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Forests
Volume 15
Issue 7
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Forests, Volume 15, Issue 7 (July 2024) – 204 articles

Cover Story (view full-size image): In European mountains, most beech forests are managed for timber production. In Italy's central Apennines (Tuscany), we studied beetle abundance, diversity, similarity, and commonness/rarity in five beech-dominated forests with increasing management intensity. Three forests were managed with even-aged shelterwood systems, including one with continuous cover forestry and one with old growth. We found that the old-growth forest harbored more threatened species than the managed sites. The variation in taxonomic spectrum of saproxylic communities reflected differences in forest management. The impact of management on beetle communities was better explained by evaluating their taxonomic structure rather than only total species abundance and diversity, offering more insights into sustainable forestry. View this paper
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18 pages, 2089 KiB  
Article
Trade Creation or Diversion?—Evidence from China’s Forest Wood Product Trade
by Lei Gao, Taowu Pei and Yu Tian
Forests 2024, 15(7), 1276; https://doi.org/10.3390/f15071276 - 22 Jul 2024
Cited by 1 | Viewed by 959
Abstract
In recent years, trade protectionism and unilateralism have prevailed, and countries around the world have imposed restrictions on log exports. It has also become more difficult for China to import wood resources and export deep-processed wood forest products. Based on panel data from [...] Read more.
In recent years, trade protectionism and unilateralism have prevailed, and countries around the world have imposed restrictions on log exports. It has also become more difficult for China to import wood resources and export deep-processed wood forest products. Based on panel data from 2000 to 2019, this study uses social network analysis to measure the level of the Chinese wood forest product trade network, takes the Chinese free trade agreements (FTAs) as the natural experiment, and uses the multi-stage double-difference method to investigate the impact of the signed FTAs on China’s wood forest product trade. The study finds that the trade network of Chinese wood forest products is becoming increasingly complex, and the central position of China and the Association of Southeast Asian Nations (ASEAN) in the network is increasing year by year. The signing of FTAs has had a significant positive impact on the trade of wood forest products in China and a significant trade creation effect. This finding remains true after conducting the placebo test and propensity score-matched regression control. At the same time, the import of wood forest products in China will have a significant trade transfer effect due to the signing of FTAs, and this will not affect exports. Although FTAs show significant trade creation and trade transfer effects in China’s wood forest product trade, they also increase, to a certain extent, the mismatch of forest resources worldwide. Full article
(This article belongs to the Special Issue Economic Valuation of Forest Resources)
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13 pages, 2075 KiB  
Article
The Effect of Hardwood Veneer Densification on Plywood Density, Surface Hardness, and Screw Withdrawal Capacity
by Heikko Kallakas, Tolgay Akkurt, Alexander Scharf, Fred Mühls, Anti Rohumaa and Jaan Kers
Forests 2024, 15(7), 1275; https://doi.org/10.3390/f15071275 - 22 Jul 2024
Viewed by 720
Abstract
Increasing environmental awareness and the carbon-storing capability of wood have amplified its relevance as a building material. The demand for high-quality wood species necessitates exploring alternative, underutilized wood sources due to limited forest areas and premium wood volume. Consequently, the veneer-based industry is [...] Read more.
Increasing environmental awareness and the carbon-storing capability of wood have amplified its relevance as a building material. The demand for high-quality wood species necessitates exploring alternative, underutilized wood sources due to limited forest areas and premium wood volume. Consequently, the veneer-based industry is considering lower-value hardwood species like grey alder (Alnus Incania), black alder (Alnus glutinosa), and aspen (Populus tremula) as substitutes for high-quality birch (Betula pendula). Initially less appealing due to their lower density and mechanical properties, these species show promise through densification, which enhances their density, strength, and hardness. This study aims to enhance plywood screw withdrawal capacity and surface hardness by densifying low-density wood species and using them in plywood face-veneer layers, or in all layers. The relationship between the wood density, surface hardness, and screw withdrawal capacity of plywood made of low-value species like aspen and black alder is examined. Experimental work with a pilot-scale veneer and plywood production line demonstrates improved surface hardness (65% and 93% for aspen and black alder, respectively) and screw withdrawal capacity (16% and 35% for aspen and black alder, respectively) in densified face veneer plywood. This research highlights the potential of densified low-value wood species to meet construction requirements, expanding their practical applications. Full article
(This article belongs to the Section Wood Science and Forest Products)
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13 pages, 24160 KiB  
Article
Evaluation of the Potentials of Tobacco Waste Extract as Wood Preservatives against Wood Decay Fungi
by Lin Liu, Junkai Tian, Ziyao Zhou, Chunwang Yang, Susu Yang, Kangkang Zhang, Yushan Yang and Jian Qiu
Forests 2024, 15(7), 1274; https://doi.org/10.3390/f15071274 - 22 Jul 2024
Viewed by 854
Abstract
Utilizing conventional wood preservatives poses potential risks to ecosystems and human health. Therefore, the wood protection industry must develop alternatives that are both efficient and environmentally friendly. In this paper, industrial tobacco waste extracts were used as eco-friendly wood preservatives against wood decay [...] Read more.
Utilizing conventional wood preservatives poses potential risks to ecosystems and human health. Therefore, the wood protection industry must develop alternatives that are both efficient and environmentally friendly. In this paper, industrial tobacco waste extracts were used as eco-friendly wood preservatives against wood decay fungi. Three major constituents in the extracts were identified via gas chromatography-mass spectrometry (GC-MS) and included nicotine, neophytadiene, and 2,7,11-cembratriene-4,6-diol. The antifungal activities of waste tobacco extracts and these three major constituents against wood decay fungi were tested. At a concentration of 40 mg/mL, the tobacco waste extract treated with 50% ethanol significantly inhibited the activity of wood decay fungi. This was because the extract contained nicotine as the primary active component and neophytadiene as a synergistic active component. Wood decay resistance tests were conducted on Pinus yunnanensis and Hevea brasiliensis treated with a 50% ethanol extract of tobacco waste at a concentration of 40 mg/mL. The mass losses of Pinus yunnanensis exposed to G. trabeum and T. versicolor were 4.11% and 5.03%, respectively, while the mass losses in Hevea brasiliensis exposed to G. trabeum and T. versicolor were 7.85% and 9.85%, respectively, which were classified as highly resistant. The acute ecotoxicity of the tobacco waste extract was assessed using a kinetic luminescent bacteria test with Aliivibrio fischeri, which revealed significantly lower acute toxicity than a commercial copper-based wood preservative. This study offers insights into high-value utilization of tobacco waste and advancement of natural wood preservatives. Full article
(This article belongs to the Special Issue Advances in Testing the Biological Durability and Quality Assurance of Wood-Based Materials and Products)
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23 pages, 3969 KiB  
Article
Distribution Patterns and Environmental Determinants of Invasive Alien Plants on Subtropical Islands (Fujian, China)
by Yanqiu Xie, Xinran Xie, Feifan Weng, Liebo Nong, Manni Lin, Jingyao Ou, Yingxue Wang, Yue Mao, Ying Chen, Zhijun Qian, Xiaoxue Lu, Zujian Chen, Yushan Zheng, Chuanyuan Deng and Hui Huang
Forests 2024, 15(7), 1273; https://doi.org/10.3390/f15071273 - 22 Jul 2024
Cited by 1 | Viewed by 715
Abstract
Plant invasions threaten the biodiversity of islands, causing serious impacts on their ecosystems. To investigate the distribution patterns of invasive alien plants on subtropical islands, the environmental determinants of species richness, and the growth forms of invasive alien plants, this study analyzed the [...] Read more.
Plant invasions threaten the biodiversity of islands, causing serious impacts on their ecosystems. To investigate the distribution patterns of invasive alien plants on subtropical islands, the environmental determinants of species richness, and the growth forms of invasive alien plants, this study analyzed the composition and origin of invasive alien plants on 77 islands in Fujian. The similarity in the distribution of invasive alien plants between islands was assessed using the UPGMA. Moreover, feature selection, best-subset regression, and variance decomposition were performed using 19 environmental variables characterizing climate, anthropogenic disturbance, and landscape/geography, as well as the species richness and growth forms of invasive alien plants. Through the analysis, the main environmental factors affecting the species richness and growth forms of invasive alien plants on the Fujian islands were identified. The results showed 142 species of invasive alien plants in 38 families and 102 genera on 77 islands in Fujian. Annual herbs constituted the most representative growth form of invasive alien plants and tropical America was the main origin of invasive alien plants. The distribution of invasive alien plants across the 77 islands in Fujian showed a high degree of similarity, suggesting a nested pattern in their distribution. The proportions of building and farmland area (BFA), island area (A), and maximum elevation (ME) were the main driving factors of species richness and growth forms for invasive alien plants. In particular, BFA played a key role in driving plant invasion. The results of this study can help establish an early warning mechanism for invasive alien plants and better implement island ecological management, which are important for the protection of subtropical island ecosystems. Full article
(This article belongs to the Section Forest Ecology and Management)
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14 pages, 4802 KiB  
Article
Tree-Ring δ13C and Intrinsic Water-Use Efficiency Reveal Physiological Responses to Climate Change in Semi-Arid Areas of North China
by Weiwei Lu, Bo Wu, Xinxiao Yu, Guodong Jia, Ying Gao, Lili Wang and Anran Lu
Forests 2024, 15(7), 1272; https://doi.org/10.3390/f15071272 - 22 Jul 2024
Viewed by 701
Abstract
Climate change has had a widespread and profound impact on global temperature and precipitation patterns, especially in semi-arid areas. Plant δ13C and iWUE indicate the trade-off between carbon uptake and water loss, which is pivotal for understanding plant responses to climate [...] Read more.
Climate change has had a widespread and profound impact on global temperature and precipitation patterns, especially in semi-arid areas. Plant δ13C and iWUE indicate the trade-off between carbon uptake and water loss, which is pivotal for understanding plant responses to climate change. Information about the long-term responses of the physiological and ecological processes of different tree species to climate change is also required. To investigate the impact of different forest stand structures and site conditions on long-term growth and physiological processes of coniferous and broad-leaved trees in the mountainous area of Beijing, we analyzed the tree-ring δ13C variation of four tree species (Platycladus orientalis, Pinus tabuliformis, Quercus variabilis, Robinia pseudoacacia) sampled from 64 plots with varying site and stand conditions. We found that the tree-ring δ13C of the four tree species varied from each other and was mainly affected by density and slope aspect, followed by slope and age. Both tree-ring δ13C and iWUE of the four tree species showed increasing trends over time, mechanistically linked to long-term changes in global CO2 concentration. This indicates the four native tree species have adapted well to climate change, and the risk of decline is relatively low. The increased iWUE translated into different growth patterns which varied with tree species, site, and stand condition. Different tree species have varying sensitivities to environmental factors. The iWUE of coniferous tree species is more sensitive to climate change than that of broad-leaved tree species, especially to temperature (T), the Standardized Precipitation Evapotranspiration Index (SPEI), and vapor pressure deficit (VPD). Full article
(This article belongs to the Special Issue Construction and Maintenance of Desert Forest Plantation)
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18 pages, 4474 KiB  
Article
Effects and Modification Mechanisms of Different Plasma Treatments on the Surface Wettability of Different Woods
by Zhigang Duan, Yongzhi Fu, Guanben Du, Xiaojian Zhou, Linkun Xie and Taohong Li
Forests 2024, 15(7), 1271; https://doi.org/10.3390/f15071271 - 21 Jul 2024
Viewed by 896
Abstract
Plasma treatment of wood surfaces has shown significant effects, but different excitation methods used for different species of wood generally result in varied characteristics of wood surfaces. Secondly, plasma modification greatly enhances the absorption of liquids by wood, but the relationship between liquid [...] Read more.
Plasma treatment of wood surfaces has shown significant effects, but different excitation methods used for different species of wood generally result in varied characteristics of wood surfaces. Secondly, plasma modification greatly enhances the absorption of liquids by wood, but the relationship between liquid absorption and surface wettability is rarely studied. Limited detailed investigation of the modification effects and mechanisms has hindered the large-scale applications of plasma treatment in the wood industry. In this study, two typical plasmas, radio frequency (RF) plasma and gliding arc discharge (GAD) plasma, were employed to treat three species of wood: poplar, black walnut, and sapele. By focusing on changes in the contact angle of the wood surface, an exponential equation fitting method is used to determine the measurement time for contact angles. The research identified that factors contributing to the decrease in contact angle after plasma modification include not only the increase in surface energy but also liquid absorption. SEM and XPS analyses demonstrate that plasma etching accelerated liquid absorption by modifying the surface topography, while the increase in surface energy was due to the addition of oxygen-containing groups. High-valence C=O and O-C=O groups serve as indicators of plasma-induced surface chemical reactions. RF modification primarily features surface etching, whereas GAD significantly increases the active surface groups. Thus, different plasmas, due to their distinct excitation modes, produce diverse modification effects on wood. Considering the various physical and chemical properties of plasma-modified wood surfaces, recommendations for adhesive use on plasma-modified wood are provided. Full article
(This article belongs to the Section Wood Science and Forest Products)
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17 pages, 9896 KiB  
Article
Effects of Natural Vegetation Restoration on Soil Physicochemical Properties in Tropical Karst Areas, Southwestern China
by Bei Zhang, Gang Hu, Chaohao Xu, Cong Hu, Chaofang Zhong, Siyu Chen and Zhonghua Zhang
Forests 2024, 15(7), 1270; https://doi.org/10.3390/f15071270 - 21 Jul 2024
Cited by 1 | Viewed by 895
Abstract
Natural soil and vegetation recovery following human disturbance is the primary means of restoring degraded ecosystems globally. However, it remains unclear how vegetation recovery in the tropical karst areas of China affects the soil physicochemical properties. Here, we investigated the impacts of natural [...] Read more.
Natural soil and vegetation recovery following human disturbance is the primary means of restoring degraded ecosystems globally. However, it remains unclear how vegetation recovery in the tropical karst areas of China affects the soil physicochemical properties. Here, we investigated the impacts of natural vegetation recovery on soil physicochemical properties at different soil depths in tropical karst areas in southwestern China, using a space–time substitution method. We found that with the natural vegetation recovery, soil bulk density (SBD) decreased. Soil pH initially decreased and then increased, reaching its lowest value during the shrubland stage. There was a significant increase in other soil physicochemical factors. In the soil profiles, SBD tended to increase with depth. The pH, total potassium (TK), total phosphorus (TP), and exchangeable calcium remained relatively stable across the different soil layers. TK, TP, available phosphorus, SBD, total nitrogen, pH, exchangeable magnesium, and available potassium significantly contributed to the soil physicochemical properties. Soil physicochemical properties were predominantly directly affected by litter and biological factors, albeit indirectly influenced by topographic factors. Our study provides crucial insights into karst soils and their relationship with vegetation recovery, which are pivotal for steering vegetation restoration and soil amelioration in karst areas. Full article
(This article belongs to the Section Forest Soil)
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16 pages, 8131 KiB  
Article
Forest Structure Regulates Response of Erosion-Induced Carbon Loss to Rainfall Characteristics
by Weiwei Wang, Chao Xu, Teng-Chiu Lin, Zhijie Yang, Xiaofei Liu, Decheng Xiong, Shidong Chen, Guangshui Chen and Yusheng Yang
Forests 2024, 15(7), 1269; https://doi.org/10.3390/f15071269 - 21 Jul 2024
Viewed by 675
Abstract
Forestation is a common measure to control erosion-induced soil and carbon (C) loss, but the effect can vary substantially between different types of forest. Here, we measured event-based runoff, soil, dissolved organic carbon (DOC), particulate organic carbon (POC) and total C loss with [...] Read more.
Forestation is a common measure to control erosion-induced soil and carbon (C) loss, but the effect can vary substantially between different types of forest. Here, we measured event-based runoff, soil, dissolved organic carbon (DOC), particulate organic carbon (POC) and total C loss with runoff plots (20 m × 5 m) in a broad-leaved and a coniferous forest in subtropical China and explored their relationships with rainfall amount, average intensity, maximum 5-min intensity and rainfall erosivity. The broad-leaved forest had a denser canopy but sparse understory vegetation while the coniferous forest had a relatively open canopy but dense understory vegetation. The results showed that runoff, soil, DOC, POC and total C losses were all significantly higher in the broad-leaved forest than the coniferous forest despite the potentially higher canopy interception associated with the greater leaf area index of the broad-leaved forest. The mean runoff in the broad-leaved forest was 3.03 ± 0.20 m3 ha−1 event−1 (mean ± standard error) and 12.49 ± 0.18 m3 ha−1 event−1 in the coniferous forest. The mean soil, DOC, POC and total C loss (kg ha−1 event−1) was 1.12 ± 0.16, 0.045 ± 0.003, 0.118 ± 0.016 and 0.163 ± 0.017, respectively, in the broad-leaved forest and 0.66 ± 0.09, 0.020 ± 0.002, 0.060 ± 0.009 and 0.081 ± 0.010, respectively, in the coniferous forest. Runoff and DOC losses were driven by rainfall in two forests, but the key rainfall characteristic driving soil, POC and total C losses was different in the broad-leaved forest from that in the coniferous forest due to their different understory patterns. Soil, POC and total C losses were mostly driven by rainfall amount in the broad-leaved forest but by EI30 in the conifer forest. Our findings highlight that the response of erosion-induced carbon loss to rainfall characteristics differs between different forest types of the same age but contrasting overstory and understory vegetation covers. Moreover, our study underscores the overlooked significance of understory vegetation in regulating these effects. Thus, we call for the inclusion of understory vegetation in the modeling of soil and carbon erosion in forest ecosystems. Full article
(This article belongs to the Section Forest Ecology and Management)
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4 pages, 665 KiB  
Editorial
Wood Modification—Trends and Combinations
by Morwenna J. Spear and Miklós Bak
Forests 2024, 15(7), 1268; https://doi.org/10.3390/f15071268 - 20 Jul 2024
Viewed by 608
Abstract
Wood modification is a field that has enjoyed sustained interest over the past two decades, although its history can be tracked back significantly further, to the pioneering work of Alfred Stamm and co-workers at the Forest Products Laboratory in the USA in the [...] Read more.
Wood modification is a field that has enjoyed sustained interest over the past two decades, although its history can be tracked back significantly further, to the pioneering work of Alfred Stamm and co-workers at the Forest Products Laboratory in the USA in the 1930s, 1940s, and 1950s [...] Full article
(This article belongs to the Special Issue Wood Modification: Optimisation and Characterisation of Modified Timbers)
17 pages, 4790 KiB  
Article
Integration of Illumina and PacBio HiFi Sequencing Reveals a Three-Linear-Molecule Mitogenome with RNA-Editing Sites and Phylogeny in Arrow Bamboo (Fargesia qinlingensis)
by Hao Wu, Xue Li, Ke Qu, Lele Yang, Tao Su, Lijun Yong, Mei Han and Fuliang Cao
Forests 2024, 15(7), 1267; https://doi.org/10.3390/f15071267 - 20 Jul 2024
Viewed by 870
Abstract
Arrow bamboo (Fargesia qinlingensis) is endemic to the Qinling Mountains and has remarkable adaptive resilience to changing climates. However, its complete mitogenome remains unknown. Using the Illumina and PacBio HiFi sequencing platforms, we found that the mitogenome assembly of the F. [...] Read more.
Arrow bamboo (Fargesia qinlingensis) is endemic to the Qinling Mountains and has remarkable adaptive resilience to changing climates. However, its complete mitogenome remains unknown. Using the Illumina and PacBio HiFi sequencing platforms, we found that the mitogenome assembly of the F. qinlingensis has a multi-branched skeleton comprising three linear molecules (M1, M2, and M3), with a length of 442,368 bp and a GC content of 44.05%. Thirty-five unique PCGs were identified in the complete mitogenome, including twenty-four core structural genes, eleven noncore structural genes, three rRNAs, and sixteen tRNAs. The GCU for alanine and CAA for glutamine represented the most significant frequency (RSCU = 1.55) in the codon usage preference. A total of 51, 28, and 14 SSRs were determined on M1, M2, and M3, respectively. The mitogenome contained 149 pairs of dispersed repeats with lengths greater than 30 bp, the most abundant of which were 82 forward and 67 palindromic repeats. A long repeat sequence (14,342 bp) was characterized in mediating mitogenome recombination. DNA transfer analyses suggested that 44 MTPTs (30,943 bp, 6.99%) originated from the plastome. Among the 482 potential C-U/T RNA-editing sites predicted in 35 PCGs, ccmFn (38 times) and ccmC (36 times) shoed the highest frequency. Collinearity and phylogenetic trees revealed the close relationship between F. qinlingensis and Bambusa oldhamii. The primary features of the mitogenome of F. qinlingensis will help decipher the functional mitochondrial traits related to growth performance and climate resilience. Moreover, our findings provide insights into the evolution, environmental adaptation, and sustainable use of subalpine bamboo resources in the Qinling Mountains. Full article
(This article belongs to the Special Issue Genomic Analysis of Growth and Stress Adaptation in Forest Trees)
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21 pages, 2561 KiB  
Article
Predicting the Integrated Fire Resistance of Wildland–Urban Interface Plant Communities by Spatial Structure Analysis Learning for Shanghai, China
by Manqing Yao, Deshun Zhang, Ruilin Zhu, Zhen Zhang and Mohamed Elsadek
Forests 2024, 15(7), 1266; https://doi.org/10.3390/f15071266 - 20 Jul 2024
Viewed by 629
Abstract
Fire is a prevalent hazard that poses a significant risk to public safety and societal progress. The continuous expansion of densely populated urban areas, exacerbated by global warming and the increasing intensification of urban heat islands, has led to a notable increase in [...] Read more.
Fire is a prevalent hazard that poses a significant risk to public safety and societal progress. The continuous expansion of densely populated urban areas, exacerbated by global warming and the increasing intensification of urban heat islands, has led to a notable increase in the frequency and severity of fires worldwide. Incorporating measures to withstand different types of calamities has always been a crucial aspect of urban infrastructure. Well-designed plant communities play a pivotal role as a component of green space systems in addressing climate-related challenges, effectively mitigating the occurrence and spread of fires. This study conducted field research on 21 sites in the green belt around Shanghai, China, quantifying tree morphological indexes and coordinate positions. The spatial structure attributes of different plant communities were analyzed by principal component analysis, CRITIC weighting approach, and stepwise regression analysis to build a comprehensive fire resistance prediction model. Through this research, the relationship between community spatial structures and fire resistance was explored. A systematic construction of a prediction model based on community spatial structures for fire resistance was undertaken, and the fire resistance performance could be quickly judged by easily measured tree morphological indexes, providing valuable insights for the dynamic prediction of fire resistance. According to the evaluation and ranking conducted by the prediction model, the Celtis sinensis, Sapindus saponaria, Osmanthus fragrans, Koelreuteria paniculata, and Distylium racemosum + Populus euramericana ‘I-214’ communities exhibited a high level of fire resistance. On the other hand, the Koelreuteria bipinnata + Ligustrum lucidum, Ginkgo biloba + Camphora officinarum + Ligustrum lucidum, and Ligustrum lucidum + Sapindus saponaria communities obtained lower scores and were positioned lower in the ranking. It is emphasized that the integration of monitoring and regulation is essential to ensure the ecological integrity and well-being of green areas in the Wildland–Urban Interface. Full article
(This article belongs to the Section Urban Forestry)
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16 pages, 5399 KiB  
Article
Altitudinal Difference of Growth–Climate Response Models in the Coniferous Forests of Southeastern Tibetan Plateau, China
by Shanshan Xu, Chaogang Zheng, Zhigang Zhang, Zhiyuan Shang, Xinggong Kong and Zhijun Zhao
Forests 2024, 15(7), 1265; https://doi.org/10.3390/f15071265 - 20 Jul 2024
Viewed by 667
Abstract
Characterized as a climatologically sensitive region, the southeastern Tibetan Plateau (STP) is an ideal location for dendrochronological research. Here, five tree-ring width (TRW) chronologies were developed: three for Picea likiangensis along altitudinal gradients from 3600 to 4400 m a.s.l. and two for Sabina [...] Read more.
Characterized as a climatologically sensitive region, the southeastern Tibetan Plateau (STP) is an ideal location for dendrochronological research. Here, five tree-ring width (TRW) chronologies were developed: three for Picea likiangensis along altitudinal gradients from 3600 to 4400 m a.s.l. and two for Sabina saltuaria and Abies squamata from 4200 m a.s.l. Significant differences in the growth rates and age composition of Picea likiangensis were observed at various elevation gradients. The chronology statistics (mean sensitivity, etc.) fluctuated with the elevation gradient. Picea likiangensis showed distinct growth patterns in response to climatic variability along the altitude gradient: the minimum temperature influenced tree growth at lower and middle altitudes, while higher altitudes were affected by precipitation. The radial growth of different tree species growing in the same region is controlled by the same climatic factors. Sabina saltuaria and Abies squamata exhibited similar growth responses to Picea likiangensis. Stand conditions (wind speeds, slope, and elevation) and biotic factors (the depth of root, forest type, tree age, and sensitivity) can partially explain why the ring width–climate relationships change with altitude. Full article
(This article belongs to the Section Forest Meteorology and Climate Change)
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16 pages, 2871 KiB  
Article
Sensitivity of Fire Indicators on Forest Inventory Plots Is Affected by Fire Severity and Time since Burning
by James E. Smith and Coeli M. Hoover
Forests 2024, 15(7), 1264; https://doi.org/10.3390/f15071264 - 20 Jul 2024
Viewed by 800
Abstract
Forest inventory data are useful for determining forest stand structure, growth, and change. Among the information collected on forest inventory plots by the USDA Forest Service Forest Inventory and Analysis Program, attributes characterizing various types of disturbance provide researchers a means of selecting [...] Read more.
Forest inventory data are useful for determining forest stand structure, growth, and change. Among the information collected on forest inventory plots by the USDA Forest Service Forest Inventory and Analysis Program, attributes characterizing various types of disturbance provide researchers a means of selecting plots specifically affected by disturbances, such as fire. We determine the performance of three of these attributes as indicators of recent fires on forest inventory plots of the United States by comparing them to independent records of wildland fire occurrence. The indicators are plot-level observations of fire effects on (1) general site appearance, (2) tree mortality, and (3) damage to live trees. Independent spatial layers of wildland fire perimeters provide an approach to test indicator performance and identify characteristics of fires that may affect detection. The sensitivities of indicators are generally higher in the West relative to the East. Detection rates exceed 90 percent for the Pacific Coast forests but seldom reach 80 percent in the East. Among the individual indicators, site appearance has higher identification rates than tree indicators for fires in the Pacific Coast, Great Plains, North, and South regions. Tree mortality is the most important single indicator for identifying Rocky Mountain fires. Tree damage is more important than tree mortality in the South; otherwise, the tree damage indicator is of relatively lower importance, particularly where high-severity fires are common, and tree survival is low. The rate of detection by the indicators is affected by the severity of the fire or the recency of the fire. The joint effect of severity and recency influence all three indicators for the Pacific Coast and Rocky Mountain fires, as well as the site appearance indicator in the South. Only a small proportion of fires are clearly missed by all three of the indicators. Full article
(This article belongs to the Section Natural Hazards and Risk Management)
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21 pages, 58839 KiB  
Article
Analysis of Driving Factors for Vegetation Ecological Quality Based on Bayesian Network
by Jin Cai, Xiaojian Wei, Fuqing Zhang and Yuanping Xia
Forests 2024, 15(7), 1263; https://doi.org/10.3390/f15071263 - 19 Jul 2024
Viewed by 796
Abstract
Vegetation is a crucial component of ecosystems, and understanding the drivers and spatial optimization patterns of its ecological quality is vital for environmental management in the middle reaches of the Yangtze River Urban Agglomeration. Traditional evaluations employing single indices may not fully capture [...] Read more.
Vegetation is a crucial component of ecosystems, and understanding the drivers and spatial optimization patterns of its ecological quality is vital for environmental management in the middle reaches of the Yangtze River Urban Agglomeration. Traditional evaluations employing single indices may not fully capture the complexity of vegetation elements and require evaluation through various indicators. Therefore, this study introduced the Multi Criteria Vegetation Ecological Quality Index (VEQI), coupled with vegetation cover and vegetation ecological function indicators, to explore the driving factors of vegetation quality in the middle reaches of the Yangtze River and identify key areas where vegetation quality declines or improves. By constructing a Bayesian network for VEQI, we identified the driving variables that influence the index. Additionally, we delineated spatial optimization zones for VEQI. The results indicate that the VEQI exhibits a trend of transitioning from low values in urban centers to high values in suburban and rural areas. Over 20 years, the average VEQI of the study region ranged from 10.85% to 94.94%. Slope, DEM, and vegetation type were identified as significant drivers of VEQI, while precipitation, temperature, and nighttime light were considered secondary factors. Notably, areas in Hunan, Jiangxi, and Hubei provinces, especially the western part of Hunan, were pinpointed as spatial optimization regions. This research not only enhances the understanding of vegetation’s ecological quality in the urban agglomeration of the middle reaches of the Yangtze River but also provides scientific insights for the protection and management of vegetation. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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13 pages, 3722 KiB  
Article
Temporal Variations in Enzymatic and Non-Enzymatic Antioxidant Activity in Silver Birch (Betula pendula Roth.): The Genetic Component
by Vaida Sirgedaitė-Šėžienė, Ieva Čėsnienė and Dorotėja Vaitiekūnaitė
Forests 2024, 15(7), 1262; https://doi.org/10.3390/f15071262 - 19 Jul 2024
Viewed by 774
Abstract
Betula pendula Roth. (silver birch) is a pioneer species in the Northern Hemisphere forests. It plays a significant role in various ecosystems, human industries, and biodiversity. Taking all this into account, understanding the genetic diversity within B. pendula populations is crucial for fully [...] Read more.
Betula pendula Roth. (silver birch) is a pioneer species in the Northern Hemisphere forests. It plays a significant role in various ecosystems, human industries, and biodiversity. Taking all this into account, understanding the genetic diversity within B. pendula populations is crucial for fully exploiting their potential, particularly regarding their production of phenolic compounds and antioxidants. We tested the non-enzymatic and enzymatic antioxidant activity in seven silver birch half-sib family leaves. Spectrophotometric data from leaf extracts showed that there was a significant variation between families in terms of total phenol content (TPC) and antioxidant enzyme (superoxide dismutase, peroxidase (POX), catalase, glutathione reductase, and ascorbate peroxidase) levels. The data were gathered during two consecutive seasons, resulting in a variance in antioxidant production, which generally increased in the tested families during the second year (except for POX) as opposed to the first vegetative season. For example, SOD levels increased in the second year by 15% to 243% and TPC increased by 46%–189%, depending on the half-sib family. A more thorough study of this variation should prove beneficial in various research fields, ranging from climate change to cosmetics. Full article
(This article belongs to the Special Issue Adaptive Mechanisms of Tree Seedlings to Adapt to Stress—Second Edition)
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17 pages, 5108 KiB  
Article
Spatial Pattern and Environmental Driving Factors of Treeline Elevations in Yulong Snow Mountain, China
by Chuan Lin, Lisha Yang, Ruliang Zhou, Tianxiang Zhang, Yuling Han and Yanxia Wang
Forests 2024, 15(7), 1261; https://doi.org/10.3390/f15071261 - 19 Jul 2024
Viewed by 727
Abstract
The southwestern region of China is a global biodiversity hotspot. Understanding the environmental mechanisms behind treeline formation in high-altitude areas is crucial for predicting ecosystem changes, such as the upward movement of the treeline due to climate warming and the disappearance of high-altitude [...] Read more.
The southwestern region of China is a global biodiversity hotspot. Understanding the environmental mechanisms behind treeline formation in high-altitude areas is crucial for predicting ecosystem changes, such as the upward movement of the treeline due to climate warming and the disappearance of high-altitude rocky beach and shrub ecosystems. Globally, observations show that growing seasonal temperatures at treelines are typically 6–7 °C, but trees do not always reach the predicted elevations. Spatial heterogeneity exists in the deviation (Dtreeline) between actual treeline elevation and the thermal treeline; however, the main driving factors for Dtreeline in many areas remain unclear. This study uses Yulong Snow Mountain as an example, employing machine learning methods like Support Vector Machine (SVM) to precisely identify actual treeline elevation and Extreme Gradient Boosting Tree (XGBoost) to explore the main environmental factors driving the spatial heterogeneity of Dtreeline. Our research found that (1) more than half of the treelines deviated from the thermal treeline, with the average elevation of the thermal treeline (3924 ± 391 m) being about 56 m higher than the actual treeline (3863 ± 223 m); (2) Dtreeline has a complex relationship with environmental factors. In addition to being highly correlated with temperature, precipitation and wind speed also significantly influence the treeline in this region; and (3) the influence of individual variables such as precipitation and wind speed on the spatial variation of Dtreeline is limited, often nonlinear, and involves threshold effects. This knowledge is essential for developing comprehensive protection strategies for Yunnan’s high-altitude ecological systems in response to climate warming. Furthermore, it plays a significant role in understanding the changes in biological communities and the response of high-altitude areas to climate change. Full article
(This article belongs to the Section Forest Ecology and Management)
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18 pages, 3283 KiB  
Article
Soil Organic Carbon in Mid-Atlantic Region Forest Soils: Stocks and Vertical Distribution
by Daniel J. Colopietro and Ray R. Weil
Forests 2024, 15(7), 1260; https://doi.org/10.3390/f15071260 - 19 Jul 2024
Viewed by 880
Abstract
Over a period of 10 years, 418 forested plots within the US National Capital Region parks were visited for morphological descriptions and to inventory carbon (C) stocks. Samples were collected from organic horizons, the loose leaf litter, and, using a hand auger, from [...] Read more.
Over a period of 10 years, 418 forested plots within the US National Capital Region parks were visited for morphological descriptions and to inventory carbon (C) stocks. Samples were collected from organic horizons, the loose leaf litter, and, using a hand auger, from each mineral horizon to a depth of 1 m. Soil C concentration was determined using high-temperature combustion, and organic carbon (OC) stocks were then calculated for each master horizon. Soil bulk density (Db) was determined using the core method for O and A horizons. For deeper mineral horizons, a strong linear relationship between NRCS SSURGO representative values and measured Db values averaged according to soil series (R2 = 0.75) was observed. Thus, the NRCS SSURGO representative Db values were used for mineral horizons below the A horizon. An average of 0.5 ± 0.0 kg C m−2 was contained in the loose leaf litter. For plots with O horizons, the organic layer contained 2.9 ± 0.3 kg C m−2. An average of 4.6 ± 0.2 kg C m−2 was stored in the A horizon, down to an average lower boundary of 18.8 cm. The mineral horizons below the A horizon averaged 8.5 kg C m−2. In these forested soil profiles, 52.8% of the TOC is found below the A horizon and 18.0% of the TOC is in the organic horizons. The predictive strength of the thickness of and SOC in the A horizon was also evaluated in terms of explaining and predicting TOC in the profile and in the subsoil. The thickness and SOC in the A horizon explained 54% of the variation in TOC stock; however, it was a poor predictor of OC stored in the subsoil (R2 = 0.04). This study demonstrates the importance of deeper sampling to encompass more of the rooting depth when investigating SOC stocks. Full article
(This article belongs to the Section Forest Soil)
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13 pages, 2574 KiB  
Article
Energetic Features of Hardwood Pellet Evaluated by Effect Size Summarisation
by Rodolfo Picchio, Rachele Venanzi, Vincenzo Civitarese, Aurora Bonaudo, Angela Lo Monaco and Francesco Latterini
Forests 2024, 15(7), 1259; https://doi.org/10.3390/f15071259 - 19 Jul 2024
Viewed by 615
Abstract
High-quality pellets are typically produced from coniferous sawdust. However, achieving comparable quality from alternative feedstocks, such as broadleaf wood, often necessitates pre-treatments or additives. Yet, within the framework of small-scale pellet production, local forest enterprises may lack the resources for such treatments and [...] Read more.
High-quality pellets are typically produced from coniferous sawdust. However, achieving comparable quality from alternative feedstocks, such as broadleaf wood, often necessitates pre-treatments or additives. Yet, within the framework of small-scale pellet production, local forest enterprises may lack the resources for such treatments and usually produce pellets from the whole trees, including branches, leaves and tops. This can have an impact on the quality of the pellets obtained in this manner. To be classified as high-quality pellets (A1 class), the specific features of the pellet must be higher or fall below the thresholds specified in the EN ISO 17225 standard. In this study, we developed an alternative statistical approach to evaluate pellet quality in comparison to the constant thresholds reported in the technical standard. We applied such an approach to evaluate the quality of pellets produced from the broadleaved species common in the Mediterranean forestry, including European beech (Fagus sylvatica L.), Turkey oak (Quercus cerris L.), Eucalyptus (clone Eucalyptus camaldulensis x C. bicostata), and Poplar clone AF6. In particular, we focused on three variables that are generally the most troublesome for the production of high-quality pellets from the broadleaved species, namely bulk density, ash content, and lower heating value. We found that the beech pellets showed satisfactory bulk density (average effect size of −1.2, with no statistical difference in comparison to the standard’s threshold) and ash content (average effect size of about −5 and significantly lower than the standard’s threshold), but the heating value was significantly lower than the threshold required by the standard (average effect size of about −3). Conversely, other investigated species exhibited notable deficiencies, with turkey oak pellets displaying acceptable heating values. We found a significant improvement in ash content and heating value with increasing stem age within the same species thus suggesting that material derived from thinning interventions might be preferable over coppice-derived biomass for high-quality pellet production. We suggest that future research on the topic should focus on investigating pellets produced from blends of beech and turkey oak biomass. We further recommend a wider application of the proposed statistical approach, considering that it is clear and easy to interpret, and allows for a statistical comparison of the obtained values against the requirements of the technical standard. Full article
(This article belongs to the Special Issue Novelties in Wood Engineering and Forestry—2nd Edition)
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16 pages, 3080 KiB  
Article
Interactive Effects of Salinity and Hydrology on Radial Growth of Bald Cypress (Taxodium distichum (L.) Rich.) in Coastal Louisiana, USA
by Richard H. Day, Andrew S. From, Darren J. Johnson and Ken W. Krauss
Forests 2024, 15(7), 1258; https://doi.org/10.3390/f15071258 - 19 Jul 2024
Cited by 1 | Viewed by 663
Abstract
Tidal freshwater forests are usually located at or above the level of mean high water. Some Louisiana coastal forests are below mean high water, especially bald cypress (Taxodium distichum (L.) Rich.) forests because flooding has increased due to the combined effects of [...] Read more.
Tidal freshwater forests are usually located at or above the level of mean high water. Some Louisiana coastal forests are below mean high water, especially bald cypress (Taxodium distichum (L.) Rich.) forests because flooding has increased due to the combined effects of global sea level rise and local subsidence. In addition, constructed channels from the coast inland act as conduits for saltwater. As a result, saltwater intrusion affects the productivity of Louisiana’s coastal bald cypress forests. To study the long-term effects of hydrology and salinity on the health of these systems, we fitted dendrometer bands on selected trees to record basal area increment as a measure of growth in permanent forest productivity plots established within six bald cypress stands. Three stands were in freshwater sites with low salinity rooting zone groundwater (0.1–1.3 ppt), while the other three had higher salinity rooting zone groundwater (0.2–4.9 ppt). Water level was logged continuously, and salinity was measured monthly to quarterly on the surface and in groundwater wells. Higher groundwater salinity levels were related to decreased bald cypress radial growth, while higher freshwater flooding increased radial growth. With these data, coastal managers can model rates of bald cypress forest change as a function of salinity and flooding. Full article
(This article belongs to the Special Issue Coastal Forest Dynamics and Coastline Erosion, 2nd Edition)
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22 pages, 9521 KiB  
Article
Estimation of Leaf Area Index for Dendrocalamus giganteus Based on Multi-Source Remote Sensing Data
by Zhen Qin, Huanfen Yang, Qingtai Shu, Jinge Yu, Li Xu, Mingxing Wang, Cuifen Xia and Dandan Duan
Forests 2024, 15(7), 1257; https://doi.org/10.3390/f15071257 - 19 Jul 2024
Viewed by 1055
Abstract
The Leaf Area Index (LAI) plays a crucial role in assessing the health of forest ecosystems. This study utilized ICESat-2/ATLAS as the primary information source, integrating 51 measured sample datasets, and employed the Sequential Gaussian Conditional Simulation (SGCS) method to derive surface grid [...] Read more.
The Leaf Area Index (LAI) plays a crucial role in assessing the health of forest ecosystems. This study utilized ICESat-2/ATLAS as the primary information source, integrating 51 measured sample datasets, and employed the Sequential Gaussian Conditional Simulation (SGCS) method to derive surface grid information for the study area. The backscattering coefficient and texture feature factor from Sentinel-1, as well as the spectral band and vegetation index factors from Sentinel-2, were integrated. The random forest (RF), gradient-boosted regression tree (GBRT) model, and K-nearest neighbor (KNN) method were employed to construct the LAI estimation model. The optimal model, RF, was selected to conduct accuracy analysis of various remote sensing data combinations. The spatial distribution map of Dendrocalamus giganteus in Xinping County was then generated using the optimal combination model. The findings reveal the following: (1) Four key parameters—optimal fitted segmented terrain height, interpolated terrain surface height, absolute mean canopy height, and solar elevation angle—are significantly correlated. (2) The RF model constructed using a combination of ICESat-2/ATLAS, Sentinel-1, and Sentinel-2 data achieved optimal accuracy, with a coefficient of determination (R2) of 0.904, root mean square error (RMSE) of 0.384, mean absolute error (MAE) of 0.319, overall estimation accuracy (P1) of 88.96%, and relative root mean square error (RRMSE) of 11.04%. (3) The accuracy of LAI estimation using a combination of ICESat-2/ATLAS, Sentinel-1, and Sentinel-2 remote sensing data showed slight improvement compared to using either ICESat-2/ATLAS data combined with Sentinel-1 or Sentinel-2 data alone, with a significant enhancement in LAI estimation accuracy compared to using ICESat-2/ATLAS data alone. (4) LAI values in the study area ranged mainly from 2.29 to 2.51, averaging 2.4. Research indicates that employing ICESat-2/ATLAS spaceborne LiDAR data for regional-scale LAI estimation presents clear advantages. Incorporating SAR data and optical imagery and utilizing diverse data types for complementary information significantly enhances the accuracy of LAI estimation, demonstrating the feasibility of LAI inversion with multi-source remote sensing data. This approach offers an innovative framework for utilizing multi-source remote sensing data for regional-scale LAI inversion, demonstrates a methodology for integrating various remote sensing data, and serves as a reference for low-cost high-precision regional-scale LAI estimation. Full article
(This article belongs to the Topic Remote Sensing and Visualization Methods: Monitoring, Modeling, Simulations and Interaction of Forest Resource)
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18 pages, 7099 KiB  
Article
Variation in Niche and Interspecific Associations across Elevations in Subtropical Forest Communities of the Wuyi Mountains, Southeastern China
by Jintao Hu, Zhaoliang Zheng, Xinyi Wen, Xisheng Hu, Yongming Lin, Jian Li, Jian Ni and Chengzhen Wu
Forests 2024, 15(7), 1256; https://doi.org/10.3390/f15071256 - 19 Jul 2024
Viewed by 624
Abstract
Elucidating changes in the structure and function of plant communities along different elevation ranges will help researchers to analyze the strategies plant communities use in environments and processes influencing niche differentiation. The aims of this paper are to reveal the underlying mechanisms and [...] Read more.
Elucidating changes in the structure and function of plant communities along different elevation ranges will help researchers to analyze the strategies plant communities use in environments and processes influencing niche differentiation. The aims of this paper are to reveal the underlying mechanisms and ecological processes governing the development of subtropical forest ecosystem plant communities. This paper analyzes the forest vegetation of the Wuyi Mountains across the following three elevation ranges: low elevation, mid elevation, and high elevation, spanning from 560 to 2150 m. Twenty and twenty-three dominant tree and shrub layer species, respectively, were identified based on their importance values, and their niches and species associations were further analyzed based on the elevation range. The results showed interspecific associations between tree and shrub species, with the strongest associations observed at mid-elevations. The analysis of niche width and overlap showed that the number of pairs of species with a higher degree of niche overlap decreased with increasing elevation, suggesting that resource use varied at different elevations for both tree and shrub layer species, which may be related to the adaptive capacity of plants at different elevations to the environment and resource use strategies. These findings should contribute to a deeper understanding of the ecological functioning and structural framework of plant communities on Wuyi Mountain. Full article
(This article belongs to the Special Issue Ecological Dynamics of Tropical Forests: Structure, Species Richness and Regeneration)
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15 pages, 2399 KiB  
Article
Range-Wide Assessment of Recent Longleaf Pine (Pinus palustris Mill.) Area and Regeneration Trends
by Kevin M. Potter, Christopher M. Oswalt and James M. Guldin
Forests 2024, 15(7), 1255; https://doi.org/10.3390/f15071255 - 19 Jul 2024
Cited by 1 | Viewed by 733
Abstract
Longleaf pine (Pinus palustris Mill.) is a conifer historically associated with an open forest ecosystem that extended across much of the coastal plain of the Southeastern United States. It now exists mainly in isolated fragments following the conversion of forests and the [...] Read more.
Longleaf pine (Pinus palustris Mill.) is a conifer historically associated with an open forest ecosystem that extended across much of the coastal plain of the Southeastern United States. It now exists mainly in isolated fragments following the conversion of forests and the long-term disruption of the low-intensity fire regime upon which the species depends. Recent decades have seen efforts to restore longleaf pine forests by government and private landowners. This was reflected in analyses of national forest inventory data during two time periods, ca. 2009–2015 and 2016–2021, that showed increases in the estimated number of longleaf pine trees, the area of the longleaf pine forest type, and the number and area of planted longleaf pine, along with growth in mean plot-level longleaf pine carbon and importance value. At the same time, we found a decrease in the overall forest area containing longleaf pine, manifested across a variety of other forest types. These results point to a dynamic through which forests dominated by longleaf pine are becoming more widespread via restoration, while forests in which the species is a less important component are transitioning to other forest types or land uses. We also detected a decrease over time in the estimated number of longleaf seedlings across most states and forest types and a decline in naturally regenerated longleaf pine. To further assess regeneration trends in longleaf pine, we calculated the estimated proportion of small trees (seedlings and saplings) for the entire species and for seed zone sub-populations. We found a species-wide decrease in the proportion of small trees, from 82.1 percent to 75.1 percent. This reduction was most pronounced along the edges of the species distribution and could indicate less sustainable levels of regeneration in some areas. These results underscore the challenges of facilitating natural regeneration in this important species. Full article
(This article belongs to the Special Issue Longleaf Pine Ecology, Restoration, and Management)
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10 pages, 1653 KiB  
Article
Effects of Forest Bathing on Blood Pressure and Heart Rate in Older Adults in Mexico
by María Guadalupe Garibay-Chávez, Arturo Curiel-Ballesteros, Javier García de Alba-García, Miriam Borja-Arreola, Daniela Moreno-Ramírez and Eliana Santos-Zamora
Forests 2024, 15(7), 1254; https://doi.org/10.3390/f15071254 - 19 Jul 2024
Viewed by 946
Abstract
Currently, in cities in different regions of the world, forest bathing (FB) is considered a practice to promote public health in vulnerable groups, such as the elderly, who have a higher risk of hypertension. This practice has had limited development in Latin American [...] Read more.
Currently, in cities in different regions of the world, forest bathing (FB) is considered a practice to promote public health in vulnerable groups, such as the elderly, who have a higher risk of hypertension. This practice has had limited development in Latin American countries, and therefore, the objective of this study was to evaluate the benefits of forest baths on blood pressure and heart rate in a group of older adults in Guadalajara, Mexico. A program of six sessions was designed, the first to welcome and recognize the natural environment of the urban forest and the other five dedicated to each of the senses (hearing, touch, smell, sight, and taste), using the methodology of the Forest Therapy Hub (FTHub). The type of study was observational (before and after) with a single group, where the participants’ blood pressure and heart rate were evaluated. The results obtained showed significant effects of FB on reduction in high systolic blood pressure and diastolic hypertension before and after FB, with no significance on heart rate. Forest baths can be considered as an alternative strategy to manage the risk of hypertension in older adults, due to their ability to induce relaxation and normalize blood pressure levels. Full article
(This article belongs to the Special Issue Forests for Public Health—Selected Papers from the 3rd World Conference on Forests for Public Health)
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19 pages, 8302 KiB  
Article
Evaluating the Impact of Climate Change and Human Activities on the Potential Distribution of Pine Wood Nematode (Bursaphelenchus xylophilus) in China
by Liang Zhang, Ping Wang, Guanglin Xie and Wenkai Wang
Forests 2024, 15(7), 1253; https://doi.org/10.3390/f15071253 - 18 Jul 2024
Viewed by 829
Abstract
Bursaphelenchus xylophilus is a pest that interferes with the health of forests and hinders the development of the forestry industry, and its spread is influenced by changes in abiotic factors and human activities. The potential distribution areas of B. xylophilus in China under [...] Read more.
Bursaphelenchus xylophilus is a pest that interferes with the health of forests and hinders the development of the forestry industry, and its spread is influenced by changes in abiotic factors and human activities. The potential distribution areas of B. xylophilus in China under four shared-economic pathways were predicted using the optimized MaxEnt model (version 3.4.3), combining data from a variety of environmental variables: (1) prediction of natural environmental variables predicted under current climate models; (2) prediction of natural environmental variables + human activities under current climate models; and (3) prediction of natural environmental variables under the future climate models (2050s and 2070s). Meanwhile, whether the niche of B. xylophilus has changed over time is analyzed. The results showed that human activities, precipitation in the driest month, annual precipitation, and elevation had significant effects on the distribution of B. xylophilus. In the current conditions, human activities greatly reduced the survival area of B. xylophilus, and its suitable distribution area was mainly concentrated in the southwestern and central regions of China. Under the influence of climate change in the future, the habitat of B. xylophilus will gradually spread to the northeast. In addition, the ecological niche overlap analysis showed that B. xylophilus in future climate was greater than 0.74. This study provides important information for understanding the ecological adaptation and potential risk of B. xylophilus, which can help guide the decision making of pest control and forest protection. Full article
(This article belongs to the Topic Plant Invasion)
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19 pages, 8480 KiB  
Article
Mapping Characteristics in Vaccinium uliginosum Populations Predicted Using Filtered Machine Learning Modeling
by Yadong Duan, Xin Wei, Ning Wang, Dandan Zang, Wenbo Zhao, Yuchun Yang, Xingdong Wang, Yige Xu, Xiaoyan Zhang and Cheng Liu
Forests 2024, 15(7), 1252; https://doi.org/10.3390/f15071252 - 18 Jul 2024
Cited by 1 | Viewed by 625
Abstract
Bog bilberry (Vaccinium uliginosum L.) is considered a highly valued non-wood forest product (NWFP) species with edible and medicinal uses in East Asia. It grows in the northeastern forests of China, where stand attributes and structure jointly determine its population characteristics and [...] Read more.
Bog bilberry (Vaccinium uliginosum L.) is considered a highly valued non-wood forest product (NWFP) species with edible and medicinal uses in East Asia. It grows in the northeastern forests of China, where stand attributes and structure jointly determine its population characteristics and individuals’ growth. Mapping the regional distributions of its population characteristics can be beneficial in the management of its natural resources, and this mapping should be predicted using machine learning modeling to obtain accurate results. In this study, a total of 60 stands were randomly chosen and screened to investigate natural bog bilberry populations in the eastern mountains of Heilongjiang and Jilin provinces in northeastern China. Individual height, canopy cover area, and fresh weight all increased in stands at higher latitudes, and shoot height was also higher in the eastern stands. The rootstock grove density showed a polynomial quadratic distribution pattern along increasing topographical gradients, resulting in a minimum density of 0.43–0.52 groves m−2 in stands in the southern part (44.3016° N, 129.4558° E) of Heilongjiang. Multivariate linear regression indicated that the bog bilberry density was depressed by host forest tree species diversity; this was assessed using both the Simpson and Shannon–Wiener indices, which also showed polynomial quadratic distribution patterns (with a modeling minimum of 0.27 and a maximum of 1.21, respectively) in response to the increase in latitude. Structural equation models identified positive contributions of tree diameter at breast height and latitude to shoot height and a negative contribution of longitude to the bog bilberry canopy area. Random forest modeling indicated that dense populations with heavy individuals were distributed in eastern Heilongjiang, and large-canopy individuals were distributed in Mudanjiang and Tonghua. In conclusion, bog bilberry populations showed better attributes in northeastern stands where host forest trees had low species diversity, but the dominant species had strong trunks. Full article
(This article belongs to the Section Wood Science and Forest Products)
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32 pages, 7087 KiB  
Article
Biogeochemical Migration of Some Rare Elements in the “Leaf Debris–Soil” System of the Catenary Landscapes in Tropical Mountainous Forests in Southern Vietnam
by Yaroslav Lebedev, Anna Drygval, Cam Nhung Pham, Roman Gorbunov, Tatiana Gorbunova, Andrei Kuznetsov, Svetlana Kuznetsova, Van Thinh Nguyen and Vladimir Tabunshchik
Forests 2024, 15(7), 1251; https://doi.org/10.3390/f15071251 - 18 Jul 2024
Viewed by 793
Abstract
Expeditionary studies of the functioning of landscapes of mid-mountain monsoon (including fog) forests have been being conducted within the landscape and ecological station in the territory of the Bidoup-Nui Ba National Park and the adjacent Hon Giao since 2018 and are currently underway. [...] Read more.
Expeditionary studies of the functioning of landscapes of mid-mountain monsoon (including fog) forests have been being conducted within the landscape and ecological station in the territory of the Bidoup-Nui Ba National Park and the adjacent Hon Giao since 2018 and are currently underway. One of the research objectives is to clarify the biogeochemical migrations of the material composition of soils in the “leaf debris–soil” system. We have consistently studied natural objects for their material composition as well as the intensity and rate of involvement of chemical elements in physicochemical migration processes in the “leaf debris–soil” system. Our findings indicate an active influx of a select group of examined elements (Se, Pd, Ag, Cd, Sn, Bi), particularly Bi, Pd, Se, and Cd, through the leaf debris and the detachment of aboveground plant organs, warranting their integration into organogenic soil horizons. Subsequently, lateral migration (Pd, Cd, Se) ensues. Slope processes within subordinate landscape facets, in addition to soil moisture and aeration processes, contribute to the subsequent redistribution of elemental volumes introduced into organogenic soil horizons. Full article
(This article belongs to the Special Issue Biogeochemical Cycles in Forests)
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14 pages, 1952 KiB  
Article
Trait Assessment of 1122 Populus deltoides Clones: Unveiling Correlations among Growth, Wood Properties, and Disease Susceptibility
by Tianyu Ma and Jing Hou
Forests 2024, 15(7), 1250; https://doi.org/10.3390/f15071250 - 18 Jul 2024
Viewed by 590
Abstract
This study aimed to evaluate the growth, wood properties, disease susceptibility, and sex traits of 1122 Populus deltoides clones to reveal the trait variability and correlations, providing a basis for genetic improvement and breeding. The measurements included the diameter at breast height (DBH), [...] Read more.
This study aimed to evaluate the growth, wood properties, disease susceptibility, and sex traits of 1122 Populus deltoides clones to reveal the trait variability and correlations, providing a basis for genetic improvement and breeding. The measurements included the diameter at breast height (DBH), leaf area, basic wood density (BWD), content of cellulose, hemicellulose, lignin, and disease susceptibility index (DSI). The coefficients of variation ranged 6.91%–41.96%, with the BWD showing the lowest variability. Significant sexual dimorphism was observed, with male clones exhibiting higher DBH and hemicellulose content, and female clones displaying larger leaf areas and greater phenotypic variability. Correlation analysis revealed that the leaf area was positively correlated with the BWD and hemicellulose, and it was negatively correlated with the DBH and lignin; lignin was negatively correlated with cellulose. PCA confirmed these relationships and additionally highlighted a positive correlation between the DSI and DBH. These findings established links between the growth traits and wood properties, enhancing our understanding of trait diversity in P. deltoides and providing insights for breeding strategies to develop high-quality, high-yielding cultivars. Full article
(This article belongs to the Section Wood Science and Forest Products)
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10 pages, 3531 KiB  
Article
Evaluation of the Effectiveness of the Elderly Cognitive and Exercise Forest Therapy Program According to Brain Wave and Autonomic Nervous System Parameters
by Jeong-Woo Seo, Kahye Kim, Seul Gee Kim, Jiyune Yi, Wonsop Shin, Jungmi Choi and Jaeuk U. Kim
Forests 2024, 15(7), 1249; https://doi.org/10.3390/f15071249 - 18 Jul 2024
Viewed by 712
Abstract
The purpose of this study is to more quantitatively identify changes in body function through various bio-signal parameters. (1) Background: Forest therapy is effective in stabilizing cognitive, emotional, cardiovascular, and autonomic nervous systems. In particular, it is necessary to more quantitatively confirm changes [...] Read more.
The purpose of this study is to more quantitatively identify changes in body function through various bio-signal parameters. (1) Background: Forest therapy is effective in stabilizing cognitive, emotional, cardiovascular, and autonomic nervous systems. In particular, it is necessary to more quantitatively confirm changes in body functions through various bio signals. (2) Methods: As a forest therapy program (FTP) for the elderly, it consisted of strength training in the forest, respiratory aerobic exercises, and cognitive function training, and a total of 19 sessions were performed for 12 weeks. The electroencephalography (EEG) and Photoplethysmography (PPG) before and after the program were measured and compared between program participants (FTP group) and non-participants (control group). (3) Results: the FTP group showed increase in the alpha band power in EEG and a decrease in the PRV index, Tad, and Tae after the program compared to the control group; (4) Conclusions: Significant differences occurred in the physiological functioning of the elderly participants after the program. This is a result that can confirm the effectiveness of forest therapy more quantitatively. Forest therapy has a positive effect on mental stress reduction and cardiovascular function. Full article
(This article belongs to the Special Issue Forest Bathing and Smart Devices)
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27 pages, 14689 KiB  
Article
Spatiotemporal Changes in Ecological Quality and Its Response to Forest Landscape Connectivity—A Study from the Perspective of Landscape Structural and Functional Connectivity
by Miaomiao Liu, Guanmin Liang, Ziyi Wu, Xueman Zuo, Xisheng Hu, Sen Lin and Zhilong Wu
Forests 2024, 15(7), 1248; https://doi.org/10.3390/f15071248 - 18 Jul 2024
Viewed by 697
Abstract
Understanding the response of ecological quality (EQ) to forest landscape connectivity is essential to global biodiversity conservation and national ecological security. However, quantitatively measuring the properties and intensities within these relationships from a spatial heterogeneity perspective remains challenging. This study takes the Fujian [...] Read more.
Understanding the response of ecological quality (EQ) to forest landscape connectivity is essential to global biodiversity conservation and national ecological security. However, quantitatively measuring the properties and intensities within these relationships from a spatial heterogeneity perspective remains challenging. This study takes the Fujian Delta region as its case study. The Google Earth Engine platform was employed to compute the remote sensing ecological index (RSEI), the landscape metrics were applied to represent the structural connectivity of the forest landscape, and the minimum cumulative resistance model was adopted to measure the cost distance index representing the functional connectivity of the forest landscape. Then, the spatial correlation and heterogeneity between the EQ and forest landscape connectivity were analyzed based on spatial autocorrelation and geographical weighted regression at three scales (3, 4, and 5 km). The results showed the following: (1) from 2000 to 2020, the overall EQ increased, improving in 37.5% of the region and deteriorating in 13.8% of the region; (2) the forest landscape structural and functional connectivity showed a small decreasing trend from 2000 to 2020, decreasing by 1.3% and 0.9%, respectively; (3) eight forest landscape structural and functional connectivity change modes were detected under the conditions of an improving or degrading EQ based on the change in RSEI and forest landscape structural and functional connectivity; (4) the geographical weighted regression results showed that compared with the forest landscape structural connectivity index, the cost distance index had the highest explanatory power to RSEI in different scales. The effect of forest landscape functional connectivity on EQ is greater than that of structural connectivity. It provides a scientific reference for ecological environmental monitoring and the ecological conservation decision-making of managers. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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15 pages, 3396 KiB  
Article
Variations in the Forest Productivity of Pinus patula Plantations in Tanzania: The Need for an Improved Site Classification System
by Joshua Maguzu, Ulrik Ilstedt, Josiah Zephaniah Katani and Salim S. M. Maliondo
Forests 2024, 15(7), 1247; https://doi.org/10.3390/f15071247 - 18 Jul 2024
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Abstract
The productivity of forests in sub-Saharan Africa is often summarized into large compartments or site classes. However, the classification of forest productivity levels based on the original site index model in Tanzania and the techniques applied to generate the model did not include [...] Read more.
The productivity of forests in sub-Saharan Africa is often summarized into large compartments or site classes. However, the classification of forest productivity levels based on the original site index model in Tanzania and the techniques applied to generate the model did not include the micro-toposequence variations within compartments. This may create false expectations of wood supply and hinder the estimation of sustainable harvesting processes. This study analyzed variations in forest productivity and the site index in P. patula stands in two forest plantations of Tanzania to assess the applicability and generality of the present site classification system. We used dominant height as a proxy for forest productivity in 48 plots at the Sao Hill forest plantation (SHFP) and 24 plots at the Shume forest plantation (SFP). We stratified the sampling plots in each site class along the soil catena and recorded the elevation, slope, and slope positions (summit, mid, and lower). Our results showed that the site classes did not generally match the previously assigned site classes and the productivity of a given site class varied between the two plantations. We found a consistently higher productivity than that implied by the original site index in SFP, while in SHFP, the productivity was both higher and lower than estimated in different compartments. Both elevations and slope significantly contributed to predicting the productivity variations within site classes. Overall, the results indicate that physiographic factors affect variations in forest productivity within the assigned site classes. We recommend a more comprehensive site productivity assessment that takes into account physiographic variations and hence provides more accurate information for sustainable forest plantation management in Tanzania and in the region at large. Full article
(This article belongs to the Special Issue Forest Growth and Yield under Environmental Changes)
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