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Forests, Volume 9, Issue 4 (April 2018)

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Cover Story (view full-size image) In a long-term experiment in Costa Rica, we evaluated the effects of four native tree species on [...] Read more.
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Editorial

Jump to: Research, Review

Open AccessEditorial Decision Support Approaches in Adaptive Forest Management
Forests 2018, 9(4), 215; https://doi.org/10.3390/f9040215
Received: 9 April 2018 / Revised: 14 April 2018 / Accepted: 16 April 2018 / Published: 18 April 2018
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Abstract
Climate and social changes place strong demands on forest managers. Forest managers need powerful approaches and tools, which could help them to be able to react to the rapidly changing conditions. However, the complexity of quantifying forest ecosystems services as well as the
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Climate and social changes place strong demands on forest managers. Forest managers need powerful approaches and tools, which could help them to be able to react to the rapidly changing conditions. However, the complexity of quantifying forest ecosystems services as well as the complexity of current decision theories, technologies and operation research methods, complicate the creation of one general tool. The continuous research and development in this area is an indispensable part of the success of adaptive management as well as the sharing of knowledge and information between research teams around the world. The Community of Practice of Forest Management Decision Support Systems provides a platform for broad discussion among scientists, researchers as well as forest professionals. This special issue provides papers which resulted from a conference session of the International Union of Forest Research Organizations’ (IUFRO) 125th Anniversary Congress in Freiburg, Germany in 2017. The joint sessions and other meetings (and resulting publications) are appropriate opportunities for knowledge sharing on these important methods and systems for protecting and managing forest ecosystems in the future. Full article

Research

Jump to: Editorial, Review

Open AccessArticle Shifts in Forest Structure in Northwest Montana from 1972 to 2015 Using the Landsat Archive from Multispectral Scanner to Operational Land Imager
Forests 2018, 9(4), 157; https://doi.org/10.3390/f9040157
Received: 15 February 2018 / Revised: 15 March 2018 / Accepted: 19 March 2018 / Published: 21 March 2018
Cited by 1 | PDF Full-text (4154 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
There is a pressing need to map changes in forest structure from the earliest time period possible given forest management policies and accelerated disturbances from climate change. The availability of Landsat data from over four decades helps researchers study an ecologically meaningful length
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There is a pressing need to map changes in forest structure from the earliest time period possible given forest management policies and accelerated disturbances from climate change. The availability of Landsat data from over four decades helps researchers study an ecologically meaningful length of time. Forest structure is most often mapped utilizing lidar data, however these data are prohibitively expensive and cover a narrow temporal window relative to the Landsat archive. Here we describe a technique to use the entire length of the Landsat archive from Multispectral Scanner to Operational Land Imager (M2O) to produce three novel outcomes: (1) we used the M2O dataset and standard change vector analysis methods to classify annual forest structure in northwestern Montana from 1972 to 2015, (2) we improved the accuracy of each yearly forest structure classification by applying temporal continuity rules to the whole time series, with final accuracies ranging from 97% to 68% respectively for two and six-category classifications, and (3) we demonstrated the importance of pre-1984 Landsat data for long-term change studies. As the Landsat program continues to acquire Earth imagery into the foreseeable future, time series analyses that aid in classifying forest structure accurately will be key to the success of any land management changes in the future. Full article
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Open AccessArticle Estimation of Total Biomass in Aleppo Pine Forest Stands Applying Parametric and Nonparametric Methods to Low-Density Airborne Laser Scanning Data
Forests 2018, 9(4), 158; https://doi.org/10.3390/f9040158
Received: 31 January 2018 / Revised: 12 March 2018 / Accepted: 19 March 2018 / Published: 21 March 2018
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Abstract
The account of total biomass can assist with the evaluation of climate regulation policies from local to global scales. This study estimates total biomass (TB), including tree and shrub biomass fractions, in Pinus halepensis Miller forest stands located in the Aragon Region (Spain)
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The account of total biomass can assist with the evaluation of climate regulation policies from local to global scales. This study estimates total biomass (TB), including tree and shrub biomass fractions, in Pinus halepensis Miller forest stands located in the Aragon Region (Spain) using Airborne Laser Scanning (ALS) data and fieldwork. A comparison of five selection methods and five regression models was performed to relate the TB, estimated in 83 field plots through allometric equations, to several independent variables extracted from ALS point cloud. A height threshold was used to include returns above 0.2 m when calculating ALS variables. The sample was divided into training and test sets composed of 62 and 21 plots, respectively. The model with the lower root mean square error (15.14 tons/ha) after validation was the multiple linear regression model including three ALS variables: the 25th percentile of the return heights, the variance, and the percentage of first returns above the mean. This study confirms the usefulness of low-density ALS data to accurately estimate total biomass, and thus better assess the availability of biomass and carbon content in a Mediterranean Aleppo pine forest. Full article
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Open AccessArticle Temporal Patterns of Wildfire Activity in Areas of Contrasting Human Influence in the Canadian Boreal Forest
Forests 2018, 9(4), 159; https://doi.org/10.3390/f9040159
Received: 15 February 2018 / Revised: 15 March 2018 / Accepted: 19 March 2018 / Published: 21 March 2018
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Abstract
The influence of humans on the boreal forest has altered the temporal and spatial patterns of wildfire activity through modification of the physical environment and through fire management for the protection of human and economic values. Wildfires are actively suppressed in areas with
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The influence of humans on the boreal forest has altered the temporal and spatial patterns of wildfire activity through modification of the physical environment and through fire management for the protection of human and economic values. Wildfires are actively suppressed in areas with higher human influence, but, paradoxically, these areas have more numerous ignitions than low-impact ones because of the high rates of human-ignited fires, especially during the springtime. The aim of this study is to evaluate how humans have altered the temporal patterns of wildfire activity in the Canadian boreal forest by comparing two adjacent areas of low and high human influence, respectively: Wood Buffalo National Park (WBNP) and the Lower Athabasca Plains (LAP). We carried out Singular Spectrum Analysis to identify trends and cycles in wildfires from 1970 to 2015 for the two areas and examined their association with climate conditions. We found human influence to be reflected in wildfire activity in multiple ways: (1) by dampening (i.e., for area burned)—and even reversing (i.e., for the number of fires)—the increasing trends of fire activity usually associated with drier and warmer conditions; (2) by shifting the peak of fire activity from the summer to the spring; (3) by altering the fire-climate association; and (4) by exhibiting more recurrent (<8 year periodicities) cyclical patterns of fire activity than WBNP (>9 years). Full article
(This article belongs to the Special Issue Wildland Fire, Forest Dynamics, and Their Interactions)
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Open AccessArticle Evaluation of Tree Species for Biomass Energy Production in Northwest Spain
Forests 2018, 9(4), 160; https://doi.org/10.3390/f9040160
Received: 23 February 2018 / Revised: 16 March 2018 / Accepted: 20 March 2018 / Published: 23 March 2018
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Abstract
Three types of forest stands (chestnut coppice, maritime pine stands, and poplar and willow short-rotation woody crops (SRWC)) were evaluated to determine their potential for energy production. The properties of the main aboveground biomass fractions (wood, bark and crown) and also the whole
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Three types of forest stands (chestnut coppice, maritime pine stands, and poplar and willow short-rotation woody crops (SRWC)) were evaluated to determine their potential for energy production. The properties of the main aboveground biomass fractions (wood, bark and crown) and also the whole tree were analysed, thus providing data that could be used for management purposes and for evaluating potential forest, biomass energy yields and atmospheric emissions. Proximate, elemental and energetic analyses of the biomass provided important information for evaluating the fuel potential. The energetic value of the biomass derived from the maritime pine stands was higher than that of the poplar and willow clonal stands and chestnut coppice stands. The high ash content of the chestnut bark, relative to that of the wood and crown material, is also an important consideration in relation to energy production. The proportion of carbon concentration accumulated per tree was very similar in all types of material studied, although the N and S contents were higher in the maritime pine stands than in the other stands. For this reason, selection of species and fractions can help to improve fuel quality and the efficiency of the combustion processes, and to minimize atmospheric emissions. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle Genetic Variation for Resistance to Phytophthora Root Rot in Eastern White Pine Seedlings
Forests 2018, 9(4), 161; https://doi.org/10.3390/f9040161
Received: 28 February 2018 / Revised: 12 March 2018 / Accepted: 22 March 2018 / Published: 23 March 2018
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Abstract
Deployment of genetically resistant Eastern white pine (Pinus strobus L.) planting stock could reduce economic losses to root rot caused by Phytophthora cinnamomi Rands in Christmas tree and forest plantations. This study aimed to determine the degree of genetic control of resistance
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Deployment of genetically resistant Eastern white pine (Pinus strobus L.) planting stock could reduce economic losses to root rot caused by Phytophthora cinnamomi Rands in Christmas tree and forest plantations. This study aimed to determine the degree of genetic control of resistance to P. cinnamomi in Eastern white pine and secondarily, to compare the aggressiveness of two P. cinnamomi isolates derived from different host species. Phytophthora isolates from Fraser fir (Abies fraseri (Pursh) Poir.) and Eastern white pine were used in a main and supplemental study, respectively, including 83 and 20 open-pollinated families. In each study, two-year-old seedlings were inoculated twice each of two consecutive years and mortality was assessed biweekly for 16 weeks each year. During the first year, mortality increased over time to 18.6% and 40.4% while family variation in mortality ranged from 1.3% to 60.0% and 12.5% to 73.0% in the main and supplemental studies, respectively. At the end of the first year, individual-tree and family-mean heritability estimates were, respectively, 0.44 ± 0.0935 and 0.85 ± 0.180 for the main study, and 0.57 ± 0.216 and 0.90 ± 0.343 for the supplemental study. The P. cinnamomi isolate from Eastern white pine was more aggressive and there was a large interaction between isolates and pine families. Deploying resistant families will be complicated by this interaction but should, nevertheless, reduce economic losses. Full article
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Open AccessArticle Stand Transpiration Estimates from Recalibrated Parameters for the Granier Equation in a Chinese Fir (Cunninghamia lanceolata) Plantation in Southern China
Forests 2018, 9(4), 162; https://doi.org/10.3390/f9040162
Received: 2 February 2018 / Revised: 19 March 2018 / Accepted: 22 March 2018 / Published: 23 March 2018
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Abstract
Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) is an important native tree species that is widely distributed in subtropical areas of southern China and cultivated for wood extraction. However, information on water use by Chinese fir plantations is still scarce. In this study,
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Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) is an important native tree species that is widely distributed in subtropical areas of southern China and cultivated for wood extraction. However, information on water use by Chinese fir plantations is still scarce. In this study, we performed species-specific parameter calibrations for the original Granier equation for sap flow density (SFD) estimates. Stand transpiration (Es) was related to environmental inputs, such as rainfall, air temperature (Ta), vapor pressure deficit (VPD), photosynthetically-active radiation (PAR), air relative humidity (RH), and potential evapotranspiration (PET) in order to examine how environmental factors affect the Es of Chinese fir plantations. According to our results, Granier’s original parameters set underestimated C. lanceolata SFD by up to 54% compared to our species-specific calibrated parameters set. A strong positive correlation was found between SFD, diameter at breast height (DBH), and tree height among trees populations. The total Es in 2015 was 522.1 mm, with obvious seasonal dynamics and an average of 1.4 mm·day−1. Daily and monthly Es were positively correlated with VPD, PAR, Ta, and PET. A negative relationship between Es and RH was detected only at a daily timescale. Our findings indicate that the original Granier equation requires a parameter calibration when it is applied to species-specific thermal dissipation probe (TDP) estimates, and our findings can also provide novel insights on the water use of Chinese fir in major wood production areas in Southern China. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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Open AccessArticle Forest Above-Ground Biomass Estimation Using Single-Baseline Polarization Coherence Tomography with P-Band PolInSAR Data
Forests 2018, 9(4), 163; https://doi.org/10.3390/f9040163
Received: 8 February 2018 / Revised: 20 March 2018 / Accepted: 21 March 2018 / Published: 23 March 2018
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Abstract
Forest above ground biomass (AGB) extraction using Synthetic Aperture Radar (SAR) images has been widely used in global carbon cycle research. Classical AGB inversion methods using SAR images are mainly based on backscattering coefficients. The polarization coherence tomography (PCT) technology which can generate
[...] Read more.
Forest above ground biomass (AGB) extraction using Synthetic Aperture Radar (SAR) images has been widely used in global carbon cycle research. Classical AGB inversion methods using SAR images are mainly based on backscattering coefficients. The polarization coherence tomography (PCT) technology which can generate vertical profiles of forest relative reflectivity, has the potential to improve the accuracy of biomass inversion. The relationship between vertical profiles and forest AGB is modeled by some parameters defined based on geometric characteristics of the relative reflectivity distribution curve. But these parameters are defined without physical characteristics. Among these parameters, tomographic height (TomoH) is considered as the most important one. However, TomoH only corresponds to the highest volume relative reflectivity, which is lower than the actual forest height, affecting the accuracy of forest height and AGB inversion. In this paper, we introduce a new parameter, the canopy height (Hac), for AGB inversion by analyzing the vertical backscatter power loss. Then, we construct an inversion model based on the combination of the new parameter (Hac) and other parameters from the tomographic profile. The P-band polarimetric SAR datasets of the European Space Agency (ESA) BioSAR 2008 campaign acquired over Krycklan Catchment are selected for the verification experiment at two different flight directions. The results show that Hac performs better in estimating forest height and AGB than TomoH does. The inversion root mean square error (RMSE) of the proposed method is 18.325 t ha−1, and the result of using TomoH is 21.126 t ha−1. Full article
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Open AccessArticle Total Weight and Axle Loads of Truck Units in the Transport of Timber Depending on the Timber Cargo
Forests 2018, 9(4), 164; https://doi.org/10.3390/f9040164
Received: 31 January 2018 / Revised: 19 March 2018 / Accepted: 22 March 2018 / Published: 23 March 2018
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Abstract
When transporting timber, the high variability of species, assortments and moisture content of the wood raw material does not allow the weight of the transported timber to be precisely determined. This often contributes to the excessive weight loading of the entire truck unit.
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When transporting timber, the high variability of species, assortments and moisture content of the wood raw material does not allow the weight of the transported timber to be precisely determined. This often contributes to the excessive weight loading of the entire truck unit. The aim of the research is to present the variability of the total weight of truck units with wood cargoes (GVW—gross vehicle weight) depending on the weight of the empty unit and the transported timber load, as well as to analyze the changes in GVW, unit loads of wood and load on individual truck unit axles depending on the season. This study analyzes the total weight of truck units for 376 transports of Scots pine timber at different times of the year. The total weight of the truck units depends on the weight of an empty unit and the weight of the load. GVW was determined by using a weighbridge to weigh the vehicles and then the empty unit after unloading. The weight of the load was obtained as the difference between GVW and the tare. It was found that GVW differed significantly depending on the truck unit used, ranging from 43.60–58.80 Mg, often exceeding permissible limits for public roads. The individual axle loads for various truck units were also analyzed. The obtained results indicate that these loads are more equally distributed in the case of five-axle trucks compared to six-axle ones. Full article
(This article belongs to the Special Issue Forest Operations, Engineering and Management)
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Open AccessArticle What Drives Low-Severity Fire in the Southwestern USA?
Forests 2018, 9(4), 165; https://doi.org/10.3390/f9040165
Received: 27 February 2018 / Revised: 20 March 2018 / Accepted: 21 March 2018 / Published: 24 March 2018
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Abstract
Many dry conifer forests in the southwestern USA and elsewhere historically (prior to the late 1800’s) experienced fairly frequent surface fire at intervals ranging from roughly five to 30 years. Due to more than 100 years of successful fire exclusion, however, many of
[...] Read more.
Many dry conifer forests in the southwestern USA and elsewhere historically (prior to the late 1800’s) experienced fairly frequent surface fire at intervals ranging from roughly five to 30 years. Due to more than 100 years of successful fire exclusion, however, many of these forests are now denser and more homogenous, and therefore they have a greater probability of experiencing stand-replacing fire compared to prior centuries. Consequently, there is keen interest in restoring such forests to conditions that are conducive to low-severity fire. Yet, there have been no regional assessments in the southwestern USA that have specifically evaluated those factors that promote low-severity fire. Here, we defined low-severity fire using satellite imagery and evaluated the influence of several variables that potentially drive such fire; these variables characterize live fuel, topography, climate (30-year normals), and inter-annual climate variation. We found that live fuel and climate variation (i.e., year-of-fire climate) were the main factors driving low-severity fire; fuel was ~2.4 times more influential than climate variation. Low-severity fire was more likely in settings with lower levels of fuel and in years that were wetter and cooler than average. Surprisingly, the influence of topography and climatic normals was negligible. Our findings elucidate those conditions conducive to low-severity fire and provide valuable information to land managers tasked with restoring forest structures and processes in the southwestern USA and other regions dominated by dry forest types. Full article
(This article belongs to the Special Issue Wildland Fire, Forest Dynamics, and Their Interactions)
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Open AccessArticle A Generalized Lidar-Based Model for Predicting the Merchantable Volume of Balsam Fir of Sites Located along a Bioclimatic Gradient in Quebec, Canada
Forests 2018, 9(4), 166; https://doi.org/10.3390/f9040166
Received: 22 February 2018 / Revised: 19 March 2018 / Accepted: 21 March 2018 / Published: 24 March 2018
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Abstract
Lidar-based models rely on an optimal relationship between the field and the lidar data for accurate predictions of forest attributes. This relationship may be altered by the variability in the stand growth conditions or by the temporal discrepancy between the field inventory and
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Lidar-based models rely on an optimal relationship between the field and the lidar data for accurate predictions of forest attributes. This relationship may be altered by the variability in the stand growth conditions or by the temporal discrepancy between the field inventory and the lidar survey. In this study, we used lidar data to predict the timber merchantable volume (MV) of five sites located along a bioclimatic gradient of temperature and elevation. The temporal discrepancies were up to three years. We adjusted a random canopy height coefficient (accounting for the variability amongst sites), and a growth function (accounting for the growth during the temporal discrepancy), to the predictive model. The MV could be predicted with a pseudo-R2 of 0.86 and a residual standard deviation of 24.3 m3 ha−1. The average biases between the field-measured and the predicted MVs were small. The variability of MV predictions was related to the bioclimatic gradient. Fixed-effect models that included a bioclimatic variable provided similar prediction accuracies. This study suggests that the variability amongst sites, the occurrence of a bioclimatic gradient and temporal discrepancies are essential in building a generalized lidar-based model for timber volume. Full article
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Open AccessArticle Forecasting Forest Inventory Using Imputed Tree Lists for LiDAR Grid Cells and a Tree-List Growth Model
Forests 2018, 9(4), 167; https://doi.org/10.3390/f9040167
Received: 1 February 2018 / Revised: 22 March 2018 / Accepted: 23 March 2018 / Published: 25 March 2018
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Abstract
A method to forecast forest inventory variables derived from light detection and ranging (LiDAR) would increase the usefulness of such data in future forest management. We evaluated the accuracy of forecasted inventory from imputed tree lists for LiDAR grid cells (20 × 20
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A method to forecast forest inventory variables derived from light detection and ranging (LiDAR) would increase the usefulness of such data in future forest management. We evaluated the accuracy of forecasted inventory from imputed tree lists for LiDAR grid cells (20 × 20 m) in spruce (Picea sp.) plantations and tree growth predicted using a locally calibrated tree-list growth model. Tree lists were imputed by matching measurements from a library of sample plots with grid cells based on planted species and the smallest sum of squared difference between six inventory variables. Total and merchantable basal area, total and merchantable volume, Lorey’s height, and quadratic mean diameter increments predicted using imputed tree lists were highly correlated (0.75–0.86) with those from measured tree lists in 98 validation plots. Percent root mean squared error ranged from 12.8–49.0% but was much lower (4.9–13.5%) for plots with ≤10% LiDAR-derived error for all plot-matched variables. When compared with volumes from 15 blocks harvested 3–5 years after LiDAR acquisition, average forecasted volume differed by only 1.5%. To demonstrate the novel application of this method for operational management decisions, annual commercial thinning was planned at grid-cell resolution from 2018–2020 using forecasted inventory variables and commercial thinning eligibility rules. Full article
(This article belongs to the Section Forest Inventory, Quantitative Methods and Remote Sensing)
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Open AccessArticle The Evaluation of Radiation Use Efficiency and Leaf Area Index Development for the Estimation of Biomass Accumulation in Short Rotation Poplar and Annual Field Crops
Forests 2018, 9(4), 168; https://doi.org/10.3390/f9040168
Received: 15 February 2018 / Revised: 14 March 2018 / Accepted: 23 March 2018 / Published: 27 March 2018
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Abstract
We evaluated the long-term pattern of leaf area index (LAI) dynamics and radiation use efficiency (RUE) in short rotation poplar in uncoppice (single stem) and coppice (multi-stem) plantations, and compared them to annual field crops (AFCs) as an alternative for bioenergy production while
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We evaluated the long-term pattern of leaf area index (LAI) dynamics and radiation use efficiency (RUE) in short rotation poplar in uncoppice (single stem) and coppice (multi-stem) plantations, and compared them to annual field crops (AFCs) as an alternative for bioenergy production while being more sensitive to weather fluctuation and climate change. The aim of this study was to evaluate the potential of LAI and RUE as indicators for bioenergy production and indicators of response to changing environmental conditions. For this study, we selected poplar clone J-105 (Populus nigra L. × P. maximowiczii A. Henry) and AFCs such as barley (Hordeum vulgare L.), wheat (Triticum aestivum L.), maize (Zea mays L.), and oilseed rape (Brassica napus L.), and compared their aboveground dry mass (AGDM) production in relation to their LAI development and RUE. The results of the study showed the long-term maximum LAI (LAImax) to be 9.5 in coppice poplar when compared to AFCs, where LAImax did not exceed the value 6. The RUE varied between 1.02 and 1.48 g MJ−1 in short rotation poplar and between 0.72 and 2.06 g MJ−1 in AFCs. We found both LAI and RUE contributed to AGDM production in short rotation poplar and RUE only contributed in AFCs. The study confirms that RUE may be considered an AGDM predictor of short rotation poplar and AFCs. This may be utilized for empirical estimates of yields and also contribute to improve the models of short rotation poplar and AFCs for the precise prediction of biomass accumulation in different environmental conditions. Full article
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Open AccessArticle A Spatially Explicit Method to Assess the Economic Suitability of a Forest Road Network for Timber Harvest in Steep Terrain
Forests 2018, 9(4), 169; https://doi.org/10.3390/f9040169
Received: 31 January 2018 / Revised: 21 March 2018 / Accepted: 23 March 2018 / Published: 27 March 2018
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Abstract
Despite relatively high road density in the forests of Switzerland, a large percentage of that road network does not fulfill best practice requirements. Before upgrading or rebuilding the road network, harvesting planners must first determine which areas have insufficient access. Traditional assessment methods
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Despite relatively high road density in the forests of Switzerland, a large percentage of that road network does not fulfill best practice requirements. Before upgrading or rebuilding the road network, harvesting planners must first determine which areas have insufficient access. Traditional assessment methods tend to only report specific values such as road density. However, those values do not identify the exact parcels or areas that are inaccessible. Here, we present a model that assesses the economic suitability of each timbered parcel for wood-harvesting operations, including tree-felling and processing, and off- and on-road transport (hauling), based on the existing road network. The entire wood supply chain from forest (standing trees) to a virtual pile at the border of the planning unit was captured. This method was particularly designed for steep terrain and was tested in the Canton of Grisons in Switzerland. Compared with classical approaches, such as the road density concept, which only deliver average values, this new method enables planners to assess the development of a road network in a spatially explicit manner and to easily identify the reason and the location of shortcomings in the road network. Moreover, while other related spatially explicit approaches focus only on harvesting operations, the assessment method proposed here also includes limitations (road standards) of the road network. Full article
(This article belongs to the Special Issue Forest Operations, Engineering and Management)
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Open AccessArticle Managing the Early Warning Systems of Invasive Species of Plants, Birds, and Mammals in Natural and Planted Pine Forests
Forests 2018, 9(4), 170; https://doi.org/10.3390/f9040170
Received: 15 March 2018 / Revised: 23 March 2018 / Accepted: 26 March 2018 / Published: 28 March 2018
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Abstract
Plantations with alien forest species could be a major way for invasive plant and animal species to become introduced and naturally established in a territory, but the sensitivity of plantations with native forest species to invasive plant and animal species is still unknown.
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Plantations with alien forest species could be a major way for invasive plant and animal species to become introduced and naturally established in a territory, but the sensitivity of plantations with native forest species to invasive plant and animal species is still unknown. This paper studies the probability of the presence and the richness of invasive species of three different taxa (plants, birds, and mammals) in pine forests of southwestern Europe. To do so, the relative contribution from natural and planted forests is analysed to explain the presence and the richness of invasive species in 3950 cells (10 km × 10 km) covering Spain after controlling for the possible effects of variables related to geography, climate, land use, landscape, and human pressure on the environment. Our results show that man’s influence on the establishment of invasive species is notable. However, those forests that are the most intensely managed by man, such as pine plantations with native species, seem less susceptible to the establishment and propagation of invasive species. Reasons may be found in those planted pine forests being closely monitored, controlled, and managed by man. Therefore, it is argued that efforts related to the early warning systems of invasive species should be focused on natural pine forests. Full article
(This article belongs to the Special Issue Ecology and Management of Invasive Species in Forest Ecosystems)
Open AccessFeature PaperArticle Does Plant Knowledge within Urban Forests and Parks Directly Influence Visitor Pro-Environmental Behaviors
Forests 2018, 9(4), 171; https://doi.org/10.3390/f9040171
Received: 14 February 2018 / Revised: 8 March 2018 / Accepted: 27 March 2018 / Published: 28 March 2018
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Abstract
Urban parks and forests provide many services to society and are becoming essential components within urban landscapes worldwide. While substantial research and actions have been taken to understand various ecosystem services of urban forests and parks, significantly less effort has been made on
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Urban parks and forests provide many services to society and are becoming essential components within urban landscapes worldwide. While substantial research and actions have been taken to understand various ecosystem services of urban forests and parks, significantly less effort has been made on people’s perceptions toward the effectiveness of these services. In addressing the above research needs, we conducted a field survey and hypothesized that an individual’s knowledge will lead to different pro-environmental behaviors in urban forests and parks. Using the Toledo, Ohio, USA as our study site, we collected 267 interviews from five of the area’s most frequented urban parks. A three-way ANOVA and two Partial Least Square Structural Equation Models quantified the causal relationship among demography, plant knowledge, environmental knowledge, and pro-environmental behaviors. We found that: (1) different levels of plant knowledge will have different influences on environmental behaviors; (2) pro-environmental behavioral models can be based on planned behaviors or habitual behaviors; and that (3) gender may not be an influential factor in determining pro-environmental behaviors. Environmental knowledge, especially plant knowledge, plays a key role in fostering pro-environmental behaviors. Therefore, we reason that disseminating plant knowledge education materials will profoundly raise visitors’ pro-environmental behaviors. Full article
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Open AccessArticle The Effects of Dynamic Root Distribution on Land–Atmosphere Carbon and Water Fluxes in the Community Earth System Model (CESM1.2.0)
Forests 2018, 9(4), 172; https://doi.org/10.3390/f9040172
Received: 30 January 2018 / Revised: 23 March 2018 / Accepted: 23 March 2018 / Published: 29 March 2018
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Abstract
Roots are responsible for the uptake of water and nutrients by plants, and they have the plasticity to respond dynamically to different environmental conditions. However, currently, most climate models only prescribe rooting profiles as a function of the vegetation type of the land
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Roots are responsible for the uptake of water and nutrients by plants, and they have the plasticity to respond dynamically to different environmental conditions. However, currently, most climate models only prescribe rooting profiles as a function of the vegetation type of the land component, with no consideration of the surroundings. In this study, a dynamic rooting scheme describing root growth as a compromise between water and nitrogen availability in the subsurface was incorporated into the Community Earth System Model 1.2.0 (CESM1.2.0). The dynamic rooting scheme was incorporated to investigate the effects of land–atmosphere carbon and water fluxes, and their subsequent influences on climate. The modeling results of global land–atmosphere coupling simulations from 1982 to 2005 show that the dynamic rooting scheme can improve gross primary production (GPP) and evapotranspiration (ET) in most tropical regions, and in some high-latitude regions with lower mean biases (MBEs) and root mean square errors (RMSEs). Obvious differences in 2-m air temperature were found in low-latitude areas, with decreases of up to 2 °C. Under the influence of local land-surface feedback and large-scale moisture advection, total precipitation in the northeastern area of the Amazon and the west coast of Africa increased by 200 mm year−1, and that of South America, central Africa, and Indonesia increased by 50 to 100 mm year−1. Overall, the model incorporating the dynamic rooting scheme may reveal cooling and humidifying effects, especially for tropical regions. Full article
(This article belongs to the Special Issue Forest Fine Roots in Changing Climate)
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Open AccessArticle Reasons for Choosing Forest Stewardship Council (FSC) and Sustainable Green Ecosystem Council (SGEC) Schemes and the Effects of Certification Acquisition by Forestry Enterprises in Japan
Forests 2018, 9(4), 173; https://doi.org/10.3390/f9040173
Received: 8 March 2018 / Revised: 22 March 2018 / Accepted: 27 March 2018 / Published: 29 March 2018
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Abstract
The Forest Stewardship Council (FSC) and the Sustainable Green Ecosystem Council (SGEC) are deployed as forest certification schemes in Japan. This study aimed to identify the reasons that enterprises choose the FSC or the SGEC scheme and the effects of certification. A questionnaire
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The Forest Stewardship Council (FSC) and the Sustainable Green Ecosystem Council (SGEC) are deployed as forest certification schemes in Japan. This study aimed to identify the reasons that enterprises choose the FSC or the SGEC scheme and the effects of certification. A questionnaire survey was conducted on 126 forestry enterprises with certification as of May 2014. The results of questionnaire tabulation found different reasons for choosing FSC (high reliability of the international certification system) or SGEC (examination costs and difficulty of acquisition, certification acquisition by neighboring enterprises in the region, and guidance and information from familiar people and enterprises). The results suggest that choosing FSC or SGEC depended on international or domestic emphasis, reliability, cost, and difficulty of acquisition. Both schemes reportedly improved management planning, environmental impact assessments, and monitoring, but increased timber value was not reported. Japanese consumers’ understanding of forest certification should be enhanced and attention to forest management certification in Japan should increase because the SGEC now offers international certification. If SGEC certification is easier to obtain than FSC certification, and FSC is relatively expensive, the SGEC forest area should continue to expand. Full article
(This article belongs to the Special Issue Policies Affecting Development and Forest Conservation)
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Open AccessArticle Comparative Analysis of the Effects of Stem Height and Artificial Pruning on Seasonal Radial Growth Dynamics of Wild Cherry (Prunus avium L.) and Sycamore (Acer pseudoplatanus L.) in a Widely Spaced System
Forests 2018, 9(4), 174; https://doi.org/10.3390/f9040174
Received: 26 February 2018 / Revised: 19 March 2018 / Accepted: 27 March 2018 / Published: 29 March 2018
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Abstract
Intensive artificial pruning of trees increases the proportion of high-value timber but simultaneously reduces the crown and consequently the capacity to assimilate photosynthates. Here, midterm effects of two intensive pruning treatments, a classical and a selective approach, on radial growth dynamics at different
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Intensive artificial pruning of trees increases the proportion of high-value timber but simultaneously reduces the crown and consequently the capacity to assimilate photosynthates. Here, midterm effects of two intensive pruning treatments, a classical and a selective approach, on radial growth dynamics at different stem heights is comparatively analyzed for the broadleaved tree species sycamore (Acer pseudoplatanus L.) and wild cherry (Prunus avium L.) at a site in the upper Rhine valley in southwest Germany using high-resolution point-dendrometers starting three years after pruning. We fitted shape-constrained additive models to the dendrometer data and derived estimates of growth phenology and performance of individual trees over the 2010–2016 observation period. The statistical analysis based on linear mixed-effects models showed significantly later growth cessation and in individual years also higher rates of radial growth in sycamore compared to wild cherry. Growth onset for both tree species initiated systematically earlier at the higher dendrometer location compared to breast height. While no main effects of treatment or interactions of treatment with year were detected, we found significantly higher average daily growth rates and annual radial growth of wild cherry at the top dendrometer location compared to breast height in the selective pruning treatment. Our results provide new insights into seasonal growth patterns of sycamore and wild cherry in a widely spaced system and contribute to a better understanding of the effects of stem height, pruning treatment and climate on radial growth dynamics of valuable broadleaved tree species. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle Day Extension with Far-Red Light Enhances Growth of Subalpine Fir (Abies lasiocarpa (Hooker) Nuttall) Seedlings
Forests 2018, 9(4), 175; https://doi.org/10.3390/f9040175
Received: 1 March 2018 / Revised: 25 March 2018 / Accepted: 29 March 2018 / Published: 29 March 2018
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Abstract
Subalpine fir (Abies lasiocarpa (Hooker) Nuttall), which is native to western North America, is of considerable interest for Christmas tree production in northern Europe. Seedlings are usually grown from seeds under combined nursery greenhouse/outdoors conditions, but commonly show early growth cessation in
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Subalpine fir (Abies lasiocarpa (Hooker) Nuttall), which is native to western North America, is of considerable interest for Christmas tree production in northern Europe. Seedlings are usually grown from seeds under combined nursery greenhouse/outdoors conditions, but commonly show early growth cessation in the nursery, resulting in small plants for field transplanting. This increases the production time and makes the seedlings vulnerable to stressors at the planting site. Day extension with far-red (FR) light was shown to enhance elongation and delay bud set in seedlings of some woody species, but such information is limited for Abies. Here, we investigated the effects of day extension with FR, red (R), different R:FR-ratios or blue (B) light from light emitting diodes on subalpine fir seedlings grown at different temperatures. Day extension with FR or combined R-FR light, in contrast to R or B light, increased shoot elongation significantly as compared to short days without day extension, often with more growth at 18 °C than 24 °C. The FR treatments delayed terminal bud development, although bud set was not completely prevented. These results demonstrate that larger seedlings of subalpine fir seedlings for Christmas tree production can be obtained by employing day extension with FR or combined R:FR light, preferably under cool temperature. Full article
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Open AccessArticle Seasonal Changes in Photosynthetic Energy Utilization in a Desert Shrub (Artemisia ordosica Krasch.) during Its Different Phenophases
Forests 2018, 9(4), 176; https://doi.org/10.3390/f9040176
Received: 26 February 2018 / Revised: 25 March 2018 / Accepted: 26 March 2018 / Published: 30 March 2018
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Abstract
Our understanding of the mechanisms of plant response to environment fluctuations during plants’ phenological phases (phenophases) remains incomplete. Continuous chlorophyll fluorescence (ChlF) measurements were acquired from the field to quantify the responses in a desert shrub species (i.e., Artemesia ordosica Krasch. (A.
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Our understanding of the mechanisms of plant response to environment fluctuations during plants’ phenological phases (phenophases) remains incomplete. Continuous chlorophyll fluorescence (ChlF) measurements were acquired from the field to quantify the responses in a desert shrub species (i.e., Artemesia ordosica Krasch. (A. ordosica)) to environmental factors by assessing variation in several ChlF-linked parameters and to understand plant acclimation to environmental stresses. Maximal quantum yield of PSII photochemistry (Fv/Fm) was shown to be reduced by environmental stressors and to be positively correlated to air temperature (Ta) during the early and late plant-growing stages, indicating a low temperature-induced inhibition during the leaf expansion and coloration phases. Effective quantum yield of PSII photochemistry (ΦPSII) was negatively correlated to incident photosynthetically active radiation (PAR) irrespective of phenophase, suggesting excessive radiation-induced inhibition at all phenophases. The main mechanism for acclimating to environmental stress was the regulatory thermal dissipation (ΦNPQ) and the long-term regulation of relative changes in Chl a to Chl b. The relative changes in photosynthetic energy utilization and dissipation in energy partitioning meant A. ordosica could acclimatize dynamically to environmental changes. This mechanism may enable plants in arid and semi-arid environments to acclimatize to increasingly extreme environmental conditions under future projected climate change. Full article
(This article belongs to the Special Issue Afforestation and Reforestation: Drivers, Dynamics, and Impacts)
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Open AccessArticle Regional Scale Determinants of Nutrient Content of Soil in a Cold-Temperate Forest
Forests 2018, 9(4), 177; https://doi.org/10.3390/f9040177
Received: 1 February 2018 / Revised: 20 March 2018 / Accepted: 22 March 2018 / Published: 30 March 2018
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Abstract
The effect of climatic factors on soil nutrients is significant. Identifying whether soil nutrients respond to local climate and how the forest types modulate this responsiveness is critical for forest management. Therefore, six soil nutrients from five main forest types found for a
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The effect of climatic factors on soil nutrients is significant. Identifying whether soil nutrients respond to local climate and how the forest types modulate this responsiveness is critical for forest management. Therefore, six soil nutrients from five main forest types found for a range of sites within the Daxing’an Mountains, China, were investigated. Climatic factors were obtained from the WorldClim dataset. Pearson correlations and stepwise regressions were employed to elucidate and model the response of the six soil nutrients to the four different climatic factors in this study. On the whole, climate was correlated with all the nutrients. Further, from stepwise regressions, climatic factors could affect soil nutrients in distinct forests. Our findings suggest that climatic factors are instrumental in affecting soil nutrients in different forest types. Identifying the relationships between soil nutrients, climatic factors and forest types, as suggested in this research, can provide theoretical foundations to further comprehend nutrient cycling in the forest ecosystem. Full article
(This article belongs to the Special Issue Carbon, Nitrogen and Phosphorus Cycling in Forest Soils)
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Open AccessArticle Evaluating the Multi-Functionality of Forest Ecosystems in Northern Mexico
Forests 2018, 9(4), 178; https://doi.org/10.3390/f9040178
Received: 2 March 2018 / Revised: 23 March 2018 / Accepted: 23 March 2018 / Published: 2 April 2018
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Abstract
Managing multiple ecosystem services is a complex task that involves special interactions among different resources, services, and stakeholders. Mexican forests have been traditionally managed for the single purpose of obtaining wood, benefiting a small sector of society. In this study, we evaluated the
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Managing multiple ecosystem services is a complex task that involves special interactions among different resources, services, and stakeholders. Mexican forests have been traditionally managed for the single purpose of obtaining wood, benefiting a small sector of society. In this study, we evaluated the interactions among various ecosystem services, namely carbon content, tree diversity, surface water runoff, and the net present value of timber production. We also attempted to determine the most suitable basal area level that best satisfies the management of these services combined. Bivariate correlations, non-linear regression models, and a multiobjective decision-making technique are used to analyze the data in the study. Results indicate that trade-offs exist between surface water runoff and tree basal area. A synergistic relationship, between net present value and carbon content with basal area, was also observed. Tree diversity has a synergistic relationship with basal area in open forests, but a trade-off relationship in denser forests. The most preferred forest management level that satisfies the desired ecosystem services is between 17 and 21 m2/ha of residual basal area. We hope that adopting this multiobjective study can cement collaborative strategies among Mexican resource managers, landowners, environmental groups, and others interested in forest management. Full article
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Open AccessArticle Review of Ecosystem Level Impacts of Emerald Ash Borer on Black Ash Wetlands: What Does the Future Hold?
Forests 2018, 9(4), 179; https://doi.org/10.3390/f9040179
Received: 5 March 2018 / Revised: 26 March 2018 / Accepted: 29 March 2018 / Published: 2 April 2018
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Abstract
The emerald ash borer (EAB) is rapidly spreading throughout eastern North America and devastating ecosystems where ash is a component tree. This rapid and sustained loss of ash trees has already resulted in ecological impacts on both terrestrial and aquatic ecosystems and is
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The emerald ash borer (EAB) is rapidly spreading throughout eastern North America and devastating ecosystems where ash is a component tree. This rapid and sustained loss of ash trees has already resulted in ecological impacts on both terrestrial and aquatic ecosystems and is projected to be even more severe as EAB invades black ash-dominated wetlands of the western Great Lakes region. Using two companion studies that are simulating short- and long-term EAB infestations and what is known from the literature, we synthesize our current limited understanding and predict anticipated future impacts of EAB on black ash wetlands. A key response to the die-back of mature black ash will be higher water tables and the potential for flooding and resulting changes to both the vegetation and animal communities. Although seedling planting studies have shown some possible replacement species, little is known about how the removal of black ash from the canopy will affect non-ash species growth and regeneration. Because black ash litter is relatively high in nitrogen, it is expected that there will be important changes in nutrient and carbon cycling and subsequent rates of productivity and decomposition. Changes in hydrology and nutrient and carbon cycling will have cascading effects on the biological community which have been scarcely studied. Research to address these important gaps is currently underway and should lead to alternatives to mitigate the effects of EAB on black ash wetland forests and develop management options pre- and post-EAB invasion. Full article
(This article belongs to the Special Issue Understanding and Managing Emerald Ash Borer Impacts on Ash Forests)
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Open AccessArticle Tamarix microRNA Profiling Reveals New Insight into Salt Tolerance
Forests 2018, 9(4), 180; https://doi.org/10.3390/f9040180
Received: 27 February 2018 / Revised: 26 March 2018 / Accepted: 27 March 2018 / Published: 3 April 2018
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Abstract
The halophyte tamarisk (Tamarix) is extremely salt tolerant, making it an ideal material for salt tolerance-related studies. Although many salt-responsive genes of Tamarix were identified in previous studies, there are no reports on the role of post-transcriptional regulation in its salt
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The halophyte tamarisk (Tamarix) is extremely salt tolerant, making it an ideal material for salt tolerance-related studies. Although many salt-responsive genes of Tamarix were identified in previous studies, there are no reports on the role of post-transcriptional regulation in its salt tolerance. We constructed six small RNA libraries of Tamarix chinensis roots with NaCl treatments. High-throughput sequencing of the six libraries was performed and microRNA expression profiles were constructed. We investigated salt-responsive microRNAs to uncover the microRNA-mediated genes regulation. From these analyses, 251 conserved and 18 novel microRNA were identified from all small RNAs. From 191 differentially expressed microRNAs, 74 co-expressed microRNAs were identified as salt-responsive candidate microRNAs. The most enriched GO (gene ontology) terms for the 157 genes targeted by differentially expressed microRNAs suggested that transcriptions factors were highly active. Two hub microRNAs (miR414, miR5658), which connected by several target genes into an organic microRNA regulatory network, appeared to be the key regulators of post-transcriptional salt-stress responses. As the first survey on the tamarisk small RNAome, this study improves the understanding of tamarisk salt-tolerance mechanisms and will contribute to the molecular-assisted resistance breeding. Full article
(This article belongs to the Special Issue Genetics and Genomics of Forest Trees)
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Open AccessArticle Traffic-Induced Changes and Processes in Forest Road Aggregate Particle-Size Distributions
Forests 2018, 9(4), 181; https://doi.org/10.3390/f9040181
Received: 20 February 2018 / Revised: 29 March 2018 / Accepted: 30 March 2018 / Published: 3 April 2018
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Abstract
Traffic can alter forest road aggregate material in various ways, such as by crushing, mixing it with subgrade material, and sweeping large-size, loose particles (gravel) toward the outside of the road. Understanding the changes and physical processes of the aggregate is essential to
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Traffic can alter forest road aggregate material in various ways, such as by crushing, mixing it with subgrade material, and sweeping large-size, loose particles (gravel) toward the outside of the road. Understanding the changes and physical processes of the aggregate is essential to mitigate sediment production from forest roads and reduce road maintenance efforts. We compared the particle-size distributions of forest road aggregate from the Clearwater National Forest in Idaho, USA in three vertical layers (upper, middle, and bottom of the road aggregate), three horizontal locations (tire track, shoulder, and half-way between them), and three traffic uses (none, light (no logging vehicles), and heavy (logging vehicles and equipment)) using Tukey’s multiple comparison test. Light traffic appears to cause aggregate crushing where vehicle tires passed and caused sweeping on the road surface. Heavy traffic caused aggregate crushing at all vertical and horizontal locations, and subgrade mixing with the bottom layer at the shoulder location. Logging vehicles and heavy equipment with wide axles drove on the shoulder and exerted enough stress to cause subgrade mixing. These results can help identify the sediment source and define adequate mitigation measures to reduce sediment production from forest roads and reduce road maintenance efforts by providing information for best management practices. Full article
(This article belongs to the Special Issue Forest Operations, Engineering and Management)
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Open AccessArticle Ortet Age and Clonal Effects on Growth and Market Value of Fraser Fir (Abies fraseri) Grafts as Christmas Trees
Forests 2018, 9(4), 182; https://doi.org/10.3390/f9040182
Received: 14 February 2018 / Revised: 26 March 2018 / Accepted: 30 March 2018 / Published: 3 April 2018
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Abstract
Grafting provides a means to clonally produce Fraser fir (Abies fraseri (Pursh) Poir.) Christmas trees that have desirable traits such as faster growth, greater crown density, increased pest resistance, or more desirable foliage attributes than seedling stock. Grafting Fraser fir to disease
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Grafting provides a means to clonally produce Fraser fir (Abies fraseri (Pursh) Poir.) Christmas trees that have desirable traits such as faster growth, greater crown density, increased pest resistance, or more desirable foliage attributes than seedling stock. Grafting Fraser fir to disease resistant rootstocks also provides a means to ameliorate the impact of root rot, predominantly caused by Phytophthora cinnamomi Rands. The influence of ortet age on growth and market value of grafts has not been studied for Fraser fir Christmas tree production. A field trial was established in 2004 near Independence, Virginia (USA), with the objectives of assessing (1) the effect of ortet age (stock plants = 6 to 8, 10 to 12, and 18 to 20 years) and (2) shearing regimes (fixed leader length versus variable leader length) on growth, quality, and market value of Fraser fir Christmas trees. Commercial height, Christmas tree grade (based on U. S. Dept. of Agric. standards), and net present value (US dollars) were assessed at the time of harvest. Cone damage to quality was rated after 8 years in the field. Scions from Fraser fir Christmas trees 2 m or taller produced grafts that expressed maturation, resulting in lower tree quality, heavier cone damage, and decreased market value compared to seedling stock. In contrast, the quality and market value of grafts was similar to that of seedlings when scions were collected from young Fraser fir Christmas trees. For Christmas tree production, scions should be collected from the upper whorls of trees no older than 2 to 3 years in the field (6 to 8 years from seed). The effect of age on Fraser fir clones varies so that pre-screening might identify some older selections suitable for use as scion donors. Fixed versus variable shearing regimes had little effect on tree value, although some individual clones responded better to one regime or the other. Full article
Open AccessArticle Neighboring Tree Effects and Soil Nutrient Associations with Surviving Green Ash (Fraxinus pennsylvanica) in an Emerald Ash Borer (Agrilus planipennis) Infested Floodplain Forest
Forests 2018, 9(4), 183; https://doi.org/10.3390/f9040183
Received: 2 March 2018 / Revised: 27 March 2018 / Accepted: 2 April 2018 / Published: 4 April 2018
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Abstract
Few ash trees (Fraxinus spp.) have survived the initial devastation that emerald ash borer beetle (EAB) (Agrilus planipennis) has caused in natural populations. We studied green ash (Fraxinus pennsylvanica) trees in a floodplain population after >90% of ash
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Few ash trees (Fraxinus spp.) have survived the initial devastation that emerald ash borer beetle (EAB) (Agrilus planipennis) has caused in natural populations. We studied green ash (Fraxinus pennsylvanica) trees in a floodplain population after >90% of ash had died from EAB infestation. We examined the relationship among the canopy health classes of surviving ash trees and their nearest neighboring trees (within 6 m) and available soil nutrients. A subset of focal ash trees was randomly selected within health classes ranging from healthy to recently deceased. Focal trees with the healthiest canopy class had significantly fewer ash neighbors compared to declining health classes. Other species of tree neighbors did not have a significant impact on surviving ash tree canopy health. Nutrients in soils immediately surrounding focal trees were compared among health classes. Samples from treeless areas were also used for comparison. There was a significantly greater amount of sulfur (ppm) and phosphorus (mg/kg) in ash tree soil compared to treeless area soil. The relationships between these soil nutrient differences may be from nutrient effects on trees, tree effects on nutrients, or microsite variation in flooded areas. Our data do not directly assess whether these ash trees with healthier canopies have increased resistance to EAB but do indicate that at neighborhood scales in EAB aftermath forests, the surviving ash trees have healthier canopies when separated at least 6 m from other ash trees. This research highlights scale-dependent neighborhood composition drivers of tree susceptibility to pests and suggests that drivers during initial infestation differ from drivers in aftermath forests. Full article
(This article belongs to the Special Issue Understanding and Managing Emerald Ash Borer Impacts on Ash Forests)
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Open AccessArticle Tropical Tree Species Effects on Soil pH and Biotic Factors and the Consequences for Macroaggregate Dynamics
Forests 2018, 9(4), 184; https://doi.org/10.3390/f9040184
Received: 9 March 2018 / Revised: 9 March 2018 / Accepted: 2 April 2018 / Published: 4 April 2018
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Abstract
Physicochemical and biotic factors influence the binding and dispersivity of soil particles, and thus control soil macroaggregate formation and stability. Although soil pH influences dispersivity, it is usually relatively constant within a site, and thus not considered a driver of aggregation dynamics. However,
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Physicochemical and biotic factors influence the binding and dispersivity of soil particles, and thus control soil macroaggregate formation and stability. Although soil pH influences dispersivity, it is usually relatively constant within a site, and thus not considered a driver of aggregation dynamics. However, land-use change that results in shifts in tree-species composition can result in alteration of soil pH, owing to species-specific traits, e.g., support of nitrogen fixation and Al accumulation. In a long-term, randomized complete block experiment in which climate, soil type, and previous land-use history were similar, we evaluated effects of individual native tropical tree species on water-stable macroaggregate size distributions in an Oxisol. We conducted this study at La Selva Biological Station in Costa Rica, in six vegetation types: 25-year-old plantations of four tree species grown in monodominant stands; an unplanted Control; and an adjacent mature forest. Tree species significantly influenced aggregate proportions in smaller size classes (0.25–1.0 mm), which were correlated with fine-root growth and litterfall. Tree species altered soil pH differentially. Across all vegetation types, the proportion of smaller macroaggregates declined significantly as soil pH increased (p ≤ 0.0184). This suggests that alteration of pH influences dispersivity, and thus macroaggregate dynamics, thereby playing a role in soil C, N, and P cycling. Full article
(This article belongs to the Special Issue Carbon, Nitrogen and Phosphorus Cycling in Forest Soils)
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Open AccessArticle Investigating the Effect of a Mixed Mycorrhizal Inoculum on the Productivity of Biomass Plantation Willows Grown on Marginal Farm Land
Forests 2018, 9(4), 185; https://doi.org/10.3390/f9040185
Received: 28 February 2018 / Revised: 26 March 2018 / Accepted: 30 March 2018 / Published: 4 April 2018
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Abstract
Inoculation with mycorrhizal fungi, proven mediators of soil fertility, has great potential in agricultural and silvicultural systems. This is particularly true in short-rotation coppices (SRCs), where questions of food displacement and fertilization are causes of concern for researchers and policy makers. We set
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Inoculation with mycorrhizal fungi, proven mediators of soil fertility, has great potential in agricultural and silvicultural systems. This is particularly true in short-rotation coppices (SRCs), where questions of food displacement and fertilization are causes of concern for researchers and policy makers. We set out to thoroughly test if current inoculation methods, coupled with reduced fertilization, can demonstrate a growth benefit in SRC willows on marginal lands. Roughly 21,600 Salix miyabeana Seeman (‘SX61’ and ‘SX64’) were planted in a hierarchical design with inoculation treatments randomized first, cultivars randomized second, and fertilization treatments randomized third. This process was repeated across three fields of different marginal soil type (which, in our experiment, were given the descriptive names Sandy, Rocky, and Dry). The inoculum species, Rhizoglomus irregulare Błaszk., Wubet, Renker & Buscot Sieverd., G.A. Silva & Oehl and Hebeloma longicaudum (Pers.) P. Kumm., were chosen as they are most likely to be commercially available, and because they represent both arbuscular and ectomycorrhizal inoculum types. Growth was measured over 2.5 years, or three growing seasons. Fertilization treatment (75 kg/ha Nitrogen), however, was only applied during the second growing season. Our results conclusively showed no benefit from mycorrhizal inoculation across fields that exhibited significantly different growth rates, as well as significant differentiation from fertilization. Full article
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Open AccessArticle Evidence of Ash Tree (Fraxinus spp.) Specific Associations with Soil Bacterial Community Structure and Functional Capacity
Forests 2018, 9(4), 187; https://doi.org/10.3390/f9040187
Received: 1 March 2018 / Revised: 29 March 2018 / Accepted: 3 April 2018 / Published: 5 April 2018
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Abstract
The spread of the invasive emerald ash borer (EAB) across North America has had enormous impacts on temperate forest ecosystems. The selective removal of ash trees (Fraxinus spp.) has resulted in abnormally large inputs of coarse woody debris and altered forest tree
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The spread of the invasive emerald ash borer (EAB) across North America has had enormous impacts on temperate forest ecosystems. The selective removal of ash trees (Fraxinus spp.) has resulted in abnormally large inputs of coarse woody debris and altered forest tree community composition, ultimately affecting a variety of ecosystem processes. The goal of this study was to determine if the presence of ash trees influences soil bacterial communities and/or functions to better understand the impacts of EAB on forest successional dynamics and biogeochemical cycling. Using 16S rRNA amplicon sequencing of soil DNA collected from ash and non-ash plots in central Ohio during the early stages of EAB infestation, we found that bacterial communities in plots with ash differed from those without ash. These differences were largely driven by Acidobacteria, which had a greater relative abundance in non-ash plots. Functional genes required for sulfur cycling, phosphorus cycling, and carbohydrate metabolism (specifically those which breakdown complex sugars to glucose) were estimated to be more abundant in non-ash plots, while nitrogen cycling gene abundance did not differ. This ash-soil microbiome association implies that EAB-induced ash decline may promote belowground successional shifts, altering carbon and nutrient cycling and changing soil properties beyond the effects of litter additions caused by ash mortality. Full article
(This article belongs to the Special Issue Understanding and Managing Emerald Ash Borer Impacts on Ash Forests)
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Open AccessArticle Comparing Thinning System Effects on Ecosystem Services Provision in Artificial Black Pine (Pinus nigra J. F. Arnold) Forests
Forests 2018, 9(4), 188; https://doi.org/10.3390/f9040188
Received: 26 February 2018 / Revised: 30 March 2018 / Accepted: 3 April 2018 / Published: 5 April 2018
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Abstract
Provision of forest ecosystem services is influenced by site and stand characteristics as well as forest management practices. In order to evaluate the influence of forest management on ecosystem services provision, two artificial black pine forests located in Central Italy were studied where
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Provision of forest ecosystem services is influenced by site and stand characteristics as well as forest management practices. In order to evaluate the influence of forest management on ecosystem services provision, two artificial black pine forests located in Central Italy were studied where two different thinning approaches (traditional and selective) were applied under the SelPiBio LIFE project. Four main ecosystem services were selected and assessed: timber and bioenergy production, carbon sequestration, forest stand stability-protection, and biodiversity conservation. Even if not supported by statistical evidence, results highlighted an interesting trend just 2 years after treatment. The selective thinning was able to enhance the majority of ecosystem services compared to the traditional one. A higher growth rate of selected crop trees was measured (i.e., carbon sequestration). The slenderness ratio was sensibly reduced (i.e., mechanical stability) with a positive implication on soil retention and the prevention of landslides. Moreover, valuable and interesting commercial assortments have been proven to be retrieved from the stands with the selective approach. Larger and also better formed trees were harvested, given the impact of selective thinning on the co-dominant class. The Shannon index increased only with the selective thinning intervention. In conclusion, the provided results and methods are encouraging and might represent the basis for novel and longer monitoring efforts. Full article
(This article belongs to the Special Issue Ecological Management of Pine Forests)
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Open AccessArticle Conditional Performance Evaluation: Using Wildfire Observations for Systematic Fire Simulator Development
Forests 2018, 9(4), 189; https://doi.org/10.3390/f9040189
Received: 2 February 2018 / Revised: 26 March 2018 / Accepted: 2 April 2018 / Published: 6 April 2018
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Abstract
Faster than real-time wildland fire simulators are being increasingly adopted by land managers to provide decision support for tactical wildfire management and assist with strategic risk planning. These simulators are typically based on simple forward rate-of-spread algorithms that were predominantly developed using observations
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Faster than real-time wildland fire simulators are being increasingly adopted by land managers to provide decision support for tactical wildfire management and assist with strategic risk planning. These simulators are typically based on simple forward rate-of-spread algorithms that were predominantly developed using observations of experimental fires. Given their operational use, it is important that fire simulators be assessed in terms of their performance for their intended use; predicting the spatial progression of wildfires. However, the conditions under which wildfires occur cannot be easily replicated experimentally. We describe and demonstrate a method for use in model development, whereby a dataset comprised of wildfire case-studies is used for evaluating the predictive performance of fire simulators. Two different versions of the model PHOENIX RapidFire were assessed, one incorporating a novel algorithm that accounts fine-scale spatial variation in landscape dryness. Evaluation was done by comparing simulator predictions against contemporaneous observations of 9 different wildfires that occurred in Australia. Performance was quantified using the sum of the Area Difference Indices—a measure of prediction overlap calculated for each prediction/observation pair. The two versions of the model performed similarly, with the newer version being marginally (but not statistically significantly) better when outcomes were summarised across all fires. Despite this, it did not perform better in all cases, with three of the 9 fires better predicted using the original model. Wildfire evaluation datasets were demonstrated to provide valuable feedback for model development, however the limited availability of data means power is lacking for detailed comparisons. With increasingly extreme weather conditions resulting from climate change, conditions under which wildfires occur are likely to continue to extend well beyond those under which fire models algorithms were developed. Consequently, the adoption of improved methods for collecting and utilising wildfire data is critical to ensure fire simulators retain relevance. Full article
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Open AccessArticle Developing Models to Predict the Number of Fire Hotspots from an Accumulated Fuel Dryness Index by Vegetation Type and Region in Mexico
Forests 2018, 9(4), 190; https://doi.org/10.3390/f9040190
Received: 20 February 2018 / Revised: 24 March 2018 / Accepted: 29 March 2018 / Published: 7 April 2018
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Abstract
Understanding the linkage between accumulated fuel dryness and temporal fire occurrence risk is key for improving decision-making in forest fire management, especially under growing conditions of vegetation stress associated with climate change. This study addresses the development of models to predict the number
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Understanding the linkage between accumulated fuel dryness and temporal fire occurrence risk is key for improving decision-making in forest fire management, especially under growing conditions of vegetation stress associated with climate change. This study addresses the development of models to predict the number of 10-day observed Moderate-Resolution Imaging Spectroradiometer (MODIS) active fire hotspots—expressed as a Fire Hotspot Density index (FHD)—from an Accumulated Fuel Dryness Index (AcFDI), for 17 main vegetation types and regions in Mexico, for the period 2011–2015. The AcFDI was calculated by applying vegetation-specific thresholds for fire occurrence to a satellite-based fuel dryness index (FDI), which was developed after the structure of the Fire Potential Index (FPI). Linear and non-linear models were tested for the prediction of FHD from FDI and AcFDI. Non-linear quantile regression models gave the best results for predicting FHD using AcFDI, together with auto-regression from previously observed hotspot density values. The predictions of 10-day observed FHD values were reasonably good with R2 values of 0.5 to 0.7 suggesting the potential to be used as an operational tool for predicting the expected number of fire hotspots by vegetation type and region in Mexico. The presented modeling strategy could be replicated for any fire danger index in any region, based on information from MODIS or other remote sensors. Full article
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Open AccessArticle Downed Coarse Woody Debris Dynamics in Ash (Fraxinus spp.) Stands Invaded by Emerald Ash Borer (Agrilus planipennis Fairmaire)
Forests 2018, 9(4), 191; https://doi.org/10.3390/f9040191
Received: 2 March 2018 / Revised: 5 April 2018 / Accepted: 5 April 2018 / Published: 7 April 2018
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Abstract
Emerald ash borer (EAB; Agrilus planipennis Fairmaire) has had major ecological impacts in forests of eastern North America. In 2008 and 2012, we characterized dynamics of downed coarse woody debris (DCWD) in southeastern Michigan, USA near the epicenter of the invasion, where the
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Emerald ash borer (EAB; Agrilus planipennis Fairmaire) has had major ecological impacts in forests of eastern North America. In 2008 and 2012, we characterized dynamics of downed coarse woody debris (DCWD) in southeastern Michigan, USA near the epicenter of the invasion, where the mortality of white (Fraxinus americana L.), green (F. pennsylvanica Marshall), and black (F. nigra Marshall) ash exceeded 99% by 2009. Percentage of fallen dead ash trees and volume of ash DCWD on the forest floor increased by 76% and 53%, respectively, from 2008 to 2012. Ash and non-ash fell non-randomly to the east and southeast, conforming to prevailing winds. More ash fell by snapping along the bole than by uprooting. By 2012, however, only 31% of ash snags had fallen, indicating that DCWD will increase substantially, especially if it accelerates from the rate of 3.5% per year documented during the study period. Decay of ash DCWD increased over time, with most categorized as minimally decayed (decay classes 1 and 2) in 2008 and more decayed (decay classes 2 and 3) in 2012. As the range of EAB expands, similar patterns of DCWD dynamics are expected in response to extensive ash mortality. Full article
(This article belongs to the Special Issue Understanding and Managing Emerald Ash Borer Impacts on Ash Forests)
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Open AccessArticle Can Land Management Buffer Impacts of Climate Changes and Altered Fire Regimes on Ecosystems of the Southwestern United States?
Forests 2018, 9(4), 192; https://doi.org/10.3390/f9040192
Received: 15 February 2018 / Revised: 2 April 2018 / Accepted: 4 April 2018 / Published: 7 April 2018
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Abstract
Climate changes and associated shifts in ecosystems and fire regimes present enormous challenges for the management of landscapes in the Southwestern US. A central question is whether management strategies can maintain or promote desired ecological conditions under projected future climates. We modeled wildfire
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Climate changes and associated shifts in ecosystems and fire regimes present enormous challenges for the management of landscapes in the Southwestern US. A central question is whether management strategies can maintain or promote desired ecological conditions under projected future climates. We modeled wildfire and forest responses to climate changes and management activities using two ecosystem process models: FireBGCv2, simulated for the Jemez Mountains, New Mexico, and LANDIS-II, simulated for the Kaibab Plateau, Arizona. We modeled contemporary and two future climates—“Warm-Dry” (CCSM4 RCP 4.5) and “Hot-Arid” (HadGEM2ES RCP 8.5)—and four levels of management including fire suppression alone, a current treatment strategy, and two intensified treatment strategies. We found that Hot-Arid future climate resulted in a fundamental, persistent reorganization of ecosystems in both study areas, including biomass reduction, compositional shifts, and altered forest structure. Climate changes increased the potential for high-severity fire in the Jemez study area, but did not impact fire regime characteristics in the Kaibab. Intensified management treatments somewhat reduced wildfire frequency and severity; however, management strategies did not prevent the reorganization of forest ecosystems in either landscape. Our results suggest that novel approaches may be required to manage future forests for desired conditions. Full article
(This article belongs to the Special Issue Wildland Fire, Forest Dynamics, and Their Interactions)
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Open AccessArticle Robust Model Predicts Shoot Phenology of Fraser Fir under Extreme Conditions
Forests 2018, 9(4), 193; https://doi.org/10.3390/f9040193
Received: 28 February 2018 / Revised: 28 March 2018 / Accepted: 5 April 2018 / Published: 8 April 2018
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Abstract
Fraser fir (Abies fraseri [Pursh] Poir.) is an important Christmas tree species in the United States, and understanding its phenology is important for managing Fraser fir trees in plantations or forests. Many management decisions are informed by and dependent on shoot phenology,
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Fraser fir (Abies fraseri [Pursh] Poir.) is an important Christmas tree species in the United States, and understanding its phenology is important for managing Fraser fir trees in plantations or forests. Many management decisions are informed by and dependent on shoot phenology, from late spring frost protection to shearing, and from timing pesticide sprays to managing cone production. The ability to predict important phenological stages will become increasingly important as the climate warms, as is predicted for the primary regions where Fraser fir is grown for Christmas trees. Here, we report on the development of a model of shoot phenology in Fraser fir, and present one example of how this model may be applied to the problem of managing cone production. We surveyed shoot phenology at nine Christmas tree plantations in Michigan over three years, and used the data obtained to develop a phenology model of shoot growth. Derived from the beta sigmoid function and based on growing degree days, this phenology model offers a high predictive power and is robust to extremes of temperature and precipitation. When applied to cone production, our model provides guidance for timing practices that influence cone bud formation, both for reducing nuisance cones in Christmas tree plantations and for enhancing cone production in seed orchards. In addition, the model may assist with timing other practices tied to shoot phenology. The performance of our model under extreme heat and drought conditions suggests a role for this and other phenology models in predicting and mitigating the effects of climate change on tree growth and development. Full article
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Open AccessArticle Comparative Time Study of Conventional Cut-To-Length and an Integrated Harvesting Method—A Case Study
Forests 2018, 9(4), 194; https://doi.org/10.3390/f9040194
Received: 15 February 2018 / Revised: 3 April 2018 / Accepted: 6 April 2018 / Published: 9 April 2018
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Abstract
Logging residues offer a significant contribution to the economical profitability and sustainability of forest-based resources. It is always desirable to optimise the harvesting and extraction method to improve the economy of the process along with ensuring sustainability from an environmental point of view.
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Logging residues offer a significant contribution to the economical profitability and sustainability of forest-based resources. It is always desirable to optimise the harvesting and extraction method to improve the economy of the process along with ensuring sustainability from an environmental point of view. This study compares two harvesting methods, i.e., conventional cut-to-length (CTL) followed by harvesting residue extraction for energy and an integrated harvesting method combining CTL with harvesting residue pre-piling by the harvester followed by the extraction of both timber and logging residues for energy. The study was carried out in spruce stands (Picea abies (L.) Karst.) in South Moravia (Czech Republic) at Pozořice and Kuničky. Two methods utilized by harvesters and forwarders were compared. The first case was a conventional CTL method when trees are felled, delimbed, and cross-cut by the harvester. The resulting logs are pre-piled and then transported by the forwarder. In this case, the harvesting residues remain in the stand. The method does not involve utilizing harvesting residues such as brash mat on striproads but rather extracting them in an independent step as an energy source. In the second case, the resulting harvesting residues are piled up by the harvester to be later extracted by the forwarder. Such extracted harvesting residues are stored at the roadside for seasoning and future comminution. The aim was to obtain input data for internal analysis of a private entity contracting in a logging operation. The client demanded that the increase in time needed for the production of one timber unit with simultaneous harvesting residue preparation be measured. By our estimates, the integrated harvesting method required 33% more (harvester) and 16% less (forwarder) time compared to the alternate method for the extraction of harvesting residues, which in turn results in approximately 8% longer total operational time for the complete operation. Full article
(This article belongs to the Special Issue Forest Operations: Planning, Innovation and Sustainability)
Open AccessArticle Elevated CO2 and O3 Levels Influence the Uptake and Leaf Concentration of Mineral N, P, K in Phyllostachys edulis (Carrière) J.Houz. and Oligostachyum lubricum (wen) King f.
Forests 2018, 9(4), 195; https://doi.org/10.3390/f9040195
Received: 5 March 2018 / Revised: 26 March 2018 / Accepted: 27 March 2018 / Published: 10 April 2018
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Abstract
Rising CO2 and O3 concentrations significantly affect plant growth and can alter nutrient cycles. However, the effects of elevated CO2 and O3 concentrations on the nutrient dynamics of bamboo species are not well understood. In this study, using open
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Rising CO2 and O3 concentrations significantly affect plant growth and can alter nutrient cycles. However, the effects of elevated CO2 and O3 concentrations on the nutrient dynamics of bamboo species are not well understood. In this study, using open top chambers (OTCs), we examined the effects of elevated CO2 and O3 concentrations on leaf biomass and nutrient (N, P, and K) dynamics in two bamboo species, Phyllostachys edulis (Carrière) J.Houz. and Oligostachyum lubricum (wen) King f. Elevated O3 significantly decreased leaf biomass and nutrient uptake of both bamboo species, with the exception of no observed change in K uptake by O. lubricum. Elevated CO2 increased leaf biomass, N and K uptake of both bamboo species. Elevated CO2 and O3 simultaneously had no significant influence on leaf biomass of either species but decreased P and N uptake in P. edulis and O. lubricum, respectively, and increased K uptake in O. lubricum. The results indicate that elevated CO2 alleviated the damage caused by elevated O3 in the two bamboo species by altering the uptake of certain nutrients, which further highlights the potential interactive effects between the two gases on nutrient uptake. In addition, we found differential responses of nutrient dynamics in the two bamboo species to the two elevated gases, alone or in combination. These findings will facilitate the development of effective nutrient management strategies for sustainable management of P. edulis and O. lubricum under global change scenarios. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle Biomass Carbon Sequestration Potential by Riparian Forest in the Tarim River Watershed, Northwest China: Implication for the Mitigation of Climate Change Impact
Forests 2018, 9(4), 196; https://doi.org/10.3390/f9040196
Received: 14 February 2018 / Revised: 30 March 2018 / Accepted: 3 April 2018 / Published: 10 April 2018
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Abstract
Carbon management in forests has become the most important agenda of the first half of the 21st century in China in the context of the mitigation of climate change impact. As the main producer of the inland river basin ecosystem in arid region
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Carbon management in forests has become the most important agenda of the first half of the 21st century in China in the context of the mitigation of climate change impact. As the main producer of the inland river basin ecosystem in arid region of Northwest China, the desert riparian forest maintains the regional environment and also holds a great significance in regulating the regional/global carbon cycle. In this study, we estimated the total biomass, carbon storage, as well as monetary ecosystem service values of desert riparian Populus euphratica Oliv. in the lower reaches of the Tarim River based on terrestrial forest inventory data within an area of 100 ha (100 plots with sizes of 100 m × 100 m) and digitized tree data within 1000 ha (with 10 m × 10 m grid) using a statistical model of biomass estimation against tree height (TH) and diameter at breast height (DBH) data. Our results show that total estimated biomass and carbon storage of P. euphratica within the investigated area ranged from 3.00 to 4317.00 kg/ha and from 1.82 to 2158.73 kg/ha, respectively. There was a significant negative relationship (p < 0.001) between biomass productivity of these forests and distance to the river and groundwater level. Large proportions of biomass (64% of total biomass) are estimated within 200 m distance to the river where groundwater is relatively favorable for vegetation growth and biomass production. However, our data demonstrated that total biomass showed a sharp decreasing trend with increasing distance to the river; above 800 m distance, less biomass and carbon storage were estimated. The total monetary value of the ecosystem service “carbon storage” provided by P. euphratica was estimated to be $6.8 × 104 USD within the investigated area, while the average monetary value was approximately $70 USD per ha, suggesting that the riparian forest ecosystem in the Tarim River Basin should be considered a relevant regional carbon sink. The findings of this study help to establish a better understanding of the spatial distribution pattern of P. euphratica forest under water scarcity and can also provide an alternative approach to local decision-makers for efficient and precise assessment of forest carbon resources for emission reduction programs. Full article
(This article belongs to the Special Issue Forest Hydrology and Watershed)
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Open AccessArticle Elastic and Strength Properties of Heat-Treated Beech and Birch Wood
Forests 2018, 9(4), 197; https://doi.org/10.3390/f9040197
Received: 20 February 2018 / Revised: 20 March 2018 / Accepted: 8 April 2018 / Published: 10 April 2018
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Abstract
This paper deals with the impact of heat treatment on the elastic and strength properties of two diffuse porous hardwoods, namely Fagus sylvatica and Betula pendula. Two degrees of the heat treatment were used at temperatures of 165 °C and 210 °C.
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This paper deals with the impact of heat treatment on the elastic and strength properties of two diffuse porous hardwoods, namely Fagus sylvatica and Betula pendula. Two degrees of the heat treatment were used at temperatures of 165 °C and 210 °C. The dynamic and static elasticity modulus, bending strength, impact toughness, hardness, and density were tested. It is already known that an increase in treatment temperature decreases the mechanical properties and, on the other hand, leads to a better shape and dimensional stability. Higher temperatures of the heat treatment correlated with lower elastic and strength properties. In the case of higher temperature treatments, the decline of tested properties was noticeable as a result of serious changes in the chemical composition of wood. It was confirmed that at higher temperature stages of treatment, there was a more pronounced decrease in beech properties compared to those of the birch, which was the most evident in their bending strength and hardness. Our research confirmed that there is no reason to consider birch wood to be of a lesser quality, although it is regarded by foresters as an inferior tree species. After the heat treatment, the wood properties are almost the same as in the case of beech wood. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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Open AccessArticle Effect of Vertical Canopy Architecture on Transpiration, Thermoregulation and Carbon Assimilation
Forests 2018, 9(4), 198; https://doi.org/10.3390/f9040198
Received: 5 March 2018 / Revised: 3 April 2018 / Accepted: 9 April 2018 / Published: 11 April 2018
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Abstract
Quantifying the impact of natural and anthropogenic disturbances such as deforestation, forest fires and vegetation thinning among others on net ecosystem—atmosphere exchanges of carbon dioxide, water vapor and heat—is an important aspect in the context of modeling global carbon, water and energy cycles.
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Quantifying the impact of natural and anthropogenic disturbances such as deforestation, forest fires and vegetation thinning among others on net ecosystem—atmosphere exchanges of carbon dioxide, water vapor and heat—is an important aspect in the context of modeling global carbon, water and energy cycles. The absence of canopy architectural variation in horizontal and vertical directions is a major source of uncertainty in current climate models attempting to address these issues. This manuscript demonstrates the importance of considering the vertical distribution of foliage density by coupling a leaf level plant biophysics model with analytical solutions of wind flow and light attenuation in a horizontally homogeneous canopy. It is demonstrated that plant physiological response in terms of carbon assimilation, transpiration and canopy surface temperature can be widely different for two canopies with the same leaf area index (LAI) but different leaf area density distributions, under several conditions of wind speed, light availability, soil moisture availability and atmospheric evaporative demand. Full article
(This article belongs to the Special Issue Defining, Quantifying, Observing and Modeling Forest Canopy Traits)
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Open AccessArticle Susceptibility of Trees to Windthrow Storm Damage in Partially Harvested Complex-Structured Multi-Species Forests
Forests 2018, 9(4), 199; https://doi.org/10.3390/f9040199
Received: 23 March 2018 / Revised: 4 April 2018 / Accepted: 5 April 2018 / Published: 11 April 2018
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Abstract
In Canada and elsewhere, logging practices in natural-origin forests have shifted toward retention systems where variable levels of mature trees are retained post-logging to promote a diversity of values. We examine multiple sites that experienced a wide range of prior harvest regimes (0–76%
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In Canada and elsewhere, logging practices in natural-origin forests have shifted toward retention systems where variable levels of mature trees are retained post-logging to promote a diversity of values. We examine multiple sites that experienced a wide range of prior harvest regimes (0–76% basal area removal) to evaluate how harvest intensity and proximity to a logging-created edge affects susceptibility to windthrow for a suite of tree species in complex-structured mature and old-growth mixed-species stand types in British Columbia. We found no increased susceptibility to windthrow as a function of the level of partial harvesting. We observed a reduced susceptibility to windthrow of smaller trees after partial harvesting. There were clear differences in susceptibility to windthrow among different tree species close to the edge of gaps and small openings (<1 ha in size) created by partial harvesting. Hemlock and redcedar, the two most common trees species, were unaffected by edge environments, whereas the less common conifers and deciduous species were more susceptible to windthrow along partial harvest edges. This suggests tree-marking guidelines should remove the species most prone to windthrow from edges around small openings in these forest types. Our study and others suggest use of retention systems in structurally diverse, multi-species forests does not lead to elevated risk of windthrow, especially if retention levels exceed 20–30%. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle Toward a Social-Ecological Theory of Forest Macrosystems for Improved Ecosystem Management
Forests 2018, 9(4), 200; https://doi.org/10.3390/f9040200
Received: 6 March 2018 / Revised: 29 March 2018 / Accepted: 2 April 2018 / Published: 11 April 2018
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Abstract
The implications of cumulative land-use decisions and shifting climate on forests, require us to integrate our understanding of ecosystems, markets, policy, and resource management into a social-ecological system. Humans play a central role in macrosystem dynamics, which complicates ecological theories that do not
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The implications of cumulative land-use decisions and shifting climate on forests, require us to integrate our understanding of ecosystems, markets, policy, and resource management into a social-ecological system. Humans play a central role in macrosystem dynamics, which complicates ecological theories that do not explicitly include human interactions. These dynamics also impact ecological services and related markets, which challenges economic theory. Here, we use two forest macroscale management initiatives to develop a theoretical understanding of how management interacts with ecological functions and services at these scales and how the multiple large-scale management goals work either in consort or conflict with other forest functions and services. We suggest that calling upon theories developed for organismal ecology, ecosystem ecology, and ecological economics adds to our understanding of social-ecological macrosystems. To initiate progress, we propose future research questions to add rigor to macrosystem-scale studies: (1) What are the ecosystem functions that operate at macroscales, their necessary structural components, and how do we observe them? (2) How do systems at one scale respond if altered at another scale? (3) How do we both effectively measure these components and interactions, and communicate that information in a meaningful manner for policy and management across different scales? Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle Improved Water Consumption Estimates of Black Locust Plantations in China’s Loess Plateau
Forests 2018, 9(4), 201; https://doi.org/10.3390/f9040201
Received: 7 March 2018 / Revised: 27 March 2018 / Accepted: 11 April 2018 / Published: 11 April 2018
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Abstract
Black locust (Robinia pseudoacacia L.) is a major tree species in China’s large-scale afforestation. Despite its significance, black locust is underrepresented in sap flow literature; moreover, the published water consumption data might be biased. We applied two field methods to estimate water
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Black locust (Robinia pseudoacacia L.) is a major tree species in China’s large-scale afforestation. Despite its significance, black locust is underrepresented in sap flow literature; moreover, the published water consumption data might be biased. We applied two field methods to estimate water consumption of black locust during the growing seasons in 2012 and 2013. The application of Granier’s original sap flow method produced a very low transpiration rate (0.08 mm d−1) while the soil water balance method yielded a much higher rate (1.4 mm d−1). A dye experiment to determine the active sapwood area showed that only the outermost annual ring is responsible for conducting water, which was not considered in many previous studies. Moreover, an in situ calibration experiment was conducted to improve the reliability of Granier’s method. Validation showed a good agreement in estimates of the transpiration rate between the different methods. It is known from many studies that black locust plantations contribute to the significant decline of discharge in the Yellow River basin. Our estimate of tree transpiration at stand scale confirms these results. This study provides a basis for and advances the argument for the development of more sustainable forest management strategies, which better balance forest-related ecosystem services such as soil conservation and water supply. Full article
(This article belongs to the Special Issue Afforestation and Reforestation: Drivers, Dynamics, and Impacts)
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Open AccessArticle Optimizing Conservation Strategies for a Threatened Tree Species: In Situ Conservation of White Ash (Fraxinus americana L.) Genetic Diversity through Insecticide Treatment
Forests 2018, 9(4), 202; https://doi.org/10.3390/f9040202
Received: 20 February 2018 / Revised: 9 April 2018 / Accepted: 10 April 2018 / Published: 13 April 2018
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Abstract
Forest resources face numerous threats that require costly management. Hence, there is an increasing need for data-informed strategies to guide conservation practices. The introduction of the emerald ash borer to North America has caused rapid declines in ash populations (Fraxinus spp. L.).
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Forest resources face numerous threats that require costly management. Hence, there is an increasing need for data-informed strategies to guide conservation practices. The introduction of the emerald ash borer to North America has caused rapid declines in ash populations (Fraxinus spp. L.). Natural resource managers are faced with a choice of either allowing ash trees to die, risking forest degradation and reduced functional resilience, or investing in conserving trees to preserve ecosystem structure and standing genetic diversity. The information needed to guide these decisions is not always readily available. Therefore, to address this concern, we used eight microsatellites to genotype 352 white ash trees (Fraxinus americana L.) across 17 populations in the Allegheny National Forest; a subset of individuals sampled are part of an insecticide treatment regimen. Genetic diversity (number of alleles and He) was equivalent in treated and untreated trees, with little evidence of differentiation or inbreeding, suggesting current insecticidal treatment is conserving local, neutral genetic diversity. Using simulations, we demonstrated that best practice is treating more populations rather than more trees in fewer populations. Furthermore, through genetic screening, conservation practitioners can select highly diverse and unique populations to maximize diversity and reduce expenditures (by up to 21%). These findings will help practitioners develop cost-effective strategies to conserve genetic diversity. Full article
(This article belongs to the Special Issue Understanding and Managing Emerald Ash Borer Impacts on Ash Forests)
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Open AccessArticle Phytophthora cinnamomi Colonized Reclaimed Surface Mined Sites in Eastern Kentucky: Implications for the Restoration of Susceptible Species
Forests 2018, 9(4), 203; https://doi.org/10.3390/f9040203
Received: 21 March 2018 / Revised: 9 April 2018 / Accepted: 12 April 2018 / Published: 13 April 2018
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Abstract
Appalachian forests are threatened by a number of factors, especially introduced pests and pathogens. Among these is Phytophthora cinnamomi, a soil-borne oomycete pathogen known to cause root rot in American chestnut, shortleaf pine, and other native tree species. This study was initiated
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Appalachian forests are threatened by a number of factors, especially introduced pests and pathogens. Among these is Phytophthora cinnamomi, a soil-borne oomycete pathogen known to cause root rot in American chestnut, shortleaf pine, and other native tree species. This study was initiated to characterize the incidence of P. cinnamomi on surface mined lands in eastern Kentucky, USA, representing a range of time since reclamation (10, 12, 15, and 20 years since reclamation). Incidence of P. cinnamomi was correlated to soil properties including overall soil development, as indicated by a variety of measured soil physical and chemical parameters, especially the accumulation of soil organic carbon. P. cinnamomi was detected in only two of the four sites studied, aged 15 and 20 years since reclamation. These sites were generally characterized by higher organic matter accumulation than the younger sites in which P. cinnamomi was not detected. These results demonstrate that P. cinnamomi is capable of colonizing reclaimed mine sites in Appalachia; additional research is necessary to determine the impact of P. cinnamomi on susceptible tree species at these sites. Full article
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Open AccessArticle Variation in Soil Methane Fluxes and Comparison between Two Forests in China
Forests 2018, 9(4), 204; https://doi.org/10.3390/f9040204
Received: 23 January 2018 / Revised: 26 March 2018 / Accepted: 5 April 2018 / Published: 13 April 2018
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Abstract
Methane (CH4) is a vital greenhouse gas with a 28-fold higher global warming potential than carbon dioxide when considering a molar basis for the time horizon of 100 years. Here, we investigated the variation of soil CH4 fluxes, soil physiochemical
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Methane (CH4) is a vital greenhouse gas with a 28-fold higher global warming potential than carbon dioxide when considering a molar basis for the time horizon of 100 years. Here, we investigated the variation of soil CH4 fluxes, soil physiochemical properties, and CH4-related bacteria community composition of two forests in China. We measured CH4 fluxes using static chambers and analyzed soil bacterial communities using next-generation high-throughput sequencing in a temperate broad-leaved deciduous forest at Baotianman Nature Reserve (TBDF-BTM) and a tropical rainforest at Jianfengling National Natural Reserve (TRF-JFL). Our results showed that the soils from both sites were CH4 sinks. Significant variation in soil CH4 fluxes was found at TBDF-BTM exclusively, while no seasonal variation in the CH4 uptake was observed at TRF-JFL. The CH4 fluxes at TBDF-BTM were substantially higher than those at TRF-JFL during all seasons. One genus of methanotrophs and three genera of methylotrophs were detected at both sites, though they had no direct relationship with soil CH4 fluxes. Water-filled pore space and soil total carbon content are the main factors controlling the soil CH4 fluxes at TBDF-BTM. At TRF-JFL, the soil CH4 fluxes showed no significant correlations with any of the soil properties. This study improves our understanding of soil CH4 fluxes and their influencing factors in forests in different climatic zones and provides a reference for future investigation of forest soil CH4 fluxes, the forest ecosystem carbon cycle, and the forest CH4 model. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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Open AccessArticle Drought Decreases Growth and Increases Mortality of Coexisting Native and Introduced Tree Species in a Temperate Floodplain Forest
Forests 2018, 9(4), 205; https://doi.org/10.3390/f9040205
Received: 9 March 2018 / Revised: 2 April 2018 / Accepted: 11 April 2018 / Published: 13 April 2018
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Abstract
Forest dieback and mortality events induced by drought stress are widely reported. However, few studies have jointly examined the role played by drought on growth and mortality in tree species inhabiting floodplain forests. Here, we focused on mortality events occurring since the early
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Forest dieback and mortality events induced by drought stress are widely reported. However, few studies have jointly examined the role played by drought on growth and mortality in tree species inhabiting floodplain forests. Here, we focused on mortality events occurring since the early 2000s on large areas in a floodplain forest located within the Ticino regional park in Northwest Italy, where affected native (pedunculate oak, Quercus robur L.) and introduced tree species (black locust, Robinia pseudoacacia L.) coexist. We related growth with climate data and drought severity to discern if these species were similarly affected by drought. Then, we: (i) evaluated the presence of pathogens of the genus Phytophthora in recently dead oak trees since this was the most affected species and pathogens are often associated with oak decline cases; and (ii) compared xylem vessel diameter and tree-ring C isotope discrimination (δ13C) to highlight differences in water-use strategies between living and dead trees in both species. The radial growth of living and dead trees started diverging in the 1970s, although only after warm-drought periods occurred during 1990s did this divergence become significant. Growth of trees that died responded more negatively to drought than in the case of living trees. Moreover, trees that died formed smaller xylem vessels in the past than living trees and also showed more negative δ13C values in both tree species, indicating a higher intrinsic water-use efficiency in living than in dead trees. The pathogen Phytophthora cinnamomi Rands was only detected in one recently dead tree, suggesting that it is unlikely that dead oaks were predisposed to drought damage by the pathogen. We conclude that a climate shift from wet to warm-dry summer conditions in the early 1990s triggered forest dieback and induced mortality in both tree species. Temperate floodplain forests are susceptible to drought-induced dieback. The drought-sensitivity of both species could lead to successional shifts driven by a reduction of N inputs through N-fixing by black locust and the replacement of oak by drought-tolerant species. Full article
(This article belongs to the Special Issue Tree-Ring Records of Climatic Impacts on Forests)
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Open AccessArticle Delimbing and Cross-cutting of Coniferous Trees–Time Consumption, Work Productivity and Performance
Forests 2018, 9(4), 206; https://doi.org/10.3390/f9040206
Received: 15 March 2018 / Revised: 11 April 2018 / Accepted: 13 April 2018 / Published: 15 April 2018
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Abstract
This research established the time consumption, work time structure, and productivity for primary processing in felling areas of coniferous trees felled with a chainsaw. Delimbing and partial cross-cutting were taken into consideration. The research was conducted in a mixed spruce and fir tree
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This research established the time consumption, work time structure, and productivity for primary processing in felling areas of coniferous trees felled with a chainsaw. Delimbing and partial cross-cutting were taken into consideration. The research was conducted in a mixed spruce and fir tree stand situated in the Carpathian Mountains. The team of workers consisted of a chainsaw operator and assistant with over 10 years of experience. The results indicated a total time of 536.32 s·m−3 (1145.26 s·tree−1), work performance (including delays) of 6.716 m3·h−1 (3.14 tree·h−1), and work productivity (without delays) of 35.459 m3·h−1 (16.58 tree·h−1). The chainsaw productivity during tree cross-cutting was 82.29 cm2·s−1. Delimbing accounted for 96.18% of the real work time, while cross-cutting accounted for 3.82%. The time consumption for delimbing and cross-cutting, as well as the work productivity and performance in the primary processing of coniferous trees in the felling area, were influenced by the breast height diameter, stem length, and tree volume, while the chainsaw productivity was influenced by the diameter of the cross-cut sections. The relationships between the aforementioned dependent and independent variables were determined by simple and linear multiple regression equations. Full article
(This article belongs to the Special Issue Forest Operations: Planning, Innovation and Sustainability)
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Open AccessArticle Stem Photosynthesis of Twig and Its Contribution to New Organ Development in Cutting Seedlings of Salix Matsudana Koidz.
Forests 2018, 9(4), 207; https://doi.org/10.3390/f9040207
Received: 27 February 2018 / Revised: 29 March 2018 / Accepted: 5 April 2018 / Published: 16 April 2018
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Abstract
The objective of this study was to illustrate the photosynthetic characteristics of current twigs of Salix matsudana Koidz., and clarify the effect of stem photosynthesis on the new organ development in cutting seedlings. Excised twigs were taken as the experimental samples. The response
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The objective of this study was to illustrate the photosynthetic characteristics of current twigs of Salix matsudana Koidz., and clarify the effect of stem photosynthesis on the new organ development in cutting seedlings. Excised twigs were taken as the experimental samples. The response of the stem photosynthesis rate to increasing light intensity and the effective photochemical efficiency of the cross section of the twig were determined. Then, twigs were used as cuttings and exposed to 0, 20, and 100 μmol m−2 s−1 light intensities, respectively, to achieve distinctive stem photosynthetic rates. After 14 days of treatment, stem water and non-structural carbohydrate (NSC) content, as well as the biomass and carbon isotopic composition, of new organs in the cutting seedlings under different light treatments were examined. The results showed that the gross photosynthetic rate significantly increased within 400 μmol m−2 s−1 of light intensity, and the maximum rate was approximately 1.27 μmol m−2 s−1. The effective photochemical efficiency of the PSⅡ of the cortex was significantly higher than the inner tissues in the cross section of the twig. When twig cuttings were exposed to different light intensities, stem water and starch content, as well as bud and root biomass, were significantly higher in the cutting seedling subjected to 100 μmol m−2 s−1 than the case treated in darkness; however, the bud δ13C trend was the opposite. Stem photosynthesis played a positive role in the maintenance of stem water and starch supply for the cutting seedlings, and 13C depleted assimilates produced by stem photosynthesis contributed to bud biomass, revealing that stem photosynthesis promotes organ development in cutting seedlings of Salix matsudana. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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Open AccessArticle Effects of CMIP5 Projections on Volume Growth, Carbon Stock and Timber Yield in Managed Scots Pine, Norway Spruce and Silver Birch Stands under Southern and Northern Boreal Conditions
Forests 2018, 9(4), 208; https://doi.org/10.3390/f9040208
Received: 5 March 2018 / Revised: 9 April 2018 / Accepted: 13 April 2018 / Published: 16 April 2018
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Abstract
We investigated how recent-generation (CMIP5) global climate model projections affect the volume growth, carbon stock, timber yield and its profitability in managed Scots pine, Norway spruce and Silver birch stands on medium fertile upland sites under southern and northern boreal conditions in Finland.
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We investigated how recent-generation (CMIP5) global climate model projections affect the volume growth, carbon stock, timber yield and its profitability in managed Scots pine, Norway spruce and Silver birch stands on medium fertile upland sites under southern and northern boreal conditions in Finland. Forest ecosystem model simulations were conducted for the current climate and changing climate, under two representative concentration pathways (RCP4.5 and RCP8.5), using 10 individual global climate model (GCM) projections. In addition to the baseline thinning, we maintained either 20% higher or lower stocking in thinning over a 90-year period. In the south, the severe climate projections, such as HadGEM2-ES RCP8.5 and GFDL-CM3 RCP8.5, as opposed to MPI-ESM-MR RCP4.5, considerably decreased the volume growth, carbon stock and timber yield, as well as its profitability, in Norway spruce stands, but also partially in Scots pine stands, compared to the current climate. Silver birch gained the most from the climate change in the south and Scots pine in the north. The impacts of the thinning regime varied, depending on tree species, site and climate applied. Depending on the severity of the climate change, even opposing adaptive management measures may be needed in different boreal regions. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle Stock Volume Dependency of Forest Drought Responses in Yunnan, China
Forests 2018, 9(4), 209; https://doi.org/10.3390/f9040209
Received: 20 February 2018 / Revised: 5 April 2018 / Accepted: 13 April 2018 / Published: 16 April 2018
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Abstract
Revealing forest drought response characteristics and the potential impact factors is quite an important scientific issue against the background of global climate change, which is the foundation to reliably evaluate and predict the effects of future drought. Due to the high spatial heterogeneity
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Revealing forest drought response characteristics and the potential impact factors is quite an important scientific issue against the background of global climate change, which is the foundation to reliably evaluate and predict the effects of future drought. Due to the high spatial heterogeneity of forest properties such as biomass, forest age, and height, and the distinct differences in drought stress in terms of frequency, intensity, and duration, current studies still contain many uncertainties. In this research, we used the forests in Yunnan Province in Southwest China as an example and aimed to reveal the potential impacts of forest properties (i.e., stock volume) on drought response characteristics. Specifically, we divided the forest into five groups of stock volume density values and then analyzed their drought response differences. To depict forest response to drought intensity, the standardized precipitation evapotranspiration index (SPEI) was chosen as the explanatory variable, and the change in remote sensing-based enhanced vegetation index (deficit of MODIS-EVI, dEVI) was chosen as the response variable of drought stress. Given that the SPEI has different time scales, we first analyzed the statistical dependency of SPEIs with different time scales (1 to 36 months) to the response variable (i.e., dEVI). The optimal time scale of SPEI (SPEIopt) to interpret the maximum variation of dEVI (R-square) was then chosen to build the ultimate statistical models for the five groups of stock volume density. The main findings were as follows: (1) the impacts of drought showed hysteresis and cumulative effects, and the length of the hysteresis increased with stock volume densities; (2) forests with high stock volume densities required more soil water and were therefore more sensitive to the changes in water deficit; (3) compared with the optimal time scale of SPEI (SPEIopt), the SPEI with the commonly used time scale (e.g., 1, 6, and 12 months) could not well reflect the impacts of drought on forests and the simulation error of dEVI increased with stock volume densities; and (4) forests with higher stock volume densities were likely to experience a greater risk of degradation following higher atmospheric concentrations of greenhouse gases (Representative Concentration Pathway (RCP) 8.5). As a result, both the time scale of the meteorological drought index and the spatial difference in forest stock volumes should be considered when evaluating forest drought responses at regional and global scales. Full article
(This article belongs to the Special Issue Remotely Sensing of Drought-Induced Forest Change and Recovery)
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Open AccessArticle Exploring the Future of Fuel Loads in Tasmania, Australia: Shifts in Vegetation in Response to Changing Fire Weather, Productivity, and Fire Frequency
Forests 2018, 9(4), 210; https://doi.org/10.3390/f9040210
Received: 23 February 2018 / Revised: 7 April 2018 / Accepted: 9 April 2018 / Published: 16 April 2018
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Abstract
Changes to the frequency of fire due to management decisions and climate change have the potential to affect the flammability of vegetation, with long-term effects on the vegetation structure and composition. Frequent fire in some vegetation types can lead to transformational change beyond
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Changes to the frequency of fire due to management decisions and climate change have the potential to affect the flammability of vegetation, with long-term effects on the vegetation structure and composition. Frequent fire in some vegetation types can lead to transformational change beyond which the vegetation type is radically altered. Such feedbacks limit our ability to project fuel loads under future climatic conditions or to consider the ecological tradeoffs associated with management burns. We present a “pathway modelling” approach to consider multiple transitional pathways that may occur under different fire frequencies. The model combines spatial layers representing current and future fire danger, biomass, flammability, and sensitivity to fire to assess potential future fire activity. The layers are derived from a dynamically downscaled regional climate model, attributes from a regional vegetation map, and information about fuel characteristics. Fire frequency is demonstrated to be an important factor influencing flammability and availability to burn and therefore an important determinant of future fire activity. Regional shifts in vegetation type occur in response to frequent fire, as the rate of change differs across vegetation type. Fire-sensitive vegetation types move towards drier, more fire-adapted vegetation quickly, as they may be irreversibly impacted by even a single fire, and require very long recovery times. Understanding the interaction between climate change and fire is important to identify appropriate management regimes to sustain fire-sensitive communities and maintain the distribution of broad vegetation types across the landscape. Full article
(This article belongs to the Special Issue Wildland Fire, Forest Dynamics, and Their Interactions)
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Open AccessArticle Toward an Elasticity of Chip-N-Saw: Demand and Supply Models of Chip-N-Saw Stumpage in Louisiana
Forests 2018, 9(4), 211; https://doi.org/10.3390/f9040211
Received: 19 February 2018 / Revised: 10 April 2018 / Accepted: 12 April 2018 / Published: 17 April 2018
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Abstract
Softwood chip-n-saw (CNS) is a relatively new stumpage product in the sawtimber- and pulpwood-dominated stumpage markets in the U.S. South. Based on a quarterly data series from 2003 to 2016, this study estimates the demand and supply models of the softwood CNS stumpage
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Softwood chip-n-saw (CNS) is a relatively new stumpage product in the sawtimber- and pulpwood-dominated stumpage markets in the U.S. South. Based on a quarterly data series from 2003 to 2016, this study estimates the demand and supply models of the softwood CNS stumpage market in Louisiana. The two-stage least squares (2SLS) results reveal that own price elasticity of demand (PED) is price elastic, and the cross-price elasticity (XED)with sawtimber approaches unit elasticity. On the supply side, CNS is price inelastic in supply (PES), but more responsive to own price changesthan sawtimber quantity supplied. Further, severance tax increases are found to decrease the supply of CNS, indicating that suppliers are responsive to severance tax incidence. As the first empirical estimation of CNS, the findings should be of interest to those involved in the analysis of Southeastern stumpage markets. Full article
(This article belongs to the Section Forest Economics and Human Dimensions)
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Open AccessArticle An Inventory-Based Regeneration Biomass Model to Initialize Landscape Scale Simulation Scenarios
Forests 2018, 9(4), 212; https://doi.org/10.3390/f9040212
Received: 18 March 2018 / Revised: 5 April 2018 / Accepted: 12 April 2018 / Published: 17 April 2018
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Abstract
Dynamic landscape simulation of the forest requires an initial regeneration stock specific to the characteristics of each simulated stand. Forest inventories, however, are sparse with regard to regeneration. Moreover, statistical regeneration models are rare. We introduce an inventory-based statistical model type that (1)
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Dynamic landscape simulation of the forest requires an initial regeneration stock specific to the characteristics of each simulated stand. Forest inventories, however, are sparse with regard to regeneration. Moreover, statistical regeneration models are rare. We introduce an inventory-based statistical model type that (1) quantifies regeneration biomass as a fundamental regeneration attribute and (2) uses the overstory’s quadratic mean diameter (Dq) together with several other structure attributes and the Site Index as predictors. We form two such models from plots dominated by European beech (Fagus sylvatica L.), one from national forest inventory data and the other from spatially denser federal state forest inventory data. We evaluate the first one for capturing the predictors specific to the larger scale level and the latter one to infer the degree of landscape discretization above which the model bias becomes critical due to yet unquantified determinants of regeneration. The most relevant predictors were Dq, stand density, and maximum height (significance level p < 0.0001). If plot data sets for evaluation differed by the forest management unit in addition to the average diameter, the bias range among them increased from 0.1-fold of predicted biomass to 0.3-fold. Full article
(This article belongs to the Special Issue Simulation Modeling of Forest Ecosystems)
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Open AccessArticle Radial Growth Behavior of Pines on Romanian Degraded Lands
Forests 2018, 9(4), 213; https://doi.org/10.3390/f9040213
Received: 20 February 2018 / Revised: 6 April 2018 / Accepted: 9 April 2018 / Published: 17 April 2018
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Abstract
More than a third of Romania’s surface has low-productive soils, at the same time exposed to risks of climatic phenomena and generating high economic loss. Afforestation with pine has been the most common solution for the recovery of sheet erosion. Many of the
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More than a third of Romania’s surface has low-productive soils, at the same time exposed to risks of climatic phenomena and generating high economic loss. Afforestation with pine has been the most common solution for the recovery of sheet erosion. Many of the pines grown on such land have run down. This paper presents the results of the first dendroecological investigation of degraded lands in Romania, 80 years after the first ecological reconstruction. In this way, the effects of reconstruction were assessed, supporting the adoption of future solutions for the improvement and efficiency of recovered ecosystems. Reconstructed radial growth was set against rainfall, air temperature, and management history. A total of 330 black pine and Scots pine trees (Pinus sylvestris L. and Pinus nigra Arn.) of different ages and social positions from 11 stands of different densities were cored for retrospective tree-ring analysis. Scots pine has made better use of these sites, with a better growth rate than black pine especially in plantations with lower survival and on dominant trees. The dynamics of radial growth distinguish the two pine species, with Scots pine showing an accentuated juvenile growth spurt and bigger growth range. The growth decline is predominantly a maturation effect that begins when the tree is around 40 years old and seems to be irreversible. After this age, weak or moderated removal is not enough to revive growth. The contribution of climate (air temperature and rainfall) to the last radial increments in decline is 3–57% and is higher than in the previous decades. On moderately degraded land by farming and grazing, the mixture of Scots pine and black pine, rather than monocultures, proved to be a sustainable solution. Dendrochronological surveying of restored ecosystems allows development of management strategies, which becomes critically important in the circumstances of climate warming. Full article
(This article belongs to the Special Issue Ecological Management of Pine Forests)
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Open AccessArticle Simulating Forest Dynamics of Lowland Rainforests in Eastern Madagascar
Forests 2018, 9(4), 214; https://doi.org/10.3390/f9040214
Received: 22 February 2018 / Revised: 9 April 2018 / Accepted: 11 April 2018 / Published: 18 April 2018
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Abstract
Ecological modeling and forecasting are essential tools for the understanding of complex vegetation dynamics. The parametric demands of some of these models are often lacking or scant for threatened ecosystems, particularly in diverse tropical ecosystems. One such ecosystem and also one of the
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Ecological modeling and forecasting are essential tools for the understanding of complex vegetation dynamics. The parametric demands of some of these models are often lacking or scant for threatened ecosystems, particularly in diverse tropical ecosystems. One such ecosystem and also one of the world’s biodiversity hotspots, Madagascar’s lowland rainforests, have disappeared at an alarming rate. The processes that drive tree species growth and distribution remain as poorly understood as the species themselves. We investigated the application of the process-based individual-based FORMIND model to successfully simulate a Madagascar lowland rainforest using previously collected multi-year forest inventory plot data. We inspected the model’s ability to characterize growth and species abundance distributions over the study site, and then validated the model with an independently collected forest-inventory dataset from another lowland rainforest in eastern Madagascar. Following a comparative analysis using inventory data from the two study sites, we found that FORMIND accurately captures the structure and biomass of the study forest, with r2 values of 0.976, 0.895, and 0.995 for 1:1 lines comparing observed and simulated values across all plant functional types for aboveground biomass (tonnes/ha), stem numbers, and basal area (m2/ha), respectively. Further, in validation with a second study forest site, FORMIND also compared well, only slightly over-estimating shade-intermediate species as compared to the study site, and slightly under-representing shade-tolerant species in percentage of total aboveground biomass. As an important application of the FORMIND model, we measured the net ecosystem exchange (NEE, in tons of carbon per hectare per year) for 50 ha of simulated forest over a 1000-year run from bare ground. We found that NEE values ranged between 1 and −1 t Cha−1 year−1, consequently the study forest can be considered as a net neutral or a very slight carbon sink ecosystem, after the initial 130 years of growth. Our study found that FORMIND represents a valuable tool toward simulating forest dynamics in the immensely diverse Madagascar rainforests. Full article
(This article belongs to the Special Issue Simulation Modeling of Forest Ecosystems)
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Open AccessArticle Visualizing Individual Tree Differences in Tree-Ring Studies
Forests 2018, 9(4), 216; https://doi.org/10.3390/f9040216
Received: 29 March 2018 / Revised: 11 April 2018 / Accepted: 16 April 2018 / Published: 19 April 2018
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Abstract
Averaging tree-ring measurements from multiple individuals is one of the most common procedures in dendrochronology. It serves to filter out noise from individual differences between trees, such as competition, height, and micro-site effects, which ideally results in a site chronology sensitive to regional
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Averaging tree-ring measurements from multiple individuals is one of the most common procedures in dendrochronology. It serves to filter out noise from individual differences between trees, such as competition, height, and micro-site effects, which ideally results in a site chronology sensitive to regional scale factors such as climate. However, the climate sensitivity of individual trees can be modulated by factors like competition, height, and nitrogen deposition, calling attention to whether average chronologies adequately assess climatic growth-control. In this study, we demonstrate four simple but effective methods to visually assess differences between individual trees. Using individual tree climate-correlations we: (1) employed jitter plots with superimposed metadata to assess potential causes for these differences; (2) plotted the frequency distributions of climate correlations over time as heat maps; (3) mapped the spatial distribution of climate sensitivity over time to assess spatio-temporal dynamics; and (4) used t-distributed Stochastic Neighborhood Embedding (t-SNE) to assess which trees were generally more similar in terms of their tree-ring pattern and their correlation with climate variables. This suite of exploratory methods can indicate if individuals in tree-ring datasets respond differently to climate variability, and therefore, should not solely be explored with climate correlations of the mean population chronology. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle Contrast Effects of Vegetation Cover Change on Evapotranspiration during a Revegetation Period in the Poyang Lake Basin, China
Forests 2018, 9(4), 217; https://doi.org/10.3390/f9040217
Received: 5 March 2018 / Revised: 16 April 2018 / Accepted: 17 April 2018 / Published: 19 April 2018
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Abstract
It is known that evapotranspiration (ET) differs before and after vegetation change in watersheds. However, impacts of vegetation change on ET remain incompletely understood. In this paper, we investigated the process-specific, nonclimatic contribution (mainly vegetation coverage changes) to ET at grid, sub-basin, and
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It is known that evapotranspiration (ET) differs before and after vegetation change in watersheds. However, impacts of vegetation change on ET remain incompletely understood. In this paper, we investigated the process-specific, nonclimatic contribution (mainly vegetation coverage changes) to ET at grid, sub-basin, and basin scales using observation and remote sensing data. The Poyang Lake Basin was selected as the study area, which experienced a fast vegetation restoration from 1983 to 2014. Our results showed that vegetation cover change produced contrasting effects on annual ET in magnitude and direction during shifts from a less covered to a more covered stage. At the early stage (1983–1990), with vegetation cover of 30%, vegetation cover change produced negative effects on ET over the basin. At the middle stage (1990–2000), the vegetation coverage increased at a fast pace and the negative effects gradually shifted to positive. At the late stage (2000–2014), the vegetation coverage remained high (over 60%) and maintained a positive relationship with ET. In summary, the vegetation effects are collaboratively influenced by both vegetation coverage and its change rate. Our findings should be helpful for a comprehensive understanding of complicated hydrological responses to anthropogenic revegetation. Full article
(This article belongs to the Special Issue Afforestation and Reforestation: Drivers, Dynamics, and Impacts)
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Open AccessArticle Fine Scale Determinants of Soil Litter Fauna on a Mediterranean Mixed Oak Forest Invaded by the Exotic Soil-Borne Pathogen Phytophthora cinnamomi
Forests 2018, 9(4), 218; https://doi.org/10.3390/f9040218
Received: 24 February 2018 / Revised: 16 April 2018 / Accepted: 17 April 2018 / Published: 19 April 2018
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Abstract
There is growing recognition of the importance of soil fauna for modulating nutrient cycling processes such as litter decomposition. However, little is known about the drivers promoting changes in soil fauna abundance on a local scale. We explored this gap of knowledge in
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There is growing recognition of the importance of soil fauna for modulating nutrient cycling processes such as litter decomposition. However, little is known about the drivers promoting changes in soil fauna abundance on a local scale. We explored this gap of knowledge in a mixed oak forest of Southern Spain, which is under decline due to the invasion of the exotic soil-borne pathogen Phytophthora cinnamomi. Meso-invertebrate abundance found in soil litter was estimated at the suborder level. We then explored their statistical correlations with respect to light availability, tree and litter characteristics, and P. cinnamomi abundance. Oribatida and Entomobryomporpha were the most abundant groups of Acari and Collembola, respectively. According to their trophic level, predator and detritivore abundances were positively correlated while detritivores were, in turn, positively correlated with pathogen abundance and negatively influenced by light availability and tree defoliation. These overall trends differed between groups. Among detritivores, Diplopoda preferred highly decomposed litter while Oribatida and Psocoptera preferred darker environments and Poduromorpha were selected for environments with lower tree defoliation. Our results show the predominant role of light availability in influencing litter fauna abundances at local scales and suggest that the invasive soil-borne pathogen P. cinnamomi is integrated in these complex relationships. Full article
(This article belongs to the Special Issue Ecology and Management of Invasive Species in Forest Ecosystems)
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Open AccessArticle Discriminating between Seasonal and Chemical Variation in Extracellular Enzyme Activities within Two Italian Beech Forests by Means of Multilevel Models
Forests 2018, 9(4), 219; https://doi.org/10.3390/f9040219
Received: 10 March 2018 / Revised: 16 April 2018 / Accepted: 18 April 2018 / Published: 19 April 2018
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Abstract
Enzymes play a key-role in organic matter dynamics and strong scientific attention has been given to them lately, especially to their response to climate and substrate chemical composition. Accordingly, in this study, we investigated the effects of chemical composition and seasons on extracellular
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Enzymes play a key-role in organic matter dynamics and strong scientific attention has been given to them lately, especially to their response to climate and substrate chemical composition. Accordingly, in this study, we investigated the effects of chemical composition and seasons on extracellular enzyme activities (laccase, peroxidase, cellulase, chitinase, acid phosphomonoesterase, and dehydrogenase) by means of multilevel models within two Italian mountain beech forests. We used chemical variables as the fixed part in the model, season as random variation and layers (decomposition continuum for leaf litter and 0–5, 5–15, 15–30, and 30–40 cm for soil) as nested factors within the two forests. Our results showed that seasonal changes explained a higher amount of variance in enzyme activities compared to substrate chemistry in leaf litter, whereas chemical variation had a stronger impact on soil. Moreover, the effect of seasonality and chemistry was in general larger than the differences between forest sites, soils, and litter layers. Full article
(This article belongs to the Special Issue Carbon, Nitrogen and Phosphorus Cycling in Forest Soils)
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Open AccessFeature PaperArticle Interaction between Ailanthus altissima and Native Robinia pseudoacacia in Early Succession: Implications for Forest Management
Forests 2018, 9(4), 221; https://doi.org/10.3390/f9040221
Received: 12 March 2018 / Revised: 16 April 2018 / Accepted: 17 April 2018 / Published: 20 April 2018
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Abstract
The goal of this study was to discover the nature and intensity of the interaction between an exotic invader Ailanthus altissima (Mill.) Swingle and its coexisting native Robinia pseudoacacia L. and consider management implications. The study occurred in the Mid-Appalachian region of the
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The goal of this study was to discover the nature and intensity of the interaction between an exotic invader Ailanthus altissima (Mill.) Swingle and its coexisting native Robinia pseudoacacia L. and consider management implications. The study occurred in the Mid-Appalachian region of the eastern United States. Ailanthus altissima can have a strong negative influence on community diversity and succession due to its allelopathic nature while R. pseudoacacia can have a positive effect on community diversity and succession because of its ability to fix nitrogen. How these trees interact and the influence of the interaction on succession will have important implications for forests in many regions of the world. An additive-replacement series common garden experiment was established to identify the type and extent of interactions between these trees over a three-year period. Both A. altissima and R. pseudoacacia grown in monoculture were inhibited by intraspecific competition. In the first year, A. altissima grown with R. pseudoacacia tended to be larger than A. altissima in monoculture, suggesting that R. pseudoacacia may facilitate the growth of A. altissima at the seedling stage. After the second year, R. pseudoacacia growth decreased as the proportion of coexisting A. altissima increased, indicating inhibition of R. pseudoacacia by A. altissima even though the R. pseudoacacia plants were much larger aboveground than the A. altissima plants. In early successional sites A. altissima should be removed, particularly in the presence of R. pseudoacacia in order to promote long-term community succession. Full article
(This article belongs to the Special Issue Ecology and Management of Invasive Species in Forest Ecosystems)
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Open AccessArticle First-Year Vitality of Reforestation Plantings in Response to Herbivore Exclusion on Reclaimed Appalachian Surface-Mined Land
Forests 2018, 9(4), 222; https://doi.org/10.3390/f9040222
Received: 30 March 2018 / Revised: 18 April 2018 / Accepted: 19 April 2018 / Published: 21 April 2018
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Abstract
Conventional Appalachian surface-mine reclamation techniques repress natural forest regeneration, and tree plantings are often necessary for reforestation. Reclaimed Appalachian surface mines harbor a suite of mammal herbivores that forage on recently planted seedlings. Anecdotal reports across Appalachia have implicated herbivory in the hindrance
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Conventional Appalachian surface-mine reclamation techniques repress natural forest regeneration, and tree plantings are often necessary for reforestation. Reclaimed Appalachian surface mines harbor a suite of mammal herbivores that forage on recently planted seedlings. Anecdotal reports across Appalachia have implicated herbivory in the hindrance and failure of reforestation efforts, yet empirical evaluation of herbivory impacts on planted seedling vitality in this region remains relatively uninitiated. First growing-season survival, height growth, and mammal herbivory damage of black locust (Robinia pseudoacacia L.), shortleaf pine (Pinus echinata Mill.), and white oak (Quercus alba L.) are presented in response to varying intensities of herbivore exclusion. Seedling survival was generally high, and height growth was positive for all species. The highest herbivory incidence of all tree species was observed in treatments offering no herbivore exclusion. While seedling protectors lowered herbivory incidence compared with no exclusion, full exclusion treatments resulted in the greatest reduction of herbivore damage. Although herbivory from rabbits, small mammals, and domestic animals was observed, cervids (deer and elk) were responsible for 95.8% of all damaged seedlings. This study indicates that cervids forage heavily on planted seedlings during the first growing-season, but exclusion is effective at reducing herbivory. Full article
(This article belongs to the Special Issue Seedling Production and Field Performance of Seedlings)
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Open AccessArticle Sustainable Forest Bioenergy Development Strategies in Indochina: Collaborative Effort to Establish Regional Policies
Forests 2018, 9(4), 223; https://doi.org/10.3390/f9040223
Received: 26 March 2018 / Revised: 9 April 2018 / Accepted: 17 April 2018 / Published: 21 April 2018
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Abstract
We conducted a feasibility study in Indochina (Cambodia, Laos, Myanmar, Thailand, and Vietnam) with the aim of promoting biomass and bioenergy markets, technology transfer, rural development, and income generation. Policy development is guided by the International Union of Forest Research Institutions (IUFRO) Task
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We conducted a feasibility study in Indochina (Cambodia, Laos, Myanmar, Thailand, and Vietnam) with the aim of promoting biomass and bioenergy markets, technology transfer, rural development, and income generation. Policy development is guided by the International Union of Forest Research Institutions (IUFRO) Task Force “Sustainable Forest Bioenergy Network”. In this paper, we highlight the achievements up to now and present results of a multi-stakeholder questionnaire in combination with a quantitative analysis of the National Bioenergy Development Plans (NBDPs). We found a gap between official documents and working group assessments. NBDPs are focused on the market development, technology transfer, and funding possibilities of a regional bioenergy strategy, while the respondents of a questionnaire (working groups) favored more altruistic goals, i.e., sustainable resource management, environmental protection and climate change mitigation, generation of rural income, and community involvement, etc. We therefore suggest the following measures to ensure regulations that support the original aims of the network (climate change mitigation, poverty alleviation, sustainable resource use, and diversification of energy generation): (i) Consideration of science-based evidence for drafting bioenergy policies, particularly in the field of biomass production and harvesting; (ii) invitation of stakeholders representing rural communities to participate in this process; (iii) development of sustainability criteria; (iv) feedback cycles ensuring more intensive discussion of policy drafts; (v) association of an international board of experts to provide scientifically sound feedback and input; and (vi) establishment of a local demonstration region, containing various steps in the biomass/bioenergy supply chain including transboundary collaboration in the ACMECS region. Full article
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Open AccessArticle The Impact of Green Space Layouts on Microclimate and Air Quality in Residential Districts of Nanjing, China
Forests 2018, 9(4), 224; https://doi.org/10.3390/f9040224
Received: 6 February 2018 / Revised: 31 March 2018 / Accepted: 16 April 2018 / Published: 23 April 2018
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Abstract
This study numerically investigates the influence of different vegetation types and layouts on microclimate and air quality in residential districts based on the morphology and green layout of Nanjing, China. Simulations were performed using Computational Fluid Dynamics and the microclimate model ENVI-met. Four
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This study numerically investigates the influence of different vegetation types and layouts on microclimate and air quality in residential districts based on the morphology and green layout of Nanjing, China. Simulations were performed using Computational Fluid Dynamics and the microclimate model ENVI-met. Four green indices, i.e., the green cover ratio, the grass and shrub cover ratio, the ecological landscaping plot ratio and the landscaping isolation index, were combined to evaluate thermal and wind fields, as well as air quality in district models. Results show that under the same green cover ratio (i.e., the same quantity of all types of vegetation), the reduction of grass and shrub cover ratio (i.e., the quantity of grass and shrubs), replaced by trees, has an impact, even though small, on thermal comfort, wind speed and air pollution, and increases the leisure space for occupants. When trees are present, a low ecological landscaping plot ratio (which expresses the weight of carbon dioxide absorption and is larger in the presence of trees) is preferable due to a lower blocking effect on wind and pollutant dispersion. In conjunction with a low landscaping plot ratio, a high landscaping isolation index (which means a distributed structure of vegetation) enhances the capability of local cooling and the general thermal comfort, decreasing the average temperature up to about 0.5 °C and the average predicted mean vote (PMV) up to about 20% compared with the non-green scenario. This paper shows that the relationship vegetation-microclimate-air quality should be analyzed taking into account not only the total area covered by vegetation but also its layout and degree of aggregation. Full article
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Open AccessArticle A Participatory Approach to Evaluating Strategies for Forest Carbon Mitigation in British Columbia
Forests 2018, 9(4), 225; https://doi.org/10.3390/f9040225
Received: 26 March 2018 / Revised: 18 April 2018 / Accepted: 19 April 2018 / Published: 23 April 2018
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Abstract
To be successful, actions for mitigating climate change in the forest and forest sector will not only need to be informed by the best available science, but will also require strong public and/or political acceptability. This paper presents the results of a novel
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To be successful, actions for mitigating climate change in the forest and forest sector will not only need to be informed by the best available science, but will also require strong public and/or political acceptability. This paper presents the results of a novel analytical-deliberative engagement process that brings together stakeholders and Indigenous Peoples in participatory workshops in the interior and coastal regions of British Columbia (BC) to evaluate a set of potential forest carbon mitigation alternatives. In particular, this study examines what objectives are prioritized by stakeholders and Indigenous Peoples when discussing forest carbon mitigation in BC’s forests, as well as the perceived effectiveness of, and levels of support for, six forest-based carbon mitigation strategies. We start by describing the methodological framework involving two series of workshops. We then describe the results from the first round of workshops where participants identified 11 objectives that can be classified into four categories: biophysical, economic, social, and procedural. Afterwards, we discuss the second series of workshops, which allowed participants to evaluate six climate change mitigation strategies against the objectives previously identified, and highlight geographical differences, if any, between BC’s coastal and interior regions. Our results effectively illustrate the potential and efficacy of our novel methodology in informing a variety of stakeholders in different regions, and generating consistent results with a surprising degree of consensus on both key objectives and preference for mitigation alternatives. We conclude with policy recommendations on how to consider various management objectives during the design and implementation of forest carbon mitigation strategies. Full article
(This article belongs to the Special Issue Participatory Forestry: Involvement, Information and Science)
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Open AccessReview Challenges and Opportunities for North American Hardwood Manufacturers to Adopt Customization Strategies in an Era of Increased Competition
Forests 2018, 9(4), 186; https://doi.org/10.3390/f9040186
Received: 1 March 2018 / Revised: 27 March 2018 / Accepted: 3 April 2018 / Published: 5 April 2018
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Abstract
Much of the North American wood products industry was severely impacted by the recession of 2008–2009. In addition, many sectors within this industry face intense global competition. Against this backdrop, we examine economic opportunities for hardwood manufacturers to achieve greater competitive advantage via
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Much of the North American wood products industry was severely impacted by the recession of 2008–2009. In addition, many sectors within this industry face intense global competition. Against this backdrop, we examine economic opportunities for hardwood manufacturers to achieve greater competitive advantage via product customization, through a literature review and synthesis. We also discuss several related themes including agility, lean manufacturing, and clustering. We found that, in globally competitive environments, hardwood producers must be agile to adapt to economic conditions and dynamic customer demand. We discuss how some sectors of the hardwood industry have effectively exhibited customized production, and subsequently fared relatively well in the current economy. We conclude the synthesis by evaluating the importance of supply chains to achieving customization for hardwood producers. In the future, supply chains will need to be configured to rapidly respond to changing consumer demands, and pressure to provide more services will likely extend further back up the supply chain to hardwood sawmills. It is expected that sustainability practices, including green supply chain management, will impact operational and economic performance of hardwood firms as well. Full article
(This article belongs to the Special Issue At the Frontiers of Knowledge in Forest Economics)
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Open AccessReview Forest Accountancy Data Networks—A European Approach of Empirical Research, Its Achievements, and Potentials in Regard to Sustainable Multiple Use Forestry
Forests 2018, 9(4), 220; https://doi.org/10.3390/f9040220
Received: 1 March 2018 / Revised: 22 March 2018 / Accepted: 17 April 2018 / Published: 19 April 2018
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Abstract
A Forest Accountancy Data Network represents an intermediate approach of empirical economic research between surveys based on questionnaires on the one hand and case studies on the other, with time as a third dimension. Over the past decades, the few institutions operating such
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A Forest Accountancy Data Network represents an intermediate approach of empirical economic research between surveys based on questionnaires on the one hand and case studies on the other, with time as a third dimension. Over the past decades, the few institutions operating such networks have accumulated a bulk of experience with this methodology and the possibilities for its adaptation to upcoming requirements. By summarizing and evaluating the potential of this methodology, we provide an up-to-date reference for designing empirical studies in forest economics at the enterprise level. Aspects of sustainability as well as the economics of multiple use forestry are specifically addressed. Forestry-specific extensions to existing agricultural networks could be a cost saving approach for investigating such crucial questions like the role of forestry for regional development and for the livelihood of farms. The study is based on an extended literature research which has been complemented by expert interviews. Full article
(This article belongs to the Special Issue At the Frontiers of Knowledge in Forest Economics)
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