lin Tang, Chih-Yu Chiu
      First page: 294
      Abstract: The productivity of forests is often considered to be limited by the availability of phosphorus (P). Knowledge of the role of organic and inorganic P in humid subtropical forest soils is lacking. In this study, we used chemical fractionation and 31P nuclear magnetic resonance (NMR) spectroscopy to characterize the form of P and its distribution in undisturbed perhumid Taiwan false cypress (Chamaecyparis formosensis Matsum.) forest soils. The toposequence of transects was investigated for the humic layer from summit to footslope and lakeshore. The clay layer combined with a placic-like horizon in the subsoil may affect the distribution of soil P because both total P and organic P (Po) contents in all studied soils decreased with soil depth. In addition, Po content was negatively correlated with soil crystalline Fe oxide content, whereas inorganic P (Pi) content was positively correlated with soil crystalline Fe oxide content and slightly increased with soil depth. Thus, Pi may be mostly adsorbed by soil crystalline Fe oxides in the soils. Among all extractable P fractions, the NaOH-Po fraction appeared to be the major component, followed by NaHCO3-Po; the resin-P and HCl-Pi fractions were lowest. In addition, we found no typical trend for Pi and Po contents in soils with topographical change among the three sites. From the 31P-NMR spectra, the dominant Po form in soils from all study sites was monoesters with similar spectra. The 31P-NMR findings were basically consistent with those from chemical extraction. Soil formation processes may be the critical factor affecting the distribution of soil P. High precipitation and year-round high humidity may be important in the differentiation of the P species in this landscape.
      Citation: Forests
      PubDate: 2018-05-25
      DOI: 10.3390/f9060294
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 295: Allometric Equations for Predicting Culm
           Surface Area of Three Bamboo Species (Phyllostachys spp.)

    • Authors: Akio Inoue, Yoshiyuki Miyazawa, Motohiro Sato, Hiroyuki Shima
      First page: 295
      Abstract: It is strongly debated whether bamboo forest ecosystems are a carbon sink or a carbon source because of insufficient knowledge regarding carbon loss via CO2 emissions from these forests. The surface area (S) of bamboo culms (stems) is important for estimating culm respiration, a major component of carbon cycling in bamboo forests. However, few studies have attempted to formulate predictive equations for S. In this study, we developed allometric equations for predicting S in three bamboo species grown in Kyushu Island, western Japan: Phyllostachys pubescens Mazel ex Houz., P. bambusoides Sieb. et Zucc. and P. nigra var. henonis. We used a power equation between S and diameter at breast height (D) and a linear equation between S and D × total culm length (H). The results indicated that P. bambusoides and P. nigra shared common site-independent equations. In contrast, P. pubescens required species-specific equations due to interspecific variation in culm slenderness and tapering. We also found that D was a better predictive variable than DH when quantifying S because of its satisfactory predictive performance and simplicity. These findings will be beneficial for evaluating the contribution of bamboo forest ecosystems to carbon cycling.
      Citation: Forests
      PubDate: 2018-05-25
      DOI: 10.3390/f9060295
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 296: Potential Impacts of Emerald Ash Borer
           Biocontrol on Ash Health and Recovery in Southern Michigan

    • Authors: Daniel M. Kashian, Leah S. Bauer, Benjamin A. Spei, Jian J. Duan, Juli R. Gould
      First page: 296
      Abstract: Emerald ash borer (EAB) is an invasive beetle that kills native North American ash species, threatening their persistence. A classical biological control program for EAB was initiated in 2007 with the release of three specialized EAB parasitoids. Monitoring changes in the health and regeneration of ash where EAB biocontrol agents have been released is critical for assessing the success of EAB biocontrol and predicting future changes to the ash component of North American forests. We sampled release and control plots across southern Michigan over a three-year period to measure ash health and recruitment to begin assessing the long-term impact of EAB biological control on ash populations. We noted a reduced mortality of larger trees between 2012 and 2015 in release plots compared to control plots and increases in ash diameter, but our results were otherwise inconsistent. Ash regeneration was generally higher in release plots compared to control plots but highly variable among sites, suggesting some protection of ash saplings from EAB by parasitoids. We conclude that EAB biocontrol is likely to have a positive effect on ash populations, but that the study duration was not long enough to definitively deduce the long-term success of the biocontrol program in this region.
      Citation: Forests
      PubDate: 2018-05-25
      DOI: 10.3390/f9060296
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 297: Spatial Variation in Leaf Stable Carbon
           Isotope Composition of Three Caragana Species in Northern China

    • Authors: Fei Ma, Wenyu Liang, Zhaona Zhou, Guoju Xiao, Jili Liu, Jun He, Bingzhong Jiao, Tingting Xu
      First page: 297
      Abstract: Leaf stable carbon isotope (δ13C) composition provides comprehensive insight into plant carbon cycles and water use efficiency and has also been widely used to evaluate the response of plants to environmental change. In the present study, leaf δ13C was analyzed in samples of Caragana microphylla Lam., C. liouana Zhao, and C. korshinskii Kom. from 38 populations. These species provide great environmental benefits and economic value and are distributed east to west continuously across northern China. We studied the relationship of δ13C to altitude, mean annual precipitation (MAP), mean annual temperature (MAT), mean annual relative humidity (RH), leaf nitrogen (N), and phosphorus (P) concentrations to examine the patterns and controls of leaf δ13C variation in each species. Results indicated that, across the three species, leaf δ13C significantly decreased with MAP, RH, and leaf N and P concentrations, while it increased with altitude and MAT. However, patterns and environmental controls of leaf δ13C varied proportionally with species. C. korshinskii was mainly controlled by MAP and leaf N concentration, C. liouana was controlled by both MAT and MAP, and C. microphylla was mainly controlled by MAT. Further analysis indicated significant differences in leaf δ13C between species, which tended to increase from C. microphylla to C. korshinskii. Overall, these results suggest that the three Caragana species may respond differently to future climate change due to different controlling factors on leaf δ13C variation, as well as differentiation in water use efficiency, which likely contributes to the geographical distribution of these species.
      Citation: Forests
      PubDate: 2018-05-25
      DOI: 10.3390/f9060297
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 298: Wood and Fiber Quality of Plantation-Grown
           Conifers: A Summary of Research with an Emphasis on Loblolly and Radiata
           Pine

    • Authors: Laurence Schimleck, Finto Antony, Joseph Dahlen, John Moore
      First page: 298
      Abstract: With conifer plantations having an increasingly important role in meeting the fiber needs of society, an understanding of the effect of silvicultural practices on wood quality is critical. The perception of wood quality varies, making it hard to define in a single statement; however, possibly the most succinct definition is “a measure of the aptness of wood for a given use”. In general, properties that have a positive influence on a specific product assist in defining changes in wood quality. Since wood properties exhibit large variability within annual rings, within trees, and among trees in a stand, and have both genetic and environmental components (i.e., vary with different physiographical regions), it is imperative to have an understanding of wood properties at multiple levels. In this paper, we review the typical variation patterns in wood properties of conifers, with specific emphasis on loblolly pine (Pinus taeda L.), and radiata pine (Pinus radiata D.Don), two of the most common conifer plantation species globally. We also describe the impact of conventional silvicultural treatments on wood quality. Modeling efforts to predict variation in wood properties within trees, and in response to silvicultural treatments are also summarized.
      Citation: Forests
      PubDate: 2018-05-26
      DOI: 10.3390/f9060298
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 299: Post-Fire Regeneration and Diversity Response
           to Burn Severity in Pinus halepensis Mill. Forests

    • Authors: Sonsoles González-De Vega, Jorge de las Heras, Daniel Moya
      First page: 299
      Abstract: In recent decades, fire regimes have been modified by various factors such as changes in land use, global change or forest management policies. The vulnerability of Mediterranean terrestrial ecosystems is increasing due to more severe and frequent droughts. This study aimed to determine the plant response of ecosystems during the short-term post-fire period by relating alpha diversity, floristic richness and tree recruitment dynamics to burn severity 5 years after a wildfire. Our results conclude that in the short term, Pinus halepensis Mill. stands in southeastern Spain quickly recovered alpha diversity values, mainly in areas burned with low severity. We observed that moderate and high severities affected the ecosystem more significantly, showing higher values for the Shannon Index but lower for the Simpson index. Pine recruitment was higher in burned areas, and we found the highest number of Aleppo pine seedlings under a moderate burn severity. Post-fire regeneration functional groups (obligate seeders and resprouters) were promoted under moderate and high burn severity, increasing their abundance. Annual species (mainly herbs) colonized burned areas, persisting with higher presence under moderate burn severity. Restoration tools should be focused on reducing fire severity, mainly in areas at high risk of desertification, and promoting resistance, vulnerability and resilience of these ecosystems.
      Citation: Forests
      PubDate: 2018-05-26
      DOI: 10.3390/f9060299
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 300: Workload, Exposure to Noise, and Risk of
           Musculoskeletal Disorders: A Case Study of Motor-Manual Tree Feeling and
           Processing in Poplar Clear Cuts

    • Authors: Marius Cheţa, Marina Viorela Marcu, Stelian Alexandru Borz
      First page: 300
      Abstract: Motor-manual tree felling and processing (MMTFP) is among the most used options in timber harvesting operations and it is formally known to be a heavy job exposing the workers to safety hazards and harmful factors. Nevertheless, both workload and exposure depend on many operational, organizational, and worker-related parameters. Few studies have evaluated the ergonomics of such operations and fewer have been carried out using an integrated approach able to collect and interpret data for more than one ergonomic parameter. This study evaluated the ergonomic conditions of task-based MMTFP operations in flatland poplar forests by the means of workload, exposure to noise, and risk of musculoskeletal disorders. A fully-automatic approach was used to collect and pair the heart rate and noise exposure data that was complemented by video recording to collect postural data. Workload experienced by the worker was evaluated in terms of heart rate reserve (%HRR), indicating a heavy load during the productive time (%HRR = 46%); exposure to noise was calculated at the task and study level, exceeding (LAeq = 97.15 dB(A); LEX,8h = 96.18 dB(A)) the acceptable limits; and the risk of musculoskeletal disorders was evaluated using the concepts and procedures of the Ovako Working Posture Analysis System, indicating a high postural risk index (PRI = 275), which can cause musculoskeletal disorders (MSD). For more conclusive results, the research should be extended to cover the relevant variability factors.
      Citation: Forests
      PubDate: 2018-05-27
      DOI: 10.3390/f9060300
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 301: Biotic and Abiotic Drivers of Sap Flux in
           Mature Green Ash Trees (Fraxinus pennsylvanica) Experiencing Varying
           Levels of Emerald Ash Borer (Agrilus planipennis) Infestation

    • Authors: Charles E. Flower, Douglas J. Lynch, Kathleen S. Knight, Miquel A. Gonzalez-Meler
      First page: 301
      Abstract: While the relationship between abiotic drivers of sap flux are well established, the role of biotic disturbances on sap flux remain understudied. The invasion of the emerald ash borer (Agrilus planipennis Fairmaire, EAB) into North America in the 1990s represents a significant threat to ash trees (Fraxinus spp.), which are a substantial component of temperate forests. Serpentine feeding galleries excavated by EAB larvae in the cambial and phloem tissue are linked to rapid tree mortality. To assess how varying levels of EAB infestation impact the plant water status and stress levels of mature green ash (Fraxinus pennsylvanica Marshall) trees, we combined tree-level sap flux measurements with leaf-level gas exchange, isotopes, morphology and labile carbohydrate measurements. Results show sap flux and whole tree water use are reduced by as much as 80% as EAB damage increases. Heavily EAB impacted trees exhibited reduced leaf area and leaf mass, but maintained constant levels of specific leaf area relative to lightly EAB-impacted trees. Altered foliar gas exchange (reduced light saturated assimilation, internal CO2 concentrations) paired with depleted foliar δ13C values of heavily EAB impacted trees point to chronic water stress at the canopy level, indicative of xylem damage. Reduced photosynthetic rates in trees more impacted by EAB likely contributed to the lack of nonstructural carbohydrate (soluble sugars and starch) accumulation in leaf tissue, further supporting the notion that EAB damages not only phloem, but xylem tissue as well, resulting in reduced water availability. These findings can be incorporated into modeling efforts to untangle post disturbance shifts in ecosystem hydrology.
      Citation: Forests
      PubDate: 2018-05-28
      DOI: 10.3390/f9060301
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 302: Comparative Analysis of MicroRNA Expression in
           Three Paulownia Species with Phytoplasma Infection

    • Authors: Xibing Cao, Xiaoqiao Zhai, Yanfang Zhang, Zhiyuan Cheng, Xiyao Li, Guoqiang Fan
      First page: 302
      Abstract: Paulownia witches’ broom (PaWB), caused by phytoplasma, is an important disease of Paulownia. To further identify the key miRNAs associated with the formation of PaWB symptoms, miRNA and degradome sequencing were performed to explore important miRNAs–target regulation in healthy and diseased Paulownia tomentosa, Paulownia fortunei, and P. tomentosa × P. fortunei seedlings, and the corresponding diseased seedlings treated with 75 mg L−1 dimethyl sulfate. A total of 212, 111, and 197 differentially expressed miRNAs (DEMs) were obtained in P. tomentosa, P. fortunei, and P. tomentosa × P. fortunei, respectively. Degradome sequencing detected 559, 251, and 568 target genes of the DEMs in P. tomentosa, P. fortunei, and P. tomentosa × P. fortunei, respectively. The expression patterns of selected miRNAs and the target genes were verified be qRT-PCR. Through analysis of the expression level of the DEMs in this study, combined with the results in our previous studies, as well as with those reported in other phytoplasma-infected plants, we concluded that miR156 is an important miRNA related to witches’ broom. According to the functions of the target genes of DEMs, we constructed a co-regulatory network of the DEMs-target genes interaction. These results will help to advance the understanding of the mechanism of PaWB.
      Citation: Forests
      PubDate: 2018-05-29
      DOI: 10.3390/f9060302
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 303: The Potential of Multisource Remote Sensing
           for Mapping the Biomass of a Degraded Amazonian Forest

    • Authors: Clément Bourgoin, Lilian Blanc, Jean-Stéphane Bailly, Guillaume Cornu, Erika Berenguer, Johan Oszwald, Isabelle Tritsch, François Laurent, Ali F. Hasan, Plinio Sist, Valéry Gond
      First page: 303
      Abstract: In the agricultural frontiers of Brazil, the distinction between forested and deforested lands traditionally used to map the state of the Amazon does not reflect the reality of the forest situation. A whole gradient exists for these forests, spanning from well conserved to severely degraded. For decision makers, there is an urgent need to better characterize the status of the forest resource at the regional scale. Until now, few studies have been carried out on the potential of multisource, freely accessible remote sensing for modelling and mapping degraded forest structural parameters such as aboveground biomass (AGB). The aim of this article is to address that gap and to evaluate the potential of optical (Landsat, MODIS) and radar (ALOS-1 PALSAR, Sentinel-1) remote sensing sources in modelling and mapping forest AGB in the old pioneer front of Paragominas municipality (Para state). We derived a wide range of vegetation and textural indices and combined them with in situ collected AGB data into a random forest regression model to predict AGB at a resolution of 20 m. The model explained 28% of the variance with a root mean square error of 97.1 Mg·ha−1 and captured all spatial variability. We identified Landsat spectral unmixing and mid-infrared indicators to be the most robust indicators with the highest explanatory power. AGB mapping reveals that 87% of forest is degraded, with illegal logging activities, impacted forest edges and other spatial distribution of AGB that are not captured with pantropical datasets. We validated this map with a field-based forest degradation typology built on canopy height and structure observations. We conclude that the modelling framework developed here combined with high-resolution vegetation status indicators can help improve the management of degraded forests at the regional scale.
      Citation: Forests
      PubDate: 2018-05-29
      DOI: 10.3390/f9060303
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 304: Genome-Wide Identification and
           Characterization of MADS-box Family Genes Related to Floral Organ
           Development and Stress Resistance in Hevea brasiliensis Müll. Arg.

    • Authors: Mingming Wei, Yajie Wang, Ranran Pan, Weiguo Li
      First page: 304
      Abstract: Elucidating the genetic mechanisms associated with the transition from the vegetative to reproductive phase in the rubber tree has great importance for both theoretical guidance and practical application to yield genetic improvement. At present, many transcription factors, including those that belong to the MADS-box gene family, have been revealed to have roles in regulating the transition from vegetative growth to reproductive growth. However, to the best of our knowledge, the Mad-box gene family from H. brasiliensis Müll. Arg. has not been characterized in detail. To investigate members of the HbMADS-box gene family associated with floral organ and inflorescence development in H. brasiliensis, we performed genome-wide identification and analysis of the MADS-box gene family related to flower development in H. brasiliensis, and a total of 20 MADS-box genes were newly identified in the H. brasiliensis genome. Expression profiling revealed that HbMad-box genes were differentially expressed in various tissues, which indicated that HbMad-box genes may exert different functions throughout the life cycle. Additionally, 12 genes (HbSEP, HbAGL9.1, HbAGL9.2, HbCMB1, HbCMB1-L, HbAGL6, HbAGL8, HbAP1, HbAG, HbDEFL, HbTT16, and HbPADS2) were found to be associated with the differentiation of flower buds and may be involved in flower development in H. brasiliensis. All of these floral-enriched HbMADS-box genes were regulated by hormone, salt, cold, high-temperature, and drought stresses. The present study is the first to carry out the genome-wide identification and analysis of the MADS-box gene family related to flower development in H. brasiliensis, and 20 new HbMad-box genes were identified in H. brasiliensis. Most of the newly identified HbMad-box genes were found to be associated with the differentiation of flower buds and may be involved in flower development in H. brasiliensis. Our results demonstrated that HbMad-box genes may be multifunctional regulators that have roles in distinct aspects of development, and are mainly involved in the maintenance of floral organ and inflorescence development.
      Citation: Forests
      PubDate: 2018-05-29
      DOI: 10.3390/f9060304
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 305: Deforestation-Induced Fragmentation Increases
           Forest Fire Occurrence in Central Brazilian Amazonia

    • Authors: Celso H. L. Silva Junior, Luiz E. O. C. Aragão, Marisa G. Fonseca, Catherine T. Almeida, Laura B. Vedovato, Liana O. Anderson
      First page: 305
      Abstract: Amazonia is home to more than half of the world’s remaining tropical forests, playing a key role as reservoirs of carbon and biodiversity. However, whether at a slower or faster pace, continued deforestation causes forest fragmentation in this region. Thus, understanding the relationship between forest fragmentation and fire incidence and intensity in this region is critical. Here, we use MODIS Active Fire Product (MCD14ML, Collection 6) as a proxy of forest fire incidence and intensity (measured as Fire Radiative Power—FRP), and the Brazilian official Land-use and Land-cover Map to understand the relationship among deforestation, fragmentation, and forest fire on a deforestation frontier in the Brazilian Amazonia. Our results showed that forest fire incidence and intensity vary with levels of habitat loss and forest fragmentation. About 95% of active fires and the most intense ones (FRP > 500 megawatts) were found in the first kilometre from the edges in forest areas. Changes made in 2012 in the Brazilian main law regulating the conservation of forests within private properties reduced the obligation to recover illegally deforested areas, thus allowing for the maintenance of fragmented areas in the Brazilian Amazonia. Our results reinforce the need to guarantee low levels of fragmentation in the Brazilian Amazonia in order to avoid the degradation of its forests by fire and the related carbon emissions.
      Citation: Forests
      PubDate: 2018-06-01
      DOI: 10.3390/f9060305
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 306: Anthropogenic and Biophysical Factors
           Associated with Vegetation Restoration in Changting, China

    • Authors: Wenhui Wang, Xiangqing Ma, Syed Moazzam Nizami, Chao Tian, Futao Guo
      First page: 306
      Abstract: Changting has been promoted by the Chinese government as a demonstration for the soil and water conservation works in recent years. As the experience in Changting is now being explored and summarized and will be further promoted to the nation, it is important to understand the factors affecting the vegetation restoration process. Random forest and multiple linear regression approaches were applied to investigate the influential factors and their relative importance on the dynamic change of vegetation coverage of Changting during the period of 2000–2010. The Normalized Difference Vegetation Index (NDVI) was used to calculate Fractional Vegetation Cover (FVC) dynamics in response to topographic, climatic, infrastructure, and economic factors. The results show that overall, there was a dramatic increase in the FVC of Changting from 2000–2010. The percentage of the FVC-increased area reached 87.86% with an increase rate of 0.142. Factors such as precipitation, temperature, elevation, slope and financial investment for soil conservation were important drivers of local FVC change. Our findings reveal that climatic factors along with the strict implementation of government policies played a role in driving vegetation cover dynamics, and the continuation of implementation of soil erosion management in Changting is required.
      Citation: Forests
      PubDate: 2018-06-01
      DOI: 10.3390/f9060306
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 307: Differences in Leaf Temperature between Lianas
           and Trees in the Neotropical Canopy

    • Authors: J. Antonio Guzmán Q., G. Arturo Sánchez-Azofeifa, Benoit Rivard
      First page: 307
      Abstract: Leaf temperature (Tleaf) influences photosynthesis and respiration. Currently, there is a growing interest in including lianas in productivity models due to their increasing abundance and their detrimental effects in the carbon stock of tropical ecosystems. Therefore, understanding the differences of Tleaf between lianas and trees is important for future predictions of productivity. Here, we determined the displayed leaf temperature (Td = Tleaf − air temperature) of several species of lianas and their host trees during El Niño-Southern Oscillation (ENSO) and non-ENSO years to evaluate if the presence of lianas affects the Td of their host trees, and if leaves of lianas and their host trees exhibit differences in Td. Our results suggest that close to midday, the presence of lianas does not affect the Td of their host trees; however, lianas tend to have higher values of Td than their hosts across seasons, in both ENSO and non-ENSO years. Although lianas and trees tend to have similar physiological-temperature responses, differences in Td could lead to significant differences in rates of photosynthesis and respiration based on temperature response curves. Future models should thus consider differences in leaf temperature between these two life forms to achieve robust predictions of productivity.
      Citation: Forests
      PubDate: 2018-06-01
      DOI: 10.3390/f9060307
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 308: Adverse Genetic Correlations and Impacts of
           Silviculture Involving Wood Properties: Analysis of Issues for Radiata
           Pine

    • Authors: Rowland D. Burdon, John R. Moore
      First page: 308
      Abstract: Plantation forestry is now an imperative to meet wood requirements efficiently on the finite land available for wood production. Three main determinants of profitability are productivity, price per unit of wood harvested, and harvest age (the sooner the better). The first two are largely self-evident, while reducing harvest age lowers the effective cost of growing wood. Among these determinants, however, are strong interplays which include trade-offs. Key trade-offs involve adverse genetic correlations between various wood properties and growth-rate variables, and adverse effects on the wood quality of silvicultural interventions that raise site productivity and/or reduce harvest age. Moreover, the adverse effects of silviculture on wood properties tend to be accompanied by heightened expressions of genetic variation in wood properties. The trade-offs involve both increasing the percentage of corewood (‘juvenile wood’) and some more direct effects on wood quality. The pervasiveness of the trade-offs, and the heightened genetic expression, accentuate the call for genetic selection to defend wood quality. Such selection, however, will entail some costs in the appropriate emphasis on breeding for productivity. In this paper we review these issues, identify gaps in research information and offer guidance for tree breeders and silviculturists. While radiata pine is the special case, the applicability to some other species is briefly discussed.
      Citation: Forests
      PubDate: 2018-06-01
      DOI: 10.3390/f9060308
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 309: Responses of Two Litter-Based Invertebrate
           Communities to Changes in Canopy Cover in a Forest Subject to Hurricanes

    • Authors: Barbara Richardson, Michael Richardson, Grizelle González
      First page: 309
      Abstract: Tropical forests are subject to seasonal hurricanes resulting in cycles of canopy opening and deposition of litter, followed by periods of recovery and canopy closure. Herein, we review two studies of litter-based communities in Puerto Rico; (i) a survey of bromeliad invertebrates in three montane forest types along an elevational gradient in 1993–1997, during a period of canopy recovery after two severe hurricanes, and the results compared with those from a resurvey in 2010, and (ii) a large scale canopy trimming experiment in the lower montane (Tabonuco) forest designed to simulate an hurricane event, and to separate the effects of canopy opening from debris deposition. Measurements of changes in invertebrate community parameters and decay rates of litter were made in a litter bag experiment as part of this major experiment. As the canopy closed, during the periods of study, bromeliad density reduced, especially in the Tabonuco forest. This was associated with a decline in both alpha and gamma invertebrate diversity, which appears to have involved the loss of rarer species. In the Tabonuco forest, two endemic bromeliad specialists were not found during resampling in 2010, though the most common species were remarkably stable over the two decades. Canopy opening significantly altered the diversity, biomass, and composition of litter communities, irrespective of litter deposition. It particularly reduced organisms responsible for comminution of litter and increased the activity of fungivores and microbiovores. Both studies showed that canopy disturbance, either indirectly or directly, adversely affects invertebrate diversity and detrital processing.
      Citation: Forests
      PubDate: 2018-06-01
      DOI: 10.3390/f9060309
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 310: Local and General Above-Ground Biomass
           Functions for Pinus palustris Trees

    • Authors: Carlos A. Gonzalez-Benecke, Dehai Zhao, Lisa J. Samuelson, Timothy A. Martin, Daniel J. Leduc, Steven B. Jack
      First page: 310
      Abstract: There is an increasing interest in estimating biomass for longleaf pine (Pinus palustris Mill.), an important tree species in the southeastern U.S. Most of the individual-tree allometric models available for the species are local, relying on stem diameter outside bark at breast height (DBH) and total tree height (HT), but seldom include stand-level variables such as stand age, basal area or stand density. Using the biomass dataset of 296 longleaf pine trees sampled in the southeastern U.S. by different forestry research institutions, we developed a set of local and general systems of tree biomass equations to predict total tree total above-stump biomass, bole biomass outside bark, live branch biomass and live foliage biomass. The local systems were based on DBH or DBH and HT, and the general systems included in addition to DBH and HT, stand-level variables such as age, basal area and stand density. This paper reports the first set of general allometric equations reported for longleaf pine trees. These systems of biomass equations provide tools to support managers in making management decisions for the species in a variety of ecological, silvicultural and economics applications. The systems can be applied to trees growing over a large geographical area and having a wide range of ages and stand characteristics.
      Citation: Forests
      PubDate: 2018-06-01
      DOI: 10.3390/f9060310
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 311: Growth Response of Whitebark Pine (Pinus
           albicaulis Engelm) Regeneration to Thinning and Prescribed Burn Treatments
           

    • Authors: Molly L. Retzlaff, Robert E. Keane, David L. Affleck, Sharon M. Hood
      First page: 311
      Abstract: Whitebark pine (Pinus albicaulis Engelm.) forests play a prominent role throughout high-elevation ecosystems in the northern Rocky Mountains, however, they are vanishing from the high mountain landscape due to three factors: exotic white pine blister rust (Cronartium ribicola Fischer) invasions, mountain pine beetle (Dendroctonus ponderosae Hopkins) outbreaks, and successional replacement by more shade-tolerant tree species historically controlled by wildfire. Land managers are attempting to restore whitebark pine communities using prescribed fire and silvicultural cuttings, but they are unsure if these techniques are effective. The objective of this study was to determine how whitebark pine regeneration responds to selective thinning and prescribed burn treatments. We studied changes in diameter growth after restoration treatments using ring width measurements obtained from 93 trees at four sites in Montana and Idaho that were treated in the late 1990s. Overall, the average annual radial growth rates of the trees in treated areas were greater than those of trees in control areas. Specifically, there were significant increases in the growth ratio (180%) in the two sites that were both thinned and later burned. Younger regeneration showed more response to the treatments than older regeneration. All sites showed high variability in post-treatment growth rates across individual trees, with greater variability for trees in treated areas than in trees from the control areas. Results suggest that whitebark pine regeneration can respond to thin and burn release treatments and that managers may see positive results in areas that are treated similarly.
      Citation: Forests
      PubDate: 2018-06-01
      DOI: 10.3390/f9060311
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 312: Improved Estimates of Biomass Expansion
           Factors for Russian Forests

    • Authors: Dmitry Schepaschenko, Elena Moltchanova, Anatoly Shvidenko, Volodymyr Blyshchyk, Egor Dmitriev, Olga Martynenko, Linda See, Florian Kraxner
      First page: 312
      Abstract: Biomass structure is an important feature of terrestrial vegetation. The parameters of forest biomass structure are important for forest monitoring, biomass modelling and the optimal utilization and management of forests. In this paper, we used the most comprehensive database of sample plots available to build a set of multi-dimensional regression models that describe the proportion of different live biomass fractions (i.e., the stem, branches, foliage, roots) of forest stands as a function of average stand age, density (relative stocking) and site quality for forests of the major tree species of northern Eurasia. Bootstrapping was used to determine the accuracy of the estimates and also provides the associated uncertainties in these estimates. The species-specific mean percentage errors were then calculated between the sample plot data and the model estimates, resulting in overall relative errors in the regression model of −0.6%, −1.0% and 11.6% for biomass conversion and expansion factor (BCEF), biomass expansion factor (BEF), and root-to-shoot ratio respectively. The equations were then applied to data obtained from the Russian State Forest Register (SFR) and a map of forest cover to produce spatially distributed estimators of biomass conversion and expansion factors and root-to-shoot ratios for Russian forests. The equations and the resulting maps can be used to convert growing stock volume to the components of both above-ground and below-ground live biomass. The new live biomass conversion factors can be used in different applications, in particular to substitute those that are currently used by Russia in national reporting to the UNFCCC (United Nations Framework Convention on Climate Change) and the FAO FRA (Food and Agriculture Organization’s Forest Resource Assessment), among others.
      Citation: Forests
      PubDate: 2018-06-01
      DOI: 10.3390/f9060312
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 313: Leaf Temperature Fluctuations of Typical
           Psammophytic Plants and Their Application to Stomatal Conductance
           Estimation

    • Authors: Minghan Yu, Guodong Ding, Guanglei Gao, Yuanyuan Zhao, Ke Sai
      First page: 313
      Abstract: Monitoring of stomatal conductance to water vapor in psammophytes is important in studies of vegetation transpiration in sandy areas. Leaf temperature monitoring has the advantages of convenience, reduced damage to the plant without contact, and a larger measurement area. Stomatal conductance to water vapor estimation models, based on leaf temperature, have been proposed in agricultural studies in recent years. However, observations for verification of these models are still lacking, which has limited the application of these models. We performed a drought stress experiment on three typical psammophytes: Artemisia ordosica, Salix psammophila, and Caragana korshinskii. We monitored their leaf temperature and built two leaf temperature-based models to test whether the models could accurately estimate stomatal conductance. Results verified that neither of the two models accurately quantified psammophytes’ stomatal conductance in field operations. We further tested the differences among plants and identified that the differences in stomatal mechanism and physical morphology of the leaves drives leaf temperature differences, which affects the accuracy of stomatal conductance estimation using the models. We concluded that more precise measurements of leaf temperature-related parameters, such as wind speed and leaf physical morphology, are needed to improve the models’ estimation accuracy. Our study offers references for developing a practical application of stomatal conductance estimation models in field operations.
      Citation: Forests
      PubDate: 2018-06-01
      DOI: 10.3390/f9060313
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 314: Permafrost Regime Affects the Nutritional
           Status and Productivity of Larches in Central Siberia

    • Authors: Anatoly S. Prokushkin, Frank Hagedorn, Oleg S. Pokrovsky, Jerome Viers, Alexander V. Kirdyanov, Oxana V. Masyagina, Marina P. Prokushkina, William H. McDowell
      First page: 314
      Abstract: Permafrost exerts strong controls on forest development through nutrient availability. The key question of this study was to assess the effect of site conditions on macroelement concentration and stable isotope (δ13C and δ15N) dynamics during the growing season, and nutrient stoichiometry and resorption efficiency in the foliage of two common larch species in Siberia. Foliar nutrient (N, P and K) concentrations of larches grown on permafrost soils were exceptionally high in juvenile needles compared to those from a permafrost-free region (+50% and 130% for P and K), but were two-fold lower at needle maturation. Within permafrost terrain trees, sites with a warmer and deeper soil active layer had 15–60% greater nutrient concentrations and higher δ15N in their needles compared to shallower, colder soils. Larch of permafrost-free sites demonstrated an enrichment of foliage in 15N (+1.4% to +2.4‰) in comparison to permafrost terrain (−2.0% to −6.9‰). At all sites, foliar δ13C decreased from June to August, which very likely results from an increasing contribution of current photoassimilates to build foliar biomass. With senescence, nutrient concentrations in larch needles decreased significantly by 60–90%. This strong ability of larch to retain nutrients through resorption is the essential mechanism that maintains tree growth early in the growing season when soil remains frozen. The high resorptive efficiency found for K and P for larches established on permafrost suggests nutrient limitation of tree growth within the Central Siberian Plateau not only by N, as previously reported, but also by P and K. The increasing nutrient concentrations and a 15N enrichment of foliage towards warmer sites was paralleled by an up to 50-fold increase in biomass production, strongly suggesting that accelerated nutrient cycling with permafrost degradation contributes to an increased productivity of Siberian larch forests.
      Citation: Forests
      PubDate: 2018-06-01
      DOI: 10.3390/f9060314
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 315: Non-Structural Carbohydrate Dynamics in Leaves
           and Branches of Pinus massoniana (Lamb.) Following 3-Year Rainfall
           Exclusion

    • Authors: Tian Lin, Huaizhou Zheng, Zhihong Huang, Jian Wang, Jinmao Zhu
      First page: 315
      Abstract: Drought-induced tree mortality is an increasing and global ecological problem. Stored non-structural carbohydrates (NSCs) may be a key determinant of drought resistance, but most existing studies are temporally limited. In this study, a 3-year 100% rainfall exclusion manipulation experiment was conducted to evaluate the response of NSC dynamics to drought stress in 25-year-old Pinus massoniana leaves and branches. The results showed: (1) compared with the control condition, leaf NSC concentration in the drought treatment increased 90% in the early stage (days 115–542) (p < 0.05), and then decreased 15% in the late stage (days 542–1032), which was attributed to water limitation instead of phenology; (2) the response of leaf NSCs to drought was more significant than branch NSCs, demonstrating a time lag effect; and (3) the response of P. massoniana to mild drought stress was to increase the soluble sugars and starch in the early stage, followed by an increase in soluble sugars caused by decreasing starch in the later stress period. Considering these results, mid-term drought stress had no significant effect on the total NSC concentration in P. massoniana, removing carbon storage as a potential adaptation to drought stress.
      Citation: Forests
      PubDate: 2018-06-01
      DOI: 10.3390/f9060315
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 316: Changes in Species Composition in Alder Swamp
           Forest Following Forest Dieback

    • Authors: Remigiusz Pielech, Marek Malicki
      First page: 316
      Abstract: It is generally hypothesized that forest dieback is a characteristic of alder swamp forests (alder carrs, Alnion glutinosae alliance). Different internal and external factors may trigger this process, including human disturbance, changes in river discharge, unusually severe and prolonged flooding, terminal age of an even-aged alder forest (ca. 100–150 years) and others. Although forest dieback in this type of forest may cause major changes in environmental conditions, the influence of this change on the floristic composition has not been well recognized. The study aimed to detect any possible changes in floristic variation in alder swamp forest following forest dieback. Vegetation plots in alder swamp forests affected by forest dieback were resurveyed 20 years after a previous study. PERMANOVA was used to test the significance of the compositional change and nonmetric multidimensional scaling (NMDS) with passively fitted means of the Ellenberg’s Indicator Values were used to interpret its ecological meaning. In addition, different structural and diversity indices were compared, including species richness, percentage cover of vegetation layers, Shannon and Simpson diversity and evenness. Finally, we analyzed changes in the frequency of vascular plant species using Chi square tests. We recorded clear and significant compositional changes following alder swamp forest dieback. This change was most related to the gradient of moisture, followed by the gradients of light and temperature. The analysis of the individual species showed that the species of hummocks declined, while the species of hollows increased. Moreover, the current communities are dominated by some hydrophytes that were not recorded 20 years ago. Forest dieback resulted in profound changes in the hydrological regime. The observed changes are consistent with a model of cyclic succession as proposed for alder swamps. In addition, we conclude that the natural forest dynamics have to be taken into consideration while interpreting the results of re-survey studies.
      Citation: Forests
      PubDate: 2018-06-02
      DOI: 10.3390/f9060316
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 317: Improved Prediction of Stream Flow Based on
           Updating Land Cover Maps with Remotely Sensed Forest Change Detection

    • Authors: Alexander J. Hernandez, Sean P. Healey, Hongsheng Huang, R. Douglas Ramsey
      First page: 317
      Abstract: The water balance in a watershed can be disrupted by forest disturbances such as harvests and fires. Techniques to accurately and efficiently map forest cover changes due to disturbance are evolving quickly, and it is of interest to ask how useful maps of different types of disturbances over time can be in the prediction of water yield. We assessed the benefits of using land cover maps produced at annual vs. five-year intervals in the prediction of monthly streamflows across 10 watersheds contained entirely within the US National Forest System. We found that annually updating land cover maps with forest disturbance data significantly improved water yield predictions using the Soil and Water Assessment Tool (SWAT; p < 0.01 improvement for both the Nash–Sutcliffe efficiency measure and the ratio of the root mean square error to the standard deviation of the measured data). Improvement related to using annually updated land cover maps was directly related to the amount of disturbance observed in a watershed. Our results lay a foundation to apply new high-resolution disturbance datasets in the field of hydrologic modeling to monitor ungauged watersheds and to explore potential water yield changes in watersheds if climate conditions or management practices were to change forest disturbance processes.
      Citation: Forests
      PubDate: 2018-06-02
      DOI: 10.3390/f9060317
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 318: Comparative Transcriptomics Analysis of
           Phytohormone-Related Genes and Alternative Splicing Events Related to
           Witches’ Broom in Paulownia

    • Authors: Yanpeng Dong, Huiyuan Zhang, Guoqiang Fan, Xiaoqiao Zhai, Zhe Wang, Yabing Cao
      First page: 318
      Abstract: Paulownia is a native fast-growing tree in China that has been introduced into many countries. However, it is often infected by Paulownia witches’ broom (PaWB) disease, which can lead to large declines in yield. PaWB is caused by a phytoplasma that is an obligate biotrophic plant pathogen. Until now, the molecular mechanisms of interactions between the host plants and the phytoplasma have not been clear. In previous studies, it was reported that PaWB-infected Paulownia exhibited healthy morphology after being treated with methyl methane sulfonate (MMS) at the concentration of 20 mg·L−1 (for Paulownia tomentosa (PT) and Paulownia fortunei (PF) or 15 mg·L−1 (for P. tomentosa × P. fortunei) MMS. In this study, the whole transcriptome expression profile of PaWB-infected Paulownia was studied using high-throughput sequencing technology. In total, 74 significantly differentially expressed genes were detected among three species of healthy, PaWB-infected Paulownia, and the Paulownia treated with MMS. We identified and analyzed genes related to the roles of phytohormones and alternative splicing events involved in regulating plant growth. In response to phytoplasma infection, the concentrations of the plants’ phytohormones were altered, leading to morphology transformation. This research will provide valuable information to detect the molecular mechanisms involved in the Paulownia response to phytoplasma infection.
      Citation: Forests
      PubDate: 2018-06-02
      DOI: 10.3390/f9060318
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 319: Effects of a Heat Wave on Nocturnal Stomatal
           Conductance in Eucalyptus camaldulensis

    • Authors: Víctor Resco de Dios, Michael E. Loik, Renee A. Smith, David T. Tissue
      First page: 319
      Abstract: Nocturnal transpiration constitutes a significant yet poorly understood component of the global water cycle. Modeling nocturnal transpiration has been complicated by recent findings showing that stomata respond differently to environmental drivers over day- vs. night-time periods. Here, we propose that nocturnal stomatal conductance depends on antecedent daytime conditions. We tested this hypothesis across six genotypes of Eucalyptus camaldulensis Dehnh. growing under different CO2 concentrations (ambient vs. elevated) and exposed to contrasting temperatures (ambient vs. heat wave) for four days prior to the night of measurements, when all plants experienced ambient temperature conditions. We observed significant effects after the heat wave that led to 36% reductions in nocturnal stomatal conductance. The response was partly driven by changes in daytime stomatal behavior but additional factors may have come into play. We also observed significant differences in response to the heat wave across genotypes, likely driven by local adaptation to their climate of origin, but CO2 played no effect. Stomatal models may need to incorporate the role of antecedent effects to improve projections particularly after drastic changes in the environment such as heat waves.
      Citation: Forests
      PubDate: 2018-06-03
      DOI: 10.3390/f9060319
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 320: Effects of Drought and Salinity on European
           Larch (Larix decidua Mill.) Seedlings

    • Authors: Ioana M. Plesa, Sara González-Orenga, Mohamad Al Hassan, Adriana F. Sestras, Oscar Vicente, Jaime Prohens, Radu E. Sestras, Monica Boscaiu
      First page: 320
      Abstract: Larix decidua, the European larch, is not normally affected by drought or salinity in its natural habitats, but it may be when grown as an ornamental tree, by the widespread practice of winter de-icing of mountain roads with NaCl, and because of global warming-induced environmental changes. The responses of two-month-old larch seedlings to 30 days water deficit (withholding irrigation) or salt stress (150 mM NaCl) treatments were studied by determining stress-induced changes in several growth parameters and biochemical markers (ion and osmolyte contents, level of oxidative stress, activation of enzymatic and non-enzymatic antioxidant systems). Both treatments caused the inhibition of growth, degradation of photosynthetic pigments, a small increase in malondialdehyde (MDA, an oxidative stress biomarker), and the activation of antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR). In all cases, salinity appeared to have stronger effects on the seedlings than water deficit. The presence of relatively high concentrations of glycine betaine, both in control and stressed plants, may represent a constitutive mechanism of defence against stress in European larch. Additionally, other responses were specific for salt stress and included the activation of K+ transport from roots to shoots and the accumulation of Pro as an osmoprotectant.
      Citation: Forests
      PubDate: 2018-06-04
      DOI: 10.3390/f9060320
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 321: Dynamic Patterns of Trees Species in Miombo
           Forest and Management Perspectives for Sustainable Production—Case Study
           in Huambo Province, Angola

    • Authors: Vasco Chiteculo, Peter Surovy
      First page: 321
      Abstract: This paper aims to assess important forest parameters, including tree density, diameter at breast height (DBH), and age distribution, investigate the dynamic growth of miombo tree species, and employ this information to design a management framework in miombo forests. The delineation of the management zones was based on unsupervised land cover classification that began with three zones where ground data was collected and increased to five zones. Eighteen circular plots (25.2 m radius) were randomly distributed over the study areas to assess the current situation and potential growth patterns for each species. The patterns of the six most representative tree species of miombo in Angola were described and we used KORFiT 2.4 software to fit data and develop growth curves for at least three miombo species. Growth function fitness was evaluated by root mean squared error (RMSE), coefficient of determination (R2), significance of the parameters (p < 0.05), and Akaike’s information criterion (AIC). The diameter distribution of miombo tree species resembled a typical distribution of uneven-aged forest stands; higher DBH classes had lower abundances of tree species. Logistic and Gompertz growth functions were the best fits for miombo tree species. Brachystegia spiciformis Benth., is suggested as a potential species for timber management in the region because they displayed high growth potential to more quickly reach an assumed minimum DBH of 20 cm. This study concluded that miombo forest stands present an irregular structure in which DBH distribution illustrated only two patterns: many small stems and a bimodal forest structure.
      Citation: Forests
      PubDate: 2018-06-04
      DOI: 10.3390/f9060321
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 322: Joint Control of Net Primary Productivity by
           Climate and Soil Nitrogen in the Forests of Eastern China

    • Authors: Zhan Xiaoyun, Guo Minghang, Zhang Tibin
      First page: 322
      Abstract: The nature and extent of climate and soil nutrient controls in Chinese forests remain poorly resolved. Here, we synthesized the data on carbon–climate–soil in eastern China, and litter N was firstly taken into consideration, to examine the variation of net primary productivity (NPP) and its driving forces. Results showed that NPP had significant latitude pattern and varied substantially across climate zones. Bivariate analyses indicated that mean annual temperature (MAT), mean annual precipitation (MAP), soil N content (Nsoil), and annual litter N (Nre) were the main controlling factors in spatial pattern of forest NPP. Notably, partial general linear model analysis revealed that MAT, MAP, and Nre jointly explained 84.8% of the spatial variation of NPP. Among the three major factors, Nre explained more variation of forest NPP than the other two factors, and MAT and MAP affected NPP mainly through the change of litter N rather than via themselves, highlighting the importance of litter N in estimating forest NPP. However, to accurately describe the pattern of forest NPP in China, more detailed field measurements and methodologies on NPP and relevant confounding factors should be addressed in future studies.
      Citation: Forests
      PubDate: 2018-06-04
      DOI: 10.3390/f9060322
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 323: Effects of Vegetation Management on Wood
           Properties and Plant Water Relations of Four Conifer Species in the
           Pacific Northwest of the USA

    • Authors: Joyce Aernouts, Carlos A. Gonzalez-Benecke, Laurence R. Schimleck
      First page: 323
      Abstract: In plantation forests, competition from unwanted vegetation may reduce survival and negatively impact tree growth. The goal of this study was to examine the influence of vegetation management treatments on plant water relations and wood properties. Control trees (no treatment) were compared to trees subjected to post-planting competing vegetation control for five consecutive years after planting. Four conifer species (Douglas-fir, western hemlock, western redcedar, and grand fir) were studied on two different sites in western Oregon, USA. Carbon isotope (13C) analysis was used to study intrinsic water use efficiency (iWUE) and X-ray densitometry was used to measure specific gravity, ring width, and latewood percent. We found a significant interaction between vegetation management treatment and wood ring (growing season) in iWUE for Douglas-fir. There was little effect of vegetation management treatment on ring specific gravity for all species. Only western redcedar growing at a central Coast Range site showed increased ring specific gravity under sustained competing vegetation control. When growing under conditions of sustained control of competing vegetation, western redcedar at a central Coast Range site had a significant increase in earlywood specific gravity, while Douglas-fir at a Cascade Foothills site had a significant decrease in latewood specific gravity. Western redcedar and grand fir had a significant interaction-effect on its latewood percentage, with treatment trees having a higher latewood percentage than control trees after ring 8. Further, Douglas-fir and western hemlock had a significant increase in ring, earlywood, and latewood area with treatment, and grand fir had a significant interaction-effect of treatment × ring for ring, earlywood, and latewood area. This study indicates that, for conifer trees growing under sustained vegetation control, growth gains could be achieved without compromising wood properties. However, if harvested at a target diameter, these trees will have a larger proportion of low quality corewood compared to trees from conventionally managed stands.
      Citation: Forests
      PubDate: 2018-06-04
      DOI: 10.3390/f9060323
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 324: Response of Black Ash Wetland Gaseous Soil
           Carbon Fluxes to a Simulated Emerald Ash Borer Infestation

    • Authors: Matthew Van Grinsven, Joseph Shannon, Nicholas Bolton, Joshua Davis, Nam Jin Noh, Joseph Wagenbrenner, Randall Kolka, Thomas Pypker
      First page: 324
      Abstract: The rapid and extensive expansion of emerald ash borer (EAB) in North America since 2002 may eliminate most existing ash stands, likely affecting critical ecosystem services associated with water and carbon cycling. To our knowledge, no studies have evaluated the coupled response of black ash (Fraxinus nigra Marsh.) wetland water tables, soil temperatures, and soil gas fluxes to an EAB infestation. Water table position, soil temperature, and soil CO2 and CH4 fluxes were monitored in nine depressional headwater black ash wetlands in northern Michigan. An EAB disturbance was simulated by girdling (girdle) or felling (ash-cut) all black ash trees with diameters greater than 2.5 cm within treated wetlands (n = 3 per treatment). Soil gas fluxes were sensitive to water table position, temperature, and disturbance. Soil CO2 fluxes were significantly higher, and high soil CH4 fluxes occurred more frequently in disturbed sites. Soil CH4 fluxes in ash-cut were marginally significantly higher than girdle during post-treatment, yet both were similar to control sites. The strong connection between depressional black ash wetland study sites and groundwater likely buffered the magnitude of disturbance-related impact on water tables and carbon cycling.
      Citation: Forests
      PubDate: 2018-06-04
      DOI: 10.3390/f9060324
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 325: Development of Somatic Embryo Maturation and
           Growing Techniques of Norway Spruce Emblings towards Large-Scale Field
           Testing

    • Authors: Mikko Tikkinen, Saila Varis, Tuija Aronen
      First page: 325
      Abstract: The possibility to utilize non-additive genetic gain in planting stock has increased the interest towards vegetative propagation. In Finland, the increased planting of Norway spruce combined with fluctuant seed yields has resulted in shortages of improved regeneration material. Somatic embryogenesis is an attractive method to rapidly facilitate breeding results, not in the least, because juvenile propagation material can be cryostored for decades. Further development of technology for the somatic embryogenesis of Norway spruce is essential, as the high cost of somatic embryo plants (emblings) limits deployment. We examined the effects of maturation media varying in abscisic acid (20, 30 or 60 µM) and polyethylene glycol 4000 (PEG) concentrations, as well as the effect of cryopreservation cycles on embryo production, and the effects of two growing techniques on embling survival and growth. Embryo production and nursery performance of 712 genotypes from 12 full-sib families were evaluated. Most embryos per gram of fresh embryogenic mass (296 ± 31) were obtained by using 30 µM abscisic acid without PEG in the maturation media. Transplanting the emblings into nursery after one-week in vitro germination resulted in 77% survival and the tallest emblings after the first growing season. Genotypes with good production properties were found in all families.
      Citation: Forests
      PubDate: 2018-06-04
      DOI: 10.3390/f9060325
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 326: The Transcriptomic Responses of Pinus
           massoniana to Drought Stress

    • Authors: Mingfeng Du, Guijie Ding, Qiong Cai
      First page: 326
      Abstract: Masson pine (Pinus massoniana) is a major fast-growing timber species planted in southern China, a region of seasonal drought. Using a drought-tolerance genotype of Masson pine, we conducted large-scale transcriptome sequencing using Illumina technology. This work aimed to evaluate the transcriptomic responses of Masson pine to different levels of drought stress. First, 3397, 1695 and 1550 unigenes with differential expression were identified by comparing plants subjected to light, moderate or severe drought with control plants. Second, several gene ontology (GO) categories (oxidation-reduction and metabolism) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways (plant hormone signal transduction and metabolic pathways) were enriched, indicating that the expression levels of some genes in these enriched GO terms and pathways were altered under drought stress. Third, several transcription factors (TFs) associated with circadian rhythms (HY5 and LHY), signal transduction (ERF), and defense responses (WRKY) were identified, and these TFs may play key roles in adapting to drought stress. Drought also caused significant changes in the expression of certain functional genes linked to osmotic adjustment (P5CS), abscisic acid (ABA) responses (NCED, PYL, PP2C and SnRK), and reactive oxygen species (ROS) scavenging (GPX, GST and GSR). These transcriptomic results provide insight into the molecular mechanisms of drought stress adaptation in Masson pine.
      Citation: Forests
      PubDate: 2018-06-04
      DOI: 10.3390/f9060326
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 327: Development and Validation of a Simulation
           Model for the Temperature Field during High-Frequency Heating of Wood

    • Authors: Haojie Chai, Jingyao Zhao, Yingchun Cai
      First page: 327
      Abstract: In the process of applying high-frequency heating technology to wood drying, controlling the material temperature affects both drying speed and drying quality. Therefore, research on the heat transfer mechanism of high-frequency heating of wood is of great significance. To study the heat transfer mechanism of high-frequency heating, the finite element method was used to establish and solve the wood high-frequency heating model, and experimental verification was carried out. With a decrease in moisture content, the heating rate decreased, then increased, and then decreased again. There was no obvious linear relationship between the moisture content and heating rate; the simulation accuracy of the heating rate was higher in the early and later drying stages and slightly lower near the fiber saturation point. For the central section temperature distribution, the simulation and actual measurement results matched poorly in the early drying stage because the model did not fully consider the differences in the moisture content distribution of the actual test materials. In the later drying stage, the moisture content distribution of the test materials became uniform, which was consistent with the model assumptions. Considering the changes in heating rate and temperature distribution, the accuracy of the model is good under the fiber saturation point, and it can be used to predict the high-frequency heating process of wood.
      Citation: Forests
      PubDate: 2018-06-04
      DOI: 10.3390/f9060327
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 328: Characteristics of Students Who Frequently
           Conduct Plant Observations: Toward Fostering Leaders and Supporters of
           Fixed-Point Observation of Forests

    • Authors: Kazuhiko W. Nakamura, Rui Fukumoto, Yuta Horie
      First page: 328
      Abstract: In order to foster leaders and supporters of fixed-point observation for sustainable forest management, it is considered effective to focus on students who have demonstrated potential for fixed-point observations of forests in the universal education stage. This study aims to identify the characteristics of students who frequently conduct plant observations, which is the basis for the fixed-point observation of forests, including methods involving photography. We conducted a questionnaire survey, which consisted of 19 questions that provided insight into junior high school students’ experiences, opportunities, and interests related to plant observation. We compared students who have conducted plant observations with those who have not, using Fisher’s exact test and multiple comparisons using the Benjamini and Hochberg method. The ratio of students who frequently conducted plant observations was significantly higher among female students than male students, and their characteristics differed by gender. The significant characteristics of male students included farm work experience and niche hobbies such as camping and lighting a bonfire, as well as using digital single-lens reflex cameras for photography; female students had relatively niche hobbies such as enjoying science. Students who increased the frequency of plant observations after the lecture about fixed-point observations of forests had an inclination toward social studies and tended not to use a smartphone for photography.
      Citation: Forests
      PubDate: 2018-06-05
      DOI: 10.3390/f9060328
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 329: Spatial and Temporal Variation of NDVI in
           Response to Climate Change and the Implication for Carbon Dynamics in
           Nepal

    • Authors: Binod Baniya, Qiuhong Tang, Zhongwei Huang, Siao Sun, Kua-anan Techato
      First page: 329
      Abstract: Nepal is a country of contrast, with varying altitude, climate and vegetation from the top of high mountains to the tropical forest in low lands. The terrestrial vegetation has rapidly been altered by climate change in Nepal. The spatial and temporal evolution of vegetation and its linkage to climatic variables were analyzed using the Normalized Difference Vegetation Index (NDVI) obtained from Advanced Very High Resolution Radiometer (AVHRR) sensors. A linear regression model and Sen’s slope method were used to estimate NDVI trends and the Pearson correlation between NDVI and climatic variable, i.e., temperature and precipitation were calculated to identify the role of climate in vegetation changes. The carbon dynamics were also measured using a biomass carbon density estimation model. Results showed that NDVI experienced an overall increasing trend in Nepal from 1982–2015. The NDVI significantly increased at the rate of 0.0008 year−1 (p < 0.05) with seasonal variation of 0.0004 year−1, p > 0.05; 0.0007 year−1, p < 0.05; 0.0008 year−1, p < 0.05 and 0.0007 year−1, p > 0.05 in winter, pre-monsoon, monsoon and post-monsoon seasons, respectively. The NDVI relative change ratio (RCR) was 6.29% during last 34 years in Nepal. The correlation between NDVI and temperature was significantly positive (r = 0.36, p = 0.03), but there was a negative correlation with precipitation (r = −0.21, p = 0.28). Altogether, 82.20% of the study areas showed a positive correlation with temperature in which 34.97% was significant and 69.23% of the area had a negative correlation (16.35% significant, p < 0.05) with precipitation. In addition, NDVI-based carbon estimation showed that Nepal’s forest total carbon stock is 685.45 × 106 t C (i.e., an average of 115.392 t C/ha) with an annual carbon sequestration rate of 0.10 t C/ha from 1982–2015. The results suggest that NDVI variation is more sensitive to temperature than precipitation and it is valuable to measure carbon dynamics in Nepal.
      Citation: Forests
      PubDate: 2018-06-05
      DOI: 10.3390/f9060329
      Issue No: Vol. 9, No. 6 (2018)
       
  • Forests, Vol. 9, Pages 230: Seed Dispersal, Microsites or
           Competition—What Drives Gap Regeneration in an Old-Growth Forest' An
           Application of Spatial Point Process Modelling

    • Authors: Georg Gratzer, Rasmus Plenge Waagepetersen
      First page: 230
      Abstract: The spatial structure of trees is a template for forest dynamics and the outcome of a variety of processes in ecosystems. Identifying the contribution and magnitude of the different drivers is an age-old task in plant ecology. Recently, the modelling of a spatial point process was used to identify factors driving the spatial distribution of trees at stand scales. Processes driving the coexistence of trees, however, frequently unfold within gaps and questions on the role of resource heterogeneity within-gaps have become central issues in community ecology. We tested the applicability of a spatial point process modelling approach for quantifying the effects of seed dispersal, within gap light environment, microsite heterogeneity, and competition on the generation of within gap spatial structure of small tree seedlings in a temperate, old growth, mixed-species forest. By fitting a non-homogeneous Neyman–Scott point process model, we could disentangle the role of seed dispersal from niche partitioning for within gap tree establishment and did not detect seed densities as a factor explaining the clustering of small trees. We found only a very weak indication for partitioning of within gap light among the three species and detected a clear niche segregation of Picea abies (L.) Karst. on nurse logs. The other two dominating species, Abies alba Mill. and Fagus sylvatica L., did not show signs of within gap segregation.
      Citation: Forests
      PubDate: 2018-04-27
      DOI: 10.3390/f9050230
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 231: National REDD+ Implications for Tenured
           Indigenous Communities in Guyana, and Communities’ Impact on Forest
           Carbon Stocks

    • Authors: Han Overman, Nathalie Butt, Anthony R. Cummings, Jeffrey B. Luzar, José M. V. Fragoso
      First page: 231
      Abstract: Early project-level initiatives of ‘reducing emissions from deforestation and forest degradation’ (REDD+) have left a negative impression among many forest-dependent peoples (FDP) across the tropics. As countries move towards national-level implementation and results-based payments, it is timely to analyze the effects of ‘national REDD+’ on FDP. We use Guyana’s technically approved United Nations Forest Reference Emission Level (FREL) submission and Opt-In Mechanism to assess how fifteen indigenous communities with tenured forestland may financially benefit from national REDD+, and evaluate whether, and to what extent, Guyana forms a best-case scenario. In addition, we provide a first-time assessment whether field estimates of the average carbon density of mature forests managed by fifteen forest-dependent communities (beyond rotational farming lands) equals that of nearby unmanaged mature forest, as this could affect REDD+ payment levels. We conclude that, notwithstanding some pending issues, Guyana’s national REDD+ program could be very beneficial for FDP, even under a modest United States (US) $5 unit carbon price. We present economic evidence to support forest governance change domestically in sovereign developing countries that may ease FDP tenure and national REDD+ implementation. The average carbon density was locally substantially less in FDP-managed forest, but had little effect on the overall carbon stock of the titled forest area, and is considered modest when incorporating ecological and socioeconomic attributes. Partnerships with FDP when combined with advances in remote sensing could have potential for economic monitoring of forest emissions across the tropics.
      Citation: Forests
      PubDate: 2018-04-27
      DOI: 10.3390/f9050231
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 232: Biochar Can Be a Suitable Replacement for
           Sphagnum Peat in Nursery Production of Pinus ponderosa Seedlings

    • Authors: R. Kasten Dumroese, Jeremiah R. Pinto, Juha Heiskanen, Arja Tervahauta, Katherine G. McBurney, Deborah S. Page-Dumroese, Karl Englund
      First page: 232
      Abstract: We replaced a control peat medium with up to 75% biochar on a volumetric basis in three different forms (powder, BC; pyrolyzed softwood pellets, PP; composite wood-biochar pellets, WP), and under two supplies of nitrogen fertilizer (20 or 80 mg N) subsequently grew seedlings with a comparable morphology to the control. Using gravimetric methods to determine irrigation frequency and exponential fertilization to ensure all treatments received the same amount of N at a given point in the growing cycle, we successfully replaced peat with 25% BC and up to 50% PP. Increasing the proportion of biochar in the media significantly increased pH and bulk density and reduced effective cation exchange capacity and air-filled porosity, although none of these variables was consistent with resultant seedling growth. Adherence to gravimetric values for irrigation at an 80% water mass threshold in the container revealed that the addition of BC and WP, but not PP, required adjustments to the irrigation schedule. For future studies, we encourage researchers to provide more details about bulk density, porosity, and irrigation regime to improve the potential inference provided by this line of biochar and growing media work.
      Citation: Forests
      PubDate: 2018-04-27
      DOI: 10.3390/f9050232
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 233: Post-Emergent Control of Nuisance Cones in
           Fraser Fir Christmas Tree Plantations

    • Authors: Bert Cregg, Dana Ellison, Jill O’Donnell
      First page: 233
      Abstract: Heavy cone production by Fraser fir Christmas trees requires significant labor inputs to remove nuisance cones. We conducted two field trials in collaboration with operational Christmas tree farms to evaluate the effectiveness of post-emergent herbicides to stop the development of newly emergent cone buds. In the first trial (2016), we applied six products (two conventional herbicides and four herbicides labeled for organic production) to trees using back-pack sprayers in operational plantations at four farms in Michigan. Three products; Scythe, Axxe, and Avenger, provided better cone kill than the other products but resulted in phytotoxicity at two locations. In 2017, we applied the three most effective products from the earlier trial at three farms either as single applications or as two applications approximately one week apart. We also evaluated a hand-held mechanical de-coning device at two farms. For all the products and the mechanical device, cone control in the 2017 trial was high (>80%). Phytotoxicity to foliage was low (mean rating, <0.3; 0 = none, 2 = severe) for single applications of the herbicides. Repeated applications increased cone control slightly but also increased risk for phytotoxicity. The mechanical device caused significant damage to shoots and foliage. We attribute the increased product effectiveness and reduced phytotoxicity between the 2016 and 2017 studies to improved coverage and earlier spray timing. Based on the current retail product cost, chemical cone control can be cost-effective compared to handpicking cones if trees have high numbers of cones that can take several minutes to remove. The effect of using surfactants and reducing product rates should be investigated along with mechanized application.
      Citation: Forests
      PubDate: 2018-04-28
      DOI: 10.3390/f9050233
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 234: Are Wildfires Knocking on the Built-Up Areas
           Door'

    • Authors: Leone D. Mancini, Mario Elia, Anna Barbati, Luca Salvati, Piermaria Corona, Raffaele Lafortezza, Giovanni Sanesi
      First page: 234
      Abstract: Human-started fires represent the vast majority of wildfires in Mediterranean countries. The current expansion of human settlements into fire-prone territories has led to the creation of landscapes where anthropogenic developments merge with wildland areas. In this context, understanding the role of distance from built-up areas in shaping coarse-scale wildfire spatial patterns is a major concern. Proximity to cities has become an important factor that may increase the probability of wildfires in wildland-urban interfaces. To this issue, we developed an assessment of wildfire distribution in Italy over an 8-year period (2007–2014) to quantify fire occurrence and recurrence as a function of distance from built-up areas. Our findings suggest a positive relationship between the distance from built-up areas and fire incidence (i.e., ratio between burnt forest area and total forest area), whereas a negative relation was found between distance from built-up areas and fire frequency and recurrence; thus, there are more recurring yet smaller sized-fires near built-up areas. Fifty percent of fire events and more than two-thirds of recurrent fires occur within 200 m from built-up areas. On the other hand, the considerable amount of such fire events never reaches an incidence higher than 10% in flat areas and 30% in hilly and mountainous areas. More broadly, quantitative knowledge about where fires occur is essential to ensure appropriate fire management throughout large territories. With this in mind, our investigation intends to provide a solid base for further studies in landscapes with a high component of human-dominated land use.
      Citation: Forests
      PubDate: 2018-04-28
      DOI: 10.3390/f9050234
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 235: Chainsaw-Carved Cavities Better Mimic the
           Thermal Properties of Natural Tree Hollows than Nest Boxes and Log Hollows
           

    • Authors: Stephen R. Griffiths, Pia E. Lentini, Kristin Semmens, Simon J. Watson, Linda F. Lumsden, Kylie A. Robert
      First page: 235
      Abstract: The creation of supplementary habitats that effectively mimic the physical and thermal characteristics of natural tree hollows should be a key priority for landscape restoration and biodiversity offset programs. Here, we compare the thermal profiles of natural tree hollows with three types of artificial hollows designed for small marsupial gliders and tree-roosting insectivorous bats: (1) ‘chainsaw hollows’ carved directly into the trunks and branches of live trees, (2) ‘log hollows’, and (3) plywood nest boxes. Chainsaw hollows had thermal profiles that were similar to natural tree hollows: they were consistently warmer than ambient conditions at night, while remaining cooler than ambient during the day. In contrast, glider and bat boxes had the opposite pattern of heating and cooling, being slightly cooler than ambient at night and substantially hotter during the day. Glider log hollows had greater variation in internal temperatures compared to natural hollows and chainsaw hollows, but fluctuated less than glider boxes. Our results provide the first empirical evidence that artificial hollows carved directly into live trees can produce thermally stable supplementary habitats that could potentially buffer hollow-dependent fauna from weather extremes; whereas, poorly insulated plywood nest boxes produce lower-quality thermal environments. Together these findings provide positive impetus for stakeholders involved in conservation management and biodiversity offset programs to consider trialing chainsaw hollows in situations where target fauna require well-insulated supplementary habitats.
      Citation: Forests
      PubDate: 2018-04-28
      DOI: 10.3390/f9050235
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 236: Interstorm Variability in the Biolability of
           Tree-Derived Dissolved Organic Matter (Tree-DOM) in Throughfall and
           Stemflow

    • Authors: Daniel H. Howard, John T. Van Stan, Ansley Whitetree, Lixin Zhu, Aron Stubbins
      First page: 236
      Abstract: Dissolved organic matter (DOM) drives carbon (C) cycling in soils. Current DOM work has paid little attention to interactions between rain and plant canopies (including their epiphytes), where rainfall is enriched with tree-derived DOM (tree-DOM) prior to reaching the soil. Tree-DOM during storms reaches soils as throughfall (drip through canopy gaps and from canopy surfaces) and stemflow (rainwater drained down the trunk). This study (1) assessed the susceptibility of tree-DOM to the consumption by microbes (biolability); (2) evaluated interstorm variability in the proportion and decay kinetics of biolabile tree-DOM (tree-BDOM), and (3) determined whether the presence of arboreal epiphytes affected tree-BDOM. Tree-BDOM from Juniperus virginiana L. was determined by subjecting throughfall and stemflow samples from five storms to 14-day microbial incubations. Tree-DOM was highly biolabile, decreasing in concentration by 36–73% within 1–4 days. Tree-BDOM yield was 3–63 mg-C m−2 mm−1 rainfall, which could represent 33–47% of annual net ecosystem exchange in Georgia (USA) forests. Amount and decay kinetics of tree-BDOM were not significantly different between throughfall versus stemflow, or epiphyte-covered versus bare canopy. However, epiphyte presence reduced water yields which reduced tree-BDOM yields. Interstorm proportions, rates and yields of tree-BDOM were highly variable, but throughfall and stemflow consistently contained high tree-BDOM proportions (>30%) compared to previously-published litter and soil leachate data (10–30%). The high biolability of tree-DOM indicates that tree-BDOM likely provides C subsidies to microbial communities at the forest floor, in soils and the rhizosphere.
      Citation: Forests
      PubDate: 2018-05-01
      DOI: 10.3390/f9050236
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 237: Automatic Assessment of Crown Projection Area
           on Single Trees and Stand-Level, Based on Three-Dimensional Point Clouds
           Derived from Terrestrial Laser-Scanning

    • Authors: Tim Ritter, Arne Nothdurft
      First page: 237
      Abstract: Crown projection area (CPA) is a critical parameter in assessing inter-tree competition and estimating biomass volume. A multi-layer seeded region growing-based approach to the fully automated assessment of CPA based on 3D-point-clouds derived from terrestrial laser scanning (TLS) is presented. Independently repeated manual CPA-measurements in a subset of the stand serve as the reference and enable quantification of the inter-observer bias. Allometric models are used to predict CPA for the whole stand and are compared to the TLS-based estimates on the single tree- and stand-level. It is shown that for single trees, the deviation between CPA measurements derived from TLS data and manual measurements is on par with the deviations between manual measurements by different observers. The inter-observer bias propagates into the allometric models, resulting in a high uncertainty of the derived estimates at tree-level. Comparing the allometric models to the TLS measurements at stand-level reveals the high influence of crown morphology, which only can be taken into account by the TLS measurements and not by the allometric models.
      Citation: Forests
      PubDate: 2018-05-01
      DOI: 10.3390/f9050237
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 238: Thinning Treatments Reduce Deep Soil Carbon
           and Nitrogen Stocks in a Coastal Pacific Northwest Forest

    • Authors: Cole D. Gross, Jason N. James, Eric C. Turnblom, Robert B. Harrison
      First page: 238
      Abstract: Forests provide valuable ecosystem and societal services, including the sequestration of carbon (C) from the atmosphere. Management practices can impact both soil C and nitrogen (N) cycling. This study examines soil organic C (SOC) and N responses to thinning and fertilization treatments. Soil was sampled at an intensively managed Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) plantation in north-western Oregon, USA. Management regimes—thinning, fertilization plus thinning, and no (control) treatment—were randomly assigned to nine 0.2-ha plots established in 1989 in a juvenile stand. Prior to harvest, forest floor and soil bulk density and chemical analysis samples were collected by depth to 150 cm. During a single rotation of ~40 years, thinning treatments significantly reduced SOC and N stocks by 25% and 27%, respectively, compared to no treatment. Most of this loss occurred in deeper soil layers (below ~20 cm). Fertilization plus thinning treatments also reduced SOC and N stocks, but not significantly. Across all management regimes, deeper soil layers comprised the majority of SOC and N stocks. This study shows that: (1) accurately quantifying and comparing SOC and N stocks requires sampling deep soil; and (2) forest management can substantially impact both surface and deep SOC and N stocks on decadal timescales.
      Citation: Forests
      PubDate: 2018-05-01
      DOI: 10.3390/f9050238
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 239: Soil Nitrogen Responses to Soil Core
           Transplanting Along an Altitudinal Gradient in an Eastern Tibetan Forest

    • Authors: Li Zhang, Ao Wang, Fuzhong Wu, Zhenfeng Xu, Bo Tan, Yang Liu, Yulian Yang, Lianghua Chen, Wanqin Yang
      First page: 239
      Abstract: To understand the differential effects of altitudinal gradient on soil inorganic nitrogen concentration and associated ammonia-oxidizingbacteria (AOB) and archaea (AOA), intact soil cores from a primary coniferous forest were in situ incubated in an alpine forest at a 3582-m altitude (A1) and transplanted to subalpine forests at a 3298-m altitude (A2) and 3023-m altitude (A3) on the eastern Tibetan Plateau. Transplant cooled the soil temperature of A2 but warmed the A3 soil temperature. Both AOA and AOB were found at the three altitudes. Compared to A1, A2 had greater AOA and AOB abundance, but A3 showed lower AOA abundance in organic soil. The AOA abundance was negatively correlated with ammonium concentration at all three altitudes, but AOB showed the reverse trend. Our results suggested that the soil nitrogen process responded differentially to soil core transplanting at different altitudes.
      Citation: Forests
      PubDate: 2018-05-02
      DOI: 10.3390/f9050239
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 240: The Challenge of Diffusion in Forest Plans: A
           Methodological Proposal and Case Study

    • Authors: Xabier Bruña-García, Manuel F. Marey-Pérez
      First page: 240
      Abstract: Society’s participation in decisions regarding land planning and management is essential for reaching viable and long-lasting solutions. The success of forest plans depends on the involvement of different stakeholders. In turn, stakeholder involvement depends on the representativity achieved in public participation in the development of the plan. The first stage, diffusion, is the key element in the process. This paper describes a methodology for the diffusion stage that obtains six times more participants than a similar process. Its aim is to achieve stakeholder representativity in the forestry sector in forest planning at a subregional level. The methodology is validated and applied in a municipality of Galicia, north-west Spain. It is evaluated in terms of efficiency considering the effort in each stage and the results achieved.
      Citation: Forests
      PubDate: 2018-05-02
      DOI: 10.3390/f9050240
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 241: Recreationists’ Perceptions of Scenic Beauty
           and Satisfaction at a Public Forest Managed for Endangered Wildlife

    • Authors: Ramesh Paudyal, Taylor V. Stein, Holly K. Ober, Marilyn E. Swisher, Eric J. Jokela, Damian C. Adams
      First page: 241
      Abstract: Prescribed burning and other active forest management treatments have been proven essential for maintaining suitable habitat conditions for many wildlife species, including the federally endangered red-cockaded woodpecker (RCW). This study examines the perception of forest management treatments of recreation users participating in various activities (hunting, hiking/backpacking, camping, off-highway vehicle riding, and canoeing/kayaking) in terms of scenic beauty and recreation satisfaction. We used photographic images to capture various forest management treatments of different intensity levels and times after treatments, and assessed users’ perception of scenic beauty and recreation satisfaction. Results indicated variation among users participating in different recreation activities, but that good quality RCW habitats offered both higher scenic beauty and higher recreation satisfaction than poor quality habitats for most activity user groups. Finally, recreation satisfaction was statistically equal to perceived scenic beauty from both good and poor-quality RCW habitats for most of the activity user groups, thus suggesting the importance of scenic beauty of forest sites in determining recreation users’ attainment of visit satisfaction. Findings conclude that forest sites developed as good quality RCW habitats in the present state also offer quality experience to recreation users, thus supporting multi-objective forestry practices in public forests.
      Citation: Forests
      PubDate: 2018-05-02
      DOI: 10.3390/f9050241
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 242: Long-Term Effect of Prescribed Burning Regimes
           and Logging on Coarse Woody Debris in South-Eastern Australia

    • Authors: Mitchell G. Stares, Luke Collins, Bradley Law, Kristine French
      First page: 242
      Abstract: Coarse woody debris (CWD) is vital within forest ecosystems for an array of fauna. Forest management practices, such as prescribed burning and logging, influence the creation or loss of CWD. We examined the effect of long-term prescribed burning and logging on (i) the abundance of hollow-bearing CWD, (ii) the volume of CWD in different decay classes, (iii) the probability of hollow presence, and (iv) the size of hollows at a long-term (28 years) experimental site. Volume of CWD in moderate and advanced stages of decomposition decreased with increasing fire frequency while moderately decomposed material was higher in logged plots. The likelihood of a hollow being present increased with diameter and decreased when CWD was extensively charred. Hollow size was smaller when material was externally charred but larger when charring affected a pre-existing hollow. Increases in moderately decayed CWD reflect a pulse input of unmerchantable timber following the one-off logging event 28 years ago, though future loss of mature trees may lead to reduced input rates of woody debris in the future. Charring effects on hollow formation, increasing hollow size but decreasing overall presence, demonstrate the complex effect of fire on this resource. Our research highlights the need to develop a fundamental understanding of CWD input and loss dynamics in response to fire and logging in order to predict changes to this resource under a broad range of management scenarios.
      Citation: Forests
      PubDate: 2018-05-02
      DOI: 10.3390/f9050242
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 243: Composition and Structure of Forest Fire
           Refugia: What Are the Ecosystem Legacies across Burned Landscapes'

    • Authors: Garrett Meigs, Meg Krawchuk
      First page: 243
      Abstract: Locations within forest fires that remain unburned or burn at low severity—known as fire refugia—are important components of contemporary burn mosaics, but their composition and structure at regional scales are poorly understood. Focusing on recent, large wildfires across the US Pacific Northwest (Oregon and Washington), our research objectives are to (1) classify fire refugia and burn severity based on relativized spectral change in Landsat time series; (2) quantify the pre-fire composition and structure of mapped fire refugia; (3) in forested areas, assess the relative abundance of fire refugia and other burn severity classes across forest composition and structure types. We analyzed a random sample of 99 recent fires in forest-dominated landscapes from 2004 to 2015 that collectively encompassed 612,629 ha. Across the region, fire refugia extent was substantial but variable from year to year, with an annual mean of 38% of fire extent and range of 15–60%. Overall, 85% of total fire extent was forested, with the other 15% being non-forest. In comparison, 31% of fire refugia extent was non-forest prior to the most recent fire, highlighting that mapped refugia do not necessarily contain tree-based ecosystem legacies. The most prevalent non-forest cover types in refugia were vegetated: shrub (40%), herbaceous (33%), and crops (18%). In forested areas, the relative abundance of fire refugia varied widely among pre-fire forest types (20–70%) and structural conditions (23–55%). Consistent with fire regime theory, fire refugia and high burn severity areas were inversely proportional. Our findings underscore that researchers, managers, and other stakeholders should interpret burn severity maps through the lens of pre-fire land cover, especially given the increasing importance of fire and fire refugia under global change.
      Citation: Forests
      PubDate: 2018-05-02
      DOI: 10.3390/f9050243
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 244: Whitebark Pine in the Northern Cascades:
           Tracking the Effects of Blister Rust on Population Health in North
           Cascades National Park Service Complex and Mount Rainier National Park

    • Authors: Regina M. Rochefort, Shay Howlin, Lacey Jeroue, John R. Boetsch, Lise P. Grace
      First page: 244
      Abstract: Whitebark pine (Pinus albicaulis Engelm.) is a key component of subalpine and alpine ecosystems in the northern Cascades. The species’ survival is threatened by white pine blister rust, mountain pine beetle, fire exclusion, and climate change. We monitored whitebark pine in permanent plots in two national parks three times between 2004 and 2016. The proportion of live trees showing evidence of blister rust infection increased in North Cascades National Park Service Complex from 32% in 2004 to 51% in 2016 and from 18% to 38% in Mount Rainier National Park. Mortality increased from 7% to 21% in North Cascades National Park Service Complex and 38% to 44% in Mount Rainier National Park. The percent of live infected and dead whitebark pine increased with south and east aspects and mortality decreased with elevation. Annualized mortality rates calculated for the entire study period were 1.5% in Mount Rainier National Park and 2.3% in North Cascades National Park Service Complex. Although these rates decreased between the first time period (2004–2009) and the second time period (2009–2016), the prevalence of infected and dead whitebark pine increased across all park landscapes over time and increased in smaller diameter whitebark pine trees.
      Citation: Forests
      PubDate: 2018-05-03
      DOI: 10.3390/f9050244
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 245: Effects of Management Practices and Topography
           on Ectomycorrhizal Fungi of Maritime Pine during Seedling Recruitment

    • Authors: Arthur Guignabert, Florian Delerue, Maya Gonzalez, Laurent Augusto, Mark R. Bakker
      First page: 245
      Abstract: Symbiosis with ectomycorrhizal (ECM) fungi can be important for regeneration success. In a context of increasing regeneration failures in the coastal forest of maritime pine in Southwest France, we tried to identity whether differences in ECM communities could partly explain the variation of regeneration success and how they are influenced by forest practices and stand characteristics. In particular, we focused on the effects of harvesting methods (comparing mature forest with seed-tree regeneration and clear-cuts) and topography (bottom-, mid-, and top positions). Five field trials (two in regeneration failure areas and three in successful areas) were used to sample 450 one-year-old seedlings. Assessments of ECM of seedling nutrient concentrations and of seedling growth based on exploration types were made. ECM root colonisation was similar in all harvesting treatments, suggesting that enough inoculum remained alive after logging. Harvesting-induced effects modifying soil properties and light availability respectively impacted ECM composition and seedling growth. Topography-induced variations in water and nutrient availability led to changes in ECM composition, but had little impact on seedling growth. Contact, short-distance, and long-distance exploration types improved the nutritional status of seedlings (Ca, K, and N), showing that mycorrhization could play an important role in seedling vitality. However, neither ECM root colonisation nor exploration types could be related to regeneration failures.
      Citation: Forests
      PubDate: 2018-05-03
      DOI: 10.3390/f9050245
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 246: Shearing Systems for Fraser Fir (Abies
           fraseri) Christmas Trees

    • Authors: Eric Hinesley, Buddy Deal, Earl Deal
      First page: 246
      Abstract: Plantation-grown Fraser fir (Abies fraseri (Pursh) Poir.) Christmas trees were subjected to nine shearing regimes over nine years in a plantation in western North Carolina (USA). Treatments differed in the year of onset as well as the length of the residual leader (25 to 46 cm). Long leaders (36 to 46 cm) yielded trees that were taller than trees sheared with short leaders (25 to 30 cm), but the gain in height was offset by a lower average U.S. Department of Agriculture grade. Late in the rotation, trees sheared with 36–46-cm leaders were 17–34% heavier than those with 25–30-cm leaders. Average wholesale price of trees sheared with long leaders was 57% greater than that of trees sheared with short leaders. Assuming good bud density on leaders and branches, and considering other factors as well, the optimum leader length for Fraser fir Christmas trees in western North Carolina appears to be 30 to 41 cm (12 to 16 inches). Depending on site quality and variation in bud density and vigor among individual trees, leader length can be reduced, if necessary, to increase crown density.
      Citation: Forests
      PubDate: 2018-05-04
      DOI: 10.3390/f9050246
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 247: Leaf Venation Variation and Phenotypic
           Plasticity in Response to Environmental Heterogeneity in Parrotia
           subaequalis (H. T. Chang) R. M. Hao et H. T. Wei, An Endemic and
           Endangered Tree Species from China

    • Authors: Lifang Zhang, Jing Yang, Yang Huang, Zhiyi Jia, Yanming Fang
      First page: 247
      Abstract: Plant leaf vein traits are partially the result of adaptation to environmental factors during long-term evolution. For terrestrial plants, leaf veins greatly vary in size and numbers. Parrotia subaequalis (H. T. Chang) R. M. Hao et H. T. Wei, an endangered tree species endemic to China, has a limited distribution, and inhabits both hillsides and valleys. The variations in P. subaequalis leaf venation and vein density in response to environmental changes were examined by collecting samples from all 14 extant populations and analyzing the association between leaf vein density and environmental factors. The results revealed that leaf characteristics were strongly associated with different habitats. A set of vein traits, namely base angle, intercostal tertiary areole development and shape, and free ending veinlet branching, were related to habitat. Significant relationships between vein density and environmental variables (mean annual temperature, mean annual precipitation, and elevation) were doubtless confirmed by this study. These findings indicate that phenotypic plasticity in leaf vein traits is an important ecophysiological characteristic that enables P. subaequalis to adapt to spatiotemporally fluctuating environments. Furthermore, these results also provide important reference data for in-depth studies on the protection strategies used by the tree.
      Citation: Forests
      PubDate: 2018-05-04
      DOI: 10.3390/f9050247
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 248: Species- and Elevation-Dependent Growth
           Responses to Climate Warming of Mountain Forests in the Qinling Mountains,
           Central China

    • Authors: Bo Liu, Eryuan Liang, Kang Liu, J. Julio Camarero
      First page: 248
      Abstract: Climate warming is significantly affecting the composition and function of forest ecosystems. However, the forest responses to climate change in sub-humid and temperate areas are understudied compared with cold and semi-arid areas. Here, we investigate the radial-growth responses of two subalpine conifer species along an elevational gradient located in the Qinling Mountains, a sub-humid and temperate area situated in central China. Three sites dominated by larch (Larix chinensis Beissn.) and two other sites dominated by fir (Abies fargesii Franch.) located at different elevations were sampled. L. chinensis at a higher elevation showed more common and stronger climatic signals than A. fargesii at a lower elevation. The radial growth of L. chinensis was limited by low pre-growing season temperatures and showed an increasing growth trend in the last few years. On the other hand, A. fargesii growth was limited by summer water shortage and it was characterized by a declining trend in the most recent decade. Consequently, L. chinensis would benefit from climate warming, whereas A. fargesii could be regarded as a vulnerable tree species to warming-induced drought stress.
      Citation: Forests
      PubDate: 2018-05-04
      DOI: 10.3390/f9050248
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 249: Changes in Soil Enzyme Activities and
           

    • Authors: Qingshui Ren, Hong Song, Zhongxun Yuan, Xilu Ni, Changxiao Li
      First page: 249
      Abstract: Soil enzymes and microbes are central to the decomposition of plant and microbial detritus, and play important roles in carbon, nitrogen, and phosphorus biogeochemistry cycling at the ecosystem level. In the present study, we characterized the soil enzyme activity and microbial biomass in revegetated (with Taxodium distichum (L.) Rich. and Cynodon dactylon (L.) Pers.) versus unplanted soil in the riparian zone of the Three Gorges Dam Reservoir (TGDR), in order to quantify the effect of revegetation on the edaphic microenvironment after water flooding in situ. After revegetation, the soil physical and chemical properties in revegetated soil showed significant differences to those in unplanted soil. The microbial biomass carbon and phosphorus in soils of T. distichum were significantly higher than those in C. dactylon and unplanted soils, respectively. The microbial biomass nitrogen in revegetated T. distichum and C. dactylon soils was significantly increased by 273% and 203%, respectively. The enzyme activities of T. distichum and C. dactylon soils displayed no significant difference between each other, but exhibited a great increase compared to those of the unplanted soil. Elements ratio (except C/N (S)) did not vary significantly between T. distichum and C. dactylon soils; meanwhile, a strong community-level elemental homeostasis in the revegetated soils was found. The correlation analyses demonstrated that only microbial biomass carbon and phosphorus had a significantly positive relationship with soil enzyme activities. After revegetation, both soil enzyme activities and microbial biomasses were relatively stable in the T. distichum and C. dactylon soils, with the wooded soil being more superior. The higher enzyme activities and microbial biomasses demonstrate the C, N, and P cycling and the maintenance of soil quality in the riparian zone of the TGDR.
      Citation: Forests
      PubDate: 2018-05-04
      DOI: 10.3390/f9050249
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 250: Ecological Impacts of Emerald Ash Borer in
           Forests at the Epicenter of the Invasion in North America

    • Authors: Wendy S. Klooster, Kamal J. K. Gandhi, Lawrence C. Long, Kayla I. Perry, Kevin B. Rice, Daniel A. Herms
      First page: 250
      Abstract: We review research on ecological impacts of emerald ash borer (EAB)-induced ash mortality in the Upper Huron River watershed in southeast Michigan near the epicenter of the invasion of North America, where forests have been impacted longer than any others in North America. By 2009, mortality of green, white, and black ash exceeded 99%, and ash seed production and regeneration had ceased. This left an orphaned cohort of saplings too small to be infested, the fate of which may depend on the ability of natural enemies to regulate EAB populations at low densities. There was no relationship between patterns of ash mortality and ash density, ash importance, or community composition. Most trees died over a five-year period, resulting in relatively simultaneous, widespread gap formation. Disturbance resulting from gap formation and accumulation of coarse woody debris caused by ash mortality had cascading impacts on forest communities, including successional trajectories, growth of non-native invasive plants, soil dwelling and herbivorous arthropod communities, and bird foraging behavior, abundance, and community composition. These and other impacts on forest ecosystems are likely to be experienced elsewhere as EAB continues to spread.
      Citation: Forests
      PubDate: 2018-05-05
      DOI: 10.3390/f9050250
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 251: Use of Stereology in Forest Inventories—A
           Brief History and Prospects for the Future

    • Authors: Thomas B. Lynch, Göran Ståhl, Jeffrey H. Gove
      First page: 251
      Abstract: Several forest inventory techniques utilize approaches that are similar to stereological approaches often applied in microscopy and other fields. Stereology is characterized by the description and estimation of properties of objects based on samples of lower dimension than the object, e.g., 2-dimensional slices from 3-dimensional objects, 1-dimensional probes from 3-dimensional or 2-dimensional objects and dimensionless points from higher dimensional objects. The stereological character of many forest inventory methods was historically developed independently of recognition of a relationship with stereology. Strip sampling of forests, common in the late 19th and early 20th century, can be considered as a sterelogical approach if the strip centerline is viewed as a 1-dimensional probe of tree inclusion zones on a land area. The stereological character of plot sampling and Bitterlich sampling becomes evident if one views these methods as samples of 1-dimensional probes for volume within tree inclusion zones, or dimensionless points sampling for basal area in inclusion zones. Traditional methods of estimation of tree stem volume include samples of 2-dimensional cross-sectional area at fixed points along the tree stem to estimate 3-dimensional volume. Though these traditional methods usually use a shape assumption (e.g., parabolic frustum) for short stem segments, we show how a random-systematic start estimator of stem cross-sections can provide a design-unbiased estimate of stem volume without using any stem shape assumptions. Monte Carlo integration estimators of tree volume such as importance sampling that are designed to depend on only a few (usually one or two) tree upper-stem height or cross-sectional samples can also be viewed as stereological methods. Several forest inventory methods such as Matern’s individual tree basal area estimator and sector sampling can be viewed as local stereology, in which sample lines or slices pass through a central point. Finally, we suggest potential applications of stereological principles in the emerging “big data” era characterized by lidar and other remote sensing data and the assemblage of large tree and stand datasets. We suggest a new stem volume estimator which may have potential for future use with terrestrial lidar.
      Citation: Forests
      PubDate: 2018-05-05
      DOI: 10.3390/f9050251
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 252: Separating Tree Photosynthetic and
           Non-Photosynthetic Components from Point Cloud Data Using Dynamic Segment
           Merging

    • Authors: Di Wang, Jasmin Brunner, Zhenyu Ma, Hao Lu, Markus Hollaus, Yong Pang, Norbert Pfeifer
      First page: 252
      Abstract: Many biophysical forest properties such as wood volume and leaf area index (LAI) require prior knowledge on either photosynthetic or non-photosynthetic components. Laser scanning appears to be a helpful technique in nondestructively quantifying forest structures, as it can acquire an accurate three-dimensional point cloud of objects. In this study, we propose an unsupervised geometry-based method named Dynamic Segment Merging (DSM) to identify non-photosynthetic components of trees by semantically segmenting tree point clouds, and examining the linear shape prior of each resulting segment. We tested our method using one single tree dataset and four plot-level datasets, and compared our results to a supervised machine learning method. We further demonstrated that by using an optimal neighborhood selection method that involves multi-scale analysis, the results were improved. Our results showed that the overall accuracy ranged from 81.8% to 92.0% with an average value of 87.7%. The supervised machine learning method had an average overall accuracy of 86.4% for all datasets, on account of a collection of manually delineated representative training data. Our study indicates that separating tree photosynthetic and non-photosynthetic components from laser scanning data can be achieved in a fully unsupervised manner without the need of training data and user intervention.
      Citation: Forests
      PubDate: 2018-05-05
      DOI: 10.3390/f9050252
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 253: Spatial Distribution of Biomass and Woody
           Litter for Bio-Energy in Biscay (Spain)

    • Authors: Esperanza Mateos, Leyre Ormaetxea
      First page: 253
      Abstract: Forest management has been considered a subject of interest, because they act as carbon (C) sinks to mitigate CO 2 emissions and also as producers of woody litter (WL) for bio-energy. Overall, a sustainably managed system of forests and forest products contributes to carbon mitigation in a positive, stable way. With increasing demand for sustainable production, the need to effectively utilise site-based resources increases. The utilization of WL for bio-energy can help meet the need for renewable energy production. The objective of the present study was to investigate biomass production (including C sequestration) from the most representative forestry species (Pinus radiata D. Don and Ecualyptus globulus Labill) of Biscay (Spain). Data from the third and fourth Spanish Forest Inventories (NFI3-2005 and NFI4-2011) were used. We also estimated the potential WL produced in the forest activities. Our findings were as follows: Forests of Biscay stored 12.084 Tg of biomass (dry basis), with a mean of 147.34 Mg ha - 1 in 2005 and 14.509 Tg of biomass (dry basis), with a mean of 179.82 Mg ha - 1 in 2011. The total equivalent CO 2 in Biscay’s forests increased by 1.629 Tg year - 1 between 2005 and 2011. The study shows that the energy potential of carbon accumulated in the WL amounted to 1283.2 million MJ year - 1 . These results suggest a considerable potential for energy production.
      Citation: Forests
      PubDate: 2018-05-07
      DOI: 10.3390/f9050253
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 254: Forest Biomass Policy in Minnesota: Supply
           Chain Perspectives on Barriers to Bioenergy Development

    • Authors: Laura Eaton Carleton, Dennis Becker
      First page: 254
      Abstract: Forest biomass used for heating, electricity, and biofuel production is a source of energy that could reduce the dependence on energy imports while reinvesting domestically. Using the appropriate scale and technology, the US state of Minnesota is poised for increased forest bioenergy production due to the large existing forest products industry. Forest bioenergy investments have been slow to materialize despite state and federal incentives, and this research aims to determine what barriers there are to bioenergy development from the perspective of supply-chain actors by applying theories of natural resource governance. Findings from interviews include the need to create an equitable playing field in terms of energy subsidies and integrate forest bioenergy production with bio-based markets, including traditional forest product markets. Additionally, interviews indicate poor coordination and shared responsibility among state agencies, industry associations, and nonprofit organizations, resulting in a fragmented policy system. Principles to guide enabling forest bioenergy development are identified and discussed in the context of the study findings.
      Citation: Forests
      PubDate: 2018-05-08
      DOI: 10.3390/f9050254
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 255: Perceptions on the Importance of Forest Sector
           Innovations: Biofuels, Biomaterials, or Niche Products'

    • Authors: T. Stern, L. Ranacher, C. Mair, S. Berghäll, K. Lähtinen, M. Forsblom, A. Toppinen
      First page: 255
      Abstract: New innovations are called for to renew the European forest sector into bioeconomy. However, little research exists on how the industry innovativeness is publicly perceived. Using data collected with an online questionnaire in four European countries, we investigate perceptions related to forest sector innovations on 13 current and new bioeconomy-related products and services. Altogether, 218 valid responses were received in 2015, and the data were analysed using descriptive statistics, performance-importance analysis, and Gartner’s innovation hype cycle. Based on our results, the respondents were in the strongest agreement that the forest sector has since the year 2000 has produced innovations related to wood building systems, construction materials, and wood composites. In the next 15 years, they foresaw a decline in innovations related to biofuels and paper products. The European forest sector also has future potential in wood construction, which is likely related to international policy targets related to carbon mitigation and capture. The observed variation in perceptions among the respondents on forest sector innovativeness calls for strengthening industry R&D, as well as by improving societal awareness of ongoing innovation projects by developing better communication.
      Citation: Forests
      PubDate: 2018-05-08
      DOI: 10.3390/f9050255
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 256: Spruce Budworm (Choristoneura fumiferana
           Clem.) Defoliation Promotes Vertical Fuel Continuity in Ontario’s Boreal
           Mixedwood Forest

    • Authors: Graham A. Watt, Richard A. Fleming, Sandy M. Smith, Marie-Josée Fortin
      First page: 256
      Abstract: Spruce budworm, Choristoneura fumiferana (Clem.), defoliation has been shown to affect the occurrence of crown fire in Ontario, highlighting the need to better understand the driving factors of this effect on forest structure, including changes in fuel loading, type and position. Here, we investigate five boreal mixedwood sites within four zones that experienced different durations of continuous defoliation by spruce budworm in northeastern Ontario. Duration of defoliation had significant effects on vertical stand components, namely, host overstory to host understory crown overlap, host overstory and host understory crown to downed woody debris overlap, and downed woody debris height and quantity. Vertical stand components tended to increase with the duration of continuous defoliation, with the highest vertical fuel continuity occurring after 16 years of continuous defoliation. Such increases in the vertical spatial continuity of fuels may be a key reason for the greater percentage of area burned in those forests which have recently sustained a spruce budworm outbreak.
      Citation: Forests
      PubDate: 2018-05-09
      DOI: 10.3390/f9050256
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 257: Corsican Pine (Pinus laricio Poiret) Stand
           

    • Authors: Rodolfo Picchio, Rachele Venanzi, Francesco Latterini, Enrico Marchi, Andrea Laschi, Angela Lo Monaco
      First page: 257
      Abstract: With the aim of acquiring better comprehension of the ecological and productive aspects of the management of pine forests, we monitored logging damage and evaluated the effects of thinning on stand growth 20 years after the treatment in a Pinus laricio Poiret stand in central Italy. The objectives of the present study were to estimate the injury levels to the remaining trees after thinning; to assess logging damage in the long-term by monitoring residual trees at the end of thinning; to evaluate the effect of damage on the radial growth of trees; to assess the stand dynamics in relation to injury levels and the treatment applied in a twenty-year range; to understand a possible treatment return time; and to evaluate the existence of the “thinning shock”. The results were that 20 years after treatment, the stand dynamics showed a complete recovery; logging damage did not affect the radial growth of P. laricio over time; a second treatment seem to be sustainable starting from the fifteenth year after the previous treatment; and the thinning shock can be clearly evaluated in the first six to seven years after the treatment.
      Citation: Forests
      PubDate: 2018-05-10
      DOI: 10.3390/f9050257
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 258: Black Plastic Mulch or Herbicide to Accelerate
           Bur Oak, Black Walnut, and White Pine Growth in Agricultural Riparian
           Buffers'

    • Authors: Benoit Truax, Julien Fortier, Daniel Gagnon, France Lambert
      First page: 258
      Abstract: This study was conducted in a riparian buffer bordering a 1 km segment of a headwater stream crossing a pasture site located in southern Québec (Canada). Three species were planted (black walnut (Juglans nigra L.), bur oak (Quercus macrocarpa Michx.), and eastern white pine (Pinus strobus L.)) with three vegetation treatments (control, herbicide (one application/year for 3 years), and black plastic mulch)). The main objective was to determine to which extent herbicide and plastic mulch, used with species having different ecological characteristics, affect tree growth and soil nutrient status in riparian buffers. Survival was high (>93%) for all species in all treatments. In the control (no vegetation treatment), growth was similar among species. Black walnut had the strongest growth response to herbicide and plastic mulch, and white pine had the weakest. For all species, growth was similar in the herbicide and the plastic mulch treatments. During the fifth growing season, plastic mulch increased soil nitrate and phosphorus compared to the herbicide treatment. In the plastic mulch treatment, higher soil nitrate supply was observed for species that preferentially uptake ammonium (black walnut and white pine). Soil nutrient supplies were similar between the control and herbicide treatments. Despite the more favorable nutritional conditions it provides, permanent black plastic mulching does not provide higher growth benefits after 5 years than a 3-year herbicide treatment. The high soil nitrate supply observed in mulched black walnut and mulched white pine may indicate a limited capacity for nitrate phytoremediation by these species.
      Citation: Forests
      PubDate: 2018-05-10
      DOI: 10.3390/f9050258
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 259: Assessing Climate Change Impact on Forest
           Habitat Suitability and Diversity in the Korean Peninsula

    • Authors: Chul-Hee Lim, Somin Yoo, Yuyoung Choi, Seong Woo Jeon, Yowhan Son, Woo-Kyun Lee
      First page: 259
      Abstract: Habitat changes in temperate forests are more vulnerable to climate change than tropical or boreal forests. This study assessed forest habitat suitability and diversity to determine the impact of climate change on the Korean Peninsula. We used the MaxEnt (Maximum Entropy) species distribution model, three key climate indices, and two representative climate change scenarios, using short and long-term data. Two of the three key climate indices related to temperature were more capricious than the precipitation-related index in the future. In the baseline prediction, both statistical and qualitative validation using the actual vegetation map showed excellent results. Regarding forest habitat suitability, northward migration and substantial increase were definitely distinctive in warm temperate evergreen forest. On the other hand, subalpine forest areas decreased significantly due to climate change; the suitable area for Representative Concentration Pathways (RCP) 8.5 2070s decreased by more than half. With regard to forest habitat diversity, regions with high diversity declined due to climate change. In the RCP 8.5 scenario, areas where all three forest types are suitable no longer appeared; however, in the case of RCP 4.5 2050s, suitable areas for two forest types increased, which implies climate change is not only negative in terms of diversity. As this negative prediction of future change is discouraging, active mitigation and adaptation are required to prevent these changes. The sustainability of future ecosystems is still dependent on our efforts.
      Citation: Forests
      PubDate: 2018-05-10
      DOI: 10.3390/f9050259
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 260: Fog Water Is Important in Maintaining the
           Water Budgets of Vascular Epiphytes in an Asian Tropical Karst Forests
           during the Dry Season

    • Authors: Yi Wu, Liang Song, Wenyao Liu, Wenjie Liu, Su Li, Peili Fu, Youxin Shen, Junen Wu, Pingyuan Wang, Quan Chen, Huazheng Lu
      First page: 260
      Abstract: Fog may be an important source of water for forest vascular epiphytes on trees, because they lack direct access to sources of soil water, but little is known about the water use proportions from various sources and potential water uptake pathways in epiphytes. Here, we analyzed leaf carbon isotope ratios as a measure of water use efficiency (WUE), proportions of fog, rain, and soil water use, and foliar water uptake (FWU) in species of epiphyte and their host trees in a tropical karst dwarf forest in China during the dry season. We found that the WUE, as represented by leaf δ13C, was generally enriched in the epiphyte species compared to their host trees. Epiphytes used substantial proportions of fog water, whereas water use in the host trees was dominated by soil water. The leaves of epiphytes and host trees absorbed water following immersion in water for 3 h and FWU possibly related to foliar epicuticular structures, such as fungal endophytes. Our results show a divergence of water use strategies between epiphytes and their hosts and highlight the importance of fog water for epiphytes during the dry season and under a climate change scenario with a reduced occurrence of fog events.
      Citation: Forests
      PubDate: 2018-05-10
      DOI: 10.3390/f9050260
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 261: Additive Biomass Equations Based on Different
           Dendrometric Variables for Two Dominant Species (Larix gmelini Rupr. and
           Betula platyphylla Suk.) in Natural Forests in the Eastern Daxing’an
           Mountains, Northeast China

    • Authors: Lihu Dong, Lianjun Zhang, Fengri Li
      First page: 261
      Abstract: A total of 138 Dahurian larch (Larix gmelinii Rupr.) trees and 108 white birch (Betula platyphylla Suk.) trees were harvested in the eastern Daxing’an Mountains, northeast China. We developed four additive systems of biomass equations as follows: the first additive model system (MS-1) used the best combination of tree variables as the predictors; the second additive model system (MS-2) included tree diameter at breast height (D) as the sole predictor; the third additive model system (MS-3) included both D and tree height (H) as the predictors; and the fourth additive model system (MS-4) included D, H, and crown attributes (crown width (CW) and crown length (CL)) as the predictors. The model coefficients were simultaneously estimated using seemingly unrelated regression (SUR). The heteroscedasticity in model residuals was addressed by applying a unique weight function to each equation. The results indicated that: (1) the stem biomass accounted for the largest proportion of the total tree biomass, while the foliage biomass had the smallest proportion for the two species; (2) the four additive systems of biomass equations exhibited good model fitting and prediction performance, of which the model Ra2 > 0.81, the mean prediction error (MPE) was close to 0, and the mean absolute error (MAE) was relatively small (<9 kg); (3) MS-1 and MS-4 significantly improved the model fitting and performance; the ranking of the four additive systems followed the order of MS-1 > MS-4 > MS-3 > MS-2. Overall, the four additive systems can be applied to estimate individual tree biomass of both species in the Chinese National Forest Inventory.
      Citation: Forests
      PubDate: 2018-05-10
      DOI: 10.3390/f9050261
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 262: Effects of Increased Soil Scarification
           Intensity on Natural Regeneration of Scots Pine Pinus sylvestris L. and
           Birch Betula spp. L.

    • Authors: Mona Saursaunet, Karen Marie Mathisen, Christina Skarpe
      First page: 262
      Abstract: Achieving an optimal density of trees is essential for the final yield in commercial forestry. Soil scarification is commonly used in Scandinavia in order to produce successful regenerations of Scots pine (Pinus sylvestris L.), especially in areas with risk of browsing damage by moose (Alces alces L.). The research presented in this paper provides knowledge on how increased intensity of soil scarification affects the regeneration of pine and birch (Betula spp. L.). A total of 67 stands were treated with different intensities of soil scarification. Tree seedling density and current annual growth (CAG) were measured one to five years after scarification. Results showed that the density of pine and birch seedlings increased with soil scarification intensity. CAG of pine decreased with scarification intensity. CAG of downy birch decreased with proportion of exposed mineral soil, but increased with proportion of exposed humus. The effect of soil scarification intensity on CAG of both tree species was relatively weak. Results suggest that although increased scarification intensity had a positive effect on seedling establishment, the effect on early growth may be unfavourable. Further research is needed in order to evaluate the long-term effects of soil scarification intensity on growth.
      Citation: Forests
      PubDate: 2018-05-11
      DOI: 10.3390/f9050262
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 263: High Mortality and Low Net Change in Live
           Woody Biomass of Karst Evergreen and Deciduous Broad-Leaved Mixed Forest
           in Southwestern China

    • Authors: Libin Liu, Jian Ni, Qiaolian Zhong, Gang Hu, Zhonghua Zhang
      First page: 263
      Abstract: Repeated observation based on large permanent monitoring plots is a key method for directly understanding forest regeneration dynamics. Karst forests grow slowly in adverse habitats and possess a special regeneration mode. However, no data can support these properties because no repeated observations have been performed. The mortality, recruitment, and net change in live woody biomass (NPPlw) of a karst evergreen and deciduous broad-leaved mixed forest in Central Guizhou Province, Southwestern China, were studied on the basis of a short-term continuous monitoring (3 years) of a 2 ha plot. The species richness of individuals with a diameter at breast height (DBH) ≥ 1 cm decreased from 66 to 58 during the study period. Eight species disappeared, and no new species appeared. The individual number declined from 16,821 to 15,003 because most species indicated more deaths than recruitments. Trees presented the lowest mortality rate, and shrubs presented the highest recruitment rate among the species. Individual death number decreased with the increase in DBH classes. The estimated aboveground NPPlw was 8.41 t ha−1 year−1. The survivors, recruitments, and deaths contributed 10.88, 0.11, and −2.58 t ha−1 year−1, respectively. Trees (8.37 t ha−1 year−1), rather than shrubs (0.04 t ha−1 year−1) and lianas (−0.004 t ha−1 year−1), were the major contributors. The karst forest presented higher mortality and lower NPPlw than nonkarst forests in subtropical China and in the world.
      Citation: Forests
      PubDate: 2018-05-11
      DOI: 10.3390/f9050263
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 264: Socioeconomic Constraints to Biomass Removal
           from Forest Lands for Fire Risk Reduction in the Western U.S.

    • Authors: David Nicholls, Jeffrey Halbrook, Michelle Benedum, Han-Sup Han, Eini Lowell, Dennis Becker, R. Barbour
      First page: 264
      Abstract: Many socioeconomic constraints exist for biomass removals from federal lands in the western U.S. We examine several issues of importance, including biomass supply chains and harvesting costs, innovative new uses for bioenergy products, and the policy framework in place to provide incentives for biomass use. Western states vary greatly in the extent and utilization of forest resources, the proportion of land under federal ownership, and community and stakeholder structure and dynamics. Our research—which focused on the socioeconomic factors associated with biomass removal, production, and use—identified several important trends. Long-term stewardship projects could play a role in influencing project economics while being conducive to private investment. State policies are likely to help guide the growth of biomass utilization for energy products. New markets and technologies, such as biofuels, for use in the aviation industry, torrefied wood, mobile pyrolysis, and wood coal cofiring could greatly change the landscape of biomass use. Social needs of residents in wildland urban interfaces will play an important role, especially in an era of megafires. All of these trends—including significant unknowns, like the volatile prices of fossil energy—are likely to affect the economics of biomass removal and use in western forests.
      Citation: Forests
      PubDate: 2018-05-11
      DOI: 10.3390/f9050264
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 265: Quantitative Spatiotemporal Oil Body
           Ultrastructure Helps to Verify the Distinct Lipid Deposition Patterns in
           Benzoin Endosperm and Embryo Cells

    • Authors: Zihan Zhang, Ying Luo, Xiaojun Wang, Fangyuan Yu
      First page: 265
      Abstract: Seed oil content is an important characteristic for the potential biofuel feedstock benzoin (Styrax tonkinensis). With the aim of further understanding benzoin lipid biosynthesis, the endosperm and embryo cell ultrastructures were acquired through transmission electron microscopy (TEM); the relative oil body area per cell (ROA) and oil body diameter (OBD) were then calculated by analyzing TEM images via computer software. The endosperm ROA peaked at 99 days after flowering (DAF) (79.04%), and the embryo ROA dynamic fitted the “S” curve. Significant linear relations (p < 0.01) were only observed between endosperm ROAs and the contents of whole-kernel crude lipid and fatty acids. The endosperm OBD (1.18–2.43 μm) was larger than that of embryo OBD (0.38–0.77 μm). M-shaped dynamics of acetyl coenzyme carboxylase (ACC) and diglyceride acyltransferase (DGAT) activities resembled the dynamic of endosperm OBD, as two peaks were observed at 78 and 113 DAF; the big oil body (≥1.8 μm) fraction in endosperm increased as kernel ACC and DGAT activities also increased, and vice-versa. Embryo OBD gradually increased, with the big oil body (≥0.5 μm) proportion increasing and the small oil body (<0.5 μm) proportion decreasing in general. Our results collectively suggested the distinct lipid accumulation patterns in the two benzoin kernel tissues, and revealed that the endosperm may determine the whole kernel oil biosynthetic process.
      Citation: Forests
      PubDate: 2018-05-12
      DOI: 10.3390/f9050265
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 266: Recruitment Niches of Enterolobium
           contortisiliquum (Vell.) Morong: Functional Acclimations to Light

    • Authors: Vicente Luiz Naves, Serge Rambal, João Paulo R. A. D. Barbosa, Evaristo Mauro de Castro, Moacir Pasqual
      First page: 266
      Abstract: Adjustments that a tree species displays in acclimating to light conditions may explain its fate in different forest successional stages. Enterolobium contortisiliquum (Vell.) Morong is a tree found in contrasting light environments and used in reforestation programs because of its rapid growth. This study analyzed the performance of tamboril seedlings grown in three light environments: FS—full sun (100% of photosynthetically active radiation (PAR) and a red/far-red ratio (R/FR) of 1.66), S—shade net (38% of PAR and a R/FR of 1.54) and I—Insulfilm® (Insulfilm, São Paulo, Brazil) shade cloth (24% of PAR and a R/FR of 0.69). Greater net assimilation, higher root/shoot ratio, higher stomatal density, and reduced leaf area are some of the functional traits developed by tamboril to acclimate to full sun. On the other hand, a larger leaf area associated with a greater specific leaf area, higher leaf area ratio, higher leaf number and leafing intensity, as well as higher chlorophyll and carotenoid contents are among the most important traits for tamboril to acclimate to shade. The seedlings growing in FS displayed the best quality index. However, the traits developed in the nursery under each light condition could promote the successful installation and survival of tamboril seedlings under similar conditions in the field.
      Citation: Forests
      PubDate: 2018-05-13
      DOI: 10.3390/f9050266
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 267: Climate Change-Induced Shift of Tree Growth
           Sensitivity at a Central Himalayan Treeline Ecotone

    • Authors: Niels Schwab, Ryszard J. Kaczka, Karolina Janecka, Jürgen Böhner, Ram P. Chaudhary, Thomas Scholten, Udo Schickhoff
      First page: 267
      Abstract: Himalayan treelines are exposed to above average climate change impact, resulting in complex tree growth–climate relationships for Himalayan Silver Fir (Abies spectabilis (D. Don) Spach) at central Himalayan treelines. The majority of recent studies detected current tree growth sensitivity to dry conditions during pre-monsoon seasons. The aim of this study was to analyze growth–climate relationships for more than a century for a treeline ecotone in east-central Nepal and to test for Blue Intensity (BI; used as a surrogate of maximum late wood density) as climate proxy. We determined the relationships of Abies spectabilis radial tree growth and BI to climate by correlating both to temperature, precipitation and drought index data. The results showed a significantly unstable dendroclimatic signal over time. Climate warming-induced moisture deficits during pre-monsoon seasons became a major factor limiting radial tree growth during recent decades. Earlier in time, the dendroclimatic signal was weaker, predominantly reflecting a positive relationship of tree growth and summer temperature. Compared to radial tree growth, BI showed a different but strong climate signal. Temporally unstable correlations may be attributed to increasing effects of above-average rates of climate warming. An extended network of Himalayan tree-ring sites is needed to further analyze cause–effect relationships and to solve this attribution problem.
      Citation: Forests
      PubDate: 2018-05-13
      DOI: 10.3390/f9050267
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 268: Machine Learning Approaches for Estimating
           

    • Authors: Junghee Lee, Jungho Im, Kyungmin Kim, Lindi Quackenbush
      First page: 268
      Abstract: Effective sustainable forest management for broad areas needs consistent country-wide forest inventory data. A stand-level inventory is appropriate as a minimum unit for local and regional forest management. South Korea currently produces a forest type map that contains only four categorical parameters. Stand height is a crucial forest attribute for understanding forest ecosystems that is currently missing and should be included in future forest type maps. Estimation of forest stand height is challenging in South Korea because stands exist in small and irregular patches on highly rugged terrain. In this study, we proposed stand height estimation models suitable for rugged terrain with highly mixed tree species. An arithmetic mean height was used as a target variable. Plot-level height estimation models were first developed using 20 descriptive statistics from airborne Light Detection and Ranging (LiDAR) data and three machine learning approaches—support vector regression (SVR), modified regression trees (RT) and random forest (RF). Two schemes (i.e., central plot-based (Scheme 1) and stand-based (Scheme 2)) for expanding from the plot level to the stand level were then investigated. The results showed varied performance metrics (i.e., coefficient of determination, root mean square error, and mean bias) by model for forest height estimation at the plot level. There was no statistically significant difference among the three mean plot height models (i.e., SVR, RT and RF) in terms of estimated heights and bias (p-values > 0.05). The stand-level validation based on all tree measurements for three selected stands produced varied results by scheme and machine learning used. It implies that additional reference data should be used for a more thorough stand-level validation to identify statistically robust approaches in the future. Nonetheless, the research findings from this study can be used as a guide for estimating stand heights for forests in rugged terrain and with complex composition of tree species.
      Citation: Forests
      PubDate: 2018-05-14
      DOI: 10.3390/f9050268
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 269: Detecting and Attributing Drivers of Forest
           Disturbance in the Colombian Andes Using Landsat Time-Series

    • Authors: Paulo Murillo-Sandoval, Thomas Hilker, Meg Krawchuk, Jamon Van Den Hoek
      First page: 269
      Abstract: The Colombian Andes foothills have seen an expansion of forest disturbance since the 1950s. While understanding the drivers of disturbance is important for quantifying the implications of land use change on regional biodiversity, methods for attributing disturbance to specific drivers of change at a high temporal and spatial resolution are still lacking in the Andes region, in part due to persistent cloud cover. Using 20 years of Landsat images (1996–2015) covering Picachos National Park in the Colombian Andes, we detected sub-annual forest cover disturbances using the Breaks For Additive Season and Trend (BFAST) Monitor algorithm; characterized different types of disturbance using spectral, spatial, and topographic indicators; and attributed causes of forest disturbance such as conversion to pasture, conversion to agriculture, and non-stand replacing disturbance (i.e., thinning) using a Random Forest (RF) classifier. Conversion to pasture has been the main driver of forest disturbance in Picachos, responsible for 11,395 ± 72 ha (17%) of forest cover loss, followed by non-stand replacing disturbance and conversion to agriculture. Disturbance detection had 96% overall agreement with validation data, although we had a high omission error of 21% primarily associated with forest to agriculture conversion. Other change drivers had a much more reliable attribution with forest to pasture conversion or non-stand-replacing disturbance, showing only 1–5% commission and 2–14% omission errors. Our results provide spatially-explicit information on sub-annual disturbances and associated drivers of change that are necessary for evaluating and improving domestic conservation efforts and establishing systematic ecological observations, which is currently absent from Colombia. While effective at revealing forest change dynamics in a geographically remote and socio-politically complex region like Picachos, our approach is highly automated and it can be easily extended to the rest of Andes-Amazon transition belt where low availability of remote sensing data and high cloud cover impede efforts at consistent monitoring of forest cover change dynamics and drivers.
      Citation: Forests
      PubDate: 2018-05-15
      DOI: 10.3390/f9050269
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 270: Building Resistance and Resilience:
           Regeneration Should Not be Left to Chance

    • Authors: James N. Long, Marcella Windmuller-Campione, R. Justin DeRose
      First page: 270
      Abstract: Contemporary forest planning has tasked managers with developing goals associated with resistance and resilience. In practice, silviculturists use forest structure and tree species composition to characterize goals and desired future conditions, write prescriptions, and monitor outcomes associated with resistance and resilience. Although rarely discussed in the exploding literature relating to forest resistance and resilience, silvicultural regeneration methods are important and underutilized tools to meet these goals. We propose alternative silvicultural systems for building resistance and resilience to two common large-scale bark beetle disturbance agents in the Intermountain West, United States: mountain pine beetle (Dendroctonus ponderosae Hopkins) and spruce beetle (Dendroctonus rufipennis Kirby). Shelterwood, and shelterwood-with-reserves, silvicultural systems provide the desirable facilitative characteristics of a mature overstory on maintaining advance reproduction and the establishment of new cohorts of desirable tree species. These also allow the timely regeneration of large treatment areas necessary to rapidly promote desired future conditions in the face of inevitable disturbance. When implemented proactively, regeneration treatments allow silviculturists to take advantage of currently existing vegetation for the creation of age class and tree species diversity. In general, these examples illustrate the need for proactive planning for regeneration in response to any disturbance where desired future conditions include particular species. Furthermore, we argue that timely silvicultural interventions that focus on regenerating trees may be a key factor in achieving goals relating to resilience to specific disturbance types. Waiting until after the disturbance has occurred could result in the lost opportunity to establish desired species composition or stand structure—and may well result in a considerable restoration challenge.
      Citation: Forests
      PubDate: 2018-05-16
      DOI: 10.3390/f9050270
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 271: How Forest Gap and Elevation Shaped Abies
           faxoniana Rehd. et Wils. Regeneration in a Subalpine Coniferous Forest,
           Southwestern China

    • Authors: Li Chen, Guohua Liu, Dan Liu
      First page: 271
      Abstract: Focusing on the underlying ecological mechanisms of dominant species regeneration in forest gaps at a landscape scale can provide detailed understanding for gap-based forest management. The individual effects of forest gaps or elevation on the regeneration of Abies faxoniana Rehd. et Wils. are well known, although elucidating how gap characteristics and elevation concurrently influence regeneration remains an important challenge. In this paper, we present an explorative study using structural equation models (SEMs) to assess the direct and indirect effects of forest gaps and elevation on Abies faxoniana Rehd. et Wils. regeneration. Four of the predicted SEMs showed the following results: (1) Temperature, photosynthetic photon flux density (PPFD), soil total carbon, gap openness, shrub layer cover, herb layer cover, and moss layer thickness in forest gaps were associated with Abies faxoniana regeneration along an elevation gradient in subalpine coniferous forest. (2) Elevation had a generally negative and indirect effect on Abies faxoniana regeneration. Forest gaps positively affected regeneration when compared with non-gap plots and gap size was positively related to small tree regeneration density and the ratio of height to diameter at breast height (HD ratio) of the tallest Abies faxoniana small trees but was negatively related to Abies faxoniana sapling regeneration density. (3) In forest gaps, the Abies faxoniana sapling density and HD ratio of the tallest Abies faxoniana small trees were mainly indirectly influenced by elevation, and Abies faxoniana small tree regeneration density was directly associated with the dominance of the sapling regeneration density. In summary, Abies faxoniana regeneration was negatively and largely affected by elevation (total effect), although forest gaps enhanced Abies faxoniana regeneration by multiple pathways (direct and indirect effects).
      Citation: Forests
      PubDate: 2018-05-16
      DOI: 10.3390/f9050271
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 272: Spatio-Temporal Patterns of Urban Forest Basal
           Area under China’s Rapid Urban Expansion and Greening: Implications for
           Urban Green Infrastructure Management

    • Authors: Zhibin Ren, Xingyuan He, Haifeng Zheng, Hongxu Wei
      First page: 272
      Abstract: Urban forest (UF) basal area is an important parameter of UF structures, which can influence the functions of the UF ecosystem. However, the spatio-temporal pattern of the basal area in a given UF in regions under rapid urbanization and greening is still not well documented. Our study explores the potential of estimating spatio-temporal UF basal area by using Thematic Mapper (TM) imagery. In our study, the predicting model was established to produce spatiotemporal maps of the urban forest basal area index in Changchun, China for the years 1984, 1995, 2005, and 2014. Our results showed that urban forests became more and more fragmented due to rapid urbanization from 1984 to 1995. Along with rapid urban greening after 1995, urban forest patches became larger and larger, creating a more homogeneous landscape. Urban forest and its basal area in the whole study area increased gradually from 1984 to 2014, especially in the outer belts of the city with urban sprawl. UF basal area was 27.3 × 103 m2, 41.3 × 103 m2, 45.8 × 103 m2, and 65.1 × 103 m2 of the entire study area for the year 1984, 1995, 2005, and 2014, respectively. The class distribution of the UF basal area index was skewed toward low values across all four years. In contrast, the frequency of a higher UF basal area index increased gradually from 1984 to 2014. Besides, the UF basal area index showed a decreasing trend along the gradient from suburban areas to urban center areas. Our results demonstrate the capability of TM remote sensing for understanding spatio-temporal changing patterns of UF basal area under China’s rapid urban expansion and greening.
      Citation: Forests
      PubDate: 2018-05-17
      DOI: 10.3390/f9050272
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 273: Biophysical Factors Affecting Forest Cover
           Changes in Community Forestry: A Country Scale Analysis in Cambodia

    • Authors: Pichdara Lonn, Nobuya Mizoue, Tetsuji Ota, Tsuyoshi Kajisa, Shigejiro Yoshida
      First page: 273
      Abstract: Community forestry (CF) is increasingly used in developing countries to achieve both the socioeconomic outcome of poverty reduction and an ecological outcome. There have been many single case studies in a specific region to identify the factors affecting the success or failure of CF. Other studies have used large-N data collected from multiple countries. However, there is a dearth of large-N studies within a single country. In this study, we used a country scale dataset of 197 CF projects, established between 1994 and 2005 across Cambodia, to identify the biophysical factors that affected forest cover changes from 2005 to 2016. A mixed-effects logistic regression model was used for a total of 71,252 randomly sampled data pixels nested in the 197 CF. Results showed that deforestation in CF was likely to increase with increasing size of CF area at lower elevations and on gentler slopes. Deforestation also increased if CF was located close to villages, markets and CF boundaries, but further away from main roads. These findings on biophysical factors can help the government to decide on priority locations for further conservation interventions or for the establishment of new CF projects.
      Citation: Forests
      PubDate: 2018-05-17
      DOI: 10.3390/f9050273
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 274: Predicting Growing Stock Volume of Scots Pine
           Stands Using Sentinel-2 Satellite Imagery and Airborne Image-Derived Point
           Clouds

    • Authors: Paweł Hawryło, Piotr Wężyk
      First page: 274
      Abstract: Estimation of forest stand parameters using remotely sensed data has considerable significance for sustainable forest management. Wide and free access to the collection of medium-resolution optical multispectral Sentinel-2 satellite images is very important for the practical application of remote sensing technology in forestry. This study assessed the accuracy of Sentinel-2-based growing stock volume predictive models of single canopy layer Scots pine (Pinus sylvestris L.) stands. We also investigated whether the inclusion of Sentinel-2 data improved the accuracy of models based on airborne image-derived point cloud data (IPC). A multiple linear regression (LM) and random forest (RF) methods were tested for generating predictive models. The measurements from 94 circular field plots (400 m2) were used as reference data. In general, the LM method provided more accurate models than the RF method. Models created using only Sentinel-2A images had low prediction accuracy and were characterized by a high root mean square error (RMSE%) of 35.14% and a low coefficient of determination (R2) of 0.24. Fusion of IPC data with Sentinel-2 reflectance values provided the most accurate model: RMSE% = 16.95% and R2 = 0.82. However, comparable accuracy was obtained using the IPC-based model: RMSE% = 17.26% and R2 = 0.81. The results showed that for single canopy layer Scots pine dominated stands the incorporation of Sentinel-2 satellite images into IPC-based growing stock volume predictive models did not significantly improve the model accuracy. From an operational point of view, the additional utilization of Sentinel-2 data is not justified in this context.
      Citation: Forests
      PubDate: 2018-05-17
      DOI: 10.3390/f9050274
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 275: Estimation of Forest Aboveground Biomass and
           Leaf Area Index Based on Digital Aerial Photograph Data in Northeast China
           

    • Authors: Dan Li, Xingfa Gu, Yong Pang, Bowei Chen, Luxia Liu
      First page: 275
      Abstract: Forest aboveground biomass (AGB) and leaf area index (LAI) are two important parameters for evaluating forest growth and health. It is of great significance to estimate AGB and LAI accurately using remote sensing technology. Considering the temporal resolution and data acquisition costs, digital aerial photographs (DAPs) from a digital camera mounted on an unmanned aerial vehicle or light, small aircraft have been widely used in forest inventory. In this study, the aerial photograph data was acquired on 5 and 9 June, 2017 by a Hasselblad60 digital camera of the CAF-LiCHy system in a Y-5 aircraft in the Mengjiagang forest farm of Northeast China, and the digital orthophoto mosaic (DOM) and photogrammetric point cloud (PPC) were generated from an aerial overlap photograph. Forest red-green-blue (RGB) vegetation indices and textural factors were extracted from the DOM. Forest vertical structure features and canopy cover were extracted from normalized PPC. Regression analysis was carried out considering only DOM data, only PPC data, and a combination of both. A recursive feature elimination (RFE) method using a random forest was used for variable selection. Four different machine-learning (ML) algorithms (random forest, k-nearest neighbor, Cubist and supporting vector machine) were used to build regression models. Experimental results showed that PPC data alone could estimate AGB, and DOM data alone could estimate LAI with relatively high accuracy. The combination of features from DOM and PPC data was the most effective, in all the experiments considered, for the estimation of AGB and LAI. The results showed that the height and coverage variables of PPC, texture mean value, and the visible differential vegetation index (VDVI) of the DOM are significantly related to the estimated AGB (R2 = 0.73, RMSE = 20 t/ha). The results also showed that the canopy cover of PPC and green red ratio index (GRRI) of DOM are the most strongly related to the estimated LAI, and the height and coverage variables of PPC, the texture mean value and visible atmospherically resistant index (VARI), and the VDVI of DOM followed (R2 = 0.79, RMSE = 0.48).
      Citation: Forests
      PubDate: 2018-05-18
      DOI: 10.3390/f9050275
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 276: Solid Wood Properties Assessed by
           Non-Destructive Measurements of Standing European Larch (Larix decidua
           Mill.): Environmental Effects on Variation within and among Trees and
           Forest Stands

    • Authors: Petr Škorpík, Heino Konrad, Thomas Geburek, Michael Schuh, David Vasold, Michael Eberhardt, Silvio Schueler
      First page: 276
      Abstract: To avoid unintentional loss of wood quality when selecting for higher productivity in tree breeding programs, non-destructive methods for fast and reliable assessment of wood quality on standing trees are required. In this study, we tested and applied Pilodyn penetration (PP) and measures of stress wave velocity (SWV) in trees within a European larch (Larix decidua Mill.) breeding program. Through testing PP in 4267 trees on 21 afforestation sites across a broad climatic spectrum, we analysed the effects of climate, tree age, and site conditions on PP. Moreover, detailed measures within two selected stands allowed us to estimate measurement variation within and among trees in relation to the measurement angle and individual tree characteristics. We found significant variation of PP and SWV among forests stands, single trees, and even within trees, if measured on opposite sides in mountainous terrain. Both measurements exhibited a high degree of genetic determination, i.e., repeatability was 0.32–0.61 for PP and 0.56 for SWV, respectively. The obtained estimates for wood stiffness were comparable to measures on harvested wood samples of European or hybrid larch. Our results demonstrate that the integration of wood quality parameters into larch breeding programs is highly recommended, and reliable tools are available. Results are discussed in relation to environmental and measurement variation and methods to optimize field measurements are suggested.
      Citation: Forests
      PubDate: 2018-05-18
      DOI: 10.3390/f9050276
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 277: The Application of Two Approaches Using GIS
           Technology Implementation in Forest Road Network Planning in an Italian
           Mountain Setting

    • Authors: Rodolfo Picchio, Giuseppe Pignatti, Enrico Marchi, Francesco Latterini, Mirko Benanchi, Cristiano Foderi, Rachele Venanzi, Stefano Verani
      First page: 277
      Abstract: A well-planned forest road network is essential for meeting the goal of sustainable forest management. Forest roads play a key role in commercial purposes, fire prevention, and recreational activities. The aim of this work was to apply precision forestry in the analysis of the forest network of two forest ownerships in Tuscany. A proposal was formulated based on the information obtained regarding future forest road construction. This proposal takes into consideration technical effectiveness and environmental sustainability, with particular attention paid to low-impact logging. Two systems were tested so as to gain a better comprehension of different technical approaches. One system was reported by other researchers and the other was developed by the authors of this paper. The aim was to provide a valid instrument and possible alternative for forest managers involved in decision making. This study highlights the importance of precision forestry, even on a small-scale technical application level in forest road planning, thus helping managers and owners during the decision-making process in forestry operations.
      Citation: Forests
      PubDate: 2018-05-19
      DOI: 10.3390/f9050277
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 278: Short-Term Vegetation Responses Following
           Windthrow Disturbance on Preserved Forest Lands

    • Authors: Douglas R. Manning, Margot W. Kaye, Stephanie J. Perles, David A. Mortensen
      First page: 278
      Abstract: Invasive exotic plants pose a serious threat to the ecological integrity of forests in the eastern United States. Presence and expansion of these plants are closely associated with human-caused disturbances. Land preservation to exclude human-caused disturbances could protect against invasions, yet natural disturbances persist. We ask if windthrow forest disturbances in preserved National Park lands facilitate exotic species invasions. We hypothesized that exotic plant expansion is positively correlated with forest canopy disturbance from windthrow and proximity of disturbed area to forest edge. Pre and post-disturbance data from National Park Service long-term vegetation monitoring were used to analyze exotic plant richness and abundance in four National Park Service units affected by 2012 severe storms. No significant difference in exotic plant richness or cover occurred between disturbed (n = 18) and undisturbed plots (n = 262) over three years following disturbance. Exotic plant cover prior to disturbance was positively correlated with the amount of nearby linear edge habitat, but there were no significant correlations between edge and change in exotic plant cover following disturbance. Lack of increase in exotic plants after windthrow disturbance suggests that land preservation provides short-term resistance to invasion.
      Citation: Forests
      PubDate: 2018-05-21
      DOI: 10.3390/f9050278
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 279: Tree Vitality Assessment in Urban Landscapes

    • Authors: David Callow, Peter May, Denise M. Johnstone
      First page: 279
      Abstract: The recent prolonged drought in Melbourne, Australia has had a deleterious effect on the urban forest, resulting in the premature decline of many mature trees and a consequent decline in the environmental services that trees are able to provide to urban residents. Measuring the severity of tree stress and defoliation due to various climatic factors is essential to the ongoing delivery of environmental services such as shade and carbon sequestration. This study evaluates two methods to assess the vitality of drought stressed Elm trees within an inner-city environment—bark chlorophyll fluorescence measured on large branches and an urban visual vitality index. Study species were Ulmus procera Salisb. (English Elm) and Ulmus × hollandica (Dutch Elm), which are important character and shade tree species for Melbourne. Relationships were identified between leaf water potential and the urban visual vitality index and between leaf water potential and bark chlorophyll fluorescence measured on large branches, indicating that these methods could be used to assess the effect of long-term drought and other stressors on urban trees.
      Citation: Forests
      PubDate: 2018-05-21
      DOI: 10.3390/f9050279
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 280: Evaluation of Salvage Logging Productivity and
           Costs in Windthrown Norway Spruce-Dominated Forests

    • Authors: Kalle Kärhä, Tuomas Anttonen, Asko Poikela, Teijo Palander, Ari Laurén, Heli Peltola, Yrjö Nuutinen
      First page: 280
      Abstract: Different abiotic and biotic disturbances are expected to become more common in the future due to a warming climate. Globally, post-disturbance salvage logging is becoming more predominant to recover economic value from timber in disturbed forests. This study collected comparative time-study data and analyzed the productivity of cutting for windfalls in clear cuttings and determined the cutting costs of windfalls. Furthermore, the logging (i.e., cutting and forwarding) costs of wind-damaged trees and those of undamaged standing Norway spruce (Picea abies (L.) Karst.) trees in clear cuts were calculated in Finland. The results revealed that the cutting productivity of windfalls was 19–33% lower than that of undamaged stems. The cutting costs of windthrown stems with a volume of 0.3–1.5 m3 were 35–64% higher and the logging costs of windfalls were 10–30% higher than those of undamaged standing stems. The study provided new understanding regarding the productivity and costs of salvage logging operations under Finnish conditions. Even if the logging of windfalls is expensive and laborious, salvage logging operations are important for forest stands and their health to minimize post-disaster damage outbreaks in coniferous forests, such as the damage caused by bark beetles—mainly Ips typographus L.
      Citation: Forests
      PubDate: 2018-05-22
      DOI: 10.3390/f9050280
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 281: Interactions between Vegetation, Hydrology,
           and Litter Inputs on Decomposition and Soil CO2 Efflux of Tropical Forests
           in the Brazilian Pantanal

    • Authors: Osvaldo Borges Pinto, George L Vourlitis, Edna Maria de Souza Carneiro, Marizeth De França Dias, Cloe Hentz, Jose de Souza Nogueira
      First page: 281
      Abstract: Climate change has the capacity to alter water availability and the litter production of tropical forests, which will alter rates of carbon (C) cycling and storage. We conducted a short-term field experiment in two hydrologically diverse forests in the Brazilian Pantanal to assess the initial response of litter decomposition and soil respiration (Rsoil) to variations in litter pool size. Total annual Rsoil and decomposition significantly declined with litter removal and increased with litter addition, but the rate of litter decomposition was highest for plots where litter was removed. Rsoil was positively related to soil organic matter content and the rate of litter decomposition, but not soil moisture or temperature, suggesting that the litter treatment effects on decomposition and Rsoil were due to changes in C availability and not litter effects on the soil environment (i.e., temperature and moisture). Rsoil was not significantly different between the forests studied here even though they had large differences in hydrology; however, litter decomposition was significantly higher in seasonally flooded forest, especially when augmented with litter. These results suggest that alterations in litter production from land use and/or climate change will alter short-term rates of decomposition and Rsoil for these and other floodplain forests of the Pantanal and Amazon Basin.
      Citation: Forests
      PubDate: 2018-05-22
      DOI: 10.3390/f9050281
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 282: Invasive Species May Disrupt Protected Area
           Networks: Insights from the Pine Wood Nematode Spread in Portugal

    • Authors: Begoña de la Fuente, Pieter S. A. Beck
      First page: 282
      Abstract: The expansion of invasive alien species is considered a major threat to forest ecosystems and biodiversity. Their potential impacts range from local changes in species composition to wider-scale effects on forest habitat and landscape functioning, although the latter has been relatively little explored in the literature. Here, we assessed the impact of an invasive forest pest, the pine wood nematode (PWN), in the Natura 2000 network of protected areas (PAs) in Portugal, the first European country in which PWN was reported. We considered the impacts of the pest’s spread (up to 2016) on individual PAs, in terms of the fraction of their coniferous forest infected, and on the corridors between PAs, which were mapped and prioritized through least-cost path modelling, geographic information system analysis, and the graph-based probability of connectivity metric. We found that PWN by 2016 had spread into 49% of the Portuguese Natura 2000 coniferous forest habitat, while it had invaded 68% of the coniferous forests that form the priority corridors between the PAs. These impacts are likely to be aggravated in the next years, given the pace of PWN expansion and the predicted rates of natural spread to new areas in Portugal and, increasingly likely, in Spain. Our results suggest that the connectivity of PA systems may be significantly disrupted by alien species, and that spatially prioritized control measures can help mitigate the impacts of invasive species on the coherence and functionality of protected area networks such as Natura 2000.
      Citation: Forests
      PubDate: 2018-05-22
      DOI: 10.3390/f9050282
      Issue No: Vol. 9, No. 5 (2018)
       
  • Forests, Vol. 9, Pages 283: Seedling Quality: History, Application, and
           Plant Attributes

    • Authors: Steven C. Grossnickle, Joanne E. MacDonald
      First page: 283
      Abstract: Since the early 20th century, silviculturists have recognized the importance of planting seedlings with desirable attributes, and that these attributes are associated with successful seedling survival and growth after outplanting. Over the ensuing century, concepts on what is meant by a quality seedling have evolved to the point that these assessments now provide value to both the nursery practitioner growing seedlings and the forester planting seedlings. Various seedling quality assessment procedures that measure numerous morphological and physiological plant attributes have been designed and applied. This paper examines the historical development of the discipline of seedling quality, as well as where it is today. It also examines how seedling quality is employed in forest restoration programs and the attributes that are measured to define quality. The intent is to provide readers with an overall perspective on the field of seedling quality and the people who developed this discipline from an idea into an operational reality.
      Citation: Forests
      PubDate: 2018-05-22
      DOI: 10.3390/f9050283
      Issue No: Vol. 9, No. 5 (2018)
       
 
 
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