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Forests, Volume 8, Issue 10 (October 2017)

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Cover Story We calculated metrics of landscape pattern using patches of intact and harvested forest in each [...] Read more.
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Open AccessArticle Variability in Larch (Larix Decidua Mill.) Tree-Ring Growth Response to Climate in the Polish Carpathian Mountains
Forests 2017, 8(10), 354; doi:10.3390/f8100354
Received: 10 July 2017 / Revised: 31 August 2017 / Accepted: 14 September 2017 / Published: 21 September 2017
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Abstract
The climate–growth relationship of larch (Larix decidua Mill.) in the Polish Carpathian Mountains was studied. We explored the spatial variability of the common signal observed in larch tree-ring growth, distinguished regions with uniform tree-ring growth patterns (dendrochronological signal), and determined the climatic
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The climate–growth relationship of larch (Larix decidua Mill.) in the Polish Carpathian Mountains was studied. We explored the spatial variability of the common signal observed in larch tree-ring growth, distinguished regions with uniform tree-ring growth patterns (dendrochronological signal), and determined the climatic factors that are particularly important for the growth of larch in this area. Uniformity in the growth reaction across the analyzed area was found in the positive response to May temperatures (significant correlation values range from 0.21 to 0.48); this indicates that the warm beginning of the growing season is important for larch growth across the study area. The signal variability from west to east found in the principal components analysis (PCA) results and differences in climate response between analyzed sites suggest their relation to increasing influence of the continental climate to the east. However, the observed relationship is not stable and does not occur systematically. Although the climate–growth response of larch at lower elevations is highly variable, a positive influence of July precipitation and a negative influence of April precipitation, and previous May and July temperature can be observed. The growth of larch from the highest study sites (Tatra Mountains, above 950 m a.s.l.) is related to temperature. This is manifested by a strong positive correlation with temperature during late spring, early summer, and the end of the previous growing season, and a negative or no response to late spring/summer precipitation. No relation between the observed correlations and slope aspect was found. Full article
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Open AccessArticle Does the Slope of the Self-thinning Line Remain a Constant Value across Different Site Qualities?—An Implication for Plantation Density Management
Forests 2017, 8(10), 355; doi:10.3390/f8100355
Received: 19 August 2017 / Revised: 15 September 2017 / Accepted: 20 September 2017 / Published: 21 September 2017
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Abstract
The self-thinning rule is regarded as one of the most important principles in plantation management. This rule, involving the assumption of a constant slope coefficient, has been universally applied when regulating stand density. In this study, we hypothesized that the slope coefficient can
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The self-thinning rule is regarded as one of the most important principles in plantation management. This rule, involving the assumption of a constant slope coefficient, has been universally applied when regulating stand density. In this study, we hypothesized that the slope coefficient can change significantly with changes in site quality. To test this hypothesis, we first grouped forest plots into 5 categories based on site index. Second, we produced the self-thinning line represented by the Reineke function for each of the 5 site categories, selecting fully stocked plots using reduced major axis regression. Third, the slope coefficients for the different categories were tested for significant differences. The results indicated that in general, the slope was significantly different with different site quality. In addition, we observed that the slope of the self-thinning line exhibited a steeper trend for sites of lower quality, which indicated increased self-thinning or reduced self-tolerance. Finally, we concluded that it is imperative to produce specific self-thinning lines for different site quality categories. Full article
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Open AccessArticle Population Spatial Dynamics of Larix potaninii in Alpine Treeline Ecotone in the Eastern Margin of the Tibetan Plateau, China
Forests 2017, 8(10), 356; doi:10.3390/f8100356
Received: 20 July 2017 / Revised: 31 August 2017 / Accepted: 18 September 2017 / Published: 22 September 2017
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Abstract
The high-altitude treeline is known to be sensitive to climate variability, and is thus considered as a bio-monitoring indicator of climate change. However, our understanding of the population dynamics and the cumulative climate-change effects on the alpine treeline ecotone in recent decades is
[...] Read more.
The high-altitude treeline is known to be sensitive to climate variability, and is thus considered as a bio-monitoring indicator of climate change. However, our understanding of the population dynamics and the cumulative climate-change effects on the alpine treeline ecotone in recent decades is limited. Here, we investigated the population dynamics of Larix potainii on the south- and north-facing slopes in the alpine treeline ecotone in the eastern margin of the Tibetan Plateau, China, including treeline position, population density, and tree recruitment. Results showed that on both south- and north-facing slopes, the treeline did not show a significant advancement in the past four decades. The population was dominated by young individuals, which tend to be established in the lower areas. Larix, here, tends to be clustered, especially in the upper areas. However, population density increased dramatically only on north-facing slopes. Larix here suffer from the stressful environment, but the warmer winter due to climate warming could facilitate the vertical growth of seedlings and saplings. Aggregated spatial patterns also provide a positive feedback in ameliorating the harsh environment. The slope-climate-moisture interactions have a pronounced impact on tree recruitment, including snow-limited tree establishment on the north-facing slopes and moisture-limited tree establishment on the south-facing slopes. Full article
(This article belongs to the Special Issue Treeline Ecotone Dynamics)
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Open AccessArticle Characterizing Rigging Crew Proximity to Hazards on Cable Logging Operations Using GNSS-RF: Effect of GNSS Positioning Error on Worker Safety Status
Forests 2017, 8(10), 357; doi:10.3390/f8100357
Received: 9 August 2017 / Revised: 7 September 2017 / Accepted: 18 September 2017 / Published: 23 September 2017
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Abstract
Logging continues to rank among the most lethal occupations in the United States. Though the hazards associated with fatalities are well-documented and safe distances from hazards is a common theme in safety education, positional relationships between workers and hazards have not been quantified
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Logging continues to rank among the most lethal occupations in the United States. Though the hazards associated with fatalities are well-documented and safe distances from hazards is a common theme in safety education, positional relationships between workers and hazards have not been quantified previously. Using GNSS-RF (Global Navigation Satellite System-Radio Frequency) transponders that allow real-time monitoring of personnel, we collected positioning data for rigging crew workers and three common cable logging hazards: a log loader, skyline carriage, and snag. We summarized distances between all ground workers and each hazard on three active operations and estimated the proportion of time crew occupied higher-risk areas, as represented by geofences. We then assessed the extent to which positioning error associated with different stand conditions affected perceived worker safety status by applying error sampled in a separate, controlled field experiment to the operational data. Root mean squared error was estimated at 11.08 m in mature stands and 3.37 m in clearcuts. Simulated error expected for mature stands altered safety status in six of nine treatment combinations, whereas error expected for clearcuts affected only one. Our results show that canopy-associated GNSS error affects real-time geofence safety applications when using single-constellation American Global Positioning System transponders. Full article
(This article belongs to the Special Issue Forest Operations, Engineering and Management)
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Open AccessArticle Available Nutrients Can Accumulate in Permanent Skid Trails
Forests 2017, 8(10), 358; doi:10.3390/f8100358
Received: 4 August 2017 / Revised: 3 September 2017 / Accepted: 20 September 2017 / Published: 23 September 2017
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Abstract
Forest harvesting removes and redistributes nutrients through felling and forwarding. Substantial quantities of nutrients can accumulate in brash mats on permanent skid trails, but their availability and uptake after multiple thinnings on soils susceptible to leaching are unknown. In this study, we modeled
[...] Read more.
Forest harvesting removes and redistributes nutrients through felling and forwarding. Substantial quantities of nutrients can accumulate in brash mats on permanent skid trails, but their availability and uptake after multiple thinnings on soils susceptible to leaching are unknown. In this study, we modeled the deposition of base cations and phosphorus on a permanent skid trail after five thinnings of a Picea abies (L.) Karst. stand, and measured the resulting nutrient stocks in both the forest floor and mineral soil. An estimated 35%, 44%, 41%, and 61% of harvested Ca, K, Mg, and P, respectively, were redistributed to the skid trail. Of those deposited stocks, 32–65% of nutrients remained in decomposed brash material on the skid trail. Mineral soil stocks for Ca, K, and P were significantly higher in the skid trail than in the stand, which included minor increases in bioavailable pools. Skid trail root densities were not lower than the stand while bulk densities were only partially higher. Both would not limit nutrient uptake. There were no significant relations between needle nutrient concentrations and distance to the skid trail. Altogether, these results indicate that nutrient uptake from the skid trail was minimal despite their accumulation, chemical availability, and physical accessibility. This suggests that other factors such as liming and frequent thinning disturbances can repress uptake of available nutrients on skid trails. Full article
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Open AccessArticle Climate-Induced Tree Growth Variations under the RCP 2.6 Scenario: A Case Study on the Southeastern Tibetan Plateau
Forests 2017, 8(10), 359; doi:10.3390/f8100359
Received: 7 July 2017 / Revised: 15 September 2017 / Accepted: 20 September 2017 / Published: 23 September 2017
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Abstract
The relationship between climate and radial tree growth is traditionally used to reconstruct past climate conditions based on interannual tree-ring variations. However, few studies have used these climate-growth relationships to model the radial tree growth based on future climate projections. To detect the
[...] Read more.
The relationship between climate and radial tree growth is traditionally used to reconstruct past climate conditions based on interannual tree-ring variations. However, few studies have used these climate-growth relationships to model the radial tree growth based on future climate projections. To detect the future forest dynamics, the climate-induced tree growth from 2006 to 2100 was projected using temperature changes under representative concentration pathway (RCP) 2.6 for the southeastern Tibetan Plateau. Radial tree growth was mainly controlled by annual mean temperature in this region. Based on the relationship between regional annual mean temperature and radial tree growth, a regression model was built that explained 62.5% of variance in the observed temperature record over the period 1911–2005. A period of unprecedented radial tree growth was found after 1998 when compared with the tree growth in the past 700 years. We found that radial tree growth would increase in the period 2006–2045 and decline after that period due to the projected temperature decrease. As forest productivity and biomass are expected to increase with the increased tree growth, these results suggest that temperature-limited systems could see future increases in productivity as growth limitations are lessened. The results of this research could be used to predict regional forest dynamics in the future. Full article
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Open AccessArticle The Effect of Customer–Contractor Alignment in Forest Harvesting Services on Contractor Profitability and the Risk for Relationship Breakdown
Forests 2017, 8(10), 360; doi:10.3390/f8100360
Received: 23 August 2017 / Revised: 16 September 2017 / Accepted: 16 September 2017 / Published: 25 September 2017
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Abstract
In forest operations, the interface between forest companies and harvesting contractors is of special importance, considering that it is the first link in the forest industry’s supply chains. Supply operations account for a significant share of the final costs of wood products (up
[...] Read more.
In forest operations, the interface between forest companies and harvesting contractors is of special importance, considering that it is the first link in the forest industry’s supply chains. Supply operations account for a significant share of the final costs of wood products (up to 50%). This study investigates the effect of customer–contractor alignment on contractors’ profit margins and on the risk for business relationship breakdown. Alignment is empirically measured for a Swedish forest company and 74 of its harvesting contractors, who were monitored during a four-year period. Two measures of alignment are employed: (1) the customer-perceived value of the contractors’ services; and (2) the contractors’ perceived alignment with the forest company expectations. Results indicate that the two measures of alignment are largely independent from each other, and that customer-perceived value affects both contractor profitability and the risk of relationship breakdown. Conflict between the two parties and lack of trust for the customer were found to be common complaints among contractors who ceased working for the studied forest company. Consequently, customer–contractor alignment should be considered a key objective by contractors who strive for business success, and also by forest companies who wish to improve their supply chain performance. Full article
(This article belongs to the Special Issue Forest Operations, Engineering and Management)
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Open AccessArticle Nonlinear Variations of Net Primary Productivity and Its Relationship with Climate and Vegetation Phenology, China
Forests 2017, 8(10), 361; doi:10.3390/f8100361
Received: 8 August 2017 / Revised: 17 September 2017 / Accepted: 19 September 2017 / Published: 25 September 2017
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Abstract
Net primary productivity (NPP) is an important component of the terrestrial carbon cycle. In this study, NPP was estimated based on two models and Moderate Resolution Imaging Spaectroradiometer (MODIS) data. The spatiotemporal patterns of NPP and the correlations with climate factors and vegetation
[...] Read more.
Net primary productivity (NPP) is an important component of the terrestrial carbon cycle. In this study, NPP was estimated based on two models and Moderate Resolution Imaging Spaectroradiometer (MODIS) data. The spatiotemporal patterns of NPP and the correlations with climate factors and vegetation phenology were then analyzed. Our results showed that NPP derived from MODIS performed well in China. Spatially, NPP decreased from the southeast toward the northwest. Temporally, NPP showed a nonlinear increasing trend at a national scale, but the magnitude became slow after 2004. At a regional scale, NPP in Northern China and the Tibetan Plateau showed a nonlinear increasing trend, while the NPP decreased in most areas of Southern China. The decreases in NPP were more than offset by the increases. At the biome level, all vegetation types displayed an increasing trend, except for shrub and evergreen broad forests (EBF). Moreover, a turning point year occurred for all vegetation types, except for EBF. Generally, climatic factors and Length of Season were all positively correlated with the NPP, while the relationships were much more diverse at a regional level. The direct effect of solar radiation on the NPP was larger (0.31) than precipitation (0.25) and temperature (0.07). Our results indicated that China could mitigate climate warming at a regional and/or global scale to some extent during the time period of 2001–2014. Full article
(This article belongs to the Special Issue Carbon and Nitrogen in Forest Ecosystems)
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Open AccessArticle Pre-Infection Stages of Austropuccinia psidii in the Epidermis of Eucalyptus Hybrid Leaves with Different Resistance Levels
Forests 2017, 8(10), 362; doi:10.3390/f8100362
Received: 25 July 2017 / Revised: 19 September 2017 / Accepted: 20 September 2017 / Published: 17 October 2017
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Abstract
Rust is a major Eucalyptus spp. disease, which is especially damaging for early-stage plants. The aim of this study was to verify the pre-infection process of Austropuccinia psidii (A. psidii) in the leaves of three phenological stages of Eucalyptus clones with
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Rust is a major Eucalyptus spp. disease, which is especially damaging for early-stage plants. The aim of this study was to verify the pre-infection process of Austropuccinia psidii (A. psidii) in the leaves of three phenological stages of Eucalyptus clones with different resistance levels. Plants from the hybrids of Eucalyptus urophylla × Eucalyptus grandis (E. grandis) with variable levels of resistance to this disease were used. The pathogen was inoculated in vitro on abaxial leaf discs of first, third, and fifth leaf stages and maintained under conditions suitable for disease development. Subsequently, samples from these discs were collected 24 and 120 h after inoculation and processed using scanning electron microscopy analysis. No symptoms were seen in any leaf stage of the resistant clone. Additionally, a low incidence of A. psidii germination (1.3–2%) and appressoria (0–0.5%) in three leaf stages was observed. However, the first leaf stage of the susceptible clone presented germination of large numbers of urediniospores (65%) with appressoria (55%) and degradation of the cuticle and wax. From the third stage, the percentage of germinated urediniospores (<15%) and appressoria (<2%) formation of this clone decreased. Protrusions on the leaf surface, associated with the pathogen, were observed on the first and third leaf stages of the resistant clone and on the fifth stage of the susceptible clone, suggesting a possible defensive plant reaction. Full article
(This article belongs to the Special Issue Forest Pathology and Plant Health)
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Open AccessArticle Tree Species Selection in the Face of Drought Risk—Uncertainty in Forest Planning
Forests 2017, 8(10), 363; doi:10.3390/f8100363
Received: 21 August 2017 / Revised: 20 September 2017 / Accepted: 23 September 2017 / Published: 26 September 2017
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Abstract
Rapid climate change leads to significant shifts in the site-productivity relationship of tree species and alters abiotic and biotic risks well beyond classical rotation ages on many forest sites worldwide. Forest conversion may be an adequate measure to counter possible negative effects of
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Rapid climate change leads to significant shifts in the site-productivity relationship of tree species and alters abiotic and biotic risks well beyond classical rotation ages on many forest sites worldwide. Forest conversion may be an adequate measure to counter possible negative effects of climate change. Unfortunately, climate-driven changes in abiotic and biotic risks bear a significant source of intrinsic uncertainty inherent in climate projections. It is our goal to appraise uncertainty in species selection under drought stress, one of the most important risk factors for many forests. We derive a method to assess drought restrictions and demonstrate the uncertainty in the process of species selection by applying three climate scenarios. Furthermore, we interpret the consequences of climate uncertainty in the light of different management goals, i.e., a business-as-usual silviculture, a climate protection strategy favoring CO2 sequestration and a biodiversity strategy increasing diversity. The methods are applied to two representative regions in the North German Plain. The results clearly show the strong need for adaptive planning when drought restrictions are considered. However, different silvicultural management objectives may alter the extent of adaptive planning. The uncertainty in the planning process arising from different underlying climate projections strongly depends on the regional site characteristics and on forest management strategy. In conclusion, it is most important in forest planning to clearly state the management goals and to carefully explore if the goals can be met under climate change and if the uncertainty due to climate projections significantly affects the results of species selection. Full article
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Open AccessArticle Forest Certification Perspectives in the Wood Products Supply Chain in Virginia, U.S.A.
Forests 2017, 8(10), 364; doi:10.3390/f8100364
Received: 30 August 2017 / Revised: 11 September 2017 / Accepted: 18 September 2017 / Published: 26 September 2017
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Abstract
Participation among private forest owners, logging contractors, and wood products manufacturers in the forest certification sector remains low. Those that enroll are mainly large-acreage owners and specialized manufacturers. Little is known about certification perspectives across the supply chain and how they relate. Comparing
[...] Read more.
Participation among private forest owners, logging contractors, and wood products manufacturers in the forest certification sector remains low. Those that enroll are mainly large-acreage owners and specialized manufacturers. Little is known about certification perspectives across the supply chain and how they relate. Comparing what owners, contractors, and manufacturers think about certification would increase insight regarding sector growth. In this study, 2741 private forest owners, logging contractors, and wood products manufacturers in Virginia, U.S.A. were surveyed about their beliefs regarding the impact of certification on economic opportunities and image and the extent to which they think it positively affects the forestry sector and understand how to certify forestland. Co-orientation was used to map alignment and predictions between respondents. Owner and contractor responses were similar and predictions about each other mostly accurate, but manufacturer responses and predictions were largely incongruent. Manufacturers generally aligned more so with contractors than owners but contractors identified slightly more with owners. Owners and contractors shared perspectives and a discernable identity, whereas manufacturers viewed certification in a less positive light. Implications for participation in forest certification focus largely on interrelationships of actor perspectives regardless of scale and emphasize the roles each can play in the forest certification sector. Full article
(This article belongs to the Special Issue Sustainable Forest Management and Forest Certification)
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Open AccessArticle Monitoring Changes in Water Use Efficiency to Understand Drought Induced Tree Mortality
Forests 2017, 8(10), 365; doi:10.3390/f8100365
Received: 3 August 2017 / Revised: 16 September 2017 / Accepted: 21 September 2017 / Published: 26 September 2017
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Abstract
Forests are becoming increasingly vulnerable to rising tree mortality rates in response to warming and drought. In California, the most severe drought on record occurred from 2012–2016 and high tree mortality rates were observed in response to this prolonged drought. Differences in satellite-derived
[...] Read more.
Forests are becoming increasingly vulnerable to rising tree mortality rates in response to warming and drought. In California, the most severe drought on record occurred from 2012–2016 and high tree mortality rates were observed in response to this prolonged drought. Differences in satellite-derived estimates of water-use efficiency (WUE) under normal (i.e., WUEBASELINE) and drought conditions (ΔWUE = WUE2014 − WUEBASELINE) captured variation in drought resilience, and is used here to understand patterns in tree mortality. Across California forests, a low WUEBASELINE under normal conditions was indicative of a low drought resilience and was associated with increasing tree mortality rates. Forested areas with high drought frequency in recent years (2002–2015) and lower WUEBASELINE were the most vulnerable to high post-drought tree mortality. Post drought tree mortality peaked in 2015 and tree mortality was detected in areas where bark beetles were active. Our results show that spatial and temporal changes in WUE can signal shifts in ecosystem resilience and that water-limited forests are sensitive to temperature- and precipitation-driven drought stress. Considering that forests with low resilience will be poised for dieback in the future if climates continue to feature rising temperatures without compensating increases in precipitation, it is becoming increasingly important that we understand drought vulnerability at the ecosystem level and how it changes over time with climate conditions. Full article
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Open AccessArticle Pine Nuts: A Review of Recent Sanitary Conditions and Market Development
Forests 2017, 8(10), 367; doi:10.3390/f8100367
Received: 16 July 2017 / Revised: 11 September 2017 / Accepted: 14 September 2017 / Published: 27 September 2017
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Abstract
Pine nuts are non-wood forest products (NWFP) with a constantly growing market notwithstanding a series of phytosanitary issues and related trade problems. The aim of this paper is to review the literature on the relationship between phytosanitary problems and trade development. Production and
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Pine nuts are non-wood forest products (NWFP) with a constantly growing market notwithstanding a series of phytosanitary issues and related trade problems. The aim of this paper is to review the literature on the relationship between phytosanitary problems and trade development. Production and trade of pine nuts in Mediterranean Europe have been negatively affected by the spreading of Diplodia sapinea (a fungus) associated with an adventive insect Leptoglossus occidentalis (fungal vector), with impacts on forest management, production and profitability and thus in value chain organization. Reduced availability of domestic production in markets with a growing demand has stimulated the import of pine nuts. China has become a leading exporter of pine nuts, but its export is affected by a symptom caused by the nuts of some pine species: ‘pine nut syndrome’ (PNS). Most of the studies mentioned in the literature review concern PNS occurrence associated with the nuts of Pinus armandii. We highlight the need for a comprehensive and interdisciplinary approach to the analysis of the pine nuts value chain organization, where research on food properties and clinical toxicology may be connected to breeding and forest management, forest pathology and entomology, and trade development. Full article
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Open AccessArticle Seasonal Water Relations and Leaf Temperature in a Deciduous Dipterocarp Forest in Northeastern Thailand
Forests 2017, 8(10), 368; doi:10.3390/f8100368
Received: 10 June 2017 / Revised: 25 September 2017 / Accepted: 26 September 2017 / Published: 28 September 2017
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Abstract
Deciduous dipterocarp forests across mainland Southeast Asia are dominated by two families: the Dipterocarpaceae and Fabaceae. Monsoon conditions produce strong seasonal climates with a hot dry season of 5–7 months extending from late November or early December through April or early May. Seasonal
[...] Read more.
Deciduous dipterocarp forests across mainland Southeast Asia are dominated by two families: the Dipterocarpaceae and Fabaceae. Monsoon conditions produce strong seasonal climates with a hot dry season of 5–7 months extending from late November or early December through April or early May. Seasonal measurements of stomatal conductance and plant water potential found important differences between members of the two families. Despite their long dry season, Shorea siamensis and S. obtusa (Dipterocarpaceae) showed little significant patterns of seasonal change in xylem water potentials, with midday potentials never dropping below −1.3 MPa. These species present a classic example of isohydric strategies of adaptation where stomatal regulation maintains a relatively stable minimum water potential over the course of the year. However, maximum rates of stomatal conductance dropped sharply in the late dry season as the leaves heated in full sun without significant transpirational cooling, reaching as high as 44–45 °C, making them potentially sensitive to global increases in extreme temperature. The woody legumes Xylia kerrii and Dalbergia oliveri present different patterns of seasonal water relations and leaf response to high temperatures. The legumes exhibit anisohydric behavior where water potential decreases over the dry season as evaporative demand increases. Dry season midday water potentials dropped from high wet season levels to −2.4 to −3.2 MPa, moderately lowering maximum stomatal conductance. The relatively small leaflets of these legumes responded to the high temperatures of the late dry season by temporarily wilting, reducing their exposure to solar radiation and taking advantage of convective cooling. Large leaf size of dipterocarps in this community may not be an adaptive trait but rather an ancestral condition compensated for with ecophysiological adaptations. Full article
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Open AccessArticle Buying Time: Preliminary Assessment of Biocontrol in the Recovery of Native Forest Vegetation in the Aftermath of the Invasive Emerald Ash Borer
Forests 2017, 8(10), 369; doi:10.3390/f8100369
Received: 27 August 2017 / Revised: 22 September 2017 / Accepted: 25 September 2017 / Published: 28 September 2017
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Abstract
Introduced forest pests have become one of the major threats to forests, and biological control is one of the few environmentally acceptable management practices. Assessing the impacts of a biocontrol program includes evaluating the establishment of biocontrol agents, the control of target pest,
[...] Read more.
Introduced forest pests have become one of the major threats to forests, and biological control is one of the few environmentally acceptable management practices. Assessing the impacts of a biocontrol program includes evaluating the establishment of biocontrol agents, the control of target pest, the impact on the affected organism, and the indirect impacts that the biocontrol agent may have on the whole community. We assessed the recovery of forest vegetation following the mortality of ash trees caused by the invasive emerald ash borer (EAB) pest in forest stands where biocontrol agents were released or not. We used a multilevel framework to evaluate potential indirect effects of the biocontrol agents on native forest seedlings. Our results showed a higher number of ash saplings where increasing numbers of the dominant EAB biocontrol agent were released, while the number of invasive and weedy saplings was negatively associated with the number of ash saplings, and the density of native seedlings was negatively associated with invasive and weedy saplings. The protection of ash saplings by the biocontrol agent may help native recruitment during forest transition by supporting the growth of native hardwood seedlings over invasive and weedy species. These results show that research on the efficacy of EAB biocontrol should include all ash size classes and the community dynamics of co-occurring species. 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 Assessing Alternative Silvicultural Prescriptions for Mid-Rotation, Unthinned, Spruce-Fir Stands in Maine
Forests 2017, 8(10), 370; doi:10.3390/f8100370
Received: 20 August 2017 / Revised: 22 September 2017 / Accepted: 26 September 2017 / Published: 28 September 2017
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Abstract
Determining the optimal timing and type of entry in mid-rotation, unthinned stands can be complicated by a variety of economic and biological factors. In this analysis, long-term data from the Commercial Thinning Research Network was used to project spruce-fir (Picea spp.—Abies
[...] Read more.
Determining the optimal timing and type of entry in mid-rotation, unthinned stands can be complicated by a variety of economic and biological factors. In this analysis, long-term data from the Commercial Thinning Research Network was used to project spruce-fir (Picea spp.—Abies balsamea (L.) Mill.) stand growth on six different sites across Maine following six alternative thinning treatments (33% and 50% relative density removal paired with low, crown, and dominant thinning methods). Results showed that the low-thinning treatment performed best in terms of maximum net present value, stand age at time of maximum net present value, and average merchantable stem size. Although the low-thinning resulted in a 10% mean reduction in maximum net present value when compared to the control, the average merchantable stem size more than doubled. Overall, results of this analysis indicate that it may be financially responsible to commercially thin these stands using a low-thinning method and a light removal intensity, as the average merchantable stems size was increased and a mid-rotation financial return provided. Full article
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Open AccessArticle Temporal Change in Aboveground Culms Carbon Stocks in the Moso Bamboo Forests and Its Driving Factors in Zhejiang Province, China
Forests 2017, 8(10), 371; doi:10.3390/f8100371
Received: 21 August 2017 / Revised: 27 September 2017 / Accepted: 28 September 2017 / Published: 30 September 2017
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Abstract
Moso bamboo (Phyllostachys pubescens) has high carbon sequestration potential and plays an important role in terrestrial carbon cycling. Quantifying the temporal change in Moso bamboo forest carbon stocks is important for understanding forest dynamics and global climate change feedback capacity. In
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Moso bamboo (Phyllostachys pubescens) has high carbon sequestration potential and plays an important role in terrestrial carbon cycling. Quantifying the temporal change in Moso bamboo forest carbon stocks is important for understanding forest dynamics and global climate change feedback capacity. In 2009, 168 Moso bamboo forest sample plots were established in Zhejiang Province using National Forest Continuous Inventory protocols and enhanced measurements. These plots were revisited and remeasured in 2014. By comparing the two years, culms number in age classes 2 and 4 increased by 12.3% and 82.5%, respectively, while that in age classes 1 and 3 decreased by 14.7% and 0.03%, respectively. The total aboveground culms carbon stocks increased by 2.95 Mg C ha−1 in the sample plots. On average, age classes 2 and 4 contributed 25.5% and 86.7% of the change in total carbon stocks, respectively. The carbon sequestrated by aboveground culms was 0.42 Tg C year−1, accounting for 1.55 Tg CO2 year−1 in Moso bamboo over an area of 0.78 million hectares in Zhejiang Province. The change in Moso bamboo carbon stocks did not correlate with environmental factors, but significantly increased with increasing culms number and average diameter at breast height (DBH). Our study helps contribute to improvements in Moso bamboo forest management strategies and promote carbon sequestration capacity. Full article
(This article belongs to the collection Forests Carbon Fluxes and Sequestration)
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Open AccessArticle Environmental Influences on Forest Fire Regime in the Greater Hinggan Mountains, Northeast China
Forests 2017, 8(10), 372; doi:10.3390/f8100372
Received: 14 June 2017 / Revised: 23 September 2017 / Accepted: 26 September 2017 / Published: 30 September 2017
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Abstract
Fires are the major disturbances in the Greater Hinggan Mountains, the only boreal forest in Northeast China. A comprehensive understanding of the fire regimes and influencing environmental parameters driving them from small to large fires is critical for effective forest fire prevention and
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Fires are the major disturbances in the Greater Hinggan Mountains, the only boreal forest in Northeast China. A comprehensive understanding of the fire regimes and influencing environmental parameters driving them from small to large fires is critical for effective forest fire prevention and management. Assisted with satellite imagery, topographic data, and climatic records in this region, this study examines its fire regimes in terms of ignition causes, frequencies, seasonality, and burned sizes in the period of 1980–2005. We found an upward trend for fire occurrences and burned areas and an elongated fire season over the three decades. The dates of the first fire in a year did not vary largely but those of the last fire were significantly delayed. Topographically, spring fires were prevalent throughout the entire region, while summer fires mainly occurred at higher elevations under severe drought conditions. Fall fires were mostly human-caused in areas at lower elevations with gentle terrains. An ordinal logistic regression revealed temperature and elevation were both significant factors to the fire size severity in spring and summer. Other than that, environmental impacts were different. Precipitation in the preceding year greatly influenced spring fires, while summer fires were significantly affected by wind speed, fuel moisture, and human accessibility. An important message from this study is that distinct seasonal variability and a significantly increasing number of summer and fall fires since the mid-1990s suggest a changing fire regime of the boreal forests in the study area. The observed and modeled results could provide insights on establishing a sustainable, localized forest fire prevention strategy in a seasonal manner. Full article
(This article belongs to the Special Issue Wildland Fire, Forest Dynamics, and Their Interactions)
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Open AccessArticle Seasonal Variations in Carbon, Nitrogen and Phosphorus Concentrations and C:N:P Stoichiometry in the Leaves of Differently Aged Larix principis-rupprechtii Mayr. Plantations
Forests 2017, 8(10), 373; doi:10.3390/f8100373
Received: 10 August 2017 / Revised: 27 September 2017 / Accepted: 28 September 2017 / Published: 30 September 2017
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Abstract
The concentrations and stoichiometry of certain elements (carbon, nitrogen and phosphorus) are critical to the maintenance of plant functional and environmental adaptation during plant growth. We explore how the concentrations of C, N and P and the ratios of C:N, C:P, and N:P
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The concentrations and stoichiometry of certain elements (carbon, nitrogen and phosphorus) are critical to the maintenance of plant functional and environmental adaptation during plant growth. We explore how the concentrations of C, N and P and the ratios of C:N, C:P, and N:P in the leaves of differently aged Larix principis-rupprechtii Mayr. plantations changed with growing season and stand age from 2012 to 2015 in the Qinling Mountains, China. The results showed that the element concentration and stoichiometric ratios in leaves were significantly affected by sampling month, stand age and sampling year; and multiple correlations with stand age were observed in different growing seasons. Compared to global element concentrations and stoichiometry in plants, the leaves of larch stands in the study region had higher C and P concentrations and C:N and C:P ratios but lower N concentrations and N:P ratios than global levels. The leaf N:P ratios of all of the larch stands were generally less than 14, suggesting that the growth of larch stands was limited by N in the study region. Our study facilitates the management and restoration of forest plantation and provides a valuable contribution to the global pool of leaf nutrition and stoichiometry data. Full article
Open AccessArticle Transcriptome Sequencing and Comparative Analysis of Piptoporus betulinus in Response to Birch Sawdust Induction
Forests 2017, 8(10), 374; doi:10.3390/f8100374
Received: 18 August 2017 / Revised: 25 September 2017 / Accepted: 27 September 2017 / Published: 7 October 2017
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Abstract
Piptoporus betulinus, a brown-rot parasitic fungus of birch trees (Betula species), has been used as a common anti-parasitic and antibacterial agent. The lack of genetic resource data for P. betulinus has limited the exploration of this species. In this present study,
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Piptoporus betulinus, a brown-rot parasitic fungus of birch trees (Betula species), has been used as a common anti-parasitic and antibacterial agent. The lack of genetic resource data for P. betulinus has limited the exploration of this species. In this present study, we used Illumina Hiseq 2500 technology to examine the transcriptome assembly of P. betulinus in response to birch sawdust induction. By de novo assembly, 21,882 non-redundant unigenes were yielded, and 21,255 (97.1%) were annotated with known gene sequences. A total of 340 responsive unigenes were highly homologous with putative lignocellulose-degrading enzyme candidates. Additionally, 86 unigenes might be involved in the chemical reaction in xenobiotics biodegradation and metabolism, which suggests that this fungus could convert xenobiotic materials and has the potential ability to clean up environmental pollutants. To our knowledge, this was the first study on transcriptome sequencing and comparative analysis of P. betulinus, which provided a better understanding of molecular mechanisms underlying birch sawdust induction and identified lignocelluloses degrading enzymes. Full article
(This article belongs to the Special Issue Genetics and Genomics of Forest Trees)
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Open AccessArticle Establishing Pine Monocultures and Mixed Pine-Hardwood Stands on Reclaimed Surface Mined Land in Eastern Kentucky: Implications for Forest Resilience in a Changing Climate
Forests 2017, 8(10), 375; doi:10.3390/f8100375
Received: 13 September 2017 / Revised: 28 September 2017 / Accepted: 29 September 2017 / Published: 4 October 2017
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Abstract
Surface mining and mine reclamation practices have caused significant forest loss and forest fragmentation in Appalachia. Shortleaf pine (Pinus echinata) is threatened by a variety of stresses, including diseases, pests, poor management, altered fire regimes, and climate change, and the species
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Surface mining and mine reclamation practices have caused significant forest loss and forest fragmentation in Appalachia. Shortleaf pine (Pinus echinata) is threatened by a variety of stresses, including diseases, pests, poor management, altered fire regimes, and climate change, and the species is the subject of a widescale restoration effort. Surface mines may present opportunity for shortleaf pine restoration; however, the survival and growth of shortleaf pine on these harsh sites has not been critically evaluated. This paper presents first-year survival and growth of native shortleaf pine planted on a reclaimed surface mine, compared to non-native loblolly pine (Pinus taeda), which has been highly successful in previous mined land reclamation plantings. Pine monoculture plots are also compared to pine-hardwood polyculture plots to evaluate effects of planting mix on tree growth and survival, as well as soil health. Initial survival of shortleaf pine is low (42%), but height growth is similar to that of loblolly pine. No differences in survival or growth were observed between monoculture and polyculture treatments. Additional surveys in coming years will address longer-term growth and survival patterns of these species, as well as changes to relevant soil health endpoints, such as soil carbon. Full article
(This article belongs to the Special Issue Seedling Production and Field Performance of Seedlings)
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Open AccessArticle Potential Impact of the REDD+ Program on Poverty Reduction in Nghe An Province, Vietnam
Forests 2017, 8(10), 376; doi:10.3390/f8100376
Received: 5 July 2017 / Revised: 28 September 2017 / Accepted: 30 September 2017 / Published: 3 October 2017
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Abstract
The REDD+ program provides a mechanism for providing financial rewards to forest owners and users who contribute to the reduction of carbon emissions from deforestation and forest degradation. This paper determines the potential impact of the REDD+ program on poverty reduction by comparing
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The REDD+ program provides a mechanism for providing financial rewards to forest owners and users who contribute to the reduction of carbon emissions from deforestation and forest degradation. This paper determines the potential impact of the REDD+ program on poverty reduction by comparing income and poverty rate between two household groups that were willing to participate in this study, but that will not participate in the REDD+. The results showed that carbon payment from forests is a significant contributor to the increase in household income of poor people. The average income of households participating in the program is VND 20.68 million in contrast to those not participating whose average income is VND 14.72 million. Results showed that the REDD+ program intervention helped reduce the poverty rate in the two communes by 6.40% (from 39.4% to 33%). The paper recommends that the REDD+ program should facilitate the distribution of land titles to provide security of tenure for individual households that are participating in the program. While the program can contribute to poverty reduction, the program payments can increase income inequality and conflicts between those involved and those not involved in the program and legal ownership of the lands. In addition, a comprehensive research study on the impact of the program on forest conservation and poverty reduction is necessary. Stakeholders of the program should recognize and acknowledge the trade-offs between conservation and economic development or poverty reduction. A comprehensive trade-off analysis of program implementation and a business-as-usual option of commodity production is needed, which could reveal the indirect economic, political, and social costs and benefits of the program. Full article
(This article belongs to the Section Forest Economics and Human Dimensions)
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Open AccessArticle Variations of Climate-Growth Response of Major Conifers at Upper Distributional Limits in Shika Snow Mountain, Northwestern Yunnan Plateau, China
Forests 2017, 8(10), 377; doi:10.3390/f8100377
Received: 11 July 2017 / Revised: 26 September 2017 / Accepted: 27 September 2017 / Published: 4 October 2017
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Abstract
Improved understanding of climate-growth relationships of multiple species is fundamental to understanding and predicting the response of forest growth to future climate change. Forests are mainly composed of conifers in Northwestern Yunnan Plateau, but variations of growth response to climate conditions among the
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Improved understanding of climate-growth relationships of multiple species is fundamental to understanding and predicting the response of forest growth to future climate change. Forests are mainly composed of conifers in Northwestern Yunnan Plateau, but variations of growth response to climate conditions among the species are not well understood. To detect the growth response of multiple species to climate change, we developed residual chronologies of four major conifers, i.e., George’s fir (Abies georgei Orr), Likiang spruce (Picea likiangensis (Franch.) E.Pritz.), Gaoshan pine (Pinus densata Mast.) and Chinese larch (Larix potaninii Batalin) at the upper distributional limits in Shika Snow Mountain. Using the dendroclimatology method, we analyzed correlations between the residual chronologies and climate variables. The results showed that conifer radial growth was influenced by both temperature and precipitation in Shika Snow Mountain. Previous November temperature, previous July temperature, and current May precipitation were the common climatic factors that had consistent influences on radial growth of the four species. Temperature in the previous post-growing season (September–October) and moisture conditions in the current growing season (June–August) were the common climatic factors that had divergent impacts on the radial growth of the four species. Based on the predictions of climate models and our understanding of the growth response of four species to climate variables, we may understand the growth response to climate change at the species level. It is difficult to predict future forest growth in the study area, since future climate change might cause both increases and decreases for the four species and indirect effects of climate change on forests should be considered. Full article
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Open AccessArticle Challenges for Uneven-Aged Silviculture in Restoration of Post-Disturbance Forests in Central Europe: A Synthesis
Forests 2017, 8(10), 378; doi:10.3390/f8100378
Received: 18 September 2017 / Revised: 28 September 2017 / Accepted: 30 September 2017 / Published: 4 October 2017
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Abstract
Forest managers are often required to restore forest stands following natural disturbances, a situation that may become more common and more challenging under global change. In parts of Central Europe, particularly in mountain regions dominated by mixed temperate forests, the use of relatively
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Forest managers are often required to restore forest stands following natural disturbances, a situation that may become more common and more challenging under global change. In parts of Central Europe, particularly in mountain regions dominated by mixed temperate forests, the use of relatively low intensity, uneven-aged silviculture is a common management approach. Because this type of management is based on mimicking less intense disturbances, the restoration of more severe disturbance patches within forested landscapes has received little attention. The goal of this paper is to synthesize research on the restoration of forests damaged by disturbances in temperate forests of Slovenia and neighbouring regions of Central Europe, where uneven-aged silviculture is practiced. Research indicates that active management aimed at favouring mixed uneven-aged forest reduces the risk of disturbance and improves the resilience of stands. Salvage logging may have positive or negative effects on regeneration, much of which is due to the method applied and the quality of work. The most prominent factors that negatively affect restoration are: lack of advanced regeneration and decomposed woody debris, high altitude, steep slopes, dense ground vegetation, and overbrowsing. Planting or sowing should be applied in post-disturbance forests where many negative factors interact and where a high demand for sustainability of forest ecosystem services is present. Full article
(This article belongs to the Special Issue Post-Disturbance Forest Management and Regeneration Dynamics)
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Open AccessArticle Carbon Dioxide Fluxes and Their Environmental Controls in a Riparian Forest within the Hyper-Arid Region of Northwest China
Forests 2017, 8(10), 379; doi:10.3390/f8100379
Received: 3 July 2017 / Revised: 27 September 2017 / Accepted: 28 September 2017 / Published: 4 October 2017
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Abstract
Hyper-arid regions are expected to undergo climatic change, but only a few research works have so far been conducted on the dynamics of carbon dioxide (CO2) fluxes and their consequent responses to various bioclimatic factors, which is mainly attributable to a
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Hyper-arid regions are expected to undergo climatic change, but only a few research works have so far been conducted on the dynamics of carbon dioxide (CO2) fluxes and their consequent responses to various bioclimatic factors, which is mainly attributable to a limited set of flux observations. In this study, the CO2 fluxes exchanged between the forest and the atmosphere have been measured continuously by the eddy covariance approach from June 2013 to December 2016 in a riparian forest, which is a primary body of natural oases located within the lower reaches of inland rivers in China. The present results revealed that the climatic conditions characterized by relatively high mean air temperatures (Ta) with fluctuating annual precipitation (P) during the prescribed study periods were comparable to the historical mean value. The annual net ecosystem productivity (NEP) ranged from approximately 278 g C m−2 year−1 to 427 g C m−2 year−1, with a mean value of 334 g C m−2 year−1. The mean annual ecosystem respiration (Re) and the gross primary productivity (GPP) were found to be 558 and 892 g C m−2 year−1, respectively. The results also ascertained that the high inter-annual variations in NEP were attributable to Re rather than to GPP, and this result was driven primarily by Ta and the groundwater depth under similar eco-physiological processes. In addition, the CO2 fluxes were also strongly correlated with the soil temperature and photosynthetically active radiation for the present study site. In conclusion, the desert riparian forest is a considerably significant carbon sink, particularly in the hyper-arid regions. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle Acoustic-Based Non-Destructive Estimation of Wood Quality Attributes within Standing Red Pine Trees
Forests 2017, 8(10), 380; doi:10.3390/f8100380
Received: 27 July 2017 / Revised: 21 September 2017 / Accepted: 30 September 2017 / Published: 4 October 2017
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Abstract
The relationship between acoustic velocity (vd) and the dynamic modulus of elasticity (me), wood density (wd), microfibril angle, tracheid wall thickness (wt,), radial and tangential diameters, fibre coarseness (co
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The relationship between acoustic velocity (vd) and the dynamic modulus of elasticity (me), wood density (wd), microfibril angle, tracheid wall thickness (wt,), radial and tangential diameters, fibre coarseness (co) and specific surface area (sa), within standing red pine (Pinus resinosa Ait.) trees, was investigated. The data acquisition phase involved 3 basic steps: (1) random selection of 54 sample trees from 2 intensively-managed 80-year-old plantations in central Canada; (2) attainment of cardinal-based vd measurements transecting the breast-height position on each sample tree; and (3) felling, sectioning and obtaining cross-sectional samples from the first 5.3 m sawlog from which Silviscan-based area-weighted mean attribute estimates were determined. The data analysis phase consisted of applying graphical and correlation analyses to specify regression models for each of the 8 attribute-acoustic velocity relationships. Results indicated that viable relationships were obtained for me, wd, wt, co and sa based on a set of statistical measures: goodness-of-fit (42%, 14%, 45%, 27% and 43% of the variability explained, respectively), lack-of-fit (unbiasedness) and predictive precision (±12%, ±8%, ±7%, ±8% and ±6% error tolerance intervals, respectively). Non-destructive approaches for estimating the prerequisite wd value when deploying the analytical framework were also empirically evaluated. Collectively, the proposed approach and associated results provide the foundation for the development of a comprehensive and precise end-product segregation strategy for use in red pine management. Full article
(This article belongs to the Section Forest Inventory, Quantitative Methods and Remote Sensing)
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Open AccessArticle Projecting Land Use Changes by Integrating Site Suitability Analysis with Historic Land Use Change Dynamics in the Context of Increasing Demand for Wood Pellets in the Southern United States
Forests 2017, 8(10), 381; doi:10.3390/f8100381
Received: 8 September 2017 / Revised: 15 September 2017 / Accepted: 30 September 2017 / Published: 5 October 2017
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Abstract
Rising export of wood pellets from southern United States would bring more land under loblolly pine (Pinus taeda L.) at the expense of other competitive land uses. We developed an approach to project potential changes in existing land uses by integrating site
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Rising export of wood pellets from southern United States would bring more land under loblolly pine (Pinus taeda L.) at the expense of other competitive land uses. We developed an approach to project potential changes in existing land uses by integrating site suitability analysis with historical land use dynamics in a watershed located within Oconee River Basin, Georgia, United States. We developed a GIS-based site suitability model to classify land into three categories (High, Medium, and Low) for loblolly pine. Then, we calculated historical rates of land use changes in the selected watershed. Finally, we integrated the output of suitability analysis with the projected rates of land use changes under the two scenarios of wood pellet demand (High and Low) to determine an increase in area under loblolly pine for 2016, 2021, and 2026 in a spatially explicit manner. Relative to 2011, the combined changes in the shrubland and evergreen forest land cover categories under High Demand scenario were 7.6, 14.6, and 21.1% and under Low Demand scenario were 3.8, 7.5, and 11.1% for the years 2016, 2021, and 2026, respectively. The developed approach could be applied in a relatively short time at modest spatial scales. The outputs of this study can also be used to determine the environmental implications of land use changes for ensuring the overall sustainability of wood-based bioenergy development in the United States and beyond. Full article
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Open AccessArticle Intra-Annual Variation of Stem Radius of Larix principis-rupprechtii and Its Response to Environmental Factors in Liupan Mountains of Northwest China
Forests 2017, 8(10), 382; doi:10.3390/f8100382
Received: 15 August 2017 / Revised: 20 September 2017 / Accepted: 2 October 2017 / Published: 7 October 2017
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Abstract
Fine-resolution studies on the stem radius variation at short timescale can provide useful information about the tree growth process and the major environmental variables that trigger and drive stem radius variation. This study investigated the stem radius variation of Larix principis-rupprechtii Mayr growing
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Fine-resolution studies on the stem radius variation at short timescale can provide useful information about the tree growth process and the major environmental variables that trigger and drive stem radius variation. This study investigated the stem radius variation of Larix principis-rupprechtii Mayr growing in the semi-humid Liupan Mountains of Northwest China at daily and seasonal scales using high-resolution automatic band dendrometers from May to October in 2015. The results showed that the stem radius variation of Larix principis-rupprechtii has a clear diurnal pattern which can be divided into contraction, recovery, and increment phases; and also a seasonal pattern which can be divided into three stages: (1) the rapid growth stage in spring (stage 1) with the radius increment of 94.0% of the total in the entire growing period; (2) the persistent shrinkage stage in the dry summer (stage 2) with a negative diurnal radius increment for most days, and a significantly larger amplitude of stem contraction and recovery than other stages; (3) the minimal growth stage in autumn (stage 3), mainly caused by the lowering temperature and leaf area. The amplitude of stem contraction was significantly correlated with air temperature (both the mean and highest value) in all three stages: vapor pressure deficit (VPD) in stage 1; relative humidity (RH), VPD and soil moisture (Ms) in stage 2; and soil temperature (Ts) in stage 3. This indicates that the stem radius contraction was mainly controlled by the factors influencing tree transpiration rate in spring and autumn stages, but jointly controlled by the factors influencing both the tree transpiration rate and the soil moisture availability in the dry summer stage. The factors controlling the stem radius recovery was similar to the stem contraction. The amplitude of stem increment was significantly correlated with the rainfall amount and air temperature (both the mean and highest value) in stage 1 and 3, Ms in stage 2, and the lowest air temperature and Ts in stage 3. This indicates that temperature and precipitation were the key factors controlling the stem radius increment in the spring and autumn stages, and soil moisture was the main factor limiting the stem radius increment in the dry summer stage at the study site with semi-humid climate in Northwest China. Full article
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Open AccessArticle Forest Harvest Patterns on Private Lands in the Cascade Mountains, Washington, USA
Forests 2017, 8(10), 383; doi:10.3390/f8100383
Received: 16 August 2017 / Revised: 28 September 2017 / Accepted: 3 October 2017 / Published: 7 October 2017
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Abstract
Forests in Washington State generate substantial economic revenue from commercial timber harvesting on private lands. To investigate the rates, causes, and spatial and temporal patterns of forest harvest on private tracts throughout the Cascade Mountains, we relied on a new generation of annual
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Forests in Washington State generate substantial economic revenue from commercial timber harvesting on private lands. To investigate the rates, causes, and spatial and temporal patterns of forest harvest on private tracts throughout the Cascade Mountains, we relied on a new generation of annual land-use/land-cover (LULC) products created from the application of the Continuous Change Detection and Classification (CCDC) algorithm to Landsat satellite imagery collected from 1985 to 2014. We calculated metrics of landscape pattern using patches of intact and harvested forest in each annual layer to identify changes throughout the time series. Patch dynamics revealed four distinct eras of logging trends that align with prevailing regulations and economic conditions. We used multiple logistic regression to determine the biophysical and anthropogenic factors that influence fine-scale selection of harvest stands in each time period. Results show that private lands forest cover became significantly reduced and more fragmented from 1985 to 2014. Variables linked to parameters of site conditions, location, climate, and vegetation greenness consistently distinguished harvest selection for each distinct era. This study demonstrates the utility of annual LULC data for investigating the underlying factors that influence land cover change. Full article
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Open AccessArticle Mapping of Shorea robusta Forest Using Time Series MODIS Data
Forests 2017, 8(10), 384; doi:10.3390/f8100384
Received: 15 August 2017 / Revised: 15 September 2017 / Accepted: 30 September 2017 / Published: 7 October 2017
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Abstract
Mapping forest types in a natural heterogeneous forest environment using remote sensing data is a long-standing challenge due to similar spectral reflectance from different tree species and significant time and resources are required for acquiring and processing the remote sensing data. The purpose
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Mapping forest types in a natural heterogeneous forest environment using remote sensing data is a long-standing challenge due to similar spectral reflectance from different tree species and significant time and resources are required for acquiring and processing the remote sensing data. The purpose of this research was to determine the optimum number of remote sensing images and map the Sal forest through the analysis of Vegetation Index (VI) signatures. We analyzed the eight days’ composite moderate resolution imaging spectroradiometer (MODIS) time series normalized differential vegetation index (NDVI), and enhanced vegetation index (EVI) for the whole year of 2015. Jeffries-Matusita (J-M) distance was used for the separability index. Performance of EVI and NDVI was tested using random forest (RF) and support vector machine (SVM) classifiers. Boruta algorithm and statistical analysis were performed to identify the optimum set of imageries. We also performed data level five-fold cross validation of the model and field level accuracy assessment of the classification map. The finding confirmed that EVI with SVM (F-score of Sal 0.88) performed better than NDVI with either SVM or RF. The optimum 12 images during growing and post monsoon season significantly decreased processing time (to one-fourth) without much deteriorating accuracy. Accordingly, we were able to map the Sal forest whose area is accounted for about 36% of the 82% forest cover in the study area. The proposed methodology can be extended to produce a temporal forest type classification map in any other location. Full article
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Open AccessArticle The Effect of Re-Planting Trees on Soil Microbial Communities in a Wildfire-Induced Subalpine Grassland
Forests 2017, 8(10), 385; doi:10.3390/f8100385
Received: 14 August 2017 / Revised: 2 October 2017 / Accepted: 3 October 2017 / Published: 7 October 2017
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Abstract
Wildfire often causes tremendous changes in ecosystems, particularly in subalpine and alpine areas, which are vulnerable due to severe climate conditions such as cold temperature and strong wind. This study aimed to clarify the effect of tree re-planting on ecosystem services such as
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Wildfire often causes tremendous changes in ecosystems, particularly in subalpine and alpine areas, which are vulnerable due to severe climate conditions such as cold temperature and strong wind. This study aimed to clarify the effect of tree re-planting on ecosystem services such as the soil microbial community after several decades. We compared the re-planted forest and grassland with the mature forest as a reference in terms of soil microbial biomass C and N (Cmic and Nmic), enzyme activities, phospholipid fatty acids (PLFA) composition, and denaturing gradient gel electrophoresis (DGGE). The Cmic and Nmic did not differ among the grassland, re-planted forest and mature forest soil; however, ratios of Cmic/Corg and Nmic/Ntot decreased from the grassland to re-planted forest and mature forest soil. The total PLFAs and those attributed to bacteria and Gram-positive and Gram-negative bacteria did not differ between the re-planted forest and grassland soil. Principle component analysis of the PLFA content separated the grassland from re-planted forest and mature forest soil. Similarly, DGGE analysis revealed changes in both bacterial and fungal community structures with changes in vegetation. Our results suggest that the microbial community structure changes with the re-planting of trees after a fire event in this subalpine area. Recovery of the soil microbial community to the original state in a fire-damaged site in a subalpine area may require decades, even under a re-planted forest. Full article
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Open AccessArticle Assessment of the Response of Photosynthetic Activity of Mediterranean Evergreen Oaks to Enhanced Drought Stress and Recovery by Using PRI and R690/R630
Forests 2017, 8(10), 386; doi:10.3390/f8100386
Received: 31 July 2017 / Revised: 16 September 2017 / Accepted: 7 October 2017 / Published: 10 October 2017
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Abstract
The photochemical reflectance index (PRI) and red-edge region of the spectrum are known to be sensitive to plant physiological processes, and through measurement of these optical signals it is possible to use non-invasive remote sensing to monitor the plant photosynthetic status in response
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The photochemical reflectance index (PRI) and red-edge region of the spectrum are known to be sensitive to plant physiological processes, and through measurement of these optical signals it is possible to use non-invasive remote sensing to monitor the plant photosynthetic status in response to environmental stresses such as drought. We conducted a greenhouse experiment using Quercus ilex, a Mediterranean evergreen oak species, to investigate the links between leaf-level PRI and the red-edge based reflectance ratio (R690/R630) with CO2 assimilation rates (A), and photochemical efficiency (FV/FM and Yield) in response to a gradient of mild to extreme drought treatments (nine progressively enhanced drought levels) and corresponding recovery. PRI and R690/R630 both decreased under enhanced drought stress, and had significant correlations with A, FV/FM and Yield. The differential values between recovery and drought treatments of PRI (ΔPRIrecovery) and R690/R630 (ΔR690/R630recovery) increased with the enhanced drought levels, and significantly correlated with the increases of ΔArecovery, ΔFV/FMrecovery and ΔYieldrecovery. We concluded that both PRI and R690/R630 were not only sensitive to enhanced drought stresses, but also highly sensitive to photosynthetic recovery. Our study makes important progress for remotely monitoring the effect of drought and recovery on photosynthetic regulation using the simple physiological indices of PRI and R690/R630. Full article
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Open AccessArticle Influence of Container Type and Growth Medium on Seedling Growth and Root Morphology of Cyclocarya paliurus during Nursery Culture
Forests 2017, 8(10), 387; doi:10.3390/f8100387
Received: 27 August 2017 / Revised: 28 September 2017 / Accepted: 7 October 2017 / Published: 10 October 2017
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Abstract
As a multiple function tree species, Cyclocarya paliurus (Batal) Iljinskaja is mainly planted and managed for timber production and medical use. To improve the seed use efficiency and outplanting performance of C. paliurus, the effects of container types and growth medium on
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As a multiple function tree species, Cyclocarya paliurus (Batal) Iljinskaja is mainly planted and managed for timber production and medical use. To improve the seed use efficiency and outplanting performance of C. paliurus, the effects of container types and growth medium on the seedling growth and root morphology of C. paliurus were investigated by using a completely randomized block experimental design with a 4 × 3 factorial arrangement during nursery culture. Both container type and growth medium significantly affected the growth, biomass, and root morphological indexes of C. paliurus seedlings, but container size had a greater effect on the seedling quality of C. paliurus than the growth medium formula. The root-collar diameter and height of the seedlings were positively and significantly correlated with the biomass variables and root morphological variables, and could be considered essential attributes for evaluating seedling quality. Based on the results from this study, the management regime used here in C. paliurus seedling production is suggested to ensure good quality seedling delivery. Our study provides not only valuable insights into the container seedling culture of C. paliurus, it also enables nursery managers to optimize seedling production. Full article
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Open AccessArticle Growth and Physiology of Senegalia senegal (L.) Britton Seedlings as Influenced by Seed Origin and Salinity and Fertility Treatments
Forests 2017, 8(10), 388; doi:10.3390/f8100388
Received: 2 August 2017 / Revised: 25 September 2017 / Accepted: 3 October 2017 / Published: 11 October 2017
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Abstract
Multipurpose trees such as Senegalia senegal are widespread in arid and semi-arid lands that have natural or induced saline soils and poor soil fertility. Such environmental problems impact growth and have the potential to influence plant physiological adaptations. Identifying superior genotypes better adapted
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Multipurpose trees such as Senegalia senegal are widespread in arid and semi-arid lands that have natural or induced saline soils and poor soil fertility. Such environmental problems impact growth and have the potential to influence plant physiological adaptations. Identifying superior genotypes better adapted to these environmental stresses will be of great importance for tree selection for reclamation of degraded drylands. The main objective of this study was to examine the growth performance, and physiological and morphological adaptations to salinity, and fertility treatments of different Senegalia senegal families. We used five families (DB16, DB14, K4B19, K17B19, NB1) selected from 60 families of a Senegalia senegal progeny trial in Dahra, Senegal. Seedlings were grown under greenhouse conditions by watering all plants for three weeks and then stopping all watering for three more weeks. In a randomized complete block design, a two-level factorial combination was used for salinity (zero and 183.1 mM NaCl added) and fertility (zero and 100 kg/ha N-P-K added) treatments. A significant family × salt × fertilizer interaction was found for all biomass parameters (leaf dry matter, stem dry matter, root dry matter, and leaf area). The fertilizer application resulted in a significant increase of total biomass of all families, ranging from 63% to 237% for NB1 and K17B19, respectively. In contrast, salt only decreased total biomass of NB1 and K17B19 increased growth. Despite similar net photosynthetic rates before treatment started, fertilizer and salinity induced different effects between families. Prior to drought stress, fertilizer did not affect photosynthesis of DB16, while salt significantly decreased stomatal conductance of all families. DB16 and N1B1, despite significant differences of stomata size and density, significantly decreased transpiration, and thereby increased their intrinsic water use efficiency. Under drought, relative growth rate was significantly decreased. Given that genotype differences were found, these families and salinity and fertilizer treatments need to be explored in field trials. Full article
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Open AccessArticle Assessing Forest Cover Dynamics and Forest Perception in the Atlantic Forest of Paraguay, Combining Remote Sensing and Household Level Data
Forests 2017, 8(10), 389; doi:10.3390/f8100389
Received: 29 August 2017 / Revised: 5 October 2017 / Accepted: 7 October 2017 / Published: 11 October 2017
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Abstract
The Upper Parana Atlantic Forest (BAAPA) in Paraguay is one of the most threatened tropical forests in the world. The rapid growth of deforestation has resulted in the loss of 91% of its original cover. Numerous efforts have been made to halt deforestation
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The Upper Parana Atlantic Forest (BAAPA) in Paraguay is one of the most threatened tropical forests in the world. The rapid growth of deforestation has resulted in the loss of 91% of its original cover. Numerous efforts have been made to halt deforestation activities, however farmers’ perception towards the forest and its benefits has not been considered either in studies conducted so far or by policy makers. This research provides the first multi-temporal analysis of the dynamics of the forest within the BAAPA region on the one hand, and assesses the way farmers perceive the forest and how this influences forest conservation at the farm level on the other. Remote sensing data acquired from Landsat images from 1999 to 2016 were used to measure the extent of the forest cover and deforestation rates over 17 years. Farmers’ influence on the dynamics of the forest was evaluated by combining earth observation data and household survey results conducted in the BAAPA region in 2016. Outcomes obtained in this study demonstrate a total loss in forest cover of 7500 km2. Deforestation rates in protected areas were determined by management regimes. The combination of household level and remote sensing data demonstrated that forest dynamics at the farm level is influenced by farm type, the level of dependency/use of forest benefits and the level of education of forest owners. An understanding of the social value awarded to the forest is a relevant contribution towards preserving natural resources. Full article
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Open AccessArticle Taxonomic and Functional Diversity of a Quercus pyrenaica Willd. Rhizospheric Microbiome in the Mediterranean Mountains
Forests 2017, 8(10), 390; doi:10.3390/f8100390
Received: 7 September 2017 / Revised: 6 October 2017 / Accepted: 9 October 2017 / Published: 12 October 2017
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Abstract
Altitude significantly affects vegetation growth and distribution, including the developmental stages of a forest. We used shotgun Illumina sequencing to analyze microbial community composition and functional potential in melojo-oak (Quercus pyrenaica Willd.) rhizospheric soil for three different development stages along an altitudinal
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Altitude significantly affects vegetation growth and distribution, including the developmental stages of a forest. We used shotgun Illumina sequencing to analyze microbial community composition and functional potential in melojo-oak (Quercus pyrenaica Willd.) rhizospheric soil for three different development stages along an altitudinal gradient: (a) a low altitude, non-optimal site for forest maintenance; (b) an intermediate altitude, optimal site for a forest; and (c) a high altitude, expansion site with isolated trees but without a real forest canopy. We observed that, at each altitude, the same microbial taxa appear both in the taxonomic analysis of the whole metagenome and in the functional analysis of the methane, sulfur and nitrogen metabolisms. Although there were no major differences at the functional level, there were significant differences in the abundance of each taxon at the phylogenetic level between the rhizospheres of the forest (low and intermediate altitudes) and the expansion site. Proteobacteria and Actinobacteria were the most differentially abundant phyla in forest soils compared to the expansion site rhizosphere. Moreover, Verrucomicrobia, Bacteroidetes and Nitrospirae phyla were more highly represented in the non-forest rhizosphere. Our study suggests that rhizospheric microbial communities of the same tree species may be affected by development stage and forest canopy cover via changes in soil pH and the C/N ratio. Full article
(This article belongs to the Special Issue Forest Fine Roots in Changing Climate)
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Open AccessArticle Tree Regeneration Spatial Patterns in Ponderosa Pine Forests Following Stand-Replacing Fire: Influence of Topography and Neighbors
Forests 2017, 8(10), 391; doi:10.3390/f8100391
Received: 11 August 2017 / Revised: 9 September 2017 / Accepted: 10 October 2017 / Published: 14 October 2017
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Abstract
Shifting fire regimes alter forest structure assembly in ponderosa pine forests and may produce structural heterogeneity following stand-replacing fire due, in part, to fine-scale variability in growing environments. We mapped tree regeneration in eighteen plots 11 to 15 years after stand-replacing fire in
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Shifting fire regimes alter forest structure assembly in ponderosa pine forests and may produce structural heterogeneity following stand-replacing fire due, in part, to fine-scale variability in growing environments. We mapped tree regeneration in eighteen plots 11 to 15 years after stand-replacing fire in Colorado and South Dakota, USA. We used point pattern analyses to examine the spatial pattern of tree locations and heights as well as the influence of tree interactions and topography on tree patterns. In these sparse, early-seral forests, we found that all species were spatially aggregated, partly attributable to the influence of (1) aspect and slope on conifers; (2) topographic position on quaking aspen; and (3) interspecific attraction between ponderosa pine and other species. Specifically, tree interactions were related to finer-scale patterns whereas topographic effects influenced coarse-scale patterns. Spatial structures of heights revealed conspecific size hierarchies with taller trees in denser neighborhoods. Topography and heterospecific tree interactions had nominal effect on tree height spatial structure. Our results demonstrate how stand-replacing fires create heterogeneous forest structures and suggest that scale-dependent, and often facilitatory, rather than competitive, processes act on regenerating trees. These early-seral processes will establish potential pathways of stand development, affecting future forest dynamics and management options. Full article
(This article belongs to the Special Issue Post-Disturbance Forest Management and Regeneration Dynamics)
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Open AccessArticle Estimation of Vegetation Cover Using Digital Photography in a Regional Survey of Central Mexico
Forests 2017, 8(10), 392; doi:10.3390/f8100392
Received: 9 September 2017 / Revised: 3 October 2017 / Accepted: 9 October 2017 / Published: 15 October 2017
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Abstract
The methods for measuring vegetation cover in Mexican forest surveys are subjective and imprecise. The objectives of this research were to compare the sampling designs used to measure the vegetation cover and estimate the over and understory cover in different land uses, using
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The methods for measuring vegetation cover in Mexican forest surveys are subjective and imprecise. The objectives of this research were to compare the sampling designs used to measure the vegetation cover and estimate the over and understory cover in different land uses, using digital photography. The study was carried out in 754 circular sampling sites in central Mexico. Four spatial sampling designs were evaluated in three spatial distribution patterns of the trees. The sampling designs with photographic captures in diagonal form had lower values of mean absolute error (MAE < 0.12) and less variation in random and grouped patterns. The Carbon and Biomass Sampling Plot (CBSP) design was chosen due to its smaller error in the different spatial tree patterns. The image processing was performed using threshold segmentation techniques and was automated through an application developed in the Python language. The two proposed methods to estimate vegetation cover through digital photographs were robust and replicable in all sampling plots with different land uses and different illumination conditions. The automation of the process avoided human estimation errors and ensured the reproducibility of the results. This method is working for regional surveys and could be used in national surveys due to its functionality. Full article
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Open AccessArticle Some Refinements on the Comparison of Areal Sampling Methods via Simulation
Forests 2017, 8(10), 393; doi:10.3390/f8100393
Received: 15 August 2017 / Revised: 15 September 2017 / Accepted: 10 October 2017 / Published: 16 October 2017
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Abstract
The design of forest inventories and development of new sampling methods useful in such inventories normally have a two-fold target of design unbiasedness and minimum variance in mind. Many considerations such as costs go into the choices of sampling method for operational and
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The design of forest inventories and development of new sampling methods useful in such inventories normally have a two-fold target of design unbiasedness and minimum variance in mind. Many considerations such as costs go into the choices of sampling method for operational and other levels of inventory. However, the variance in terms of meeting a specified level of precision is always among the most important criteria. Similarly, in designing new sampling methods, one always seeks to decrease the variance of the new method compared to existing methods. This paper provides a review of some graphical methods that may prove useful in these endeavors. In addition, in the case of the comparison of variances between new and existing methods, it introduces the use of wavelet filtering to decompose the sampling variance associated with the estimators under consideration into scale-based components of variance. This yields an analysis of variance of sorts regarding how the methods compare over different distance/area classes. The graphical tools are also shown to be applicable to the wavelet decomposition. These graphical tools may prove useful in summarizing the results for inventory design, while the wavelet results may prove helpful as we begin to look at sampling designs more in light of spatial processes for a given population of trees or downed coarse woody debris. Full article
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Open AccessArticle Ecosystem Service Supply and Capacity on U.S. Family Forestlands
Forests 2017, 8(10), 395; doi:10.3390/f8100395
Received: 15 September 2017 / Revised: 11 October 2017 / Accepted: 14 October 2017 / Published: 17 October 2017
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Abstract
Individuals and families collectively own more than 118 million ha of forestland in the USA. Using data from the USDA Forest Service’s National Woodland Owners Survey (NWOS), we characterize ecosystem services being produced on family forests as well as the beneficiaries who enjoy
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Individuals and families collectively own more than 118 million ha of forestland in the USA. Using data from the USDA Forest Service’s National Woodland Owners Survey (NWOS), we characterize ecosystem services being produced on family forests as well as the beneficiaries who enjoy them. Approximately half of family forest owners provide one or more provisioning services. With the exception of logs, the provisioning services provided by the majority of owners are enjoyed directly by owners or their close associates (i.e., family, friends, and neighbors). Similarly, while more than half of family forest owners have provided recreational opportunities, a cultural service, to their close associates, fewer than 6% of owners have sold or provided recreational services to the general public. Regulating and supporting services are linked to the maintenance of long-term forest cover. Greater than 80% of family forest owners desire to maintain the forested condition of their land, whereas a much smaller percentage of these owners have entered into conservation easements or have collected money for conservation purposes. In addition, many owners have engaged in activities expected to increase the future capacity of their land to provide multiple ecosystem services, both excludable and non-excludable. Full article
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Open AccessArticle A Robust Productivity Model for Grapple Yarding in Fast-Growing Tree Plantations
Forests 2017, 8(10), 396; doi:10.3390/f8100396
Received: 23 September 2017 / Revised: 12 October 2017 / Accepted: 13 October 2017 / Published: 17 October 2017
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Abstract
New techniques have recently appeared that can extend the advantages of grapple yarding to fast-growing plantations. The most promising technique consists of an excavator-base un-guyed yarder equipped with new radio-controlled grapple carriages, fed by another excavator stationed on the cut-over. This system is
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New techniques have recently appeared that can extend the advantages of grapple yarding to fast-growing plantations. The most promising technique consists of an excavator-base un-guyed yarder equipped with new radio-controlled grapple carriages, fed by another excavator stationed on the cut-over. This system is very productive, avoids in-stand traffic, and removes operators from positions of high risk. This paper presents the results of a long-term study conducted on 12 different teams equipped with the new technology, operating in the fast-growing black wattle (Acacia mangium Willd) plantations of Sarawak, Malaysia. Data were collected continuously for almost 8 months and represented 555 shifts, or over 55,000 cycles—each recorded individually. Production, utilization, and machine availability were estimated, respectively at: 63 m3 per productive machine hour (excluding all delays), 63% and 93%. Regression analysis of experimental data yielded a strong productivity forecast model that was highly significant, accounted for 50% of the total variability in the dataset and was validated with a non-significant error estimated at less than 1%. The figures reported in this study are especially robust, because they were obtained from a long-term study that covered multiple teams and accumulated an exceptionally large number of observations. Full article
(This article belongs to the Special Issue Forest Operations, Engineering and Management)
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Open AccessArticle Stand Dynamics and Biomass Increment in a Lucidophyllous Forest over a 28-Year Period in Central Japan
Forests 2017, 8(10), 397; doi:10.3390/f8100397
Received: 18 August 2017 / Revised: 12 October 2017 / Accepted: 15 October 2017 / Published: 17 October 2017
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Abstract
Secondary lucidophyllous forest is one of the dominant forests in human-dominated subtropical/warm-temperate regions in East Asia. There were few direct monitoring techniques to elucidate the following hypotheses: (a) self-thinning may govern the stand development process and (b) wood production decline can be observed
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Secondary lucidophyllous forest is one of the dominant forests in human-dominated subtropical/warm-temperate regions in East Asia. There were few direct monitoring techniques to elucidate the following hypotheses: (a) self-thinning may govern the stand development process and (b) wood production decline can be observed during secondary succession in a lucidophyllous forest. We conducted a long-term study at a permanent plot in central Japan, since 1989. The forest consists mainly of Castanopsis cuspidata in a canopy layer, Cleyera japonica, and Eurya japonica in a subtree layer. During the 28-year period, the basal area of the stand significantly increased due to the growth of C. cuspidata, from 29.18 ± 1.84 (87.8% of total) to 38.71 ± 2.22 m2 ha−1 (91.9%), while the stem density of C. cuspidata significantly decreased from 666 ± 13 to 404 ± 10 stems ha−1 in proportion to accumulating biomass (117.8 to 166.6 ton ha−1). The annual woody net primary production ranged from 2.40 ± 0.13 to 3.93 ± 0.33 ton ha−1 year−1 as a nearly 70-year-old forest. There was no age-related decline of woody net primary production (NPP) was found during secondary succession, and the growth of individual tree still increased when the self-thinning process governed the stand. Full article
(This article belongs to the collection Forests Carbon Fluxes and Sequestration)
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Open AccessArticle Effects of Linear Disturbances and Fire Severity on Velvet Leaf Blueberry Abundance, Vigor, and Berry Production in Recently Burned Jack Pine Forests
Forests 2017, 8(10), 398; doi:10.3390/f8100398
Received: 29 September 2017 / Revised: 12 October 2017 / Accepted: 13 October 2017 / Published: 18 October 2017
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Abstract
There is limited information on how velvet leaf blueberry (Vaccinium myrtilloides Michx.) responds to fires and existing small forest gaps associated with narrow linear disturbances. We measured the effects of narrow forest linear gaps from seismic lines used for oil and gas
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There is limited information on how velvet leaf blueberry (Vaccinium myrtilloides Michx.) responds to fires and existing small forest gaps associated with narrow linear disturbances. We measured the effects of narrow forest linear gaps from seismic lines used for oil and gas exploration versus adjacent (control) forests across a fire severity (% tree mortality) gradient on the presence, abundance (cover), vigor (height), and berry production of Vaccinium myrtilloides in recently (five-year) burned jack pine (Pinus banksiana Lamb.) forests near Fort McMurray, Alberta. Presence was greatest in forests that experienced low to moderately-high fire severities with declines at high fire severity. Abundance did not differ among seismic lines or adjacent forest, nor did it differ along a fire severity gradient. In contrast, vigor and berry production were greater on seismic lines compared to adjacent forests with fire severity positively affecting berry production, but not plant vigor. After controlling for changes in plant cover and vigor, berry production still increased with fire severity and within seismic lines compared with adjacent forests. Our findings suggest that narrow gaps from linear disturbances and fire severity interact to affect the fecundity (berry production) and growth (height) of Vaccinium myrtilloides. This has important implications for assessing the ecological effects of fire on linear disturbances associated with energy exploration in the western boreal forest. Full article
(This article belongs to the Special Issue Wildland Fire, Forest Dynamics, and Their Interactions)
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Open AccessArticle Effects of Climate Change on the Potentially Suitable Climatic Geographical Range of Liriodendron chinense
Forests 2017, 8(10), 399; doi:10.3390/f8100399
Received: 2 August 2017 / Revised: 12 October 2017 / Accepted: 17 October 2017 / Published: 19 October 2017
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Abstract
Identifying the potentially suitable climatic geographical range for Liriodendron chinense (L. chinense) and predicting its responses to climate change is urgently necessary, as L. chinense is an important tertiary relict tree species. In this study, we simulated the potentially suitable climatic
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Identifying the potentially suitable climatic geographical range for Liriodendron chinense (L. chinense) and predicting its responses to climate change is urgently necessary, as L. chinense is an important tertiary relict tree species. In this study, we simulated the potentially suitable climatic habitat of L. chinense in China using maximum entropy (MaxEnt) modeling. We found that the MaxEnt model was highly accurate with an average training Area Under the Curve (AUC) value of 0.912. Annual precipitation and mean temperature of the driest quarter are the main factors controlling the geographical distribution of L. chinense. Currently, the suitable climatic habitat of L. chinense is mainly located in Southeastern China. Forecasted patterns of predicted suitable climatic habitat show a significant change by the 2050s and 2070s, suggesting that the suitable climatic habitat of L. chinense would shift north with future climate change, based on four Representative Concentrations Pathways for carbon dioxide (CO2) emissions. The southern extent of the current distribution would become unsuitable for L. chinense, pointing to a threat of extinction and highlighting the urgent need for conservation within the next half century. The potentially suitable climatic habitat of L. chinense was predicted to move further north, but those habitat gains may be inaccessible because of dispersal limitations. Our unique findings offer a climatic suitability map for L. chinense in China, which can help to identify locations where L. chinense may already exist, but has not yet been detected; to recognize locations where L. chinense is likely to spread in the future given forecasted climate change; and to select priority areas for its introduction, cultivation, and conservation. Full article
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Open AccessArticle Fire Effects on Historical Wildfire Refugia in Contemporary Wildfires
Forests 2017, 8(10), 400; doi:10.3390/f8100400
Received: 2 August 2017 / Revised: 6 October 2017 / Accepted: 10 October 2017 / Published: 20 October 2017
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Abstract
Wildfire refugia are forest patches that are minimally-impacted by fire and provide critical habitats for fire-sensitive species and seed sources for post-fire forest regeneration. Wildfire refugia are relatively understudied, particularly concerning the impacts of subsequent fires on existing refugia. We opportunistically re-visited 122
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Wildfire refugia are forest patches that are minimally-impacted by fire and provide critical habitats for fire-sensitive species and seed sources for post-fire forest regeneration. Wildfire refugia are relatively understudied, particularly concerning the impacts of subsequent fires on existing refugia. We opportunistically re-visited 122 sites classified in 1994 for a prior fire refugia study, which were burned by two wildfires in 2012 in the Cascade mountains of central Washington, USA. We evaluated the fire effects for historically persistent fire refugia and compared them to the surrounding non-refugial forest matrix. Of 122 total refugial (43 plots) and non-refugial (79 plots) sites sampled following the 2012 wildfires, one refugial and five non-refugial plots did not burn in 2012. Refugial sites burned more severely and experienced higher tree mortality than non-refugial plots, potentially due to the greater amount of time since the last fire, producing higher fuel accumulation. Although most sites maintained the pre-fire development stage, 19 percent of sites transitioned to Early development and 31 percent of sites converted from Closed to Open canopy. These structural transitions may contribute to forest restoration in fire-adapted forests where fire has been excluded for over a century, but this requires further analysis. Full article
(This article belongs to the Special Issue Wildland Fire, Forest Dynamics, and Their Interactions)
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Open AccessArticle Countering Negative Effects of Terrain Slope on Airborne Laser Scanner Data Using Procrustean Transformation and Histogram Matching
Forests 2017, 8(10), 401; doi:10.3390/f8100401
Received: 15 August 2017 / Revised: 14 October 2017 / Accepted: 16 October 2017 / Published: 21 October 2017
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Abstract
Forest attributes such as tree heights, diameter distribution, volumes, and biomass can be modeled utilizing the relationship between remotely sensed metrics as predictor variables, and measurements of forest attributes on the ground. The quality of the models relies on the actual relationship between
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Forest attributes such as tree heights, diameter distribution, volumes, and biomass can be modeled utilizing the relationship between remotely sensed metrics as predictor variables, and measurements of forest attributes on the ground. The quality of the models relies on the actual relationship between the forest attributes and the remotely sensed metrics. The processing of airborne laser scanning (ALS) point clouds acquired under heterogeneous terrain conditions introduces a distortion of the three-dimensional shape and structure of the ALS data for tree crowns and thus errors in the derived metrics. In the present study, Procrustean transformation and histogram matching were proposed as a means of countering the distortion of the ALS data. The transformations were tested on a dataset consisting of 192 field plots of 250 m2 in size located on a gradient from gentle to steep terrain slopes in western Norway. Regression models with predictor variables derived from (1) Procrustean transformed- and (2) histogram matched point clouds were compared to models with variables derived from untransformed point clouds. Models for timber volume, basal area, dominant height, Lorey’s mean height, basal area weighted mean diameter, and number of stems were assessed. The results indicate that both (1) Procrustean transformation and (2) histogram matching can be used to counter crown distortion in ALS point clouds. Furthermore, both techniques are simple and can easily be implemented in the traditional processing chain of ALS metrics extraction. Full article
(This article belongs to the Special Issue Defining, Quantifying, Observing and Modeling Forest Canopy Traits)
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Open AccessArticle Assessing Pine Processionary Moth Defoliation Using Unmanned Aerial Systems
Forests 2017, 8(10), 402; doi:10.3390/f8100402
Received: 11 June 2017 / Revised: 13 October 2017 / Accepted: 20 October 2017 / Published: 23 October 2017
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Abstract
Pine processionary moth (PPM) is one of the most destructive insect defoliators in the Mediterranean for many conifers, causing losses of growth, vitality and eventually the death of trees during outbreaks. There is a growing need for cost-effective monitoring of the temporal and
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Pine processionary moth (PPM) is one of the most destructive insect defoliators in the Mediterranean for many conifers, causing losses of growth, vitality and eventually the death of trees during outbreaks. There is a growing need for cost-effective monitoring of the temporal and spatial impacts of PPM in forest ecology to better assess outbreak spread patterns and provide guidance on the development of measures targeting the negative impacts of the species on forests, industry and human health. Remote sensing technology mounted on unmanned aerial systems (UASs) with high-resolution image processing has been proposed to assess insect outbreak impacts at local and forest stand levels. Here, we used UAS-acquired RGB imagery in two pine sites to quantify defoliation at the tree-level and to verify the accuracy of the estimates. Our results allowed the identification of healthy, infested and completely defoliated trees and suggested that pine defoliation estimates using UASs are robust and allow high-accuracy (79%) field-based infestation indexes to be derived that are comparable to those used by forest technicians. When compared to current field-based methods, our approach provides PPM impact assessments with an efficient data acquisition method in terms of time and staff, allowing the quantitative estimation of defoliation at tree-level scale. Furthermore, our method could be expanded to a number of situations and scaled up in combination with satellite remote sensing imagery or citizen science approaches. Full article
(This article belongs to the Special Issue Optimizing Forest Inventories with Remote Sensing Techniques)
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Open AccessArticle Dynamics of Coarse Woody Debris Characteristics in the Qinling Mountain Forests in China
Forests 2017, 8(10), 403; doi:10.3390/f8100403
Received: 15 September 2017 / Revised: 18 October 2017 / Accepted: 20 October 2017 / Published: 23 October 2017
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Abstract
Coarse woody debris (CWD) is an essential component in defining the structure and function of forest ecosystems. Long-term dynamics of CWD characteristics not only affect the release rates of chemical elements from CWD, but also the species diversity of inhabiting plants, animals, insects,
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Coarse woody debris (CWD) is an essential component in defining the structure and function of forest ecosystems. Long-term dynamics of CWD characteristics not only affect the release rates of chemical elements from CWD, but also the species diversity of inhabiting plants, animals, insects, and microorganisms as well as the overall health of ecosystems. However, few quantitative studies have been done on the long-term dynamics of CWD characteristics in forest ecosystems in China. In this study, we conducted nine tree censuses between 1996 and 2016 at the Huoditang Experimental Forest in the Qinling Mountains of China. We quantified forest biomass including CWD and CWD characteristics such as decay states and diameter classes during this period and correlated with stand, site, and climatic variables. The forest biomass was dominated by live tree biomass (88%); followed by CWD mass (6%–10%). Understory biomass contributed only a small portion (1%–4%) of the overall biomass. Significant differences in average annual increment of CWD mass were found among forest stands of different species (p < 0.0001). Forest biomass, stand age, forest type, aspect, slope, stand density, annual average temperature, and precipitation were all significantly correlated with CWD mass (p < 0.05), with forest type exhibiting the strongest correlation (r2 = 0.8256). Over time, the annual mass of different CWD characteristics increased linearly from 1996–2016 across all forest types. Our study revealed that forest biomass, including CWD characteristics, varied by forest type. Stand and site characteristics (forest biomass, forest type, aspect, slope and stand density) along with temperature and precipitation played a major role in the dynamics of CWD in the studied forest ecosystems. Full article
(This article belongs to the Special Issue Coarse Woody Debris of Forests in a Changing World)
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Open AccessArticle The Floral Biology, Breeding System and Pollination Efficiency of Schima superba Gardn. et Champ. (Theaceae)
Forests 2017, 8(10), 404; doi:10.3390/f8100404
Received: 21 July 2017 / Revised: 8 October 2017 / Accepted: 11 October 2017 / Published: 24 October 2017
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Abstract
Schima superba Gardn. et Champ. is a perennial, evergreen tree valued for its eco-protection and commercial values in China. In this study, we investigate the breeding system, reproductive ecology and pollination biology of S. superba in a seed orchard. The flowers are hermaphrodite
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Schima superba Gardn. et Champ. is a perennial, evergreen tree valued for its eco-protection and commercial values in China. In this study, we investigate the breeding system, reproductive ecology and pollination biology of S. superba in a seed orchard. The flowers are hermaphrodite and protogynous. The viability of the pollen is inactivated rapidly, and the stigma maintains a high receptivity within the flower lifespan. Flowers typically offer pollen and nectar to visitors. The flowers possess a typical insect pollination syndrome, and three visitors (Apis cerana cerana Fabricius, Protaetia brevitarsis Lewis, and Popillia mutans Newman) are observed on flowers during the study period. The visitation frequency per minute and capability of pollen removal and deposition of A. cerana are significantly higher than P. brevitarsis and P. mutans, although the pollinator efficiency is lower than those shown by the two beetles. Fruit set (28.27%) and seed set (6.57%) percentages resulting from open-pollination are significantly lower than those resulting from cross-pollination (fruit/seed set, 43.73%/11.66%), and the pollen limitation index (L) was 0.34, suggesting that seed production is pollen-limited in the seed orchard. The pollen/ovule ratio (P/O) and outcrossing index (OCI) values are 6686.67 and 4, respectively. The self-incompatibility index (ISI) was estimated to be 0.95. Results from hand-pollination, pollen tube growth experiments and the ISI value show that S. superba is late-acting self-incompatible. The synthetic results indicate that A. cerana is the most efficient pollinator of S. superba, and seed production is frequently limited by pollinators, fruit abortion, and pollen quality. Full article
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Review

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Open AccessReview Application of Biotechnology in the Conservation of the Genus Castanea
Forests 2017, 8(10), 394; doi:10.3390/f8100394
Received: 5 September 2017 / Revised: 27 September 2017 / Accepted: 12 October 2017 / Published: 17 October 2017
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Abstract
Castanea is a hardwood forest genus of considerable agro-economic importance for both timber and nut production. Chestnuts are one of the most significant nut crops in the temperate zone. However, this species is threatened by pollution, social factors, economical changes, and two major
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Castanea is a hardwood forest genus of considerable agro-economic importance for both timber and nut production. Chestnuts are one of the most significant nut crops in the temperate zone. However, this species is threatened by pollution, social factors, economical changes, and two major fungal diseases: ink disease (Phytophthora spp.), and chestnut blight canker (Cryphonectria parasitica). Similar to other wood species, chestnuts are difficult to propagate both generatively by seed and vegetatively by means of grafting or cuttings. Biotechnological methods such as in vitro culture have been developed in the last few years as an alternative to conventional vegetative propagation. Biotechnology plays a very important role not only in the propagation of selected individuals (being used at a commercial level), but also in its short-term preservation, and offers the possibility of preserving the propagated material in the medium-term (cold storage) or long-term using cryopreservation. Full article
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Other

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Open AccessCorrection Correction: Schelfhout, S.; et al. Tree Species Identity Shapes Earthworm Communities. Forests 2017, 8, 85
Forests 2017, 8(10), 366; doi:10.3390/f8100366
Received: 14 September 2017 / Revised: 22 September 2017 / Accepted: 22 September 2017 / Published: 27 September 2017
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Abstract
It has come to our attention that there was a mistake in this paper [1]:[...] Full article
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