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Forests, Volume 9, Issue 1 (January 2018) – 47 articles

Cover Story (view full-size image): Above ground, evidence of the invasive emerald ash borer is striking; fragmented canopies and standing dead trees dot the northern forest landscape. But below ground, the effect of this invasive insect is less clear. In an effort to better understand how ash mortality may alter soil carbon dynamics, the authors measured carbon dioxide and methane emissions from soil beneath trees impacted by emerald ash borer in central New Hampshire, USA. View this paper
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24 pages, 2198 KiB  
Article
Temperate and Tropical Forest Canopies are Already Functioning beyond Their Thermal Thresholds for Photosynthesis
by Alida C. Mau, Sasha C. Reed, Tana E. Wood and Molly A. Cavaleri
Forests 2018, 9(1), 47; https://doi.org/10.3390/f9010047 - 22 Jan 2018
Cited by 65 | Viewed by 10505
Abstract
Tropical tree species have evolved under very narrow temperature ranges compared to temperate forest species. Studies suggest that tropical trees may be more vulnerable to continued warming compared to temperate species, as tropical trees have shown declines in growth and photosynthesis at elevated [...] Read more.
Tropical tree species have evolved under very narrow temperature ranges compared to temperate forest species. Studies suggest that tropical trees may be more vulnerable to continued warming compared to temperate species, as tropical trees have shown declines in growth and photosynthesis at elevated temperatures. However, regional and global vegetation models lack the data needed to accurately represent such physiological responses to increased temperatures, especially for tropical forests. To address this need, we compared instantaneous photosynthetic temperature responses of mature canopy foliage, leaf temperatures, and air temperatures across vertical canopy gradients in three forest types: tropical wet, tropical moist, and temperate deciduous. Temperatures at which maximum photosynthesis occurred were greater in the tropical forests canopies than the temperate canopy (30 ± 0.3 °C vs. 27 ± 0.4 °C). However, contrary to expectations that tropical species would be functioning closer to threshold temperatures, photosynthetic temperature optima was exceeded by maximum daily leaf temperatures, resulting in sub-optimal rates of carbon assimilation for much of the day, especially in upper canopy foliage (>10 m). If trees are unable to thermally acclimate to projected elevated temperatures, these forests may shift from net carbon sinks to sources, with potentially dire implications to climate feedbacks and forest community composition. Full article
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14 pages, 3950 KiB  
Article
Detecting Shoot Beetle Damage on Yunnan Pine Using Landsat Time-Series Data
by Linfeng Yu, Jixia Huang, Shixiang Zong, Huaguo Huang and Youqing Luo
Forests 2018, 9(1), 39; https://doi.org/10.3390/f9010039 - 22 Jan 2018
Cited by 32 | Viewed by 4483
Abstract
Tomicus yunnanensis and Tomicus minor have caused serious shoot damage in Yunnan pine forests in the Yunnan Province of China. However, very few remote sensing studies have estimated the shoot damage ratio (SDR). Thus, we used multi-date Landsat satellite imagery to quantify SDRs [...] Read more.
Tomicus yunnanensis and Tomicus minor have caused serious shoot damage in Yunnan pine forests in the Yunnan Province of China. However, very few remote sensing studies have estimated the shoot damage ratio (SDR). Thus, we used multi-date Landsat satellite imagery to quantify SDRs and assess the possibility of using spectral indices to determine the beetle outbreak time and spread direction. A new threshold-based classification method was proposed to identify damage levels (i.e., healthy, slightly to moderately infested, and severely infested forests) using time series of moisture stress index (MSI). Permanent plots and temporal field inspection data were both used as references for training and evaluation. Results show that a single threshold value can produce a total classification accuracy of 86.38% (Kappa = 0.80). Furthermore, time series maps detailing damage level were reconstructed from 2004 to 2016. The shoot beetle outbreak year was estimated to be 2013. Another interesting finding is the movement path of the geometric center of severe damage, which is highly consistent with the wind direction. We conclude that the time series of shoot damage level maps can be produced by using continuous MSI images. This method is very useful to foresters for determining the outbreak time and spread direction. Full article
(This article belongs to the Special Issue Disturbance, Succession, and Development of Forests)
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16 pages, 2569 KiB  
Article
Assessing the Impact of Forest Change and Climate Variability on Dry Season Runoff by an Improved Single Watershed Approach: A Comparative Study in Two Large Watersheds, China
by Yiping Hou, Mingfang Zhang, Zuozhu Meng, Shirong Liu, Pengsen Sun and Taoli Yang
Forests 2018, 9(1), 46; https://doi.org/10.3390/f9010046 - 20 Jan 2018
Cited by 21 | Viewed by 4201
Abstract
Extensive studies on hydrological responses to forest change have been published for centuries, yet partitioning the hydrological effects of forest change, climate variability and other factors in a large watershed remains a challenge. In this study, we developed a single watershed approach combining [...] Read more.
Extensive studies on hydrological responses to forest change have been published for centuries, yet partitioning the hydrological effects of forest change, climate variability and other factors in a large watershed remains a challenge. In this study, we developed a single watershed approach combining the modified double mass curve (MDMC) and the time series multivariate autoregressive integrated moving average model (ARIMAX) to separate the impact of forest change, climate variability and other factors on dry season runoff variation in two large watersheds in China. The Zagunao watershed was examined for the deforestation effect, while the Meijiang watershed was examined to study the hydrological impact of reforestation. The key findings are: (1) both deforestation and reforestation led to significant reductions in dry season runoff, while climate variability yielded positive effects in the studied watersheds; (2) the hydrological response to forest change varied over time due to changes in soil infiltration and evapotranspiration after vegetation regeneration; (3) changes of subalpine natural forests produced greater impact on dry season runoff than alteration of planted forests. These findings are beneficial to water resource and forest management under climate change and highlight a better planning of forest operations and management incorporated trade-off between carbon and water in different forests. Full article
(This article belongs to the Section Forest Ecology and Management)
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17 pages, 7472 KiB  
Article
Mixed-Severity Fire Fosters Heterogeneous Spatial Patterns of Conifer Regeneration in a Dry Conifer Forest
by Sparkle L. Malone, Paula J. Fornwalt, Mike A. Battaglia, Marin E. Chambers, Jose M. Iniguez and Carolyn H. Sieg
Forests 2018, 9(1), 45; https://doi.org/10.3390/f9010045 - 20 Jan 2018
Cited by 24 | Viewed by 4879
Abstract
We examined spatial patterns of post-fire regenerating conifers in a Colorado, USA, dry conifer forest 11–12 years following the reintroduction of mixed-severity fire. We mapped and measured all post-fire regenerating conifers, as well as all other post-fire regenerating trees and all residual (i.e., [...] Read more.
We examined spatial patterns of post-fire regenerating conifers in a Colorado, USA, dry conifer forest 11–12 years following the reintroduction of mixed-severity fire. We mapped and measured all post-fire regenerating conifers, as well as all other post-fire regenerating trees and all residual (i.e., surviving) trees, in three 4-ha plots following the 2002 Hayman Fire. Residual tree density ranged from 167 to 197 trees ha−1 (TPH), and these trees were clustered at distances up to 30 m. Post-fire regenerating conifers, which ranged in density from 241 to 1036 TPH, were also clustered at distances up to at least 30 m. Moreover, residual tree locations drove post-fire regenerating conifer locations, with the two showing a pattern of repulsion. Topography and post-fire sprouting tree species locations further drove post-fire conifer regeneration locations. These results provide a foundation for anticipating how the reintroduction of mixed-severity fire may affect long-term forest structure, and also yield insights into how historical mixed-severity fire may have regulated the spatially heterogeneous conditions commonly described for pre-settlement dry conifer forests of Colorado and elsewhere. Full article
(This article belongs to the Special Issue Wildland Fire, Forest Dynamics, and Their Interactions)
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10 pages, 737 KiB  
Article
Variation of Ring Width and Wood Density in Two Unmanaged Stands of the Mediterranean Oak Quercus faginea
by Vicelina B. Sousa, José Luís Louzada and Helena Pereira
Forests 2018, 9(1), 44; https://doi.org/10.3390/f9010044 - 20 Jan 2018
Cited by 13 | Viewed by 3140
Abstract
Ring width and wood density variation were studied from pith-to-bark and along the stem in two naturally regenerated stands of Quercus faginea Lam. in Portugal. Ring width was significantly different between sites, in both heartwood and sapwood rings, ranging from 1.83 mm to [...] Read more.
Ring width and wood density variation were studied from pith-to-bark and along the stem in two naturally regenerated stands of Quercus faginea Lam. in Portugal. Ring width was significantly different between sites, in both heartwood and sapwood rings, ranging from 1.83 mm to 2.52 mm and from 0.77 mm to 2.11 mm, respectively. Wood density was significantly different between sites only in the heartwood, i.e., 914 kg m−3 and 1037 kg m−3. Site effects were the main source of variation for ring width and wood density within the heartwood as well as for sapwood ring width, while the between-tree effects explained more the density variation within the sapwood. Wood density showed within-tree uniformity that was not affected by site. The stand characteristics such as basal area and tree age may override the environmental growth conditions. There was also a weak correlation between wood density and ring width components therefore suggesting the possibility of forestry management for both fast tree growth and high wood density. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
16 pages, 2630 KiB  
Article
Variation in the Climate Sensitivity Dependent on Neighbourhood Composition in a Secondary Mixed Forest
by Nere Amaia Laskurain, Arantza Aldezabal, Iñaki Odriozola, Jesús Julio Camarero and José Miguel Olano
Forests 2018, 9(1), 43; https://doi.org/10.3390/f9010043 - 20 Jan 2018
Cited by 5 | Viewed by 3788
Abstract
Understanding the vulnerability of individual trees to climate requires moving from population to individual level. This study evaluates individual tree response in a mixed forest by assessing how size and neighbourhood density modulated growth responses to climate among coexisting tree species. To understand [...] Read more.
Understanding the vulnerability of individual trees to climate requires moving from population to individual level. This study evaluates individual tree response in a mixed forest by assessing how size and neighbourhood density modulated growth responses to climate among coexisting tree species. To understand the complete variation in growth responses to climate, it is necessary to consider intrapopulation variability. Trees respond as individual entities, and their response is modulated by their characteristics and neighbourhood context. To assess the individual climate sensitivity, all living Iberian birches, European beeches, and pedunculate oaks trees located in a temperate mixed forest were cored in four 40 m × 40 m plots. Standard ring-width chronologies were built at tree and species level for the 1977–2007 period. Chronologies were related to climatic variables (monthly precipitation, hailstorm and mean temperature, and summer (June–August) precipitation). Growth response to climate varied among species and individual trees. Differences in climate–growth relationship among species could be partially attributed to the different xylem anatomy, since secondary growth of ring-porous pedunculate oak (Quercus robur L.) was mainly dependent on the previous-winter climatic conditions (January temperature), while for the diffuse-porous Iberian birch (Betula celtiberica Rothm. and Vasc.) and European beech (Fagus sylvatica L.), spring temperature and summer precipitation were the major constraining factors of growth. Tree features and identity of neighbourhood modulated climatic response, especially for Iberian birch and pedunculate oak. Dominant trees in less crowded neighbourhoods responded more intensely to climate factors. Understanding the individual variability of growth responses to climate will provide more realistic predictions of forests response to climate change. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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14 pages, 1542 KiB  
Article
Branch Development of Five-Year-Old Betula alnoides Plantations in Response to Planting Density
by Chun-Sheng Wang, Cheng Tang, Sebastian Hein, Jun-Jie Guo, Zhi-Gang Zhao and Jie Zeng
Forests 2018, 9(1), 42; https://doi.org/10.3390/f9010042 - 19 Jan 2018
Cited by 22 | Viewed by 3692
Abstract
Branch development in the lower part of stem is critical to both early stem growth and wood quality of the most valuable section of tree, and its regulation through planting density has always been greatly concerned. Here the effect of planting density on [...] Read more.
Branch development in the lower part of stem is critical to both early stem growth and wood quality of the most valuable section of tree, and its regulation through planting density has always been greatly concerned. Here the effect of planting density on branch development was examined in a five-year-old plantation of Betula alnoides with six planting densities (625, 833, 1111, 1250, 1667, and 2500 stems per hectare (sph)) in Guangdong Province, South China. Branch quantity (number, proportion, and density), morphology (diameter, length, and angle), position (height and orientation), and branch status (dead or alive) were investigated for 54 dominant or co-dominant trees under six treatments of planting density after the growth of each tree was measured. Factors influencing branch development were also explored by mixed modelling. The results showed that the mean tree heights of 1250 and 1667 sph treatments were higher than those of other planting density treatments. The quantity of live branches decreased with increasing planting density. However, planting density had no significant effect on the number of all branches, and there existed no remarkable difference in branch number and proportion among four orientations. As for branch morphology, only the largest branch diameter had a significantly negative correlation with planting density. In addition, high planting density significantly increased the height of the largest branch within the crown. Mixed effects models indicated that branch diameter, length, and angle were closely correlated with each other, and they were all in positively significant correlation to the branch height at the stem section below six meters. It was concluded that properly increasing planting density will promote natural pruning, improve early branch control, and be beneficial for wood production from the most valuable section of the stem. Full article
(This article belongs to the Section Forest Ecology and Management)
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9 pages, 872 KiB  
Article
Estimating Preferences for Wood Products with Environmental Attributes
by Masaji Sakagami and Daishi Sakaguchi
Forests 2018, 9(1), 41; https://doi.org/10.3390/f9010041 - 18 Jan 2018
Cited by 8 | Viewed by 3528
Abstract
Tropical deforestation and forest degradation are serious problems for the global environment; as a result, sustainable forest management and forest certification have become important. In this study, using a choice experiment, we investigated, on the demand side, consumers’ preferences and willingness to pay [...] Read more.
Tropical deforestation and forest degradation are serious problems for the global environment; as a result, sustainable forest management and forest certification have become important. In this study, using a choice experiment, we investigated, on the demand side, consumers’ preferences and willingness to pay (WTP) for certified wood products that attempt to address public concerns regarding deforestation and forest degradation. Specifically, we investigated how estimates of consumers’ preferences and WTP were influenced by product attributes such as quality, certification, and price. To the authors’ knowledge, few studies of this kind have been conducted, particularly in Japan. The study’s main finding was that Japanese consumers were willing to pay a premium for certified wood products with attributes related to sustainable forest management; most preferred were products with attributes related to preserving biodiversity. These findings indicate that consumers are willing to pay a premium for products that contribute to solving the problems of deforestation and forest degradation. Full article
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16 pages, 1274 KiB  
Article
Variability after 15 Years of Vegetation Recovery in Natural Secondary Forest with Timber Harvesting at Different Intensities in Southeastern China: Community Diversity and Stability
by Zhilong Wu, Chengjun Zhou, Xinnian Zhou, Xisheng Hu and Jianbang Gan
Forests 2018, 9(1), 40; https://doi.org/10.3390/f9010040 - 18 Jan 2018
Cited by 14 | Viewed by 3867
Abstract
The mixed Cunninghamia lanceolata (Lamb.) Hook., Pinus massoniana Lamb., and hardwood forest in southeastern China is a major assemblage in natural secondary forests, and of national and international importance in terms of both timber and ecosystem services. However, over-harvesting has threatened its long-term [...] Read more.
The mixed Cunninghamia lanceolata (Lamb.) Hook., Pinus massoniana Lamb., and hardwood forest in southeastern China is a major assemblage in natural secondary forests, and of national and international importance in terms of both timber and ecosystem services. However, over-harvesting has threatened its long-term sustainability, and there is a knowledge gap relating to the effect of harvesting on the ecosystem. After conifer species were selected for harvesting, the mixed Chinese fir, pine, and hardwood forest was changed into mixed evergreen broadleaf forest. In this context, we observed the restoration dynamics of plant communities over a period of 15 years (1996 to 2011) with different levels of harvesting intensity, including selective harvesting at low (13.0% removal of growing stock volume), medium (29.1%), high (45.8%), and extra-high (67.1%) intensities, as well as clear-cut harvesting (100.0%), with non-harvesting as the control, based on permanent sample plots established in a randomized block design in these forests in southeastern China. The impact on the richness, diversity, and evenness of plant species derived from descriptive statistical analyses was shown to initially increase, and then decrease, with an increase in harvesting intensity. The most critical impacts were on the richness, diversity, and evenness of shrub and herb species. Richness, diversity, and evenness of plant species recovered and increased under selective harvesting at low and medium intensities, while these parameters had not recovered and significantly decreased under selective harvesting at high and extra-high intensities, as well as with clear-cut harvesting. The impact on the plant community stability was derived from the stability test method of the improved Godron M. The plant community stability was closest to the point of stability (20/80) under selective harvesting at medium intensity, followed by selective harvesting at low intensity. The plant community stability was far from the point of stability (20/80) under selective harvesting at high and extra-high intensities, as well as with clear-cut harvesting. Of these treatments, clear-cut harvesting had the greatest effect with regard to reducing stability. Therefore, these results indicate that the selective harvesting at low and medium intensities is conducive to preserve or increase the species diversity and community stability. In order to prioritize promoting plant species diversity, clear-cut harvesting and selective harvesting at high and extra-high intensities should be avoided with regard to this type of forest in this region. This study sheds light on the practice of forest operation in the study region and subtropical forests with the same environment. Full article
(This article belongs to the Special Issue Disturbance, Succession, and Development of Forests)
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12 pages, 2137 KiB  
Article
Contribution of Ecological and Socioeconomic Factors to the Presence and Abundance of Invasive Tree Species in Mississippi, USA
by Jun Zhai, Donald L. Grebner, Robert K. Grala, Zhaofei Fan and Ian A. Munn
Forests 2018, 9(1), 38; https://doi.org/10.3390/f9010038 - 17 Jan 2018
Cited by 7 | Viewed by 4279
Abstract
Invasive tree species cause increasing damage to the environment and local economies. Previous studies have seldom treated the presence and abundance of invasive species as different phenomena. Using Classification and Regression Trees (CART) analysis, important driving factors affecting the presence and abundance of [...] Read more.
Invasive tree species cause increasing damage to the environment and local economies. Previous studies have seldom treated the presence and abundance of invasive species as different phenomena. Using Classification and Regression Trees (CART) analysis, important driving factors affecting the presence and abundance of invasive tree species in Mississippi were identified. These selected factors were spatially analyzed using a spatial lag model at the county level. The empirical results from the spatial lag model showed that: (1) the presence of invasive tree species was more likely at lower elevations, private ownerships, and in counties with higher per capita annual income; and (2) the abundance of invasive tree species was related to stand age, and elevation. The odds ratio revealed that the presence was most affected by per capita mean annual income. This result might reflect impacts from intensified urban development and alteration of the landscape. As revealed by the coefficients, the abundance was most strongly affected by stand age. Thus, management prescriptions designed to monitor and control invasions should target young private forestlands at low elevations in counties with higher per capita mean annual income. Full article
(This article belongs to the Section Forest Economics, Policy, and Social Science)
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27 pages, 12544 KiB  
Article
Relationship between Net Primary Productivity and Forest Stand Age under Different Site Conditions and Its Implications for Regional Carbon Cycle Study
by Bin Wang, Mingze Li, Wenyi Fan, Ying Yu and Jing M. Chen
Forests 2018, 9(1), 5; https://doi.org/10.3390/f9010005 - 16 Jan 2018
Cited by 25 | Viewed by 6773
Abstract
Net primary productivity (NPP) is a key component in the terrestrial ecosystem carbon cycle, and it varies according to stand age and site class index (SCI) for different forest types. Here we report an improved method for describing the relationships between NPP and [...] Read more.
Net primary productivity (NPP) is a key component in the terrestrial ecosystem carbon cycle, and it varies according to stand age and site class index (SCI) for different forest types. Here we report an improved method for describing the relationships between NPP and stand age at various SCI values for the main forest types and groups in Heilongjiang Province, China, using existing yield tables, biomass equations, and forest inventory data. We calculated NPP as the sum of four components: Annual accumulation of live biomass, annual mortality of biomass, foliage turnover, and fine root turnover in soil. We also consider the NPP of understory vegetation or moss. These NPP-age relationships under different site conditions indicate that the NPP values of broadleaved and coniferous, as well as broadleaved mixed forests increase rapidly and reach a maximum when in young forests. However, for coniferous forest types, the maximum NPP generally occurs in mature forests. In addition, a higher SCI leads to a higher NPP value. Finally, we input these NPP-age relationships at various SCI values into the Integrated Terrestrial Ecosystem Carbon (InTEC) model to modify NPP modeling to estimate NPP in Heilongjiang Province in China from 2001 to 2010. All of the results showed that the methods reported in this study provide a reliable approach for estimating regional forest carbon budgets. Full article
(This article belongs to the Section Forest Ecology and Management)
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16 pages, 5664 KiB  
Article
Tree Stress and Mortality from Emerald Ash Borer Does Not Systematically Alter Short-Term Soil Carbon Flux in a Mixed Northeastern U.S. Forest
by Jaclyn Hatala Matthes, Ashley K. Lang, Fiona V. Jevon and Sarah J. Russell
Forests 2018, 9(1), 37; https://doi.org/10.3390/f9010037 - 16 Jan 2018
Cited by 6 | Viewed by 7538
Abstract
Invasive insect pests are a common disturbance in temperate forests, but their effects on belowground processes in these ecosystems are poorly understood. This study examined how aboveground disturbance might impact short-term soil carbon flux in a forest impacted by emerald ash borer ( [...] Read more.
Invasive insect pests are a common disturbance in temperate forests, but their effects on belowground processes in these ecosystems are poorly understood. This study examined how aboveground disturbance might impact short-term soil carbon flux in a forest impacted by emerald ash borer (Agrilus planipennis Fairmaire) in central New Hampshire, USA. We anticipated changes to soil moisture and temperature resulting from tree mortality caused by emerald ash borer, with subsequent effects on rates of soil respiration and methane oxidation. We measured carbon dioxide emissions and methane uptake beneath trees before, during, and after infestation by emerald ash borer. In our study, emerald ash borer damage to nearby trees did not alter soil microclimate nor soil carbon fluxes. While surprising, the lack of change in soil microclimate conditions may have been a result of the sandy, well-drained soil in our study area and the diffuse spatial distribution of canopy ash trees and subsequent canopy light gaps after tree mortality. Overall, our results indicate that short-term changes in soil carbon flux following insect disturbances may be minimal, particularly in forests with well-drained soils and a mixed-species canopy. Full article
(This article belongs to the Special Issue Understanding and Managing Emerald Ash Borer Impacts on Ash Forests)
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15 pages, 4856 KiB  
Article
Ecological Structure of a Tropical Urban Forest in the Bang Kachao Peninsula, Bangkok
by Montathip Sommeechai, Chongrak Wachrinrat, Bernard Dell, Nipon Thangtam and Jamroon Srichaichana
Forests 2018, 9(1), 36; https://doi.org/10.3390/f9010036 - 16 Jan 2018
Cited by 7 | Viewed by 7435
Abstract
Rapid urbanization has changed the structure and function of natural ecosystems, especially floodplain ecosystems in SE Asia. The ecological structure of vegetation stands and the usefulness of satellite images was investigated to characterize a disturbed tropical urban forest located in the Chao Phraya [...] Read more.
Rapid urbanization has changed the structure and function of natural ecosystems, especially floodplain ecosystems in SE Asia. The ecological structure of vegetation stands and the usefulness of satellite images was investigated to characterize a disturbed tropical urban forest located in the Chao Phraya River lower floodplain, Thailand. Nine sample plots were established on the Bang Kachao Peninsula (BKP) within 4 tropical forest types in an urban area: rehabilitation forest, home-garden agroforestry, mangrove and park. The tree habitats were beach forest, swamp forest, moist evergreen forest, dry evergreen forest, mangrove forest and abandoned orchard or home-garden. Normalized difference vegetation index (NDVI) values obtained from Landsat 7 satellite images were correlated with plant structure from field surveys. NDVI had the highest relationship with stand factors for number of families, number of species, Shannon-Weiner index and total basal area. Linear regression predicted well the correlation between NDVI and stand factors for families and basal area. NDVI trends reflected urban tropical forest typing and biodiversity, being high in rehabilitation and mangrove forests, moderate in home-gardens and low in parks. We suggest that the application of NDVI for assessments can be useful for future planning, monitoring and management of the BKP and hence may contribute for increasing biodiversity and complexity of these urban forests. Full article
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11 pages, 1759 KiB  
Article
Fine Root Biomass and Its Relationship with Aboveground Traits of Larix gmelinii Trees in Northeastern China
by Shengwang Meng, Quanquan Jia, Guang Zhou, Hua Zhou, Qijing Liu and Jian Yu
Forests 2018, 9(1), 35; https://doi.org/10.3390/f9010035 - 16 Jan 2018
Cited by 30 | Viewed by 6153
Abstract
Fine roots play a prominent role in forest carbon flux, nutrient and water acquisition; however, information on fine roots remains scarce due to the limitation of measuring methods. In this study, a nested regression method was used to estimate the biomass and surface [...] Read more.
Fine roots play a prominent role in forest carbon flux, nutrient and water acquisition; however, information on fine roots remains scarce due to the limitation of measuring methods. In this study, a nested regression method was used to estimate the biomass and surface area of fine roots of individual Larix gmelinii trees that dominate northernmost China. Aboveground traits including leaf biomass, leaf area, stem volume and aboveground biomass were also investigated. In particular, the relationships between leaves and fine roots, in terms of biomass and area, were examined. The results revealed that allometric models of fine roots, total roots, and leaves consistently fit well with Adj. R2 = 0.92–0.97. The root-shoot ratio at the individual tree level was approximately 0.28. There were robust positive linear correlations between absorption (fine root biomass, fine root surface area) and production (leaf biomass, leaf area) (Adj. R2 = 0.95, p < 0.001). In conclusion, the close coupling between fine roots and leaves presented in this study provides support for the theory of functional equilibrium. Full article
(This article belongs to the Special Issue Forest Fine Roots in Changing Climate)
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18 pages, 3307 KiB  
Article
Groundwater Depth and Soil Properties Are Associated with Variation in Vegetation of a Desert Riparian Ecosystem in an Arid Area of China
by Xiaolong Zhang, Tianyu Guan, Jihua Zhou, Wentao Cai, Nannan Gao, Hui Du, Lianhe Jiang, Liming Lai and Yuanrun Zheng
Forests 2018, 9(1), 34; https://doi.org/10.3390/f9010034 - 15 Jan 2018
Cited by 68 | Viewed by 5087
Abstract
Groundwater is a major driving force for plant community distribution in arid areas worldwide. Although it is well known that groundwater has a significant impact on soil and vegetation, there is little information on how groundwater depth affects soil and vegetation in an [...] Read more.
Groundwater is a major driving force for plant community distribution in arid areas worldwide. Although it is well known that groundwater has a significant impact on soil and vegetation, there is little information on how groundwater depth affects soil and vegetation in an arid inland basin desert riparian ecosystem. Therefore, quantitative analysis of the relationships among groundwater depth, soil properties and plant community distribution is necessary. A desert riparian ecosystem in the lower reaches of the Heihe River in an arid area of Northwest China was used to determine quantitative relationships among groundwater depth, soil and vegetation. Groundwater depth significantly increased with increased distance from the river. Soil and vegetation characteristics showed a significant trend with increasing groundwater depth. With increasing groundwater depth, soil water content, soil total nitrogen, soil total carbon, soil available phosphorus and soil available potassium decreased, while the soil bulk density and soil carbon:nitrogen (C:N) ratio increased. Soil pH and soil electrical conductivity followed quadratic function relationships with groundwater depth. Species richness, aboveground biomass, community coverage, community height, foliage projective cover and leaf area index all significantly decreased with increased groundwater depth. Groundwater depth and soil were associated with vegetation variance, explaining 85.8% of the vegetation variance. Groundwater depth was more important in explaining vegetation variance than soil properties (soil bulk density) and soil pH. Our observations indicate that changes in groundwater depth would have a significant influence on desert riparian forest vegetation, and that maintaining appropriate groundwater depth is necessary to preserve the riparian ecosystem. Full article
(This article belongs to the Special Issue Forest Sustainable Management)
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14 pages, 2654 KiB  
Article
Nearest Neighborhood Characteristics of a Tropical Mixed Broadleaved Forest Stand
by Hong Hai Nguyen, Yousef Erfanifard and Ion Catalin Petritan
Forests 2018, 9(1), 33; https://doi.org/10.3390/f9010033 - 14 Jan 2018
Cited by 10 | Viewed by 3876
Abstract
Structural complexity and local biodiversity of species-rich tropical forests can be characterized by their spatial patterns, which contribute to species intra- and interspecific interactions. Aiming to describe spatial patterns of species at fine spatial scales, we applied the quantitative analyses based on the [...] Read more.
Structural complexity and local biodiversity of species-rich tropical forests can be characterized by their spatial patterns, which contribute to species intra- and interspecific interactions. Aiming to describe spatial patterns of species at fine spatial scales, we applied the quantitative analyses based on the relationships of nearest neighbors of conspecific and heterospecific trees. In a two-hectare plot of a tropical broadleaved forest stand in central Vietnam with minimal human influence, all tree individuals with diameter at breast height ≥ 2.5 cm were mapped and their characteristics were recorded. We applied two different types of analyses: (1) Intraspecific structural characteristics using nearest neighbor statistics; (2) overall interspecific associations through a classification scheme based on bivariate nearest neighbor distribution function D12(r) and Ripley’s K function K12(r). The findings showed that: (1) Most of studied species in the forest were highly mixed with other species, while conspecifics were regular to aggregated distribution at small spatial scales. Tree individuals with different diameter values were surrounded by heterospecific trees; (2) The majority of 306 species-species pairs showed spatial independence (66.7%), whereas 29.8% of all species showed an overall positive association and negative association consisted only a small percentage (3.5%) up to spatial scales of 50 m. We found significant evidences of the main ecological theories such as dispersal limitation, Neutral theory, Janzen-Connell hypothesis, and other effects like the stochastic dilution. We suggest using both the bivariate distribution of the structural parameters and the spatial point pattern analysis based on nearest neighbor distance as advantageous approaches for further understanding of population structure, as well as discovering and protecting biodiversity in the future. Full article
(This article belongs to the Special Issue Competition and Facilitation in Mixed Species Forests)
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15 pages, 4628 KiB  
Article
Responses of Sap Flow of Deciduous and Conifer Trees to Soil Drying in a Subalpine Forest
by Chunhua Yan, Bei Wang, Yang Zhang, Xiaonan Zhang, Shinichi Takeuchi and Guo Yu Qiu
Forests 2018, 9(1), 32; https://doi.org/10.3390/f9010032 - 14 Jan 2018
Cited by 16 | Viewed by 4771
Abstract
Co-occurring species may adopt different water-use strategies to adapt to limited soil water. In Jiuzhaigou Valley, a continuous decline in soil water after an initial recharge from the thawing of snow and frozen soil in early spring was observed, but its effects on [...] Read more.
Co-occurring species may adopt different water-use strategies to adapt to limited soil water. In Jiuzhaigou Valley, a continuous decline in soil water after an initial recharge from the thawing of snow and frozen soil in early spring was observed, but its effects on the sap flow dynamics of co-occurring species are not well understood. To clarify the species-specific water-use strategy, variations in sap flow and environmental conditions were investigated for two co-occurring species (Betula albosinensis Burk. and Pinus tabuliaeformis Carr.) in a mixed forest during a transition from the wet to dry period in 2014. Sap flow was measured using Granier-type thermal dissipation probes, and the soil-water content was measured using time-domain reflectometry probes for a successive period. Our study showed that B. albosinensis maintained relatively high transpiration until late into the season regardless of soil moisture, while the transpiration of P. tabuliformis showed a continuous decrease in response to seasonal soil drying. Sap flow for both species exhibited a marked hysteresis in response to meteorological factors and it was conditioned by the soil-water status, especially in the afternoon. We found that P. tabuliformis was sensitive to soil-water conditions, while for B. albosinensis, the sap flow was not very sensitive to changes in soil-water conditions. These results indicate that B. albosinensis could manage the water consumption conservatively under both dry and wet conditions. These results may have implications for evaluating the species-specific water-use strategy and carrying out proper reforestation practices. Full article
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14 pages, 3160 KiB  
Article
Citizen Science as a Tool in Biological Recording—A Case Study of Ailanthus altissima (Mill.) Swingle
by Barbara Sladonja and Danijela Poljuha
Forests 2018, 9(1), 31; https://doi.org/10.3390/f9010031 - 13 Jan 2018
Cited by 10 | Viewed by 12513
Abstract
Non-native invasive species frequently appear in urban and non-urban ecosystems and may become a threat to biodiversity. Some of these newcomers are introduced accidentally, and others are introduced through a sequence of events caused by conscious human decisions. Involving the general public in [...] Read more.
Non-native invasive species frequently appear in urban and non-urban ecosystems and may become a threat to biodiversity. Some of these newcomers are introduced accidentally, and others are introduced through a sequence of events caused by conscious human decisions. Involving the general public in biodiversity preservation activities could prevent the negative consequences of these actions. Accurate and reliable data collecting is the first step in invasive species management, and citizen science can be a useful tool to collect data and engage the public in science. We present a case study of biological recording of tree of heaven (Ailanthus altissima (Mill.) Swingle) using a participatory citizen model. The first goal in this case study was to develop a cheap, widely accessible, and effective inventory method, and to test it by mapping tree of heaven in Croatia. A total of 90.61 km of roads and trails was mapped; 20 single plants and 19 multi-plant clusters (mapped as polygons) were detected. The total infested area was 2610 m2. The second goal was to educate citizens and raise awareness of this invasive species. The developed tool and suggested approach aided in improving invasive risk management in accordance with citizen science principles and can be applied to other species or areas. Full article
(This article belongs to the Section Forest Economics, Policy, and Social Science)
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14 pages, 5413 KiB  
Article
A New Method for Characterizing Bark Microrelief Using 3D Vision Systems
by Andrzej Sioma, Jarosław Socha and Anna Klamerus-Iwan
Forests 2018, 9(1), 30; https://doi.org/10.3390/f9010030 - 13 Jan 2018
Cited by 27 | Viewed by 4716
Abstract
Bark microrelief (BM), or the spatial patterning of bark texture, is an important bark characteristic shown to significantly affect the ecophysiological functioning of forest ecosystems. BM influences bark micrometeorological conditions and stemflow generation which, in turn, impacts epiphytic vegetation and microbial community patterns, [...] Read more.
Bark microrelief (BM), or the spatial patterning of bark texture, is an important bark characteristic shown to significantly affect the ecophysiological functioning of forest ecosystems. BM influences bark micrometeorological conditions and stemflow generation which, in turn, impacts epiphytic vegetation and microbial community patterns, as well as insect foraging behavior. Thus, an objective method to quantify BM is important to understand and model hydro-biogeochemical processes in forest canopy ecosystems. The aim of this study was to develop a method for fast and automated imaging of bark surface morphology. Three-dimensional imaging methods using laser triangulation were used to describe BM. An automated system was developed and applied to calculate three new BM indices for samples collected from five trees representing species common throughout Poland (and Northern Europe): common oak, European ash, trembling aspen, Scots pine, and black alder. These new BM indices may be useful for characterizing and quantitatively relating BM to forest canopy ecophysiological functions. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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15 pages, 3251 KiB  
Article
Nutrient Uptake and Utilization by Fragrant Rosewood (Dalbergia odorifera) Seedlings Cultured with Oligosaccharide Addition under Different Lighting Spectra
by Xiao-Wen Li, Qiu-Xia Chen, Hai-Qing Lei, Jin-Wang Wang, Sheng Yang and Hong-Xu Wei
Forests 2018, 9(1), 29; https://doi.org/10.3390/f9010029 - 13 Jan 2018
Cited by 40 | Viewed by 4620
Abstract
Fragrant rosewood (Dalbergia odorifera T.C. Chen) is a highly-valued species suffering from vulnerability due to over-development for wood and medicine. In this study, Fragrant rosewood seedlings were cultured with chitosan oligosaccharide (CO) addition at rates of 0 and 1/800 (v/ [...] Read more.
Fragrant rosewood (Dalbergia odorifera T.C. Chen) is a highly-valued species suffering from vulnerability due to over-development for wood and medicine. In this study, Fragrant rosewood seedlings were cultured with chitosan oligosaccharide (CO) addition at rates of 0 and 1/800 (v/v) under artificial lightings by 200-W high-pressure sodium (HPS) lamps and 280-W light-emitting diode (LED) panels for a 15 h daily photoperiod and a natural illumination as the control. The LEDs were designed to emit lights in 85% of red (600–700 nm), 15% of green(500–600 nm), and 5% of blue (400–500 nm). The height of artificial lightings was elevated every five to seven days to keep the mean photosynthetic photon flux density (PPFD) of 72–73 µmol m−2 s−1 of artificial lighting at shoot-tips. Seedlings under LED lighting with CO addition had the greatest diameter growth and leaf biomass, as well as the highest nutrient utilization and evaluated quality, while those under HPS lighting had a higher stem sugar concentration but unchanged shoot growth and biomass compared to the control. In conclusion, we recommend Fragrant rosewood seedlings to be cultured with CO addition under LED lighting to efficiently promote synthetic quality and nutrient utilization. Full article
(This article belongs to the Section Forest Ecology and Management)
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14 pages, 3176 KiB  
Article
Predicting Volume and Biomass Change from Multi-Temporal Lidar Sampling and Remeasured Field Inventory Data in Panther Creek Watershed, Oregon, USA
by Krishna P. Poudel, James W. Flewelling and Hailemariam Temesgen
Forests 2018, 9(1), 28; https://doi.org/10.3390/f9010028 - 12 Jan 2018
Cited by 16 | Viewed by 3811
Abstract
Using lidar for large-scale forest management can improve operational and management decisions. Using multi-temporal lidar sampling and remeasured field inventory data collected from 78 plots in the Panther Creek Watershed, Oregon, USA, we evaluated the performance of different fixed and mixed models in [...] Read more.
Using lidar for large-scale forest management can improve operational and management decisions. Using multi-temporal lidar sampling and remeasured field inventory data collected from 78 plots in the Panther Creek Watershed, Oregon, USA, we evaluated the performance of different fixed and mixed models in estimating change in aboveground biomass ( AGB ) and cubic volume including top and stump ( CVTS ) over a five-year period. Actual values of CVTS and AGB were obtained using newly fitted volume and biomass equations or the equations used by the Pacific Northwest unit of the Forest Inventory and Analysis program. Estimates of change based on fixed and mixed-effect linear models were more accurate than change estimates based on differences in LIDAR-based estimates. This may have been due to the compounding of errors in LIDAR-based estimates over the two time periods. Models used to predict volume and biomass at a given time were, however, more precise than the models used to predict change. Models used to estimate CVTS were not as accurate as the models employed to estimate AGB . Final models had cross-validation root mean squared errors as low as 40.90% for AGB and 54.36% for CVTS . Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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15 pages, 8430 KiB  
Article
Landscape Transformation under Global Environmental Change in Mediterranean Mountains: Agrarian Lands as a Guarantee for Maintaining Their Multifunctionality
by Diego Varga, Josep Vila Subirós, Carles Barriocanal and Josep Pujantell
Forests 2018, 9(1), 27; https://doi.org/10.3390/f9010027 - 12 Jan 2018
Cited by 18 | Viewed by 4483
Abstract
The analysis of past and present patterns of agrarian mountain areas allows researchers to characterize the influence of landscape heterogeneity on biodiversity, cultural heritage, and forest fire hazard. This process was mapped, quantified, and described through the use of digital mapping (GIS) and [...] Read more.
The analysis of past and present patterns of agrarian mountain areas allows researchers to characterize the influence of landscape heterogeneity on biodiversity, cultural heritage, and forest fire hazard. This process was mapped, quantified, and described through the use of digital mapping (GIS) and landscape indexes in a protected area in Alta Garrotxa (Catalonia, Spain). These areas require urgent management and modelling to provide alternative management scenarios, in order to maintain and recover habitats. A set of different scenarios have been designed using a multi-criteria evaluation and geospatial information available for the study area to identify the key areas for management action and to predict the potential effects on agricultural lands by prioritizing one or another management objective: biodiversity, landscape structure and perception, cultural heritage, fire hazard, and management cost. The observed progressive land abandonment of open areas with a small size and greater isolation will have a large impact on biodiversity and cultural heritage, and increase fire risk. Sustainable development will require planning objectives compatible with the conservation of biodiversity and the preservation of Mediterranean features with support for agricultural activities. This methodology can contribute to and be easily implemented by land managers, which could help to strengthen the link between managers and stakeholders. Full article
(This article belongs to the Section Forest Ecology and Management)
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20 pages, 4466 KiB  
Article
A Comparison of Simulated and Field-Derived Leaf Area Index (LAI) and Canopy Height Values from Four Forest Complexes in the Southeastern USA
by John S. Iiames, Ellen Cooter, Donna Schwede and Jimmy Williams
Forests 2018, 9(1), 26; https://doi.org/10.3390/f9010026 - 12 Jan 2018
Cited by 7 | Viewed by 4779
Abstract
Vegetative leaf area is a critical input to models that simulate human and ecosystem exposure to atmospheric pollutants. Leaf area index (LAI) can be measured in the field or numerically simulated, but all contain some inherent uncertainty that is passed to the exposure [...] Read more.
Vegetative leaf area is a critical input to models that simulate human and ecosystem exposure to atmospheric pollutants. Leaf area index (LAI) can be measured in the field or numerically simulated, but all contain some inherent uncertainty that is passed to the exposure assessments that use them. LAI estimates for minimally managed or natural forest stands can be particularly difficult to develop as a result of interspecies competition, age and spatial distribution. Satellite-based LAI estimates hold promise for retrospective analyses, but we must continue to rely on numerical models for alternative management analysis. Our objective for this study is to calculate and validate LAI estimates generated from the USDA Environmental Policy Impact Climate (EPIC) model (a widely used, field-scale, biogeochemical model) on four forest complexes spanning three physiographic provinces in Virginia and North Carolina. Measurements of forest composition (species and number), LAI, tree diameter, basal area, and canopy height were recorded at each site during the 2002 field season. Calibrated EPIC results show stand-level temporally resolved LAI estimates with R2 values ranging from 0.69 to 0.96, and stand maximum height estimates within 20% of observation. This relatively high level of performance is attributable to EPIC’s approach to the characterization of forest stand biogeochemical budgets, stand history, interspecies competition and species-specific response to local weather conditions. We close by illustrating the extension of this site-level approach to scales that could support regional air quality model simulations. Full article
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13 pages, 2301 KiB  
Article
Ash Dieback on Sample Points of the National Forest Inventory in South-Western Germany
by Rasmus Enderle, Berthold Metzler, Uli Riemer and Gerald Kändler
Forests 2018, 9(1), 25; https://doi.org/10.3390/f9010025 - 12 Jan 2018
Cited by 16 | Viewed by 4489
Abstract
The alien invasive pathogen Hymenoscyphus fraxineus causes large-scale decline of European ash (Fraxinus excelsior). We assessed ash dieback in Germany and identified factors that were associated with this disease. Our assessment was based on a 2015 sampling of national forest inventory [...] Read more.
The alien invasive pathogen Hymenoscyphus fraxineus causes large-scale decline of European ash (Fraxinus excelsior). We assessed ash dieback in Germany and identified factors that were associated with this disease. Our assessment was based on a 2015 sampling of national forest inventory plots that represent a supra-regional area. In the time from 2012 to 2015, the number of regrown ash trees corresponded to only 42% of the number of trees that had been harvested or died. Severe defoliation was recorded for almost 40% of the living trees in 2015, and more than half of the crowns mainly consisted of epicormic shoots. Necroses were present in 24% of root collars. A total of 14% of the trees were in sound condition, which sum up to only 7% of the timber volume. On average, trees of a higher social status or with a larger diameter at breast height were healthier. Collar necroses were less prevalent at sites with a higher inclination of terrain, but there was no evidence for an influence of climatic variables on collar necroses. The disease was less severe at sites with smaller proportions of the basal area of ash compared to the total basal area of all trees and in the north-eastern part of the area of investigation. The regeneration of ash decreased drastically. Full article
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19 pages, 4382 KiB  
Article
Increased Vegetation Greenness Aggravates Water Conflicts during Lasting and Intensifying Drought in the Poyang Lake Watershed, China
by Lin-Ling Tang, Xiao-Bin Cai, Wei-Shu Gong, Jian-Zhong Lu, Xiao-Ling Chen, Qian Lei and Gong-Liang Yu
Forests 2018, 9(1), 24; https://doi.org/10.3390/f9010024 - 10 Jan 2018
Cited by 21 | Viewed by 4101
Abstract
An increase in vegetation greenness can improve ecosystem productivity, but also reduce the water supply, creating the potential for conflicting water demands between ecosystems and humans. This problem has been well-assessed and is most evident in dry environments. However, in humid regions, the [...] Read more.
An increase in vegetation greenness can improve ecosystem productivity, but also reduce the water supply, creating the potential for conflicting water demands between ecosystems and humans. This problem has been well-assessed and is most evident in dry environments. However, in humid regions, the potential effects of vegetation greenness on water yields under drought conditions are not well understood. To address this gap, we focused on the Poyang Lake watershed in the humid region of southern China. Based on the Standardized Precipitation Evapotranspiration Index and a satellite-derived leaf area index dataset during the growing seasons of 1984 to 2013, several typical dry growing seasons were selected as the study conditions. An existing Water Supply Stress Index model was modified to investigate how the changes in vegetation greenness affected water yield and to explore potentially conflicting water demands between ecosystems and humans under drought conditions. Our results showed that an increase of 20–80% in vegetation greenness generally resulted in a reduction of 3–27% in water yield under drought conditions. Large reductions in water yield mainly were observed in forested areas due to large increases in forest greenness. Moreover, increased vegetation greenness caused a 2 to 3 times greater reduction in water yield during continuing and intensifying droughts than during a short moderate drought period. Thus, in this study, during continuing and intensifying droughts, increased vegetation greenness can cause or aggravate water conflicts in sub-watersheds with high forest cover and high human water demands. Therefore, given the increasing frequency of extreme climatic events, afforestation with a targeted approach should be implemented as it would provide the most benefits. In addition, selective harvesting in forested areas with high density could be an effective strategy to maintain water supply in humid regions. Full article
(This article belongs to the Section Forest Ecology and Management)
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13 pages, 585 KiB  
Editorial
Acknowledgement to Reviewers of Forests in 2017
by Forests Editorial Office
Forests 2018, 9(1), 23; https://doi.org/10.3390/f9010023 - 10 Jan 2018
Viewed by 3033
Abstract
Peer review is an essential part in the publication process, ensuring that Forests maintains high quality standards for its published papers. In 2017, a total of 493 papers were published in the journal.[...] Full article
20 pages, 6316 KiB  
Article
Identifying Green Infrastructure as a Basis for an Incentive Mechanism at the Municipality Level in Biscay (Basque Country)
by Gloria Rodríguez-Loinaz, Lorena Peña, Igone Palacios-Agundez, Ibone Ametzaga and Miren Onaindia
Forests 2018, 9(1), 22; https://doi.org/10.3390/f9010022 - 10 Jan 2018
Cited by 10 | Viewed by 5240
Abstract
The contributions of green infrastructure (GI) to human well-being have been widely recognised; however, pathways for its systematic implementation are missing. Local governments can play a crucial role in the conservation of GI, and a formal recognition of this role in budgeting systems [...] Read more.
The contributions of green infrastructure (GI) to human well-being have been widely recognised; however, pathways for its systematic implementation are missing. Local governments can play a crucial role in the conservation of GI, and a formal recognition of this role in budgeting systems would foster the inclusion of GI in their agenda. The aim of this study is to identify the principal components of GI at the local level to form a basis for a compensatory economic scheme. We identified the principal components of GI based on the mapping of biodiversity conservation and ecosystem services provision. Furthermore, we analysed the potentiality of an incentive mechanism to promote GI based on the protection status of GI. Finally, an incentive mechanism to promote GI at the municipality level was proposed. The results showed that the GI of Biscay is mainly composed of the natural forests presented in the area, and that 50% of the principal components of the GI are not protected. Furthermore, one third of the protected principal components of the GI only has protection at the municipality level. So, we propose a Payment for Ecosystem Services (PES)-like scheme at the municipality level based on the cover of natural forests, where the objective is the conservation and promotion of the GI. Full article
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25 pages, 2719 KiB  
Article
Low Tree-Growth Elasticity of Forest Biomass Indicated by an Individual-Based Model
by Robbie A. Hember and Werner A. Kurz
Forests 2018, 9(1), 21; https://doi.org/10.3390/f9010021 - 06 Jan 2018
Cited by 7 | Viewed by 4988
Abstract
Environmental conditions and silviculture fundamentally alter the metabolism of individual trees and, therefore, need to be studied at that scale. However, changes in forest biomass density (Mg C ha−1) may be decoupled from changes in growth (kg C year−1) [...] Read more.
Environmental conditions and silviculture fundamentally alter the metabolism of individual trees and, therefore, need to be studied at that scale. However, changes in forest biomass density (Mg C ha−1) may be decoupled from changes in growth (kg C year−1) when the latter also accelerates the life cycle of trees and strains access to light, nutrients, and water. In this study, we refer to an individual-based model of forest biomass dynamics to constrain the magnitude of system feedbacks associated with ontogeny and competition and estimate the scaling relationship between changes in tree growth and forest biomass density. The model was driven by fitted equations of annual aboveground biomass growth (Gag), probability of recruitment (Pr), and probability of mortality (Pm) parameterized against field observations of black spruce (Picea mariana (Mill.) BSP), interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco), and western hemlock (Tsuga heterophylla (Raf.) Sarg.). A hypothetical positive step-change in mean tree growth was imposed half way through the simulations and landscape-scale responses were then evaluated by comparing pre- and post-stimulus periods. Imposing a 100% increase in tree growth above calibrated predictions (i.e., contemporary rates) only translated into 36% to 41% increases in forest biomass density. This corresponded with a tree-growth elasticity of forest biomass (εG,SB) ranging from 0.33 to 0.55. The inelastic nature of stand biomass density was attributed to the dependence of mortality on intensity of competition and tree size, which decreased stand density by 353 to 495 trees ha−1, and decreased biomass residence time by 10 to 23 years. Values of εG,SB depended on the magnitude of the stimulus. For example, a retrospective scenario in which tree growth increased from 50% below contemporary rates up to contemporary rates indicated values of εG,SB ranging from 0.66 to 0.75. We conclude that: (1) effects of warming and increasing atmospheric concentrations of carbon dioxide and reactive nitrogen on biomass production are greatly diminished, but not entirely precluded, scaling up from individual trees to forest landscapes; (2) the magnitude of decoupling is greater for a contemporary baseline than it is for a pre-industrial baseline; and (3) differences in the magnitude of decoupling among species were relatively small. To advance beyond these estimates, studies must test the unverified assumptions that effects of tree size and stand competition on rates of recruitment, mortality, and growth are independent of climate change and atmospheric concentrations of carbon dioxide and nitrogen. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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14 pages, 1108 KiB  
Review
Adaptation to Climate Change in Forestry: A Multiple Correspondence Analysis (MCA)
by Marielle Brunette, Robin Bourke, Marc Hanewinkel and Rasoul Yousefpour
Forests 2018, 9(1), 20; https://doi.org/10.3390/f9010020 - 06 Jan 2018
Cited by 15 | Viewed by 6003
Abstract
We analyze economic perspectives of forest adaptation to risk attributes, caused mostly by climate change. We construct a database with 89 systematically chosen articles, dealing simultaneously with climate, adaptation, risk and economy. We classify the database with regard to 18 variables bearing on [...] Read more.
We analyze economic perspectives of forest adaptation to risk attributes, caused mostly by climate change. We construct a database with 89 systematically chosen articles, dealing simultaneously with climate, adaptation, risk and economy. We classify the database with regard to 18 variables bearing on the characteristics of the paper, the description of the risk and the adaptation strategy, the topic and the corresponding results. To achieve a “high level-of-evidence”, we realize a multiple correspondence analysis (MCA) to identify which variables were found in combination with one other in the literature and make distinct groupings affecting adaptive decisions. We identify three groups: (i) profit and production; (ii) microeconomic risk-handling; and (iii) decision and behavior. The first group includes economic costs and benefits as the driver of adaptation and prioritizes simulation, and a mix of theoretical and empirical economic approach. The second group distinctly involves risk-related issues, in particular its management by adaptation. The third group gathers a large set of social and behavioral variables affecting management decisions collected through questionnaires. Such an approach allows the identification of gaps in the literature, concerning the impact of owners’ preferences towards risk and uncertainty regarding adaptation decisions, the fact that adaptation was often reduced in an attempt to adapt to the increasing risk of wildfire, or the existence of a regional bias. Full article
(This article belongs to the Special Issue At the Frontiers of Knowledge in Forest Economics)
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16 pages, 3566 KiB  
Article
The Role of Environmental Filtering in Structuring Appalachian Tree Communities: Topographic Influences on Functional Diversity Are Mediated through Soil Characteristics
by Julia I. Chapman and Ryan W. McEwan
Forests 2018, 9(1), 19; https://doi.org/10.3390/f9010019 - 06 Jan 2018
Cited by 20 | Viewed by 4334
Abstract
Identifying the drivers of community assembly has long been a central goal in ecology, and the development of functional diversity indices has provided a new way of detecting the influence of environmental gradients on biotic communities. For an old-growth Appalachian forest, we used [...] Read more.
Identifying the drivers of community assembly has long been a central goal in ecology, and the development of functional diversity indices has provided a new way of detecting the influence of environmental gradients on biotic communities. For an old-growth Appalachian forest, we used path analysis to understand how patterns of tree functional diversity relate to topography and soil gradients and to determine whether topographic effects are mediated through soil chemistry. All of our path models supported the idea of environmental filtering: stressful areas (high elevation, low soil moisture, low soil nutrients) were occupied by communities of low functional diversity, which suggests a selective effect for species with traits adapted to such harsh conditions. The effects of topography (slope, aspect, elevation) on functional diversity were often indirect and moderated through soil moisture and fertility. Soil moisture was a key component of our models and was featured consistently in each one, having either strong direct effects on functional diversity or indirect effects via soil fertility. Our results provide a comprehensive view of the interplay among functional trait assemblages, topography, and edaphic conditions and contribute to the baseline understanding of the role of environmental filtering in temperate forest community assembly. Full article
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