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Forests, Volume 10, Issue 12 (December 2019)

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Open AccessCommunication
Comparisons of Estimated Circuity Factor of Forest Roads with Different Vertical Heights in Mountainous Areas, Republic of Korea
Forests 2019, 10(12), 1147; https://doi.org/10.3390/f10121147 (registering DOI) - 16 Dec 2019
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Abstract
Distance is one of the important factors in determining transportation cost and travel time, and it can be easily estimated by measuring the circuity of road networks. This study calculated the circuity factors to estimate the network distance for 27 forest roads (about [...] Read more.
Distance is one of the important factors in determining transportation cost and travel time, and it can be easily estimated by measuring the circuity of road networks. This study calculated the circuity factors to estimate the network distance for 27 forest roads (about 105 km) in South Korea. For this purpose, ridge, mid-slope, and valley roads were classified according to the construction location of the mountain slope, and the weighted and unweighted circuity factor (each 500-m section) were calculated. The average value of weighted circuity was 1.55: mid-slope roads (2.09), ridge roads (1.36), and valley roads (1.09). The average unweighted circuity factors were 1.61 for mid-slope roads, 1.21 for ridge roads, and 1.07 for valley roads. This study found that the circuity of the forest road network was most affected by the mountain terrain. In addition, the circuity factor increased with increasing network distance in the mid-slope roads but was not affected by the network distance in ridges and valleys. To improve the efficiency of transportation in the forest road network, it is important to locate the ladings and properly connect with the public road network. Full article
(This article belongs to the Special Issue Planning, Design, and Maintenance of Forest Road Networks)
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Open AccessArticle
Control of Fungal Diseases and Increase in Yields of a Cultivated Jujube Fruit (Zizyphus jujuba Miller var. inermis Rehder) Orchard by Employing Lysobacter antibioticus HS124
Forests 2019, 10(12), 1146; https://doi.org/10.3390/f10121146 (registering DOI) - 15 Dec 2019
Viewed by 121
Abstract
The objective of this study is to investigate the inhibitory effects of Lysobacter antibioticus HS124 on fungal phytopathogens causing gray mold rot, stem rot, and anthracnose. Another objective of this study is to promote the yield of fruit in jujube farms. L. antibioticus [...] Read more.
The objective of this study is to investigate the inhibitory effects of Lysobacter antibioticus HS124 on fungal phytopathogens causing gray mold rot, stem rot, and anthracnose. Another objective of this study is to promote the yield of fruit in jujube farms. L. antibioticus HS124 produces chitinase, a lytic enzyme with the potential to reduce mycelial growth of fungal phytopathogens involving hyphal alterations with swelling and bulbous structures, by 20.6 to 27.3%. Inoculation with L. antibioticus HS124 decreased the appearance of fungal diseases in jujube farms and increased the fruit yield by decreasing fruit wilting and dropping. In addition, L. antibioticus HS124 produced the phytohormone auxin to promote vegetative growth, thereby increasing the fruit size. The yield of jujube fruits after L. antibioticus HS124 inoculation was increased by 6284.67 g/branch, which was 2.9-fold higher than that of the control. Auxin also stimulated fine root development and nutrient uptake in jujube trees. The concentrations of minerals, such as K, Ca, Mg, and P in jujube fruits after L. antibioticus HS124 inoculation were significantly increased (1.4- to 2.0-fold greater than the concentrations in the control). These results revealed that L. antibioticus HS124 could not only control fungal diseases but also promote fruit yield in jujube farms. Full article
(This article belongs to the Special Issue Forest, Foods and Nutrition)
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Open AccessArticle
Temperature and Rainfall Are Separate Agents of Selection Shaping Population Differentiation in a Forest Tree
Forests 2019, 10(12), 1145; https://doi.org/10.3390/f10121145 (registering DOI) - 14 Dec 2019
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Abstract
Research highlights: We present evidence indicating that covariation of functional traits among populations of a forest tree is not due to genetic constraints, but rather selective covariance arising from local adaptation to different facets of the climate, namely rainfall and temperature. Background [...] Read more.
Research highlights: We present evidence indicating that covariation of functional traits among populations of a forest tree is not due to genetic constraints, but rather selective covariance arising from local adaptation to different facets of the climate, namely rainfall and temperature. Background and Aims: Traits frequently covary among natural populations. Such covariation can be caused by pleiotropy and/or linkage disequilibrium, but also may arise when the traits are genetically independent as a direct consequence of natural selection, drift, mutation and/or gene flow. Of particular interest are cases of selective covariance, where natural selection directly generates among-population covariance in a set of genetically independent traits. We here studied the causes of population-level covariation in two key traits in the Australian tree Eucalyptus pauciflora. Materials and Methods: We studied covariation in seedling lignotuber size and vegetative juvenility using 37 populations sampled from throughout the geographic and ecological ranges of E. pauciflora on the island of Tasmania. We integrated evidence from multiple sources: (i) comparison of patterns of trait covariation within and among populations; (ii) climate-trait modelling using machine-learning algorithms; and (iii) selection analysis linking trait variation to field growth in an arid environment. Results: We showed strong covariation among populations compared with the weak genetic correlation within populations for the focal traits. Population differentiation in these genetically independent traits was correlated with different home-site climate variables (lignotuber size with temperature; vegetative juvenility with rainfall), which spatially covaried. The role of selection in shaping the population differentiation in lignotuber size was supported by its relationship with fitness measured in the field. Conclusions: Our study highlights the multi-trait nature of adaptation likely to occur as tree species respond to spatial and temporal changes in climate. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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Open AccessReview
Assessing the Impact of Ozone on Forest Trees in An Integrative Perspective: Are Foliar Visible Symptoms Suitable Predictors for Growth Reduction? A Critical Review
Forests 2019, 10(12), 1144; https://doi.org/10.3390/f10121144 (registering DOI) - 14 Dec 2019
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Abstract
Plant growth reduction (GR) is the most widely accepted damage parameter to assess the sensitivity of trees to tropospheric ozone (O3) pollution since it integrates different physiological processes leading to loss of photosynthetic activity and distraction of metabolic resources from growth [...] Read more.
Plant growth reduction (GR) is the most widely accepted damage parameter to assess the sensitivity of trees to tropospheric ozone (O3) pollution since it integrates different physiological processes leading to loss of photosynthetic activity and distraction of metabolic resources from growth to defense, repair, and recovery pathways. Because of the intrinsic difficulty to assess the actual O3 risk assessment for forests in field conditions, foliar visible symptoms (FVS) induced by O3 have been proposed as a proxy to estimate possible GR in forest trees. The rationale for this assumption is that the onset of FVS implies a reduction of the photosynthetic capacity of plants. In this review, we show that GR and FVS can be the consequences of independent physiological pathways involving different response mechanisms that can cause both FVS without GR and GR without FVS. The onset of FVS may not lead necessarily to significant GR at plant level for several reasons, including the rise of compensatory photosynthesis, the time lag between growth processes and the accumulation of critical O3 dose, and the negligible effect of a modest amount of injured leaves. Plant GR, on the other hand, may be induced by different physiological mechanisms not necessarily related to FVS, such as stomatal closure (i.e., carbon starvation) to avoid or reduce O3 uptake, and the increase of respiratory processes for the production of metabolic defense compounds. Growth reduction and FVS can be interpreted as different strategies for the acclimation of plants to a stressful environment, and do not mean necessarily damage. Growth reduction (without FVS) seems to prevail in species adapted to limiting environmental conditions, that avoid loss and replacement of injured leaves because of the high metabolic cost of their production; conversely, FVS manifestation (without GR) and the replacement of injured leaves is more common in species adapted to environments with low-stress levels, since they can benefit from a rapid foliar turnover to compensate for the decreased rate of photosynthesis of the whole plant. Full article
(This article belongs to the Special Issue Impacts of Ozone on Forest Plants and Ecosystems)
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Open AccessArticle
Drought-Induced Reductions and Limited Recovery in the Radial Growth, Transpiration, and Canopy Stomatal Conductance of Mongolian Scots Pine (Pinus sylvestris var. mongolica Litv): A Five-Year Observation
Forests 2019, 10(12), 1143; https://doi.org/10.3390/f10121143 (registering DOI) - 13 Dec 2019
Viewed by 156
Abstract
Determining plant–water relationships in response to drought events can provide important information about the adaptation of trees to climate change. The Mongolian Scots pine (Pinus sylvestris var. mongolica Litv), as one of the major tree species to control soil loss and desertification [...] Read more.
Determining plant–water relationships in response to drought events can provide important information about the adaptation of trees to climate change. The Mongolian Scots pine (Pinus sylvestris var. mongolica Litv), as one of the major tree species to control soil loss and desertification in northern China, has experienced severe degradation in recent decades. Here, we aimed to examine the impacts of a two-year consecutive drought and another year of drought on the radial growth, transpiration, and canopy stomatal conductance of Mongolian Scots pine over a five-year period, especially in terms of its recovery after drought. The study period during 2013–2017 consisted of a ’normal’ year, a ’dry year’, a ’very dry’ year, a ’wet’ year, and a ’dry’ year, according to annual precipitation and soil moisture conditions. Based on measurements of the sap flow and diameters at breast height of 11 sample trees as well as the concurrent environmental factors, we quantified the reductions in tree radial growth, transpiration, and canopy stomatal conductance during the drought development as well as their recovery after the drought. The results showed that the tree radial growth, transpiration, and canopy stomatal conductance of Mongolian Scots pines decreased by 33.8%, 51.9%, and 51.5%, respectively, due to the two consecutive years of drought. Moreover, these reductions did not fully recover after the two-year drought was relieved. The minimum difference of these parameters between before and after the two-year consecutive drought period was 8.5% in tree radial growth, 45.1% in transpiration levels, and 42.4% in canopy stomatal conductance. We concluded that the two consecutive years of drought resulted in not only large reductions in tree radial growth and water use, but also their lagged and limited recoveries after drought. The study also highlighted the limited resilience of Mongolian Scots pine trees to prolonged drought in semi-arid sandy environmental conditions. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
Open AccessArticle
Residents’ Attention and Awareness of Urban Edible Landscapes: A Case Study of Wuhan, China
Forests 2019, 10(12), 1142; https://doi.org/10.3390/f10121142 (registering DOI) - 13 Dec 2019
Viewed by 139
Abstract
More and more urban residents in China have suffered from food insecurity and failed to meet the national recommendation of daily fruit and vegetable consumption due to rapid urbanization in recent years. Introducing edible landscapes to urban greening systems represents an opportunity for [...] Read more.
More and more urban residents in China have suffered from food insecurity and failed to meet the national recommendation of daily fruit and vegetable consumption due to rapid urbanization in recent years. Introducing edible landscapes to urban greening systems represents an opportunity for improving urban food supply and security. However, residents’ opinion on urban edible landscapes has rarely been discussed. In this study, questionnaire surveys were performed in eight sample communities in Wuhan, China, to collect the information on residents’ attention and awareness of urban edible landscapes. Results indicated that nearly one-third of the respondents were unaware of edible landscapes before the interview. Most residents thought that an edible landscape could promote efficient land use (57.26%) and express special ornamental effects (54.64%), but quite a few didn’t believe that growing edible plants in urban public spaces could increase food output (37.10%) and improve food quality (40.12%). Overall, 45.65% and 32.73% of the growers performed their cultivation behavior in private and semiprivate spaces, respectively. Lack of public areas for agriculture use was regarded as the main barrier restricting the development of urban horticulture by 55.86% of growers and 59.51% of non-growers. The residents were also worried about their property manager’s opposition, possible conflicts, and complex relationships with their neighbors. Food policies and infrastructure support from local governments and official institutions were needed to ensure the successful implementation of edible landscapes in urban areas. Full article
(This article belongs to the Special Issue Forest, Foods and Nutrition)
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Open AccessArticle
Discovery and Profiling of microRNAs at the Critical Period of Sex Differentiation in Xanthoceras sorbifolium Bunge
Forests 2019, 10(12), 1141; https://doi.org/10.3390/f10121141 (registering DOI) - 13 Dec 2019
Viewed by 108
Abstract
Research Highlights: The critical period of sex differentiation in Xanthoceras sorbifolium was investigated. Multiple microRNAs (miRNAs) were identified to influence female and male flower development, with some complementary functions. Background and Objectives: Xanthoceras sorbifolium Bunge is widely cultivated owing to its multipurpose usefulness. [...] Read more.
Research Highlights: The critical period of sex differentiation in Xanthoceras sorbifolium was investigated. Multiple microRNAs (miRNAs) were identified to influence female and male flower development, with some complementary functions. Background and Objectives: Xanthoceras sorbifolium Bunge is widely cultivated owing to its multipurpose usefulness. However, as a monoecious plant, the low female–male flowers ratio and consequent low seed yield are the main bottlenecks for industrial-scale development of seed utilization. MiRNAs play crucial regulatory roles in flower development and sex differentiation; therefore, we evaluated the roles of miRNAs in the critical period of sex differentiation in X. sorbifolium. Materials and Methods: Four small RNA libraries for female and male flower buds of the critical period of sex differentiation were constructed from paraffin-embedded sections. The miRNAs were characterized by high-throughput sequencing, and differentially expressed miRNAs were validated by reverse transcription-quantitative polymerase chain reaction. Results: There were obvious differences in male and female pistil and stamen flower buds, with elongated inflorescence and clear separation of flower buds marking the critical period of sex differentiation. A total of 1619 conserved miRNAs (belonging to 34 families) and 219 novel miRNAs were identified. Among these, 162 conserved and 14 novel miRNAs exhibited significant differential expression in the four libraries, and 1677 putative target genes of 112 differentially expressed miRNAs were predicted. These target genes were involved in diverse developmental and metabolic processes, including 17 miRNAs directly associated with flower and gametophyte development, mainly associated with carbohydrate metabolism and glycan biosynthesis and metabolism pathways. Some miRNA functions were confirmed, and others were found to be complemented. Conclusions: Multiple miRNAs closely related to sex differentiation in X. sorbifolium were identified. The theoretical framework presented herein might guide sex ratio regulation to enhance seed yield. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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Open AccessArticle
Experimental and Numerical Determination of the Mechanical Properties of Spruce Wood
Forests 2019, 10(12), 1140; https://doi.org/10.3390/f10121140 (registering DOI) - 13 Dec 2019
Viewed by 141
Abstract
The objective of this paper is the computational and experimental study of the fracture behavior of spruce wood under quasi-static loading conditions during a three-point bending test. The experimental tests were performed on the electronic testing machine Zwick Z100 (Zwick-Roell GmbH & Co. [...] Read more.
The objective of this paper is the computational and experimental study of the fracture behavior of spruce wood under quasi-static loading conditions during a three-point bending test. The experimental tests were performed on the electronic testing machine Zwick Z100 (Zwick-Roell GmbH & Co. KG, Ulm, Germany) with displacement control, according to the standard International Standard Organisation (ISO) 13061-4: 2014. The specimens were made of Norway spruce (Picea abies) wood, with dimensions of 25 mm × 25 mm in cross-section and 549 mm in length. Six tests were performed for each orientation (radial and tangential) of the wood fibres. Based on the experimental results, the computational model was created and validated by considering the mechanical responses in two different directions due to the orientation of the wood fibres. An orthotropic material model with damage evolution was selected as the computational model. The computational model was validated using the inverse procedure for the determination of the constitutive material parameters, including the damage parameters of three-point bending test specimens. A finite element method (FEM) in the framework of program package ABAQUS was used for the computational simulation, while the open code Optimax was used for the optimization procedure. Comparison between the experimental and computational force vs. the displacement response showed a very good correlation in the results for the spruce wood specimens under three-point bending tests, with Pearson′s correlation coefficient of r = 0.994 for the tangential and r = 0.988 for the radial orientation. Therefore, validation of the proposed computational model was confirmed, and can be used further in numerical simulations of the fatigue behavior of wood specimens. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle
Patterns of Effective Pollen Dispersal in Larch: Linking Levels of Background Pollination with Pollen Dispersal Kernels
Forests 2019, 10(12), 1139; https://doi.org/10.3390/f10121139 - 12 Dec 2019
Viewed by 171
Abstract
Monitoring patterns of mating and pollen dispersal in forest tree populations subjected to nature conservation is essential to understanding the dynamics of their reproductive processes and might be helpful in making management decisions aimed at conserving genetic diversity and integrity over the long [...] Read more.
Monitoring patterns of mating and pollen dispersal in forest tree populations subjected to nature conservation is essential to understanding the dynamics of their reproductive processes and might be helpful in making management decisions aimed at conserving genetic diversity and integrity over the long term. However, little is known about effective pollen dispersal in natural populations of conifers, particularly in subdominant species such as larch. We investigated patterns of pollen dispersal in the Polish larch population of Świętokrzyski National Park. The studied population was located on Chełmowa Mountain in a forest complex 160 ha in size, which is relatively isolated from other forest stands. We assessed if local pollen dispersal inferred from pollen dispersal kernels could provide indications of the level of background pollination from sources located outside of the forest complex. The analysis focused on two plots, each encompassing 126 adult trees, and seed samples (n = 600) collected from 20 trees. Using 11 nuclear microsatellites and spatially explicit mating models, we identified details of mating patterns. The rate of self-fertilization was low (0.0268). Background pollination was moderate (0.4058), and the mean pollen dispersal was found to be 167 m and 111 m, based on exponential-power and Weibull dispersal kernels, respectively. Specific simulations performed based on the estimated pollen dispersal kernels provided background pollination levels comparable to those observed for real data, suggesting that the pollen contributing to background pollination likely originated from the studied forest complex and not from other surrounding populations. These results confirm the high potential for maintaining the genetic integrity of the larch population and support efforts aimed at promoting regeneration of the stands, either natural or through the artificial planting of seedlings derived from trees growing in the core larch population of the protected area. Full article
(This article belongs to the Section Forest Ecology and Management)
Open AccessArticle
“Diminishing Returns” in the Scaling Between Leaf Area and Twig Size in Three Forest Communities Along an Elevation Gradient of Wuyi Mountain, China
Forests 2019, 10(12), 1138; https://doi.org/10.3390/f10121138 - 12 Dec 2019
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Abstract
Background and aims: The “diminishing returns” hypothesis postulates that the scaling exponent governing the lamina area versus lamina mass scaling relationships has, on average, a numerical value less than one. Theoretically, a similar scaling relationship may exist at the twig level. However, this [...] Read more.
Background and aims: The “diminishing returns” hypothesis postulates that the scaling exponent governing the lamina area versus lamina mass scaling relationships has, on average, a numerical value less than one. Theoretically, a similar scaling relationship may exist at the twig level. However, this possibility has not been explored empirically. Methods: We tested both hypotheses by measuring the lamina area and mass, petiole mass of individual leaves, and the total foliage area and stem mass of individual current-year shoots (twigs) of 64 woody species growing in three characteristic forest community types:(1) Evergreen broad-leaved, (2) mixed coniferous and broad-leaved, and (3) deciduous. Key results: The results demonstrate that lamina area vs. mass and lamina area vs. petiole mass differ significantly among the three forest types at both the individual leaf and twig levels. Nevertheless, the scaling exponents of lamina area vs. mass were <1.0 in each of the three community types, as were the corresponding exponents for lamina area vs. petiole mass, both within and across the three community types. Similar trends were observed at the individual twig level. The numerical values of the scaling exponent for lamina area vs. petiole mass and total foliage area vs. stem mass per twig decreased with increased elevation. Conclusions: These data support the “diminishing returns” hypothesis at both the individual leaf level and at the individual twig level, phenomena that can inform future inquiries into the mechanistic basis of biomass allocation patterns to physiological (leaf) and mechanical (stem) plant organs. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
Open AccessEditorial
Protection Strategy against Spruce Budworm
Forests 2019, 10(12), 1137; https://doi.org/10.3390/f10121137 - 12 Dec 2019
Viewed by 120
Abstract
Spruce budworm is one of the most significant forest insects worldwide, in terms of outbreak extent, severity, and economic impacts. As a defoliator, spruce budworm larvae are susceptible to insecticide protection, and improvements in efficacy and reductions in non-target environmental effects have made [...] Read more.
Spruce budworm is one of the most significant forest insects worldwide, in terms of outbreak extent, severity, and economic impacts. As a defoliator, spruce budworm larvae are susceptible to insecticide protection, and improvements in efficacy and reductions in non-target environmental effects have made such protection attractive. In this Special Issue, 12 papers describe the advances in spruce budworm protection, most notably an ‘early intervention strategy’ approach that after six years of trials in New Brunswick, Canada, shows considerable success to date in reducing budworm outbreak occurrence and severity. Full article
(This article belongs to the Special Issue Protection Strategy against Spruce Budworm)
Open AccessArticle
Conversion of Pinus nigra Plantations with Natural Regeneration in the Slovenian Karst: The Importance of Intermediate, Gradually Formed Canopy Gaps
Forests 2019, 10(12), 1136; https://doi.org/10.3390/f10121136 - 12 Dec 2019
Viewed by 142
Abstract
Since the mid-19th century, Pinus nigra plantations have played a key role in the restoration of degraded European landscapes. Nowadays, these plantations are aging and prone to natural disturbances, insect infestations, and diseases. For their successful gradual conversion, knowledge of optimal gap spatiotemporal [...] Read more.
Since the mid-19th century, Pinus nigra plantations have played a key role in the restoration of degraded European landscapes. Nowadays, these plantations are aging and prone to natural disturbances, insect infestations, and diseases. For their successful gradual conversion, knowledge of optimal gap spatiotemporal dynamics is crucial. We studied herb and natural regeneration patterns along with site factors on 477 subplots within 44 plots distributed over four stand types: closed stand (14% diffuse light), open stand (21%), gap edge (23%), and gap (57%). Despite the abundant Quercus petraea, Q. cerris, and Q. pubescens mast year, no one-year seedlings were recorded, which is likely due to the summer drought. Short seedlings (h < 20 cm) of Quercus sp., Fraxinus ornus and Ostrya carpinifolia were more successful within closed stands. Short Quercus seedlings were positively associated with soil depth and negatively associated with soil nutrients, distance to seed trees, and Sesleria autumnalis coverage. Taller Quercus seedlings required more light than both of its strongest competitors and were positively related to humid soils and less rocky sites. Ungulate overbrowsing significantly impeded natural regeneration. The results indicate a satisfactory Quercus density for conversion and the importance of advanced regeneration, which should be gradually, but persistently, released by progressively widening gaps. Full article
(This article belongs to the Special Issue Role of Gap Factors in Forest Tree Regeneration and Plant Communities)
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Open AccessArticle
Measuring the Strength of Root-Reinforced Soil on Steep Natural Slopes Using the Corkscrew Extraction Method
Forests 2019, 10(12), 1135; https://doi.org/10.3390/f10121135 - 12 Dec 2019
Viewed by 113
Abstract
Roots can help to stabilise slopes against landslides and anchor trees against wind loading, but their mechanical contribution to the strength of soil is difficult to rapidly quantify under field conditions. A new field measurement method, quantifying the shear strength of rooted soil [...] Read more.
Roots can help to stabilise slopes against landslides and anchor trees against wind loading, but their mechanical contribution to the strength of soil is difficult to rapidly quantify under field conditions. A new field measurement method, quantifying the shear strength of rooted soil by measuring the resistance against extraction of soil cores using a large corkscrew device, was tested across three heterogeneous slopes (unforested, forested and clearfelled) in Scotland. The presence of roots significantly increased the measured shear strength in the surface layer of the Sitka spruce forested slope. Differences in strength between the three areas were however not significant. This could be attributed to the large variation in the soil component of the combined root–soil shear strength, which was strongly affected by variations in both soil density and gravel content. Measured strength on these natural slopes were much more variable compared to previously investigated sites. These results highlight the importance of investigating the variation in soil strength during root-reinforcement measurements, and furthermore demonstrate the need for a sufficiently large number of tests to address this variation. The corkscrew provides rapid estimation of root-reinforced soil shear strength on sites with difficult accessibility. Compared to the more conventional shear vane method, which yielded comparable soil strength results, the corkscrew proved more suitable in stony soil layers and has the additional benefit of simultaneously extracting small (rooted) soil samples that could be used for further root and soil analysis. It therefore proved a useful and effective field tool for use when a rapid estimation of root-reinforced soil shear strength is required. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle
Changes in Plant Functional Groups during Secondary Succession in a Tropical Montane Rain Forest
Forests 2019, 10(12), 1134; https://doi.org/10.3390/f10121134 - 12 Dec 2019
Viewed by 144
Abstract
Aggregating diverse plant species into a few functional groups based on functional traits provides new insights for promoting landscape planning and conserving biodiversity in species-diverse regions. Ecophysiological traits are the basis of the functioning of an ecosystem. However, studies related to the identification [...] Read more.
Aggregating diverse plant species into a few functional groups based on functional traits provides new insights for promoting landscape planning and conserving biodiversity in species-diverse regions. Ecophysiological traits are the basis of the functioning of an ecosystem. However, studies related to the identification of functional groups based on plant ecophysiological traits in tropical forests are still scarce because of the inherent difficulties in measuring them. In this study, we measured five ecophysiological traits: net photosynthetic capacity (Amax), maximum stomatal conductance (gmax), water use efficiency (WUE), transpiration rate (Trmmol), and specific leaf areas (SLA) for 87 plant species dominant in a chronosequence of secondary succession, using four time periods (5 year-primary, 15 year-early, and 40 year-middle successional stages after clear cutting and old growth) in the tropical montane rainforest on Hainan Island, China. These species were grouped using hierarchical cluster analysis and non-metric multidimensional scaling. Finally, the changes in the composition of functional groups and species richness along the chronosequence were analyzed. Results showed that the plant species in the tropical montane rainforest could be classified into eight distinct functional groups. The richness of functional groups was low during the initial early stage and increased as the early and middle stages progressed, and then declined in the late successional stage. The dominant functional groups in the primary stages had the highest Amax, gmax, Trmmol, and SLA, as well as the lowest WUE, while those in the early and middle successional stages had functional traits at a moderate level, and at the late stage they had the lowest Amax, gmax, Trmmol, and SLA, and highest WUE. Our study showed that the diverse plant species in the tropical montane rainforest could be grouped into a few functional groups according to major ecophysiological traits, and the composition and relative abundance of different groups changed with the successional dynamics of the forest ecosystem. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle
Divergent Growth Responses to Warming between Stand-Grown and Open-Grown Trees in a Dryland Montane Forest in Northwestern China
Forests 2019, 10(12), 1133; https://doi.org/10.3390/f10121133 - 11 Dec 2019
Viewed by 176
Abstract
Dryland montane forests conserve water for people living in the fluvial plains. The fate of these forests under climate warming is strongly affected by local environmental factors. The question remains of how internal factors contribute to climate change impacts on forest growth in [...] Read more.
Dryland montane forests conserve water for people living in the fluvial plains. The fate of these forests under climate warming is strongly affected by local environmental factors. The question remains of how internal factors contribute to climate change impacts on forest growth in these regions. Here, we investigated tree ring records for similar-aged stand-grown trees and their neighboring open-grown trees at elevation in a dryland montane forest (Picea crassifolia Kom.) in northwestern China. The growth rate of open-grown trees is much higher than their neighboring stand-grown trees across the entire elevation gradient, and the lower the altitude, the greater the difference. Open-grown trees at different elevations showed similar growth patterns, as tree growth at all sites was accelerated over time. In contrast, growth patterns of stand-grown trees were divergent at different altitudes, as growth at high elevations (3100–3300 m a.s.l.) was accelerated, whereas growth at low elevations (2700–2900 m a.s.l.) became stable after the year 1990. Analysis of growth–climate relationships indicated that warming promoted open-grown tree growth across the entire altitude gradient, and also stand-grown tree growth at high elevations, but negatively affected the growth of stand-grown trees at low elevations. Water scarcity can be exacerbated by competition within forests, inhibiting the warming-induced benefits on tree growth. Moving window correlation analysis suggested the negative effect of warming on tree growth at low elevations was diminished after the late 1990s, as the drought stress was alleviated. Our research shows the divergent growth responses to warming of stand-grown and open-grown trees along elevation. It reveals effects of internal factors in determining tree growth response to warming and holds the potential to aid forest management and ecosystem models in responding to climate change. Full article
(This article belongs to the Section Forest Ecology and Management)
Open AccessArticle
Carbon Limitation and Drought Sensitivity at Contrasting Elevation and Competition of Abies pinsapo Forests. Does Experimental Thinning Enhance Water Supply and Carbohydrates?
Forests 2019, 10(12), 1132; https://doi.org/10.3390/f10121132 - 11 Dec 2019
Viewed by 135
Abstract
Stand-level competition and local climate influence tree responses to increased drought at the regional scale. To evaluate stand density and elevation effects on tree carbon and water balances, we monitored seasonal changes in sap-flow density (SFD), gas exchange, xylem water potential, secondary growth, [...] Read more.
Stand-level competition and local climate influence tree responses to increased drought at the regional scale. To evaluate stand density and elevation effects on tree carbon and water balances, we monitored seasonal changes in sap-flow density (SFD), gas exchange, xylem water potential, secondary growth, and non-structural carbohydrates (NSCs) in Abies pinsapo. Trees were subjected to experimental thinning within a low-elevation stand (1200 m), and carbon and water balances were compared to control plots at low and high elevation (1700 m). The hydraulic conductivity and the resistance to cavitation were also characterized, showing relatively high values and no significant differences among treatments. Trees growing at higher elevations presented the highest SFD, photosynthetic rates, and secondary growth, mainly because their growing season was extended until summer. Trees growing at low elevation reduced SFD during late spring and summer while SFD and secondary growth were significantly higher in the thinned stands. Declining NSC concentrations in needles, branches, and sapwood suggest drought-induced control of the carbon supply status. Our results might indicate potential altitudinal shifts, as better performance occurs at higher elevations, while thinning may be suitable as adaptive management to mitigate drought effects in endangered Mediterranean trees. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
Open AccessArticle
Effects of Salt on Root Aeration, Nitrification, and Nitrogen Uptake in Mangroves
Forests 2019, 10(12), 1131; https://doi.org/10.3390/f10121131 - 11 Dec 2019
Viewed by 170
Abstract
The potential effects of salt on the growth, root anatomy, radial oxygen loss (ROL), and nitrogen (N) dynamics in mangroves were investigated using the seedlings of Avicennia marina (Forsk.) Vierh. The results showed that a moderate salinity (200 mM NaCl) appeared to have [...] Read more.
The potential effects of salt on the growth, root anatomy, radial oxygen loss (ROL), and nitrogen (N) dynamics in mangroves were investigated using the seedlings of Avicennia marina (Forsk.) Vierh. The results showed that a moderate salinity (200 mM NaCl) appeared to have little negative effect on the growth of A. marina. However, higher salt stresses (400 and 600 mM NaCl) significantly inhibited the biomass yield. Concentrations of N in the roots and leaves decreased sharply with increasing salinity. Nevertheless, the presence of salt directly altered root anatomy (e.g., reduced root porosity and promoted suberization within the exodermis and endodermis), leading to a significant reduction in ROL. The results further showed that reduced ROL induced by salt could restrain soil nitrification, resulting in less ammonia-oxidizing archaea and bacteria (AOA and AOB) gene copies and lower concentrations of NO3 in the soils. While increased root suberization induced by salt inhibited NH4+ and NO3 uptake and influx into the roots. In summary, this study indicated that inhibited root aeration may be a defense response to salt, however these root symptoms were not advantageous for rhizosphere nitrification and N uptake by A. marina. Full article
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Open AccessArticle
Anatomy of the Windmill Palm (Trachycarpus fortunei) and Its Application Potential
Forests 2019, 10(12), 1130; https://doi.org/10.3390/f10121130 (registering DOI) - 10 Dec 2019
Viewed by 178
Abstract
The windmill palm (Trachycarpus fortunei (Hook.) H. Wendl.) is widely distributed and is an important potential source of lignocellulosic materials. The lack of knowledge on the anatomy of the windmill palm has led to its inefficient use. In this paper, the diversity [...] Read more.
The windmill palm (Trachycarpus fortunei (Hook.) H. Wendl.) is widely distributed and is an important potential source of lignocellulosic materials. The lack of knowledge on the anatomy of the windmill palm has led to its inefficient use. In this paper, the diversity in vascular bundle types, shape, surface, and tissue proportions in the leaf sheaths and stems were studied with digital microscopy and scanning electron microscope (SEM). Simultaneously, fiber dimensions, fiber surfaces, cell wall ultrastructure, and micromechanics were studied with atomic force microscopy (AFM) and a nanoindenter. There is diversity among vascular bundles in stems and leaf sheaths. All vascular bundles in the stems are type B (circular vascular tissue (VT) at the edge of the fibrous sheath (FS)) while the leaf sheath vascular bundles mostly belong to type C (aliform (VT) at the center of the (FS), with the wings of the (VT) extending to the edge of the vascular bundles). In addition, variation among the vascular bundle area and tissue proportion in the radial direction of the stems and different layers of the leaf sheaths is also significant. Microscopically, the fibers in the stem are much wider and longer than that in the leaf sheath. The secondary walls of stem fibers are triple layered while those in the leaf sheath are double layered. The indentation modulus and hardness of the cell wall of leaf sheath fibers are higher than that of the stem. An independent sample t-test also showed a significant difference between stems and leaf sheaths. All this indicates that windmill palm stems and leaf sheaths are two different materials and have different application prospects. Full article
(This article belongs to the Special Issue Wood Productions and Renewable Materials)
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Open AccessArticle
Thinning Effects on the Tree Height–Diameter Allometry of Masson Pine (Pinus massoniana Lamb.)
Forests 2019, 10(12), 1129; https://doi.org/10.3390/f10121129 (registering DOI) - 10 Dec 2019
Viewed by 184
Abstract
The stem height–diameter allometric relationship is fundamental in determining forest and ecosystem structures as well as in estimating tree volume, biomass, and carbon stocks. Understanding the effects of silvicultural practices on tree height–diameter allometry is necessary for sustainable forest management, though the impact [...] Read more.
The stem height–diameter allometric relationship is fundamental in determining forest and ecosystem structures as well as in estimating tree volume, biomass, and carbon stocks. Understanding the effects of silvicultural practices on tree height–diameter allometry is necessary for sustainable forest management, though the impact of measures such as thinning on the allometric relationship remain understudied. In the present study, the effects of thinning on tree height–diameter allometry were evaluated using Masson pine height and diameter growth data from a plantation experiment that included unthinned and thinned treatments with different intensities. To determine whether thinning altered the height–diameter allometry rhythm, the optimal height–diameter model was identified and dummy variable methods were used to investigate the differences among model parameters for different thinning treatments. Periodic (annual) allometric coefficients were calculated based on height and diameter increment data and were modeled using the generalized additive mixed model (GAMM) to further illustrate the response of tree height–diameter allometry to different thinning treatments over time. Significant differences were detected among the parameters of the optimal height–diameter model (power function) for different thinning treatments, which indicated that the pattern of the height–diameter allometry relationship of Masson pine was indeed altered by thinning treatments. Results also indicated a nonlinear trend in the allometric relationship through time which was significantly affected by thinning. The height–diameter allometric coefficient exhibited a unimodal convex bell curve with time in unthinned plots, and thinning significantly interfered with the original trend of the height–diameter allometric coefficient. Thinning caused trees to increase diameter growth at the expense of height growth, resulting in a decrease of the ratio of tree height to diameter, and this trend was more obvious as the thinning intensity increased. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle
Seasonal Drought Effects on Intra-Annual Stem Growth of Taiwan Pine along an Elevational Gradient in Subtropical China
Forests 2019, 10(12), 1128; https://doi.org/10.3390/f10121128 - 10 Dec 2019
Viewed by 147
Abstract
Knowledge of intra-annual stem growth dynamics across environmental gradients is important for advancing our ability to understand the adaptability and vulnerability of subtropical tree species to future climate change. To assess the effects of seasonal drought on intra-annual stem growth, stem radial variation [...] Read more.
Knowledge of intra-annual stem growth dynamics across environmental gradients is important for advancing our ability to understand the adaptability and vulnerability of subtropical tree species to future climate change. To assess the effects of seasonal drought on intra-annual stem growth, stem radial variation of Taiwan pine (Pinus taiwanensis Hayata) was monitored with band dendrometers for two years along an elevation transect from 921 to 1402 m in the Lushan Mountains, a transect that covers the contrasting climatic growing conditions for Taiwan pine in southeastern China. We found that the onset of stem growth was nearly synchronous across the transect, in early April 2017 and in late March 2018, whereas large elevational differences were observed for the end of the growing season, which was much earlier at lower elevations. Tree stems frequently rehydrated during the dry growing seasons at the two higher elevations, suggesting that seasonal drought had minor influence on the offset of high-elevation stem growth. A substantial and continuous tree water deficit of low-elevation Taiwan pine was detected during dry seasons, leading to an early growth cessation in late July in both years. Tree water status (reflected by tree water deficit) revealed a higher sensitivity to precipitation and soil water content across wet- and dry-seasons at the lowest elevation than at high elevations, indicating that low-elevation stem radial growth was highly dependent on moisture variables over the whole growing season. Due to the influences of seasonal drought on growth cessation and rates, Taiwan pine produced a rather narrow annual growth at the lowest site, whereas high-elevation Taiwan pine could benefit from the optimal wet-season environmental conditions and the reactivation of cambial activity during dry seasons. Our findings suggest that the more frequent and intensive drought episodes in the future will reduce tree growth of Taiwan pine at the dry edge, probably resulting in upward shifting of the optimal elevation for Taiwan pine in subtropical China. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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Open AccessArticle
Radial Growth Rate Responses of Western Juniper (Juniperus occidentalis Hook.) to Atmospheric and Climatic Changes: A Longitudinal Study from Central Oregon, USA
Forests 2019, 10(12), 1127; https://doi.org/10.3390/f10121127 - 10 Dec 2019
Viewed by 153
Abstract
Research Highlights: In this longitudinal study, we explore the impacts of changing atmospheric composition and increasing aridity on the radial growth rates of western juniper (WJ; Juniperus occidentalis Hook). Since we sampled from study locations with minimal human agency, we can partially [...] Read more.
Research Highlights: In this longitudinal study, we explore the impacts of changing atmospheric composition and increasing aridity on the radial growth rates of western juniper (WJ; Juniperus occidentalis Hook). Since we sampled from study locations with minimal human agency, we can partially control for confounding influences on radial growth (e.g., grazing and logging) and better isolate the relationships between radial growth and climatic conditions. Background and Objectives: Our primary objective is to determine if carbon dioxide (CO2) enrichment continues to be a primary driving force for a tree species positively affected by increasing CO2 levels circa the late 1990s. Materials and Methods: We collected data from mature WJ trees on four minimally disturbed study sites in central Oregon and compared standardized radial growth rates to climatic conditions from 1905–2017 using correlation, moving-interval correlation, and regression techniques. Results: We found the primary climate driver of radial growth for WJ is antecedent moisture over a period of several months prior to and including the current growing season. Further, the moving-interval correlations revealed that these relationships are highly stable through time. Despite a trend toward increasing aridity manifested through significant increases in maximum temperatures during the summer growing season, WJ radial growth post-1960 exceeds growth pre-1960, especially during drought years. Our results support prior conclusions that increasing atmospheric CO2 increases water-use efficiency for this semiarid species, which allows the trees to continue to grow during climatic periods negatively associated with radial growth. Conclusions: Recent studies have shown that semiarid ecosystems are important for understanding global variations in carbon uptake from the atmosphere. As WJ woodlands cover an extensive region in western North America and have undergone rapid expansion during the 20th and 21st centuries, they may become an increasingly important carbon sink. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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Open AccessArticle
Duration Limits on Field Storage in Closed Cardboard Boxes before Planting of Norway Spruce and Scots Pine Container Seedlings in Different Planting Seasons
Forests 2019, 10(12), 1126; https://doi.org/10.3390/f10121126 - 10 Dec 2019
Viewed by 194
Abstract
For spring plantings, conifer seedlings are usually packed in closed cardboard boxes and freezer stored over winter. Additionally, seedlings are increasingly being stored in cardboard boxes in spring, summer, and autumn plantings in Finland. The aim of this study was to determine the [...] Read more.
For spring plantings, conifer seedlings are usually packed in closed cardboard boxes and freezer stored over winter. Additionally, seedlings are increasingly being stored in cardboard boxes in spring, summer, and autumn plantings in Finland. The aim of this study was to determine the maximum safe duration for the field storage of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) container seedlings in closed cardboard boxes for different planting times (dates) in Nordic boreal conditions. In the first experiment, Norway spruce seedlings (85-cm3 peat plugs) were packed in cardboard boxes in August, September, or October, and, in the second experiment, in the middle of May. In the third Scots pine experiment, mini seedlings (30-cm3 peat plugs) were packed in May. In each experiment, the seedlings were stored in closed cardboard boxes in a nursery for one, three, seven, 14, and 21 days. The control seedlings were stored in open storage in the nursery. After storage, the seedlings were planted in a field. In all of the experiments, increased closed-box storage reduced the maximum photochemical yield of photosystem II (Fv/Fm) in the needles, and reduced root growth after planting. The frost hardiness was weakened in the Norway spruce seedlings that were stored in closed boxes for 21 days in August and October. In the spring experiments, prolonged storage increased the mortality of seedlings. Mortality rates were high in the autumn experiment due to the exceptionally warm and dry weather. Our conclusions, being based on the short term effects of field storage, are that conifer seedlings can be stored in closed boxes for only three days in August and about a week in September, October, and spring. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessFeature PaperArticle
A Slash-And-Mulch Improved-Fallow Agroforestry System: Growth and Nutrient Budgets over Two Rotations
Forests 2019, 10(12), 1125; https://doi.org/10.3390/f10121125 - 10 Dec 2019
Viewed by 160
Abstract
Agroforestry systems are important, globally affecting 1.2 billion people and covering 0.6 billion hectares. They are often cited for providing ecosystem services, such as augmenting soil fertility via N accumulation and increasing soil C stocks. Improved-fallow slash-and-mulch systems have the potential to do [...] Read more.
Agroforestry systems are important, globally affecting 1.2 billion people and covering 0.6 billion hectares. They are often cited for providing ecosystem services, such as augmenting soil fertility via N accumulation and increasing soil C stocks. Improved-fallow slash-and-mulch systems have the potential to do both, while reducing nutrient losses associated with burning. In the absence of burning, these systems also have the potential to grow trees through multiple rotations. This project collected soil, mulch, and biomass data over the course of one 9-year crop-fallow rotation and the first two years of the second rotation. A split-plot design was used to assess the effects of P + K fertilization and inclusion of an N-fixing tree species, Inga edulis, on crop and tree biomass production. Fertilization increased growth and nutrient accumulation during Rotation 1 by an average of 36%, ranging from 11% in Parkia multijuga to 52% in Ceiba pentandra. Residual P + K fertilization improved tree and crop growth 20 months into Rotation 2 by an average of 50%, ranging from 15% in Cedrela odorata to 73% in Schizolobium amazonicum. The improved-fallow slash-and-mulch system increased the rates of secondary succession biomass accumulation (11−15 Mg ha−1 yr−1) by 41–64% compared to natural succession (7–8 Mg ha−1 yr−1). Furthermore, P + K fertilization increased secondary-succession biomass accumulation by 9–24%. Nutrient accumulation through biomass production was adequate to replace nutrients exported via crop root and timber stem harvests. Full article
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Open AccessArticle
Changes in Soil Microbial Biomass, Community Composition, and Enzyme Activities After Half-Century Forest Restoration in Degraded Tropical Lands
Forests 2019, 10(12), 1124; https://doi.org/10.3390/f10121124 - 09 Dec 2019
Viewed by 221
Abstract
Soil carbon (C) sequestration and stabilization are determined by not only the C input to the soil but also the decomposition rate of soil organic matter (SOM), which is mainly mediated by soil microbes. Afforestation, an effective practice to restore forests from degraded [...] Read more.
Soil carbon (C) sequestration and stabilization are determined by not only the C input to the soil but also the decomposition rate of soil organic matter (SOM), which is mainly mediated by soil microbes. Afforestation, an effective practice to restore forests from degraded or bare lands, may alter soil microbial properties, and thus soil C and nitrogen (N) dynamics. The aim of this study was to investigate the impacts of different afforestation strategies on soil microbial compositions and activities after afforestation for half a century. Soil samples were collected from two afforested sites (i.e., a restored secondary forest (RSF) and a managed Eucalyptus forest (MEP)) and two reference sites (i.e., a nearby undisturbed forest (UF), representing the climax vegetation and a bare land (BL), representing the original state before restoration) in south China. We quantified the soil microbial biomass, microbial community compositions, and activities of nine extracellular enzymes at different soil depths and in different seasons. Results showed that the soil microbial biomass, all the main soil microbial groups, and the activities of all extracellular enzymes were significantly increased after afforestation compared to the BL sites, while the ratios of fungi/bacteria (F/B), specific enzyme activities, and the ecoenzymatic stoichiometry were significantly decreased regardless of the season and soil depth. Between the two afforested sites, these microbial properties were generally higher in the RSF than MEP. However, the microbial properties in the RSF were still lower than those in the UF, although the differences varied with different seasons, soil depths, and microbial groups or enzymes. Our findings demonstrated that afforestation might significantly improve microbial properties. Afforestation is more effective in mixed-species plantation than in the monoculture Eucalyptus plantation but needs a much longer time to approach an equivalent level to the primary forests. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle
Dynamics and Vertical Distribution of Roots in European Beech Forests and Douglas Fir Plantations in Bulgaria
Forests 2019, 10(12), 1123; https://doi.org/10.3390/f10121123 (registering DOI) - 09 Dec 2019
Viewed by 214
Abstract
Identifying patterns in roots spatial distribution and dynamics, and quantifying the root stocks, annual production and turnover rates at species level is essential for understanding plant ecological responses to local environmental factors and climate change. We studied selected root traits in four different [...] Read more.
Identifying patterns in roots spatial distribution and dynamics, and quantifying the root stocks, annual production and turnover rates at species level is essential for understanding plant ecological responses to local environmental factors and climate change. We studied selected root traits in four different stands, two European beech (Fagus sylvatica L.) forests and two Douglas fir (Pseudotsuga menziezii Mirb. Franco) plantations. Root system vertical distribution and dynamics were studied using sequential coring method and characterised into three root diameter size classes (0–2, 2–5 and 5–10 mm) sampled at three different soil depths (0–15, 15–30, 30–45 cm). Root annual production and turnover rates were analysed and quantified using Decision Matrix and Maximum-Minimum estimation approaches. The overall root mass (<10 mm diameter up to 0–45 cm soil depth) was higher in the beech forests than in the Douglas fir plantations. Some root traits, e.g., the overall root mass, the fine (0–2 mm) and small (2–5 mm) roots mass, differed significantly between the sampling plots rather than between the forest types. The root system revealed a tree species specific vertical distribution pattern. More than half of the fine and small roots biomass of the Douglas fir stands were allocated in the uppermost soil layer and decreased significantly with depths, while in the beech forests the biomass was more uniformly distributed and decreased gradually with increasing soil depth. Although both tree species belong to two different plant functional types and the stands were situated in two distantly located regions with different climatic and soil characteristics, we revealed similar trends in the root biomass and necromass dynamics, and close values for the annual production and turnover rates. The mean turnover rates for all studied stands obtained by sequential coring and Decision Matrix were 1.11 yr−1 and 0.76 yr−1 based on mean and maximum biomass data, respectively. They were similar to the averaged values suggested for Central and Northern European forests but higher compared to those reported from Southern Europe. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle
Economic Valuation of Conservation of Inholdings in Protected Areas for the Institution of Payments for Ecosystem Services
Forests 2019, 10(12), 1122; https://doi.org/10.3390/f10121122 - 09 Dec 2019
Viewed by 149
Abstract
Ecosystem services, as public goods, are often undersupplied because private markets do not fully take into account the social cost of production. To alleviate the concern about this imbalance situation, payments for ecosystem services (PES) have emerged as a preferable alternative. While temples [...] Read more.
Ecosystem services, as public goods, are often undersupplied because private markets do not fully take into account the social cost of production. To alleviate the concern about this imbalance situation, payments for ecosystem services (PES) have emerged as a preferable alternative. While temples in Korea have owned a considerable part of the national parks, a PES approach can be used as a viable option to alleviate the conflicts among visitors, non-visitors, and temples. The purpose of this paper is to assess the economic values of ecosystem services provided by temple forests as a compensation mechanism. Using a contingent valuation method, an online survey was conducted with 1000 respondents. Study results showed that the economic benefits of the conservation of temple forests were estimated to be substantial, ranging from ₩5980 (US $5.42) to ₩7709 ($7.08) per household per year. The results also confirmed the effects of social factors such as individuals’ trust in the government’s environmental policies and importance on the conservation of temples’ cultural and religious values on the willingness to pay. With a growing interest in securing ecosystem services through a PES approach, estimating economic benefits of the conservation of inholdings in public protected areas will be a valuable piece of information as an important policy decision-making tool. Full article
(This article belongs to the Special Issue Environmental Valuation and Sustainable Management of Forests)
Open AccessArticle
Interspecific Differences in Canopy-Derived Water, Carbon, and Nitrogen in Upland Oak-Hickory Forest
Forests 2019, 10(12), 1121; https://doi.org/10.3390/f10121121 - 09 Dec 2019
Viewed by 200
Abstract
Oaks (Quercus) are a dominant forest species throughout much of the eastern United States. However, oak regeneration failure due to a myriad of issues (e.g., suppression of natural fire, excess nitrogen deposition, pressure from herbivore activity) is leading to a decline [...] Read more.
Oaks (Quercus) are a dominant forest species throughout much of the eastern United States. However, oak regeneration failure due to a myriad of issues (e.g., suppression of natural fire, excess nitrogen deposition, pressure from herbivore activity) is leading to a decline in oak dominance. This change may alter forest hydrology and nutrients through variation in species characteristics. Throughfall (TF) and stemflow (SF) quantity and chemistry were sampled during storm events under oak and non-oak (hickory, Carya) species to quantify differences in canopy-derived water and nutrients from an upland oak-hickory forest in Mississippi. Stemflow partitioning was 86% higher in hickory species compared to oak species (394.50 L m−2; p < 0.001). Across all species, dissolved organic carbon (DOC) was 1.5 times greater in throughfall (p = 0.024) and 8.7 times greater in stemflow (p < 0.001) compared to rainfall. White oak DOC concentrations (TF: 22.8 ± 5.5 mg L−1; SF: 75.1 ± 9.5 mg L−1) were greater compared to hickory species (TF: 21.0 ± 18.3 mg L−1; SF: 34.5 ± 21.0 mg L−1) (p = 0.048). Results show that while smoother-barked hickory species generate more stemflow volume, rougher-barked oak species generate stemflow that is more enriched in nutrients, which is a function of the canopy characteristics of each species. Within a single stand, this study demonstrates how variable water and nutrient fluxes may be and provide insights into species-level variability in oak-hickory forest types that may be undergoing compositional changes. Full article
(This article belongs to the Special Issue Forests Carbon and Water Dynamics)
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Open AccessArticle
Future Climate Change Will Have a Positive Effect on Populus davidiana in China
Forests 2019, 10(12), 1120; https://doi.org/10.3390/f10121120 - 08 Dec 2019
Viewed by 254
Abstract
Since climate change significantly affects global biodiversity, a reasonable assessment of the vulnerability of species in response to climate change is crucial for conservation. Most existing methods estimate the impact of climate change on the vulnerability of species by projecting the change of [...] Read more.
Since climate change significantly affects global biodiversity, a reasonable assessment of the vulnerability of species in response to climate change is crucial for conservation. Most existing methods estimate the impact of climate change on the vulnerability of species by projecting the change of a species’ distribution range. This single-component evaluation ignores the impact of other components on vulnerability. In this study, Populus davidiana (David’s aspen), a tree species widely used in afforestation projects, was selected as the research subject under four future climate change scenarios (representative concentration pathway (RCP)2.6, RCP4.5, RCP6.0, and RCP8.5). Exposure components of range change as well as the degree of fragmentation, degree of human disturbance, and degree of protection were considered simultaneously. Then, a multicomponent vulnerability index was established to assess the effect of future climate change on the vulnerability of P. davidiana in China. The results show that the distribution range of P. davidiana will expand to the northwest of China under future climate change scenarios, which will lead to an increased degree of protection and a decreased degree of human disturbance, and hardly any change in the degree of fragmentation. The multicomponent vulnerability index values of P. davidiana under the four emission scenarios are all positive by 2070, ranging from 14.05 to 38.18, which fully indicates that future climate change will be conducive to the survival of P. davidiana. This study provides a reference for the development of conservation strategies for the species as well as a methodological case study for multicomponent assessment of species vulnerability to future climate change. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle
Leaf Physiological Responses to Drought Stress and Community Assembly in an Asian Savanna
Forests 2019, 10(12), 1119; https://doi.org/10.3390/f10121119 - 08 Dec 2019
Viewed by 246
Abstract
Deciduous dipterocarp forest (DDF) is the most extensive forest type in continental Southeast Asia, but across much of its range is functionally more similar to tropical savannas than tropical forests. We investigated water relations and drought responses of the four dominant tree species [...] Read more.
Deciduous dipterocarp forest (DDF) is the most extensive forest type in continental Southeast Asia, but across much of its range is functionally more similar to tropical savannas than tropical forests. We investigated water relations and drought responses of the four dominant tree species (two Shorea and two Dipterocarpus species) of the DDF in central Vietnam to determine how they responded to prolonged periods of drought stress. We quantified leaf water relations in nursery- and field-grown seedlings of the four species and conducted a dry-down experiment on 258 seedlings to study leaf water potential and morphological responses of the seedlings following the drought stress. The two Shorea and two Dipterocarpus species differed significantly in leaf water potential at turgor loss point and osmotic potential at full turgor, but they showed similar responses to drought stress. All species shed leaves and suffered from stem loss when exposed to water potentials lower than their turgor loss point (approximately −1.7 MPa for Dipterocarpus and −2.6 MPa for Shorea species). Upon rewatering, all species resprouted vigorously regardless of the degree of leaf or stem loss, resulting in only 2% whole-plant mortality rate. Our results suggest that none of the four deciduous dipterocarp species is drought tolerant in terms of their water relations; instead, they employ drought-adaptive strategies such as leaf shedding and vigorous resprouting. Given that all species showed similar drought avoidance and drought-adaptive strategies, it is unlikely that seasonal drought directly influences the patterns of species assembly in the DDF of Southeast Asia. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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Open AccessArticle
Past Management Spurs Differential Plant Communities within a Giant Single-Clone Aspen Forest
Forests 2019, 10(12), 1118; https://doi.org/10.3390/f10121118 - 07 Dec 2019
Viewed by 233
Abstract
Sustainable aspen ecosystems hold great promise for global biodiversity conservation. These forests harbor relatively high species diversity, yet are threatened by fire suppression, land development, timber-focused management, extended droughts, and chronic herbivory. “Pando” is a high-profile quaking aspen (Populus tremuloides) forest in Utah, [...] Read more.
Sustainable aspen ecosystems hold great promise for global biodiversity conservation. These forests harbor relatively high species diversity, yet are threatened by fire suppression, land development, timber-focused management, extended droughts, and chronic herbivory. “Pando” is a high-profile quaking aspen (Populus tremuloides) forest in Utah, USA which is putatively the ‘largest living organism on earth.’ Pando comprises an estimated 47,000 genetically identical stems, but is threatened by human impacts. Our interest in the present study is whether changes to the giant organism were affecting understorey vegetation and whether discrete zones are displaying divergent community compositions. For instance, recent research has demonstrated strong herbivory impacts that are affecting portions of Pando differentially. This study consists of 20 randomly distributed vegetation survey plots within three de facto management regimes (hereafter, management group or type) along an herbivory protection gradient: No Fence, 2013 Fence (total protection), and 2014 Fence (imperfect protection). The plant survey was supplemented by previously-established forest and herbivore measurements to test for community assemblage explanatory agents. Sixty-eight species were found across the entire study. Analyses indicated strong links between management group orientation, species assemblages, and tree density/canopy openings. We found distinct evidence that within management group species composition was more similar than across groups for two of the three pairings. However, the other pairing, the most successfully protected area and the completely unprotected area, was not statistically distinct; likely a result a deteriorating overstorey in these two areas, whereas the third management type (2014 Fence) exhibited higher canopy cover. Indicator species analysis found that a small group of plant species had statistical allegiances to specific management groups, suggesting resource preference selection within Pando. Ordination analysis searching for causal factors reached two broad conclusions: (1) aspen regeneration, and therefore long-term resilience, is being negatively affected by chronic animal browsing and (2) current understorey species diversity is highest where forest canopy gaps are abundant. Future research at the massive Pando clone will continue informing linkages between understorey communities and overstorey-driven ecological pathways. Full article
(This article belongs to the Section Forest Ecology and Management)
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