Open AccessArticle
Fire Severity and Regeneration Strategy Influence Shrub Patch Size and Structure Following Disturbance
Forests 2017, 8(7), 221; doi:10.3390/f8070221 (registering DOI) -
Abstract
Climate change is increasing the frequency and extent of high-severity disturbance, with potential to alter vegetation community composition and structure in environments sensitive to tipping points between alternative states. Shrub species display a range of characteristics that promote resistance and resilience to disturbance,
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Climate change is increasing the frequency and extent of high-severity disturbance, with potential to alter vegetation community composition and structure in environments sensitive to tipping points between alternative states. Shrub species display a range of characteristics that promote resistance and resilience to disturbance, and which yield differential post-disturbance outcomes. We investigated differences in shrub patch size and stem density in response to variations in fire severity, vegetation community, and post-disturbance reproductive strategies in Sky Island forested ecosystems in the southwestern United States. Patterns in shrub structure reflect the effects of fire severity as well as differences among species with alternate post-fire reproductive strategies. Increased fire severity correlates with larger patch sizes and greater stem densities; these patterns are observed across multiple fire events, indicating that disturbance legacies can persist for decades. High severity fire produces the largest shrub patches, and variance in shrub patch size increases with severity. High severity fire is likely to promote expansion of shrub species on the landscape, with implications for future community structure. Resprouting species have the greatest variability in patch structure, while seeding species show a strong response to disturbance: resprouting species dominate at low disturbance severities, and obligate seeders dominate high severity areas. Differential post-fire reproductive strategies are likely to generate distinct patterns of vegetation distribution following disturbance, with implications for community composition at various scales. Shrub species demonstrate flexible responses to wildfire disturbance severity that are reflected in shrub patch dynamics at small and intermediate scales. Full article
Open AccessFeature PaperArticle
Is Biomass Accumulation in Forests an Option to Prevent Climate Change Induced Increases in Nitrate Concentrations in the North German Lowland?
Forests 2017, 8(6), 219; doi:10.3390/f8060219 -
Abstract
The North German Lowland is a region with locally high nitrate (NO3) concentrations in seepage water, inducing an increased susceptibility to the effects of climate change. The future risk of rising NO3 concentrations in seepage water from forests
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The North German Lowland is a region with locally high nitrate (NO3) concentrations in seepage water, inducing an increased susceptibility to the effects of climate change. The future risk of rising NO3 concentrations in seepage water from forests was quantified for four regions in the North German Lowland using climate projections and a modelling system comprising submodels for forest stand development (WaldPlaner), water budgets (WaSiM-ETH), and biogeochemical element cycles (VSD+). The simulations for the period from 1990 to 2070 included three different forest management scenarios (reference, biodiversity, and climate protection) and showed a general decrease in groundwater recharge which could hardly be influenced by any of the management options. The simulated soil organic matter stocks adequately represented their past increase as expected from the National Forest Soil Inventory (NFSI), but also showed a future decline under climate change conditions which leads to higher organic matter decomposition and a long-lasting increase of NO3 leaching from forest soils. While the climate protection oriented scenario shows the highest increase in NO3 concentrations during the projection period until 2070, the biodiversity scenario kept NO3 concentrations in seepage water below the legal thresholds in three of four selected model regions. Full article
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Open AccessArticle
The Role of Respiration in Estimation of Net Carbon Cycle: Coupling Soil Carbon Dynamics and Canopy Turnover in a Novel Version of 3D-CMCC Forest Ecosystem Model
Forests 2017, 8(6), 220; doi:10.3390/f8060220 -
Abstract
Understanding the dynamics of organic carbon mineralization is fundamental in forecasting biosphere to atmosphere net carbon ecosystem exchange (NEE). With this perspective, we developed 3D-CMCC-PSM, a new version of the hybrid process based model 3D‐CMCC FEM where also heterotrophic respiration (Rh)
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Understanding the dynamics of organic carbon mineralization is fundamental in forecasting biosphere to atmosphere net carbon ecosystem exchange (NEE). With this perspective, we developed 3D-CMCC-PSM, a new version of the hybrid process based model 3D‐CMCC FEM where also heterotrophic respiration (Rh) is explicitly simulated. The aim was to quantify NEE as a forward problem, by subtracting ecosystem respiration (Reco) to gross primary productivity (GPP). To do so, we developed a simplification of the soil carbon dynamics routine proposed in the DNDC (DeNitrification-DeComposition) computer simulation model. The method calculates decomposition as a function of soil moisture, temperature, state of the organic compartments, and relative abundance of microbial pools. Given the pulse dynamics of soil respiration, we introduced modifications in some of the principal constitutive relations involved in phenology and littering sub-routines. We quantified the model structure-related uncertainty in NEE, by running our training simulations over 1000 random parameter-sets extracted from parameter distributions expected from literature. 3D-CMCC-PSM predictability was tested on independent time series for 6 Fluxnet sites. The model resulted in daily and monthly estimations highly consistent with the observed time series. It showed lower predictability in Mediterranean ecosystems, suggesting that it may need further improvements in addressing evapotranspiration and water dynamics. Full article
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Open AccessArticle
Secondary Forest and Shrubland Dynamics in a Highly Transformed Landscape in the Northern Andes of Colombia (1985–2015)
Forests 2017, 8(6), 216; doi:10.3390/f8060216 -
Abstract
Understanding the dynamics of natural ecosystems in highly transformed landscapes is key to the design of regional development plans that are more sustainable and otherwise enhance conservation initiatives. We analyzed secondary forest and shrubland dynamics over 30 years (1985–2015) in a densely populated
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Understanding the dynamics of natural ecosystems in highly transformed landscapes is key to the design of regional development plans that are more sustainable and otherwise enhance conservation initiatives. We analyzed secondary forest and shrubland dynamics over 30 years (1985–2015) in a densely populated area of the Colombian Andes using satellite and biophysical data. We performed a land-cover change analysis, assessed landscape fragmentation, and applied regression models to evaluate the effects of environmental and geographical correlates with the observed forest transitions. Forest cover area increased during the 30 year-span, due mostly to forest regrowth in areas marginal for agriculture, especially during the first half of the study period. However, a high dynamic of both forest regrowth and clearing near urban centers and roads was observed. Soil fertility turned out to be a key correlate of both forest recovery and deforestation. Secondary forests, <30 years old represent the most fragmented component. Our findings reflect the complexity of the processes occurring in highly transformed and densely populated regions. Overall, this study provides elements for a better understanding of the factors driving land cover change near large urban areas, and raises new iideas for further research. Full article
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Open AccessArticle
Attribution of Disturbance Agents to Forest Change Using a Landsat Time Series in Tropical Seasonal Forests in the Bago Mountains, Myanmar
Forests 2017, 8(6), 218; doi:10.3390/f8060218 -
Abstract
In 2016, in response to forest loss, the Myanmar government banned logging operations for 1 year throughout the entire country and for 10 years in specific regions. However, it is unclear whether this measure will effectively reduce forest loss, because disturbance agents other
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In 2016, in response to forest loss, the Myanmar government banned logging operations for 1 year throughout the entire country and for 10 years in specific regions. However, it is unclear whether this measure will effectively reduce forest loss, because disturbance agents other than logging may have substantial effects on forest loss. In this study, we investigated an approach to attribute disturbance agents to forest loss, and we characterized the attribution of disturbance agents, as well as the areas affected by these agents, in tropical seasonal forests in the Bago Mountains, Myanmar. A trajectory-based analysis using a Landsat time series was performed to detect change pixels. After the aggregation process that grouped adjacent change pixels in the same year as patches, a change attribution was implemented using the spectral, geometric, and topographic information of each patch via random forest modeling. The attributed agents of change include “logging”, “plantation”, “shifting cultivation”, “urban expansion”, “water invasion”, “recovery”, “other change”, and “no change”. The overall accuracy of the attribution model at the patch and area levels was 84.7% and 96.0%, respectively. The estimated disturbance area from the attribution model accounted for 10.0% of the study area. The largest disturbance agent was found to be logging (59.8%), followed by water invasion (14.6%). This approach quantifies disturbance agents at both spatial and temporal scales in tropical seasonal forests, where limited information is available for forest management, thereby providing crucial information for assessing forest conditions in such environments. Full article
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Open AccessArticle
Potential and Limits of Retrieving Conifer Leaf Area Index Using Smartphone-Based Method
Forests 2017, 8(6), 217; doi:10.3390/f8060217 -
Abstract
Forest leaf area index (LAI) is a key characteristic affecting a field canopy microclimate. In addition to traditional professional measuring instruments, smartphone-based methods have been used to measure forest LAI. However, when smartphone methods were used to measure conifer forest LAI, very different
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Forest leaf area index (LAI) is a key characteristic affecting a field canopy microclimate. In addition to traditional professional measuring instruments, smartphone-based methods have been used to measure forest LAI. However, when smartphone methods were used to measure conifer forest LAI, very different performances were obtained depending on whether the smartphone was held at the zenith angle or at a 57.5° angle. To further validate the potential of smartphone sensors for measuring conifer LAI and to find the limits of this method, this paper reports the results of a comparison of two smartphone methods with an LAI-2000 instrument. It is shown that the method with the smartphone oriented vertically upwards always produced better consistency in magnitude with LAI-2000. The bias of the LAI between the smartphone method and the LAI-2000 instrument was explained with regards to four aspects that can affect LAI: gap fraction; leaf projection ratio; sensor field of view (FOV); and viewing zenith angle (VZA). It was concluded that large FOV and large VZA cause the 57.5° method to overestimate the gap fraction and hence underestimate conifer LAI. For the vertically upward method, the bias caused by the overestimated gap fraction is compensated for by an underestimated leaf projection ratio. Full article
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Open AccessFeature PaperArticle
Influence of Altitude on Biochemical Properties of European Beech (Fagus sylvatica L.) Forest Soils
Forests 2017, 8(6), 213; doi:10.3390/f8060213 -
Abstract
Climate warming is predicted to raise the mean global temperature by 1 °C in the next 50 years, and this change is believed to be capable of affecting soil organic matter cycling and nutrient availability. With the aim of increasing knowledge on the
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Climate warming is predicted to raise the mean global temperature by 1 °C in the next 50 years, and this change is believed to be capable of affecting soil organic matter cycling and nutrient availability. With the aim of increasing knowledge on the response of forest soils to the ongoing climate change, we used altitude as a proxy for temperature change and studied chemical and biochemical properties of European beech (Fagus sylvatica L.) forest soils at two altitudes (800 and 1000 m) from central Apennines (Italy). Results showed that 1 °C of mean annual air temperature difference between the sites at the two altitudes had greater effect on the mineral horizons than on the organic horizons. At higher altitude, mineral soil had limited development, higher pH, and higher organic matter content due to the lower efficiency of the microbial community. Enzymatic activities of the organic horizons were generally not affected by altitude. Conversely, we observed a higher activity of xylosidase, β-glucosidase, alkaline phosphomonoesterase, arylsulfatase, and leucine-aminopeptidase in the sub-superficial horizons (Bw1 and Bw2) of the soils at 1000 m. We hypothesized that, as a response to environmental and climatic constraints occurring at higher altitude, plant roots increase the production of enzymes directly and/or indirectly by triggering the microbial community through exudation. Full article
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Open AccessArticle
Comparing Airborne Laser Scanning, and Image-Based Point Clouds by Semi-Global Matching and Enhanced Automatic Terrain Extraction to Estimate Forest Timber Volume
Forests 2017, 8(6), 215; doi:10.3390/f8060215 -
Abstract
Information pertaining to forest timber volume is crucial for sustainable forest management. Remotely-sensed data have been incorporated into operational forest inventories to serve the need for ever more diverse and detailed forest statistics and to produce spatially explicit data products. In this study,
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Information pertaining to forest timber volume is crucial for sustainable forest management. Remotely-sensed data have been incorporated into operational forest inventories to serve the need for ever more diverse and detailed forest statistics and to produce spatially explicit data products. In this study, data derived from airborne laser scanning and image-based point clouds were compared using three volume estimation methods to aid wall-to-wall mapping of forest timber volume. Estimates of forest height and tree density metrics derived from remotely-sensed data are used as explanatory variables, and forest timber volumes based on sample field plots are used as response variables. When compared to data derived from image-based point clouds, airborne laser scanning produced slightly more accurate estimates of timber volume, with a root mean square error (RMSE) of 26.3% using multiple linear regression. In comparison, RMSEs for volume estimates derived from image-based point clouds were 28.3% and 29.0%, respectively, using Semi-Global Matching and enhanced Automatic Terrain Extraction methods. Multiple linear regression was the best-performing parameter estimation method when compared to k-Nearest Neighbour and Support Vector Machine. In many countries, aerial imagery is acquired and updated on regular cycles of 1–5 years when compared to more costly, once-off airborne laser scanning surveys. This study demonstrates point clouds generated from such aerial imagery can be used to enhance the estimation of forest parameters at a stand and forest compartment level-scale using small area estimation methods while at the same time achieving sampling error reduction and improving accuracy at the forest enterprise-level scale. Full article
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Open AccessArticle
Carbon and Nitrogen Accumulation and Decomposition from Coarse Woody Debris in a Naturally Regenerated Korean Red Pine (Pinus densiflora S. et Z.) Forest
Forests 2017, 8(6), 214; doi:10.3390/f8060214 -
Abstract
The contribution of coarse woody debris (CWD) to forest carbon (C) and nitrogen (N) dynamics is poorly quantified. This study quantified total C and N content in CWD and estimated the decomposition rates of CWD at different decay stages in a 70-year-old naturally
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The contribution of coarse woody debris (CWD) to forest carbon (C) and nitrogen (N) dynamics is poorly quantified. This study quantified total C and N content in CWD and estimated the decomposition rates of CWD at different decay stages in a 70-year-old naturally regenerated Korean red pine forest (Pinus densiflora S. et Z.). The N concentration in CWD varied among species and decay classes (from 0.15% to 0.82%), and exhibited a decreasing pattern in C:N ratios with increasing decay class. Total CWD amounts of 4.84 Mg C ha−1, dominated by pine logs (45.4%) and decay class III (40.0%), contained total N of 20.48 kg N ha−1, which was approximately nine times the N input from annual tree mortality. In addition, this study demonstrated that the decay constant rate k was 0.2497 for needle litter, whereas k values were 0.0438, 0.0693, 0.1054, and 0.1947 for red pine CWD of decay class I, II, III, and IV, respectively. The decay rates were significantly related to wood density, N concentration, and C:N ratio across the decay classes of CWD. The results suggest that the C:N ratio of CWD is a key factor affecting its decomposition. Full article
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Open AccessArticle
Tree Density and Forest Productivity in a Heterogeneous Alpine Environment: Insights from Airborne Laser Scanning and Imaging Spectroscopy
Forests 2017, 8(6), 212; doi:10.3390/f8060212 -
Abstract
We outline an approach combining airborne laser scanning (ALS) and imaging spectroscopy (IS) to quantify and assess patterns of tree density (TD) and forest productivity (FP) in a protected heterogeneous alpine forest in the Swiss National Park (SNP). We use ALS data and
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We outline an approach combining airborne laser scanning (ALS) and imaging spectroscopy (IS) to quantify and assess patterns of tree density (TD) and forest productivity (FP) in a protected heterogeneous alpine forest in the Swiss National Park (SNP). We use ALS data and a local maxima (LM) approach to predict TD, as well as IS data (Airborne Prism Experiment—APEX) and an empirical model to estimate FP. We investigate the dependency of TD and FP on site related factors, in particular on surface exposition and elevation. Based on reference data (i.e., 1598 trees measured in 35 field plots), we observed an underestimation of ALS-based TD estimates of 40%. Our results suggest a limited sensitivity of the ALS approach to small trees as well as a dependency of TD estimates on canopy heterogeneity, structure, and species composition. We found a weak to moderate relationship between surface elevation and TD (R2 = 0.18–0.69) and a less pronounced trend with FP (R2 = 0.0–0.56), suggesting that both variables depend on gradients of resource availability. Further to the limitations faced in the sensitivity of the applied approaches, we conclude that the combined application of ALS and IS data was convenient for estimating tree density and mapping FP in north-facing forested areas, however, the accuracy was lower in south-facing forested areas covered with multi-stemmed trees. Full article
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Open AccessArticle
De Novo Transcriptome Characterization, Gene Expression Profiling and Ionic Responses of Nitraria sibirica Pall. under Salt Stress
Forests 2017, 8(6), 211; doi:10.3390/f8060211 -
Abstract
Nitraria sibirica Pall., a typical halophyte of great ecological value, is widely distributed in desert, saline, and coastal saline-alkali environments. Consequently, researching the salt tolerance mechanism of N. sibirica Pall. has great significance to the cultivation and utilization of salt-tolerant plants. In this
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Nitraria sibirica Pall., a typical halophyte of great ecological value, is widely distributed in desert, saline, and coastal saline-alkali environments. Consequently, researching the salt tolerance mechanism of N. sibirica Pall. has great significance to the cultivation and utilization of salt-tolerant plants. In this research, RNA-seq, digital gene expression (DGE), and high flux element analysis technologies were used to investigate the molecular and physiological mechanisms related to salt tolerance of N. sibirica Pall. Integrative analysis and de novo transcriptome assembly generated 137,421 unigenes. In total, 58,340 and 34,033 unigenes were annotated with gene ontology (GO) terms and mapped in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, respectively. Three differentially expressed genes (DEGs) libraries were subsequently constructed from the leaves of N. sibirica Pall. seedlings under different treatments: control (CK), light short-term salt stress (CL2), and heavy long-term salt stress (CL6). Eight hundred and twenty-six, and 224 differentially expressed genes were identified in CL2 and CL6 compared to CK, respectively. Finally, ionomic analysis of N. sibirica Pall. seedlings treated with 0, 100, 200 or 300 mM concentrations of NaCl for one day showed that the uptake and distribution of Ca, Cu, Fe, Mg and K in different organs of N. sibirica Pall. were significantly affected by salt stress. Our findings have identified potential genes involved in salt tolerance and in the reference transcriptome and have revealed the salt tolerance mechanism in N. sibirica Pall. These findings will provide further insight into the molecular and physiological mechanisms related to salt stress in N. sibirica Pall. and in other halophytes. Full article
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Open AccessArticle
A Course of Innovations in Wood Processing Industry within the Forestry-Wood Chain in Slovakia: A Q Methodology Study to Identify Future Orientation in the Sector
Forests 2017, 8(6), 210; doi:10.3390/f8060210 -
Abstract
As innovations are the basic premise of commercial success in the market the main objective of this paper is to determine the main course of innovations in wood-processing industry within the forestry-wood chain in Slovakia from the viewpoint of representatives of wood processing
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As innovations are the basic premise of commercial success in the market the main objective of this paper is to determine the main course of innovations in wood-processing industry within the forestry-wood chain in Slovakia from the viewpoint of representatives of wood processing companies. Using a Q-methodology approach the emphasis is also put on identification of differences between the opinions of small individual entrepreneurs and representatives of capital companies. Based on the results of structured interview with representatives of 33 wood processing companies the main findings suggest that future innovation activities in the sector will be related to the technology innovations mainly in processing of coniferous timber. However, the extent of such innovations is perceived differently depending on the company size and ownership category. While small individual entrepreneurs expect only slight innovation changes in the industry aimed at the meeting of required standards, managers of capital companies tend to foresee the future vision in restructuralisation of wood-processing industry. Full article
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Open AccessArticle
Carbon Stocks across a Fifty Year Chronosequence of Rubber Plantations in Tropical China
Forests 2017, 8(6), 209; doi:10.3390/f8060209 -
Abstract
Transition from forest to rubber (Hevea brasiliensis Muell. Arg.) plantation has occurred in tropical China for decades. Rubber has been planted on 1 million ha to provide raw materials to the rubber industry. The role of various-aged rubber plantations in carbon (C)
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Transition from forest to rubber (Hevea brasiliensis Muell. Arg.) plantation has occurred in tropical China for decades. Rubber has been planted on 1 million ha to provide raw materials to the rubber industry. The role of various-aged rubber plantations in carbon (C) sequestration remains unclear. The biomass C accumulation including latex C and C distribution in soil of five different-aged stands (7, 13, 19, 25 and 47 years old) were examined. The total biomass C stock (TBC) and total net primary productivity (NPPtotal), whether with or without latex C, had a close quadratic relationship with stand age. Regardless of stand age, around 68% of the C was stored in aboveground biomass, and NPPlatex contributed to approximately 18% of C sequestration. Soil organic carbon stock in the 100-cm depth remained relatively stable, but it lost about 16.8 Mg ha−1 with stand age. The total ecosystem C stock (TEC) across stands averaged 159.6, 174.4, 229.6, 238.1 and 291.9 Mg ha−1, respectively, of which more than 45% was stored in the soil. However, biomass would become the major C sink rather than soil over a maximal rubber life expectancy. Regression analysis showed that TEC for rubber plantation at 22 years is comparable to a baseline of 230.4 Mg ha−1 for tropical forest in China, and would reach the maximum value at around 54 years. Therefore, rubber plantation can be considered as alternative land use without affecting net forest ecosystem C storage. In addition to the potential C gains, a full set of ecosystem and economic properties have to be quantified in order to assess the trade-offs associated with forest-to-rubber transition. Full article
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Open AccessReview
The Risks Associated with Glyphosate-Based Herbicide Use in Planted Forests
Forests 2017, 8(6), 208; doi:10.3390/f8060208 -
Abstract
Glyphosate-based herbicides are the dominant products used internationally for control of vegetation in planted forests. Few international, scientific syntheses on glyphosate, specific to its use in planted forests, are publically available. We provide an international overview of the current use of glyphosate-based herbicides
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Glyphosate-based herbicides are the dominant products used internationally for control of vegetation in planted forests. Few international, scientific syntheses on glyphosate, specific to its use in planted forests, are publically available. We provide an international overview of the current use of glyphosate-based herbicides in planted forests and the associated risks. Glyphosate is used infrequently in planted forests and at rates not exceeding 4 kg ha1. It is used within legal label recommendations and applied by trained applicators. While the highest risk of human exposure to glyphosate is during manual operational application, when applied according to label recommendations the risk of exposure to levels that exceed accepted toxicity standards is low. A review of the literature on the direct and indirect risks of operationally applied glyphosate-based herbicides indicated no significant adverse effects to terrestrial and aquatic fauna. While additional research in some areas is required, such as the use of glyphosate-based products in forests outside of North America, and the potential indirect effects of glyphosate stored in sediments, most of the priority questions have been addressed by scientific investigations. Based on the extensive available scientific evidence we conclude that glyphosate-based herbicides, as typically employed in planted forest management, do not pose a significant risk to humans and the terrestrial and aquatic environments. Full article
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Open AccessArticle
The Effects of Climate Change on the Development of Tree Plantations for Biodiesel Production in China
Forests 2017, 8(6), 207; doi:10.3390/f8060207 -
Abstract
Biodiesel produced from woody oil plants is a promising form of renewable energy but a combination of tree plantations’ long cultivation time and rapid climate change may put large-scale production at risk. If plantations are located in future-unsuitable places, plantations may fail or
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Biodiesel produced from woody oil plants is a promising form of renewable energy but a combination of tree plantations’ long cultivation time and rapid climate change may put large-scale production at risk. If plantations are located in future-unsuitable places, plantations may fail or yield may be poor, then significant financial, labor, and land resources invested in planting programs will be wasted. Incorporating climate change information into the planning and management of forest-based biodiesel production therefore can increase its chances of success. However, species distribution models, the main tool used to predict the influence of future climate–species distribution modeling, often contain considerable uncertainties. In this study we evaluated how these uncertainties could affect the assessment of climate suitability of the long-term development plans for forest-based biodiesel in China by using Sapindus mukorossi Gaertn as an example. The results showed that only between 59% and 75% of the planned growing areas were projected suitable habitats for the species, depending on the set-up of simulation. Our results showed the necessity for explicitly addressing the uncertainty of species distribution modeling when using it to inform forest-based bioenergy planning. We also recommend the growing area specified in China’s national development plan be modified to lower the risk associated with climate change. Full article
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Open AccessCommunication
How Cities Think: Knowledge Co-Production for Urban Sustainability and Resilience
Forests 2017, 8(6), 203; doi:10.3390/f8060203 -
Abstract
Understanding and transforming how cities think is a crucial part of developing effective knowledge infrastructures for the Anthropocene. In this article, we review knowledge co-production as a popular approach in environmental and sustainability science communities to the generation of useable knowledge for sustainability
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Understanding and transforming how cities think is a crucial part of developing effective knowledge infrastructures for the Anthropocene. In this article, we review knowledge co-production as a popular approach in environmental and sustainability science communities to the generation of useable knowledge for sustainability and resilience. We present knowledge systems analysis as a conceptual and empirical framework for understanding existing co-production processes as preconditions to the design of new knowledge infrastructures in cities. Knowledge systems are the organizational practices and routines that make, validate, communicate, and apply knowledge. The knowledge systems analysis framework examines both the workings of these practices and routines and their interplay with the visions, values, social relations, and power dynamics embedded in the governance of building sustainable cities. The framework can be useful in uncovering hidden relations and highlighting the societal foundations that shape what is (and what is not) known by cities and how cities can co-produce new knowledge with meaningful sustainability and resilience actions and transformations. We highlight key innovations and design philosophies that we think can advance research and practice on knowledge co-production for urban sustainability and resilience. Full article
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Open AccessArticle
Quantification of Phosphorus Exports from a Small Forested Headwater-Catchment in the Eastern Ore Mountains, Germany
Forests 2017, 8(6), 206; doi:10.3390/f8060206 -
Abstract
Phosphorus (P) export from forest soils is mainly driven by storm events, which induce rapid flow processes by preferential flow bypassing large parts of the soil matrix. However, little is known about the dynamics, magnitude, and driving processes of P exports into surface
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Phosphorus (P) export from forest soils is mainly driven by storm events, which induce rapid flow processes by preferential flow bypassing large parts of the soil matrix. However, little is known about the dynamics, magnitude, and driving processes of P exports into surface waters. In this paper, we present the results of a monitoring study in a small forested catchment (21 ha) situated in the low mountain ranges of Saxony, Germany. During the fixed schedule-sampling (weekly to bi-weekly sampling frequency for a three-year period), a mean total-P concentration of 8 μg·L−1 was measured. However, concentrations increased up to 203 μg·L−1 during individual storm flow events. Based on the analyzed concentrations and continuously measured discharge we calculated mean annual export rates of 19 to 44 g·ha−1·a−1 for the weekly sampling frequency with different load calculation methods. If events are included into the annual load calculation, the mean annual export fluxes can be up to 83 g·ha−1·a−1 based on the different load calculation methods. Predictions of total-P export rates based on a sampling strategy which does not consider short-term changes due to factors such as storms will substantially underestimate P exports. Full article
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Open AccessCommunication
Insights on Forest Structure and Composition from Long-Term Research in the Luquillo Mountains
Forests 2017, 8(6), 204; doi:10.3390/f8060204 -
Abstract
The science of ecology fundamentally aims to understand species and their relation to the environment. At sites where hurricane disturbance is part of the environmental context, permanent forest plots are critical to understand ecological vegetation dynamics through time. An overview of forest structure
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The science of ecology fundamentally aims to understand species and their relation to the environment. At sites where hurricane disturbance is part of the environmental context, permanent forest plots are critical to understand ecological vegetation dynamics through time. An overview of forest structure and species composition from two of the longest continuously measured tropical forest plots is presented. Long-term measurements, 72 years at the leeward site, and 25 years at windward site, of stem density are similar to initial and pre-hurricane values at both sites. For 10 years post-hurricane Hugo (1989), stem density increased at both sites. Following that increase period, stem density has remained at 1400 to 1600 stems/ha in the leeward site, and at 1200 stems/ha in the windward site. The forests had similar basal area values before hurricane Hugo in 1989, but these sites are following different patterns of basal area accumulation. The leeward forest site continues to accumulate and increase basal area with each successive measurement, currently above 50 m2/ha. The windward forest site maintains its basal area values close to an asymptote of 35 m2/ha. Currently, the most abundant species at both sites is the sierra palm. Ordinations to explore variation in tree species composition through time present the leeward site with a trajectory of directional change, while at the windward site, the composition of species seems to be converging to pre-hurricane conditions. The observed differences in forest structure and composition from sites differently affected by hurricane disturbance provide insight into how particular forest characteristics respond at shorter or longer time scales in relation to previous site conditions and intensity of disturbance effects. Full article
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Open AccessArticle
Short Rotations in Forest Plantations Accelerate Virulence Evolution in Root-Rot Pathogenic Fungi
Forests 2017, 8(6), 205; doi:10.3390/f8060205 -
Abstract
As disease outbreaks in forest plantations are causing concern worldwide, a clear understanding of the influence of silvicultural practices on the development of epidemics is still lacking. Importantly, silvicultural practices are likely to simultaneously affect epidemiological and evolutionary dynamics of pathogen populations. We
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As disease outbreaks in forest plantations are causing concern worldwide, a clear understanding of the influence of silvicultural practices on the development of epidemics is still lacking. Importantly, silvicultural practices are likely to simultaneously affect epidemiological and evolutionary dynamics of pathogen populations. We propose a genetically explicit and individual-based model of virulence evolution in a root-rot pathogenic fungus spreading across forest landscapes, taking the Armillaria ostoyae–Pinus pinaster pathosystem as reference. We used the model to study the effects of rotation length on the evolution of virulence and the propagation of the fungus within a forest landscape composed of even-aged stands regularly altered by clear-cutting and thinning operations. The life cycle of the fungus modeled combines asexual and sexual reproduction modes, and also includes parasitic and saprotrophic phases. Moreover, the tree susceptibility to the pathogen is primarily determined by the age of the stand. Our simulations indicated that the shortest rotation length accelerated both the evolution of virulence and the development of the epidemics, whatever the genetic variability in the initial fungal population and the asexuality rate of the fungal species Full article
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Open AccessArticle
Coordination and Determinants of Leaf Community Economics Spectrum for Canopy Trees and Shrubs in a Temperate Forest in Northeastern China
Forests 2017, 8(6), 202; doi:10.3390/f8060202 -
Abstract
Upscaling the leaf economics spectrum (LES) from the species level to community level is an important step to understand how assemblages are constructed based on functional traits and how these coordinated traits for a community respond to the environmental gradients and climate change.
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Upscaling the leaf economics spectrum (LES) from the species level to community level is an important step to understand how assemblages are constructed based on functional traits and how these coordinated traits for a community respond to the environmental gradients and climate change. In a 9-ha temperate forest dynamics plot located in northeastern China, we collected four LES traits and three other leaf traits from 28 tree species and 13 shrub species. We then related the LES traits at the community level to topographical and soil factors. We observed that the coordination of LES at the community level was stronger than at the species level. Soil nutrients were the primary drivers of distribution of leaf community economics spectrum with acquisition strategy communities in the resource-rich locations. We also observed that different environmental factors affected the distributions of leaf community economics spectrums for trees and shrubs. Our results provided novel evidence for the existence of leaf community economics spectrum in the continental monsoon climate zone. Both abiotic filtering and niche differentiation determined their distributions across different growth forms at the local spatial scale. Full article
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