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Forests, Volume 6, Issue 4 (April 2015) – 28 articles , Pages 859-1396

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Open AccessArticle
Exploratory Assessment of a Company’s Due Diligence System against the EU Timber Regulation: A Case Study from Northwestern Russia
Forests 2015, 6(4), 1380-1396; https://doi.org/10.3390/f6041380 - 22 Apr 2015
Cited by 9 | Viewed by 3128 | Correction
Abstract
This study uses a company’s due diligence system (DDS) as an operational tool to ensure the origin of wood coming from northwestern Russia. The company exports a majority of its wood products to European Union (EU) countries, and its DDS consists of a [...] Read more.
This study uses a company’s due diligence system (DDS) as an operational tool to ensure the origin of wood coming from northwestern Russia. The company exports a majority of its wood products to European Union (EU) countries, and its DDS consists of a statement of origin, geographical information, and field verification audits. Its DDS is assessed against the European Union Timber Regulation (EUTR). Enforcement of the EUTR began in March 2013 and is compulsory for all companies importing wood-based material from outside the EU. The DDS must contain three key components: access to information on operator’s supply of timber or timber products placed on the market, a risk assessment, and a risk mitigation method. The workflow of the conformity assessment must include a literature review, statistical and field data collection, and further analysis of the requirements. Although enforcement of the EUTR began almost two years ago, there is little research on its implementation. This DDS system showed high functionality of its existing components corresponding with the general requirements of the standards developed by the Nature Ecology and People Consult (NepCon), a non-profit organization recognized as the monitoring organization by the European Commission. This wood origin system also meets the requirements of the Forest Stewardship Council (FSC) certification system, while maintaining full harmonization with the EUTR legislation. However, major obstacles persist in implementation of legislation by EU member states, in terms of interpretation of requirements, prosecutions and fines, and the role of third-party evidence. Full article
Open AccessArticle
Spatial Forest Harvest Scheduling for Areas Involving Carbon and Timber Management Goals
Forests 2015, 6(4), 1362-1379; https://doi.org/10.3390/f6041362 - 21 Apr 2015
Cited by 22 | Viewed by 2338
Abstract
Forest carbon sequestration has become an important ecological service for human society. Given the widespread attention paid to global climate change over the last few decades, a potential need has arisen to develop forest management plans that integrate carbon management and other spatial [...] Read more.
Forest carbon sequestration has become an important ecological service for human society. Given the widespread attention paid to global climate change over the last few decades, a potential need has arisen to develop forest management plans that integrate carbon management and other spatial and non-spatial goals. The objective of this research was to develop a spatial forest planning process by which one could assess either a carbon stocks objective, a timber production objective, or a spatial objective related to the arrangement of forest management activities. This process was used to evaluate the maximization of (1) volume scheduled for harvest; (2) carbon stocks; and (3) spatial aggregation of the management activities through a utility function where all are equally weighted objectives. The process was employed for the development of 30-year plans for a forested landscape in northeast China that was approximately 120,000 ha in size. In addition, the sensitivity of the results with respect to four initial forest age structures was tested. Constraints mainly included those related to the need for an even flow of scheduled harvest volume and to the need to adhere to a maximum harvest opening size. The proposed scheduling process employed a simulated annealing algorithm to schedule harvests in an attempt to produce a high value of the utility function. Results showed that carbon stocks in the case study forests could significantly increase in the next 30 years under the proposed harvesting plans. Of the case study forest landscapes, the values of both the utility function and the computing time required were significantly different between different initial forest age structures (p < 0.05), i.e., the older forest landscape obtained the highest average solution value (0.6594 ± 0.0013) with the fastest processing speed (2.45 min per solution). For a fixed harvest level, the average carbon density (tons per hectare) at the end of planning horizon also increased by 4.48 ± 9.61 t/ha, 8.73 ± 10.85 t/ha, 2.99 ± 9.19 t/ha and 1.03 ± 9.77 t/ha when maximizing the total utility functions for the actual, young, normal and older forests, respectively, when compared those at their initial conditions. This heuristic spatial forest planning process can allow forest managers to examine a number of different management activities, for both timber production and carbon stocks, prior to selecting a preferred alternative. Full article
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Open AccessArticle
Effect of Planting Density on Knot Attributes and Branch Occlusion of Betula alnoides under Natural Pruning in Southern China
Forests 2015, 6(4), 1343-1361; https://doi.org/10.3390/f6041343 - 21 Apr 2015
Cited by 13 | Viewed by 2615
Abstract
Knot-related defects are the major cause of timber quality degradation, and diminishing this kind of defects is an important issue in forest management. For the purpose of clear-wood production, knot attributes and branch occlusion of Betula alnoides under natural pruning were investigated in [...] Read more.
Knot-related defects are the major cause of timber quality degradation, and diminishing this kind of defects is an important issue in forest management. For the purpose of clear-wood production, knot attributes and branch occlusion of Betula alnoides under natural pruning were investigated in a 14-year-old experimental plantation with five planting densities ranging from 500 to 3333 stems per hectare in southern China, and a total of 1325 occluded branches from 30 trees were sampled and dissected. The mean occluded branch diameter (OBD), radius of knots and branch insertion angle (IA) decreased significantly with increasing planting density. Planting with high stocking density significantly reduced the frequency of thick occluded branches (diameter ≥ 20 mm) while increasing the frequency of small ones (diameter < 10 mm). Branch occlusion time (OT) also tended to increase with decreasing planting density. The results of generalized linear mixed models showed that OBD was the major factor influencing OT, radius of dead portion of knot (RDP), total radius of knot (TRK) and IA. In addition, OT was positively correlated with RDP but negatively correlated with stem diameter growth rate during branch occlusion (SDGR). Silvicultural strategies with appropriate planting density for large-diameter clear-wood production of B. alnoides were discussed. Full article
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Open AccessArticle
Source Material and Concentration of Wildfire-Produced Pyrogenic Carbon Influence Post-Fire Soil Nutrient Dynamics
Forests 2015, 6(4), 1325-1342; https://doi.org/10.3390/f6041325 - 21 Apr 2015
Cited by 15 | Viewed by 3183 | Correction
Abstract
Pyrogenic carbon (PyC) is produced by the thermal decomposition of organic matter in the absence of oxygen (O). PyC affects nutrient availability, may enhance post-fire nitrogen (N) mineralization rates, and can be a significant carbon (C) pool in fire-prone ecosystems. Our objectives were [...] Read more.
Pyrogenic carbon (PyC) is produced by the thermal decomposition of organic matter in the absence of oxygen (O). PyC affects nutrient availability, may enhance post-fire nitrogen (N) mineralization rates, and can be a significant carbon (C) pool in fire-prone ecosystems. Our objectives were to characterize PyC produced by wildfires and examine the influence that contrasting types of PyC have on C and N mineralization rates. We determined C, N, O, and hydrogen (H) concentrations and atomic ratios of charred bark (BK), charred pine cones (PC), and charred woody debris (WD) using elemental analysis. We also incubated soil amended with BK, PC, and WD at two concentrations for 60 days to measure C and N mineralization rates. PC had greater H/C and O/C ratios than BK and WD, suggesting that PC may have a lesser aromatic component than BK and WD. C and N mineralization rates decreased with increasing PyC concentrations, and control samples produced more CO2 than soils amended with PyC. Soils with PC produced greater CO2 and had lower N mineralization rates than soils with BK or WD. These results demonstrate that PyC type and concentration have potential to impact nutrient dynamics and C flux to the atmosphere in post-fire forest soils. Full article
(This article belongs to the Special Issue Climate Change and Forest Fire)
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Open AccessArticle
From Public to Private Standards for Tropical Commodities: A Century of Global Discourse on Land Governance on the Forest Frontier
Forests 2015, 6(4), 1301-1324; https://doi.org/10.3390/f6041301 - 21 Apr 2015
Cited by 20 | Viewed by 3191
Abstract
Globalization and commodity exports have a long history in affecting land use changes and land rights on the tropical forest frontier. This paper reviews a century of social and environmental discourse around land issues for four commodities grown in the humid tropics—rubber, cocoa, [...] Read more.
Globalization and commodity exports have a long history in affecting land use changes and land rights on the tropical forest frontier. This paper reviews a century of social and environmental discourse around land issues for four commodities grown in the humid tropics—rubber, cocoa, oil palm and bananas. States have exercised sovereign rights over land and forest resources and the outcomes for deforestation and land rights of existing users have been quite varied depending on local institutional contexts and political economy. In the current period of globalization, as land use changes associated with tropical commodities have accelerated, land issues are now at center stage in the global discourse. However, efforts to protect forests and the rights of local communities and indigenous groups continue to be ad hoc and codification of minimum standards and their implementation remains a work in progress. Given a widespread failure of state directed policies and institutions to curb deforestation and protect land rights, the private sector, with the exception of the rubber industry, is emphasizing voluntary standards to certify sustainability of their products. This is an important step but expectations that they will effectively address concerns about the impact of tropical commodities expansion might be too high, given their voluntary nature, demand constraints, and the challenge of including smallholders. It is also doubtful that private standards can more than partially compensate for long standing weaknesses in land governance and institutions on the forest frontier. Full article
(This article belongs to the Special Issue Governing Forest Landscapes: Challenges and Ways Forward)
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Open AccessArticle
Non Destructive Method for Biomass Prediction Combining TLS Derived Tree Volume and Wood Density
Forests 2015, 6(4), 1274-1300; https://doi.org/10.3390/f6041274 - 21 Apr 2015
Cited by 62 | Viewed by 4490
Abstract
This paper presents a method for predicting the above ground leafless biomass of trees in a non destructive way. We utilize terrestrial laserscan data to predict the volume of the trees. Combining volume estimates with density measurements leads to biomass predictions. Thirty-six trees [...] Read more.
This paper presents a method for predicting the above ground leafless biomass of trees in a non destructive way. We utilize terrestrial laserscan data to predict the volume of the trees. Combining volume estimates with density measurements leads to biomass predictions. Thirty-six trees of three different species are analyzed: evergreen coniferous Pinus massoniana, evergreen broadleaved Erythrophleum fordii and leafless deciduous Quercus petraea. All scans include a large number of noise points; denoising procedures are presented in detail. Density values are considered to be a minor source of error in the method if applied to stem segments, as comparison to ground truth data reveals that prediction errors for the tree volumes are in accordance with biomass prediction errors. While tree compartments with a diameter larger than 10 cm can be modeled accurately, smaller ones, especially twigs with a diameter smaller than 4 cm, are often largely overestimated. Better prediction results could be achieved by applying a biomass expansion factor to the biomass of compartments with a diameter larger than 10 cm. With this second method the average prediction error for Q. petraea could be reduced from 33.84% overestimation to 3.56%. E. fordii results could also be improved reducing the average prediction error from Full article
(This article belongs to the Special Issue Forest Ground Observations through Terrestrial Point Clouds)
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Open AccessArticle
Elevated Atmospheric CO2 Affects Ectomycorrhizal Species Abundance and Increases Sporocarp Production under Field Conditions
Forests 2015, 6(4), 1256-1273; https://doi.org/10.3390/f6041256 - 21 Apr 2015
Cited by 8 | Viewed by 2394
Abstract
Anthropogenic activities during the last century have increased levels of atmospheric CO2. Forest net primary productivity increases in response to elevated CO2, altering the quantity and quality of carbon supplied to the rhizosphere. Ectomycorrhizal fungi form obligate symbiotic associations [...] Read more.
Anthropogenic activities during the last century have increased levels of atmospheric CO2. Forest net primary productivity increases in response to elevated CO2, altering the quantity and quality of carbon supplied to the rhizosphere. Ectomycorrhizal fungi form obligate symbiotic associations with the fine roots of trees that mediate improved scavenging for nutrients in exchange for a carbohydrate supply. Understanding how the community structure of ectomycorrhizal fungi is altered by climate change is important to further our understanding of ecosystem function. Betula pendula and Fagus sylvatica were grown in an elevated CO2 atmosphere delivered using free air carbon dioxide enrichment (FACE) under field conditions in the U.K., and Picea abies was grown under elevated CO2 in glass domes in the Czech Republic. We used morphotyping and sequencing of the internal transcribed spacer region of the fungal ribosomal operon to study ectomycorrhizal community structure. Under FACE, un-colonised roots tips increased in abundance for Fagus sylvatica, and during 2006, sporocarp biomass of Peziza badia significantly increased. In domes, ectomycorrhizal community composition shifted from short-distance and smooth medium-distance to contact exploration types. Supply and competition for carbon belowground can influence ectomycorrhizal community structure with the potential to alter ecosystem function. Full article
(This article belongs to the Special Issue Mycorrhizal Fungi of Forests)
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Open AccessArticle
Biomass, Carbon and Nutrient Storage in a 30-Year-Old Chinese Cork Oak (Quercus Variabilis) Forest on the South Slope of the Qinling Mountains, China
Forests 2015, 6(4), 1239-1255; https://doi.org/10.3390/f6041239 - 21 Apr 2015
Cited by 5 | Viewed by 2465
Abstract
Chinese cork oak (Quercus variabilis) forests are protected on a large-scale under the Natural Forest Protection (NFP) program in China to improve the ecological environment. However, information about carbon (C) storage to increase C sequestration and sustainable management is lacking. Biomass, [...] Read more.
Chinese cork oak (Quercus variabilis) forests are protected on a large-scale under the Natural Forest Protection (NFP) program in China to improve the ecological environment. However, information about carbon (C) storage to increase C sequestration and sustainable management is lacking. Biomass, C, nitrogen (N) and phosphorus (P) storage of trees, shrubs, herb, litter and soil (0–100 cm) were determined from destructive tree sampling and plot level investigation in approximately 30-year old Chinese cork oak forests on the south slope of the Qinling Mountains. There was no significant difference in tree components’ biomass estimation, with the exception of roots, among the available allometric equations developed from this study site and other previous study sites. Leaves had the highest C, N and P concentrations among tree components and stems were the major compartments for tree biomass, C, N and P storage. In contrast to finding no difference in N concentrations along the whole soil profile, higher C and P concentrations were observed in the upper 0–10 cm of soil than in the deeper soil layers. The ecosystem C, N, and P storage was 163.76, 18.54 and 2.50 t ha−1, respectively. Soil (0–100 cm) contained the largest amount of C, N and P storage, accounting for 61.76%, 92.78% and 99.72% of the total ecosystem, followed by 36.14%, 6.03% and 0.23% for trees, and 2.10%, 1.19% and 0.03% for shrubs, herbs and litter, respectively. The equations accurately estimate ecosystem biomass, and the knowledge of the distribution of C, N and P storage will contribute to increased C sequestration and sustainable management of Chinese cork oak forests under the NFP program. Full article
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Open AccessArticle
Stem Anatomy and Adventitious Root Formation in Cuttings of Angophora, Corymbia and Eucalyptus
Forests 2015, 6(4), 1227-1238; https://doi.org/10.3390/f6041227 - 15 Apr 2015
Cited by 15 | Viewed by 3297
Abstract
Many plantation eucalypts are difficult to propagate from cuttings, and their rooted cuttings often possess very few adventitious roots. We microscopically examined the stem anatomy of cuttings from 12 species of eucalypts and we determined whether adventitious root formation in auxin-treated cuttings of [...] Read more.
Many plantation eucalypts are difficult to propagate from cuttings, and their rooted cuttings often possess very few adventitious roots. We microscopically examined the stem anatomy of cuttings from 12 species of eucalypts and we determined whether adventitious root formation in auxin-treated cuttings of four species was limited to particular positions around the vascular tissue. Most species contained a central pith that was arranged in a four-pointed stellate pattern. The surrounding vascular tissue was also arranged in a stellate pattern near the shoot apex but it developed a more rectangular shape at the outer phloem as the stems enlarged radially. Adventitious roots formed at, or slightly peripheral to, the vascular cambium, and they formed at both the corners and the sides of the rectangular-shaped vascular tissue. The study highlighted that auxin-treated eucalypt cuttings can produce roots at multiple positions around the vascular tissue and so propagation methods can aim to produce more than four adventitious roots per rooted cutting. Higher numbers of adventitious roots could improve the root system symmetry, stability, survival and growth rate of clonal eucalypt trees. Full article
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Open AccessArticle
Predicting Effects of Climate Change on Habitat Suitability of Red Spruce (Picea rubens Sarg.) in the Southern Appalachian Mountains of the USA: Understanding Complex Systems Mechanisms through Modeling
Forests 2015, 6(4), 1208-1226; https://doi.org/10.3390/f6041208 - 15 Apr 2015
Cited by 7 | Viewed by 2729
Abstract
Alpine, subalpine and boreal tree species, of low genetic diversity and adapted to low optimal temperatures, are vulnerable to the warming effects of global climate change. The accurate prediction of these species’ distributions in response to climate change is critical for effective planning [...] Read more.
Alpine, subalpine and boreal tree species, of low genetic diversity and adapted to low optimal temperatures, are vulnerable to the warming effects of global climate change. The accurate prediction of these species’ distributions in response to climate change is critical for effective planning and management. The goal of this research is to predict climate change effects on the distribution of red spruce (Picea rubens Sarg.) in the Great Smoky Mountains National Park (GSMNP), eastern USA. Climate change is, however, conflated with other environmental factors, making its assessment a complex systems problem in which indirect effects are significant in causality. Predictions were made by linking a tree growth simulation model, red spruce growth model (ARIM.SIM), to a GIS spatial model, red spruce habitat model (ARIM.HAB). ARIM.SIM quantifies direct and indirect interactions between red spruce and its growth factors, revealing the latter to be dominant. ARIM.HAB spatially distributes the ARIM.SIM simulations under the assumption that greater growth reflects higher probabilities of presence. ARIM.HAB predicts the future habitat suitability of red spruce based on growth predictions of ARIM.SIM under climate change and three air pollution scenarios: 10% increase, no change and 10% decrease. Results show that suitable habitats shrink most when air pollution increases. Higher temperatures cause losses of most low-elevation habitats. Increased precipitation and air pollution produce acid rain, which causes loss of both low- and high-elevation habitats. The general prediction is that climate change will cause contraction of red spruce habitats at both lower and higher elevations in GSMNP, and the effects will be exacerbated by increased air pollution. These predictions provide valuable information for understanding potential impacts of global climate change on the spatiotemporal distribution of red spruce habitats in GSMNP. Full article
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Open AccessArticle
Can We Use Forest Inventory Mapping as a Coarse Filter in Ecosystem Based Management in the Black Spruce Boreal Forest?
Forests 2015, 6(4), 1195-1207; https://doi.org/10.3390/f6041195 - 15 Apr 2015
Cited by 13 | Viewed by 2415
Abstract
Forest inventory mapping is used worldwide to describe forests at a large spatial scale via the delimitation of portions of the landscape that are structurally homogeneous. Consequently, there is a significant amount of descriptive forest data in forest inventory maps, particularly with the [...] Read more.
Forest inventory mapping is used worldwide to describe forests at a large spatial scale via the delimitation of portions of the landscape that are structurally homogeneous. Consequently, there is a significant amount of descriptive forest data in forest inventory maps, particularly with the development of ecosystem classification, which represents a significant potential for use in ecosystem based management. With this study we propose to test whether forest inventory maps can be used to describe not only stand characteristics but also dynamic processes. The results indicate that stand types identifiable in forest inventory maps do not in fact represent unique developmental stages, but rather confound stands at multiple developmental stages that may be undergoing different ecological processes. The reasons for this are linked to both the interaction between succession, fire severity and paludification. Finally, some aspects of the process of forest inventory mapping itself contribute to the disjunction between forest types and forest succession. Given the low similarity between spruce mapping types and their actual description following forest inventories, it would be too ambitious to infer the dynamic aspects of spruce forest by map units. Full article
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Open AccessArticle
Evaluation of a Smartphone App for Forest Sample Plot Measurements
Forests 2015, 6(4), 1179-1194; https://doi.org/10.3390/f6041179 - 15 Apr 2015
Cited by 14 | Viewed by 3688
Abstract
We evaluated a smartphone app (TRESTIMATM) for forest sample plot measurements. The app interprets imagery collected from the sample plots using the camera in the smartphone and then estimates forest inventory attributes, including species-specific basal areas (G) as well as the [...] Read more.
We evaluated a smartphone app (TRESTIMATM) for forest sample plot measurements. The app interprets imagery collected from the sample plots using the camera in the smartphone and then estimates forest inventory attributes, including species-specific basal areas (G) as well as the diameter (DgM) and height (HgM) of basal area median trees. The estimates from the smartphone app were compared to forest inventory attributes derived from tree-wise measurements using calipers and a Vertex height measurement device. The data consist of 2169 measured trees from 25 sample plots (32 m × 32 m), dominated by Scots pine and Norway spruce from southern Finland. The root-mean-square errors (RMSEs) in the basal area varied from 19.7% to 29.3% and the biases from 11.4% to 18.4% depending on the number of images per sample plot and image shooting location. DgM measurement bias varied from −1.4% to 3.1% and RMSE from 5.2% to 11.6% depending on the tree species. Respectively, HgM bias varied from 5.0% to 8.3% and RMSE 10.0% to 13.6%. In general, four images captured toward the center of the plot provided more accurate results than four images captured away from the plot center. Increasing the number of captured images per plot to the analyses yielded only marginal improvement to the results. Full article
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Open AccessArticle
If Long-Term Resistance to a Spruce Beetle Epidemic is Futile, Can Silvicultural Treatments Increase Resilience in Spruce-Fir Forests in the Central Rocky Mountains?
Forests 2015, 6(4), 1157-1178; https://doi.org/10.3390/f6041157 - 15 Apr 2015
Cited by 8 | Viewed by 2350
Abstract
Within the Central Rocky Mountains, spruce beetle populations have the potential to rapidly transition from endemic to epidemic levels in the spruce-fir (Engelmann spruce and subalpine fir) forest type. Conventional management has focused on creating resistance to spruce beetle outbreaks by manipulating the [...] Read more.
Within the Central Rocky Mountains, spruce beetle populations have the potential to rapidly transition from endemic to epidemic levels in the spruce-fir (Engelmann spruce and subalpine fir) forest type. Conventional management has focused on creating resistance to spruce beetle outbreaks by manipulating the overstory density and composition. Three silvicultural treatments, single tree selection, group selection, and shelterwood with reserves, were established in a spruce-fir forest in northern Utah with the goals of increasing both resistance and resilience to outbreaks. Resistance and resilience metrics were explicitly defined. Pre-harvest and two post-harvest measurements were used to assess how the different silvicultural treatments influenced the metrics. The shelterwood with reserves was the only treatment to meet both the resistance and resilience criteria. This treatment, while not traditionally used, created a stand structure and composition that will be most resilient to climate induced increases in spruce beetle caused tree mortality. However, there will be a trade-off in composition and structure, especially Engelmann spruce, after a spruce beetle epidemic because the created structure is more uniform with fewer groups and gaps than commonly observed in spruce-fir forests. With changing climatic conditions, proactive forest management, such as the shelterwood with reserves in the spruce-fir forest type, is the best method for increasing short-term resistance and long-term resilience to spruce beetle outbreaks. Full article
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Open AccessArticle
Residual Long-Term Effects of Forest Fertilization on Tree Growth and Nitrogen Turnover in Boreal Forest
Forests 2015, 6(4), 1145-1156; https://doi.org/10.3390/f6041145 - 10 Apr 2015
Cited by 8 | Viewed by 4925
Abstract
The growth enhancing effects of forest fertilizer is considered to level off within 10 years of the application, and be restricted to one forest stand rotation. However, fertilizer induced changes in plant community composition has been shown to occur in the following stand [...] Read more.
The growth enhancing effects of forest fertilizer is considered to level off within 10 years of the application, and be restricted to one forest stand rotation. However, fertilizer induced changes in plant community composition has been shown to occur in the following stand rotation. To clarify whether effects of forest fertilization have residual long-term effects, extending into the next rotation, we compared tree growth, needle N concentrations and the availability of mobile soil N in young (10 years) Pinus sylvestris L. and Picea abies (L.) H. Karst. stands. The sites were fertilized with 150 kg·N·ha−1 once or twice during the previous stand rotation, or unfertilized. Two fertilization events increased tree height by 24% compared to the controls. Needle N concentrations of the trees on previously fertilized sites were 15% higher than those of the controls. Soil N mineralization rates and the amounts of mobile soil NH4-N and NO3-N were higher on sites that were fertilized twice than on control sites. Our study demonstrates that operational forest fertilization can cause residual long-term effects on stand N dynamics, with subsequent effects on tree growth that may be more long-lasting than previously believed, i.e., extending beyond one stand rotation. Full article
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Open AccessArticle
Tree-Level Harvest Optimization for Structure-Based Forest Management Based on the Species Mingling Index
Forests 2015, 6(4), 1121-1144; https://doi.org/10.3390/f6041121 - 09 Apr 2015
Cited by 16 | Viewed by 2334
Abstract
This novel research investigated the use of a heuristic process to inform tree-level harvest decisions guided by the need to maximize the interspersion of tree species across a forest. In the heuristic process, a species mingling value for each tree was computed using [...] Read more.
This novel research investigated the use of a heuristic process to inform tree-level harvest decisions guided by the need to maximize the interspersion of tree species across a forest. In the heuristic process, a species mingling value for each tree was computed using both (1) neighbors that were simply of a different species than the reference tree and (2) neighbors that were uniquely different species from both the reference tree and other neighbors of the reference tree. The tree-level species mingling value was averaged for the stand, which was then subject to a maximization process. Constraints included residual tree density levels and minimum tree volume harvest levels. In two case studies, results suggest that the species mingling index at the stand level can be significantly increased over randomly allocated harvest decisions using the heuristic process described. In the case studies, we illustrate how this type of process can inform management decisions by suggesting the distance between residual trees of similar species given the initial stand structure and the objectives and constraints. The work represents a unique tree-level optimization approach that one day may be of value as new technologies are developed to map the location of individual trees in a timely and efficient manner. Full article
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Open AccessArticle
Variation in the Growth Traits and Wood Properties of Hybrid White Poplar Clones
Forests 2015, 6(4), 1107-1120; https://doi.org/10.3390/f6041107 - 08 Apr 2015
Cited by 10 | Viewed by 2479
Abstract
The physical and chemical properties of poplar clones largely determine their suitability for different applications. The main objective of this study was to investigate clonal variation in four hybrid poplar clones grown at three sites in North China and identify the superior clone. [...] Read more.
The physical and chemical properties of poplar clones largely determine their suitability for different applications. The main objective of this study was to investigate clonal variation in four hybrid poplar clones grown at three sites in North China and identify the superior clone. Study materials were collected from four clones of hybrid white poplar: Populus tomentosa “LM50”, used as the control; two clones (Yiyang-1 and Yiyang-2), new hybrids of (P. tomentosa × P. bolleana) × P. tomentosa “Truncata”; and Yiyang-3, a new hybrid of (P. tomentosa × P. bolleana) × P. tomentosa “LM50”. In total, 192 individuals from four hybrid clones were randomly chosen for sampling. The growth traits of four 7-year-old clones were examined at three sites. We also measured the wood properties of four 6-year-old clones at the Fengfeng nursery. Variation in the growth traits and the ranking of stem volumes differed among sites. Fiber traits and wood chemical components showed significant interclonal variation. With regard to the comprehensive growth rate, cellulose content, holocellulose content, and fiber traits, Yiyang-1 exhibited the best performance among the four hybrid poplar clones, indicating its utility as a raw material for pulp and papermaking. Full article
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Open AccessArticle
Genetic Diversity and Population Structure of Toona Ciliata Roem. Based on Sequence-Related Amplified Polymorphism (SRAP) Markers
Forests 2015, 6(4), 1094-1106; https://doi.org/10.3390/f6041094 - 08 Apr 2015
Cited by 9 | Viewed by 2354
Abstract
Sequence-related amplified polymorphism (SRAP) markers were used to investigate the genetic diversity among 30 populations of Toona ciliata Roem. sampled from the species’ distribution area in China. To analyze the polymorphism in the SRAP profiles, 1505 primer pairs were screened and 24 selected. [...] Read more.
Sequence-related amplified polymorphism (SRAP) markers were used to investigate the genetic diversity among 30 populations of Toona ciliata Roem. sampled from the species’ distribution area in China. To analyze the polymorphism in the SRAP profiles, 1505 primer pairs were screened and 24 selected. A total of 656 SRAP bands ranging from 100 to 1500 bp were acquired, of these 505 bands (77%) were polymorphic. The polymorphism information content (PIC) values ranged from 0.32 to 0.45, with an average of 0.41. An analysis of molecular variance (AMOVA) indicated that the most significant variation was attributable to differences among the populations and that variation within the populations was small. STRUCTURE analysis divided the 30 populations into two parts. The unweighted pair group method of arithmetic averages (UPGMA) clustering and principal coordinates analysis (PCoA) showed that the 30 populations could be classified into four types. The results demonstrate a clear geographical trend for T. ciliata in China and provide a theoretical basis for future breeding and conservation strategy of T. ciliata. Full article
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Open AccessArticle
Aboveground Biomass of Glossy Buckthorn is Similar in Open and Understory Environments but Architectural Strategy Differs
Forests 2015, 6(4), 1083-1093; https://doi.org/10.3390/f6041083 - 08 Apr 2015
Cited by 11 | Viewed by 2656
Abstract
The exotic shrub glossy buckthorn (Frangula alnus) is a great concern among forest managers because it invades both open and shaded environments. To evaluate if buckthorn grows similarly across light environments, and if adopting different shapes contributes to an efficient use [...] Read more.
The exotic shrub glossy buckthorn (Frangula alnus) is a great concern among forest managers because it invades both open and shaded environments. To evaluate if buckthorn grows similarly across light environments, and if adopting different shapes contributes to an efficient use of light, we compared buckthorns growing in an open field and in the understory of a mature hybrid poplar plantation. For a given age, the relationships describing aboveground biomass of buckthorns in the open field and in the plantation were not significantly different. However, we observed a significant difference between the diameter-height relationships in the two environments. These results suggest a change in buckthorn’s architecture, depending on the light environment in which it grows. Buckthorn adopts either an arborescent shape under a tree canopy, or a shrubby shape in an open field, to optimally capture the light available. This architectural plasticity helps explain a similar invasion success for glossy buckthorn growing in both open and shaded environments, at least up to the canopy closure level of the plantation used for this study. Full article
(This article belongs to the Special Issue Exotic and Invasive Plant Species Impacting Forests)
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Open AccessArticle
Mid-Rotation Silviculture Timing Influences Nitrogen Mineralization of Loblolly Pine Plantations in the Mid-South USA
Forests 2015, 6(4), 1061-1082; https://doi.org/10.3390/f6041061 - 08 Apr 2015
Cited by 1 | Viewed by 2292
Abstract
Intensively managed loblolly pine (Pinus taeda L.) plantations often develop nutrient deficiencies near mid-rotation. Common silvicultural treatments for improving stand nutrition at this stage include thinning, fertilization, and vegetation control. It is important to better understand the influence of timing fertilization and [...] Read more.
Intensively managed loblolly pine (Pinus taeda L.) plantations often develop nutrient deficiencies near mid-rotation. Common silvicultural treatments for improving stand nutrition at this stage include thinning, fertilization, and vegetation control. It is important to better understand the influence of timing fertilization and vegetation control in relation to thinning as part of improving the efficiency of these practices. The objective of this study was to determine the effects of fertilization and vegetation control conducted within a year prior to thinning and within a year after thinning on soil N supply in mid-rotation loblolly pine plantations on a gradient of soil textures. Net N mineralization (Nmin) and exchangeable N were measured monthly. Fertilization increased annual Nmin at all sites irrespective of timing relative to thinning, with the increase more pronounced when combined with vegetation control. This finding suggests some management flexibility in the timing of mid-rotation fertilization relative to thinning for increasing soil N supply. However, the site with the highest total soil N and the lowest C:N ratio was more prone to NO3-N increases after fertilization conducted pre- and post-thinning. At all sites, fertilization with vegetation control promoted increases in NO3-N when done after thinning, which may indicate that this practice increased soil N supply to levels that exceeded stand N demand. Full article
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Open AccessArticle
Taking Stock of Carbon Rights in REDD+ Candidate Countries: Concept Meets Reality
Forests 2015, 6(4), 1031-1060; https://doi.org/10.3390/f6041031 - 08 Apr 2015
Cited by 15 | Viewed by 2992
Abstract
In the discourses on who should benefit from national REDD+ implementation, rights-based approaches are prominent across various countries. Options on how to create viable property rights arrangements are currently being debated by scholars, policy makers and practitioners alike. Many REDD+ advocates argue that [...] Read more.
In the discourses on who should benefit from national REDD+ implementation, rights-based approaches are prominent across various countries. Options on how to create viable property rights arrangements are currently being debated by scholars, policy makers and practitioners alike. Many REDD+ advocates argue that assigning carbon rights represents a solution to insecure individual and community property rights. But carbon rights, i.e., the bundle of legal rights to carbon sequestered in biomass, present their own set of theoretical and practical challenges. We assess the status and approaches chosen in emerging carbon-rights legislations in five REDD+ countries based on a literature review and country expert knowledge: Peru, Brazil, Cameroon, Vietnam and Indonesia. We find that most countries assessed have not yet made final decisions as to the type of benefit sharing mechanisms they intend to implement and that there is a lack of clarity about who owns rights to carbon as a property and who is entitled to receive benefits. However, there is a trend of linking carbon rights to land rights. As such, the technical and also political challenges that land tenure clarification has faced over the past decades will still need to be addressed in the context of carbon rights. Full article
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Open AccessArticle
Evaluating the Ecological Integrity of Structural Stand Density Management Models Developed for Boreal Conifers
Forests 2015, 6(4), 992-1030; https://doi.org/10.3390/f6040992 - 07 Apr 2015
Cited by 6 | Viewed by 2092
Abstract
Density management decision-support systems (e.g., modular-based structural stand density management models (SSDMMs)), which are built upon the modeling platform used to develop stand density management diagrams, incorporate a number of functional relationships derived from forest production theory and quantitative ecology. Empirically, however, the [...] Read more.
Density management decision-support systems (e.g., modular-based structural stand density management models (SSDMMs)), which are built upon the modeling platform used to develop stand density management diagrams, incorporate a number of functional relationships derived from forest production theory and quantitative ecology. Empirically, however, the ecological integrity of these systems has not been verified and hence the degree of their compliance with expected ecological axioms is unknown. Consequently, the objective of this study was to evaluate the ecological integrity of six SSDMMs developed for black spruce (Picea mariana) and jack pine (Pinus banksiana) stand-types (natural-origin and planted upland black spruce and jack pine stands, upland natural-origin black spruce and jack pine mixtures, and natural-origin lowland black spruce stands). The assessment included the determination of the biological reasonableness of model predictions by determining the degree of consistency between predicted developmental patterns and those expected from known ecological axioms derived from even-aged stand dynamics theoretical constructs, employing Bakuzis graphical matrices. Although the results indicated the SSDMMs performed well, a notable departure from expectation was a possible systematic site quality effect on the asymptotic yield-density relationships. Combining these results with confirmatory evidence derived from the literature suggest that the site-invariant self-thinning axiom may be untenable for certain stand-types. Full article
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Open AccessArticle
Available Nitrogen and Responses to Nitrogen Fertilizer in Brazilian Eucalypt Plantations on Soils of Contrasting Texture
Forests 2015, 6(4), 973-991; https://doi.org/10.3390/f6040973 - 02 Apr 2015
Cited by 23 | Viewed by 3023
Abstract
Eucalyptus plantations have seldom responded to N fertilization in tropical and subtropical regions of Brazil. This implies that rates of N mineralization have been adequate to supply tree needs. However, subsequent crop rotations with low N fertilization may result in declining concentrations of [...] Read more.
Eucalyptus plantations have seldom responded to N fertilization in tropical and subtropical regions of Brazil. This implies that rates of N mineralization have been adequate to supply tree needs. However, subsequent crop rotations with low N fertilization may result in declining concentrations of organic and potentially mineralizable N (N0), and consequent loss of wood productivity. This study investigated (a) in situ N mineralization and N0 in soils of eucalypt plantations in São Paulo state, Brazil; (b) tree growth responses to N fertilizer applied 6–18 months after planting; and (c) the relationships between N0, other soil attributes and tree growth. We established eleven N fertilizer trials (maximum 240 kg ha−1 of N) in E. grandis and E. grandis x urophylla plantations. The soil types at most sites were Oxisols and Quartzipsamments, with a range of organic matter (18 to 55 g kg−1) and clay contents (8% to 67%) in the 0–20 cm layer. Concentrations of N0 were measured using anaerobic incubation on soil samples collected every three months (different seasons). The samples collected in spring and summer had N0 140–400 kg ha−1 (10%–19% total soil N), which were best correlated with soil texture and organic matter content. Rates of in situ net N mineralization (0–20 cm) ranged from 100 to 200 kg ha−1 year−1 and were not correlated with clay, total N, or N0. These high N mineralization rates resulted in a low response to N fertilizer application during the early ages of stand growth, which were highest on sandy soils. At the end of the crop rotation, the response to N fertilizer was negligible and non-significant at all sites. Full article
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Open AccessArticle
LAI Variability as a Habitat Feature Determining Reptile Occurrence: A Case Study in Large Forest Complexes in Eastern Poland
Forests 2015, 6(4), 957-972; https://doi.org/10.3390/f6040957 - 31 Mar 2015
Cited by 1 | Viewed by 2402
Abstract
Reptile habitats are described using various indices. The definitions of such indices are crucial, as they are applied to habitat modelling for numerous species on local to continental scales. We examined the Leaf Area Index (LAI) for its value as a tool for [...] Read more.
Reptile habitats are described using various indices. The definitions of such indices are crucial, as they are applied to habitat modelling for numerous species on local to continental scales. We examined the Leaf Area Index (LAI) for its value as a tool for determining reptile habitat. During measurements carried out in spring and summer months between 2011 and 2013, LAI values were assessed and surveys were conducted on reptile fauna at 11 survey sites in the Solska Forest and Roztocze National Parks areas in Eastern Poland. In total, six Squamata reptiles occurring in Poland were found. We determined that LAI can be utilized as a reptile habitat index, with reptile species associated with LAI seasonal variability as well as LAI range. Moreover, we found that the higher the LAI median value, the greater the variety of reptile species. These findings are useful for development of spatial models of habitats based on LAI as they point to the importance of its seasonal variation. Full article
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Open AccessArticle
A Comparison of the Composition and Diversity of Tree Populations along a Hydrological Gradient in Floodplains (Southern Québec, Canada)
Forests 2015, 6(4), 929-956; https://doi.org/10.3390/f6040929 - 30 Mar 2015
Cited by 6 | Viewed by 2246
Abstract
With the current climate changes, it is essential to understand the mechanisms that govern floods and flow regimes and their effects on the dynamics of riparian forests. The aim is to assess the effects of new hydrological conditions (increase in flood frequency) on [...] Read more.
With the current climate changes, it is essential to understand the mechanisms that govern floods and flow regimes and their effects on the dynamics of riparian forests. The aim is to assess the effects of new hydrological conditions (increase in flood frequency) on forest stands subject to frequent floods. The sampling sites (total of 94 quadrats) are located in riverine woodlands, and the choice of location corresponds to the boundaries of the flood-risk zones established by official government maps. Our study shows that there are significant differences in the composition and diversity of forest communities following differences in the flood recurrence zones. In the active floodplains (i.e., recurrence interval of 0–20 years), the tree population stands are clearly distinguished from other intermediate flood zones (interval of 20–100 years). Differences are also noted in the structure of the communities, in particular in the frequent flood zones, which are characterized by a low renewal rate, low density and less-diversified forest stands. The frequent floods risk forest stand rejuvenation and creating decline as a result of increased tree mortality and the low renewal rate. With the expected increases in the number of flood events in the coming decades, there may be greater tree mortality and a gradual disappearance of the forest communities. Full article
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Open AccessArticle
Localized Effects of Coarse Woody Material on Soil Oribatid Communities Diminish over 700 Years of Stand Development in Black-Spruce-Feathermoss Forests
Forests 2015, 6(4), 914-928; https://doi.org/10.3390/f6040914 - 27 Mar 2015
Cited by 3 | Viewed by 2129
Abstract
In the black-spruce clay-belt region of Western Québec, soil nutrients are limited due to paludification. Under paludified conditions, nutrient subsidies from decomposing surface coarse woody material (CWM) may be important particularly during the later stages of ecosystem development when deadwood from senescent trees [...] Read more.
In the black-spruce clay-belt region of Western Québec, soil nutrients are limited due to paludification. Under paludified conditions, nutrient subsidies from decomposing surface coarse woody material (CWM) may be important particularly during the later stages of ecosystem development when deadwood from senescent trees has accumulated. For soil organisms, CWM can alter microclimatic conditions and resource availability. We compared abundance and species richness of oribatid mites below or adjacent to CWM across a chronosequence which spans ca. 700 years of stand development. We hypothesized that oribatid abundance and richness would be greater under the logs, particularly in later stages of forest development when logs may act as localized sources of carbon and nutrients in the paludified substrate. However, oribatid density was lower directly under CWM than adjacent to CWM but these differences were attenuated with time. We suggest that oribatids may be affected by soil compaction and also that such microarthropods are most likely feeding on recently fallen leaf litter, which may be rendered inaccessible by the presence of overlying CWM. This may also explain the progressive decline in oribatid density and diversity with time, which are presumably caused by decreases in litter availability due to self-thinning and Sphagnum growth. This is also supported by changes of different oribatid trophic groups, as litter feeders maintain different numbers relative to CWM with time while more generalist fungi feeders only show differences related to position in the beginning of the succession. Full article
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Open AccessCommunication
Anomalies of the Austrian Forest Fire Regime in Comparison with Other Alpine Countries: A Research Note
Forests 2015, 6(4), 903-913; https://doi.org/10.3390/f6040903 - 24 Mar 2015
Cited by 8 | Viewed by 2798
Abstract
In recent years, Austria has experienced highly variable forest fire activity with new record values regarding the number of fires and sizes of burned areas. Single seasons in 2011, 2012 and 2013 showed 20-year-peaks and significant differences regarding fire activity. A statistical overview [...] Read more.
In recent years, Austria has experienced highly variable forest fire activity with new record values regarding the number of fires and sizes of burned areas. Single seasons in 2011, 2012 and 2013 showed 20-year-peaks and significant differences regarding fire activity. A statistical overview of datasets from Austria, Switzerland, Italy and Slovenia is given, allowing a preliminary comparison between the Alpine countries. Higher temperatures in combination with local dry weather conditions are hypothesized as reasons for the observed anomalies. Further analysis will be done with new climatic data in high spatial resolution from the “AgroDroughtAustria” project to confirm these preliminary findings. Full article
(This article belongs to the Special Issue Climate Change and Forest Fire)
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Open AccessReview
Implementing Continuous Cover Forestry in Planted Forests: Experience with Sitka Spruce (Picea Sitchensis) in the British Isles
Forests 2015, 6(4), 879-902; https://doi.org/10.3390/f6040879 - 24 Mar 2015
Cited by 8 | Viewed by 2516
Abstract
Planted forests of Sitka spruce, a non-native species from north-west America, are the major forest type in Great Britain and Ireland. Standard management involves even-aged stands, rotations of 40–50 years and a patch clear-felling system with artificial regeneration. However, forest policies support managing [...] Read more.
Planted forests of Sitka spruce, a non-native species from north-west America, are the major forest type in Great Britain and Ireland. Standard management involves even-aged stands, rotations of 40–50 years and a patch clear-felling system with artificial regeneration. However, forest policies support managing these forests for multifunctional objectives with increased diversity of species composition and stand structure. Continuous cover forestry (CCF) is an alternative silvicultural approach used to provide such diversity, but the amount of CCF forest is under 10% of the forest area, and less in Sitka spruce forests; This paper reviews research carried out in the last two decades to support the implementation of CCF in Sitka spruce planted forests; Stand structures and microclimate favouring natural regeneration are understood. Harvesting systems have been adapted for use in CCF stands, a single-tree growth model has been calibrated, comparative costs and revenues have been determined, and operational trials established. The interaction between thinning and wind stability in irregular stands is problematic, together with the lack of suitable species for growing in mixture with Sitka spruce; Introduction of an alternative silvicultural approach may take decades and must overcome technical challenges and cultural resistance. Full article
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Open AccessArticle
Assisting Sustainable Forest Management and Forest Policy Planning with the Sim4Tree Decision Support System
Forests 2015, 6(4), 859-878; https://doi.org/10.3390/f6040859 - 24 Mar 2015
Cited by 5 | Viewed by 3602
Abstract
As European forest policy increasingly focuses on multiple ecosystem services and participatory decision making, forest managers and policy planners have a need for integrated, user-friendly, broad spectrum decision support systems (DSS) that address risks and uncertainties, such as climate change, in a robust [...] Read more.
As European forest policy increasingly focuses on multiple ecosystem services and participatory decision making, forest managers and policy planners have a need for integrated, user-friendly, broad spectrum decision support systems (DSS) that address risks and uncertainties, such as climate change, in a robust way and that provide credible advice in a transparent manner, enabling effective stakeholder involvement. The Sim4Tree DSS has been accordingly developed as a user-oriented, modular and multipurpose toolbox. Sim4Tree supports strategic and tactical forestry planning by providing simulations of forest development, ecosystem services potential and economic performance through time, from a regional to a stand scale, under various management and climate regimes. Sim4Tree allows comparing the performance of different scenarios with regard to diverse criteria so as to optimize management choices. This paper explains the concept, characteristics, functionalities, components and use of the current Sim4Tree DSS v2.5, which was parameterized for the region of Flanders, Belgium, but can be flexibly adapted to allow a broader use. When considering the current challenges for forestry DSS, an effort has been made towards the participatory component and towards integration, while the lack of robustness remains Sim4Tree’s weakest point. However, its structural flexibility allows many possibilities for future improvement and extension. Full article
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