Forests

31 pages, 16858 KB

Open AccessArticle

Modeling the Hydrological Regime of Litani River Basin in Lebanon for the Period 2009–2019 and Assessment of Climate Change Impacts Under RCP Scenarios

by Georgio Kallas, Salim Kattar and Guillermo Palacios-Rodríguez

Forests 2025, 16(9), 1461; https://doi.org/10.3390/f16091461 (registering DOI) - 13 Sep 2025

Abstract

This study investigates the combined impact of climate change and land use changes on water resources and soil conditions in the Litani River Basin (LRB) in Lebanon. The Mediterranean region, including the LRB, is highly vulnerable to climate change. This study utilizes the [...] Read more.

This study investigates the combined impact of climate change and land use changes on water resources and soil conditions in the Litani River Basin (LRB) in Lebanon. The Mediterranean region, including the LRB, is highly vulnerable to climate change. This study utilizes the WiMMed (Water Integrated Management for Mediterranean Watersheds) model to assess hydrological variables such as infiltration, runoff, and soil moisture for the years 2009, 2014, and 2019. It considers 2019 climate conditions to project the 2040 scenarios for Representative Concentration Pathways (RCPs) 2.6 and 8.5, incorporating the unique characteristics of the Mediterranean watershed. Results indicate a concerning trend of declining infiltration, runoff, and soil moisture, particularly under the more severe RCP 8.5 scenario, with the most significant reductions occurring during summer. Land use changes, such as deforestation and urban expansion, are identified as key contributors to reduced infiltration and increased runoff. This study highlights the critical role of soil moisture in crop productivity and ecosystem health, showing how land cover changes and climate change intensify these effects. Soil moisture is highly sensitive to precipitation variations, with a 20% reduction in precipitation and a 5 °C temperature increase leading to substantial decreases in soil moisture. These findings highlight the urgent need for sustainable land management practices and climate mitigation strategies in the Litani River Basin (LRB) and similar Mediterranean watersheds. Protecting forests, implementing soil conservation measures, and promoting responsible urban development are crucial steps to maintain water resources and soil quality. Furthermore, this research offers valuable insights for policymakers, farmers, and environmentalists to prepare for potential droughts or flooding events, contributing to the preservation of this vital ecosystem. The data from this study, along with the recommended actions, can play a crucial role in fostering resilience at the national level, addressing the challenges posed by climate change. Full article

(This article belongs to the Section Forest Hydrology)

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12 pages, 2668 KB

Open AccessArticle

The Radial Growth Responses Differences of High-Elevation Larix sibirica to Climate Change in the Altay Mountains of China and Russia

by Li Qin, Yujiang Yuan, Dongliang Zhang, Tongwen Zhang, Shulong Yu, Huaming Shang, Shengxia Jiang and Ruibo Zhang

Forests 2025, 16(9), 1460; https://doi.org/10.3390/f16091460 (registering DOI) - 13 Sep 2025

Abstract

Climate change has a profound impact on the spatio-temporal patterns and successional dynamics of forest ecosystems, particularly at forest edges. The Altay Mountains are located at the junction of China, Russia, Kazakhstan and Mongolia, and the southern edge of the boreal forest in [...] Read more.

Climate change has a profound impact on the spatio-temporal patterns and successional dynamics of forest ecosystems, particularly at forest edges. The Altay Mountains are located at the junction of China, Russia, Kazakhstan and Mongolia, and the southern edge of the boreal forest in interior Eurasia. It is highly necessary to compare the differences in the responses of forest ecosystems in large transnational mountain ranges to climate change under the background of climate change. This study analyzed 558 tree cores collected from 20 sample sites dominated by Siberian larch (Larix sibirica Ledeb.) in the high-elevation of Altay Mountains. Using tree-ring width data and meteorological observations from Altay Mountains both in China and Russia, we investigated how climate influences the radial growth of L. sibirica across these regions. The results indicate that temperature is the primary factor driving radial growth, with early summer temperatures acting as the main growth-limiting factor on both China and Russia. Notably, the radial growth-climate response is stronger in Russia than China. Despite ongoing climate change, the dominant climatic drivers of radial growth in the Altay Mountains have remained stable, with temperature continuing to exert a significant and consistent influence on L. sibirica growth in the high-elevation of Altay Mountains. This study enhances our understanding of the climate change impacts on boreal forest ecosystems and highlights potential risks to forest health in the Altay Mountains. Full article

(This article belongs to the Special Issue Effects of Climate Change on Tree-Ring Growth—2nd Edition)

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15 pages, 1057 KB

Open AccessArticle

Community Structure and Maintenance Mechanisms of Ectomycorrhizal Fungi of Four Coniferous Species in Eastern Inner Mongolia

by Jinyan Li, Zhimin Yu, Xinyu Li, Lu Wang, Jiani Lu, Fahu Li and Yongjun Fan

Forests 2025, 16(9), 1459; https://doi.org/10.3390/f16091459 (registering DOI) - 12 Sep 2025

Abstract

In this study, we focused on four major coniferous species in the eastern part of Inner Mongolia, namely Larix gmelinii var. principis-rupprechtii (Mayr) Pilg., Larix gmelinii (Rupr.) Kuzen., Pinus tabuliformis Carrière and Pinus sylvestris var. mongholica Litv. and carried out a systematic study [...] Read more.

In this study, we focused on four major coniferous species in the eastern part of Inner Mongolia, namely Larix gmelinii var. principis-rupprechtii (Mayr) Pilg., Larix gmelinii (Rupr.) Kuzen., Pinus tabuliformis Carrière and Pinus sylvestris var. mongholica Litv. and carried out a systematic study on their ectomycorrhiae (EM) fungi. The present study was based on high-throughput sequencing. Based on the high-throughput sequencing data, analyzed by bioinformatics and statistical methods, the results showed that (1) a total of 150 operational taxonomic units (OTUs) were obtained, which belonged to 26 evolutionary branches of Basidiomycota and Ascomycota, respectively. Among them, Tricholoma, Tomentella-thelephora, Suillus-rhizopogon, Wilcoxina, Piloderma, Pustularia, Hygrophorus, Sebacina and Amphinema-tylospora are the EM fungi shared by four conifer species. (2) The species diversity and community composition of EM fungi differed significantly among tree species and sample plots, while soil total nitrogen (N) content and nitrogen/phosphorus (N/P) ratio were the main factors affecting community structure. (3) The Neutral Community Model (NCM) and β-Nearest Taxon Index (β-NTI) showed that stochastic processes dominated the construction of EM fungal communities. The results of this study revealed the geographical distribution pattern and maintenance mechanisms of EM fungal communities of four coniferous species in the eastern part of Inner Mongolia, which provides a scientific basis for the restoration practice of disturbed ecosystems and the sustainable development of the regional economy. Full article

(This article belongs to the Section Forest Health)

22 pages, 3227 KB

Open AccessArticle

Age-Dependent Climate Sensitivity of Korean Pine (Pinus koraiensis) in the Southern Sikhote-Alin Mountains

by Alexander Mikhailowich Omelko, Olga Nikolaevna Ukhvatkina and Alexander Alexandrowich Zhmerenetsky

Forests 2025, 16(9), 1458; https://doi.org/10.3390/f16091458 (registering DOI) - 12 Sep 2025

Abstract

Global climate change is driving profound transformations in forest ecosystems, particularly in monsoon-influenced regions of the Pacific coast of Asia, such as the Sikhote-Alin Mountains. Long-lived conifer species, notably Korean pine (Pinus koraiensis Siebold & Zucc.), play a central ecological role in [...] Read more.

Global climate change is driving profound transformations in forest ecosystems, particularly in monsoon-influenced regions of the Pacific coast of Asia, such as the Sikhote-Alin Mountains. Long-lived conifer species, notably Korean pine (Pinus koraiensis Siebold & Zucc.), play a central ecological role in mixed broadleaf–coniferous forests of the region. We examined how the radial growth response of Korean pine to climatic variability changes with tree age and ontogenetic stage, using 191 increment cores from trees ranging from early virginile to old generative stages. We employed two approaches: (i) a stage-based analysis, constructing tree-ring chronologies for each ontogenetic stage; (ii) an individual-tree analysis, applying correlation and regression directly to individual ring-width series. Climate–growth relationships were assessed using monthly temperature, precipitation, and drought indices (PDSI, SPEI). For the stage-based approach, radial growth was positively correlated with the mean August temperature of the previous year (up to r = 0.61), minimum November temperature (up to r = 0.50), and summer drought indices (up to r = 0.57). Age-related trends in climate sensitivity, assessed from regression models under both approaches, were significant for 9 of the 18 monthly climate variables examined. For stage-specific chronologies, simple regressions across six ontogenetic stages described up to 98% of the variance, whereas cambial-age-based relationships were much weaker (R² = 0.03–0.14). These findings highlight the importance of accounting for ontogenetic structure in dendroclimatic analyses and climate reconstructions. Such insights are critical for understanding long-term forest dynamics and informing climate adaptation strategies in Korean pine-dominated ecosystems. Full article

(This article belongs to the Topic Responses of Trees and Forests to Climate Change)

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23 pages, 1976 KB

Open AccessArticle

Variability in Wood Quality and Moisture Content Measured by an Industrial X-Ray Scanner Across 700,000 Sawlogs of Picea abies, Abies alba, and Pinus sylvestris

by Tojo Ravoajanahary, Romain Rémond, Renaud Daquitaine, Enrico Ursella and Jean-Michel Leban

Forests 2025, 16(9), 1457; https://doi.org/10.3390/f16091457 - 12 Sep 2025

Abstract

Evaluating sawlog quality is vital for both forest managers and wood processors. While external traits, such as tree form, branch architecture and visible growth features can be evaluated through visual inspection, many key wood quality indicators remain hidden, such as knot type and [...] Read more.

Evaluating sawlog quality is vital for both forest managers and wood processors. While external traits, such as tree form, branch architecture and visible growth features can be evaluated through visual inspection, many key wood quality indicators remain hidden, such as knot type and distribution, or the heartwood-to-sapwood ratio. This highlights the need for technologies capable of “seeing through” logs. Today, X-ray scanners in sawmills enable comprehensive, continuous, non-destructive assessment of internal stem structure at large scale. This study leveraged a newly compiled database of approximately 726,000 scanned logs to characterize variability in knot distribution and sapwood proportion across three major European softwood species and estimate the moisture content. The analysis highlights inter-and intra-species differences. Sapwood proportion decreased with sawlog diameter in spruce and silver fir but remained high in pine. Pine also presented significantly larger and more variable knots. Between March and August, we observed a seasonal trend in sapwood moisture content, affecting fresh density, while heartwood moisture content remained stable. These findings provide valuable information to support decision-making processes, linking tree characteristics to wood qualities and guiding forest management. Full article

(This article belongs to the Section Wood Science and Forest Products)

20 pages, 2194 KB

Open AccessArticle

Discarded Small-Logs Recovery from Natural Forests: Improving the Value Chain

by María Paulina Fernández, Rosa María M. Alzamora, Francisco Chateau, Juan Pedro Pedro Elissetche and Eduardo Pérez

Forests 2025, 16(9), 1456; https://doi.org/10.3390/f16091456 - 12 Sep 2025

Abstract

This study investigates how small logs from native trees, which fail to meet standard sawing criteria, can be utilized to enhance their value by producing solid wood for direct use or remanufacture rather than being relegated to biomass or fuelwood. We analyzed a [...] Read more.

This study investigates how small logs from native trees, which fail to meet standard sawing criteria, can be utilized to enhance their value by producing solid wood for direct use or remanufacture rather than being relegated to biomass or fuelwood. We analyzed a sample of 177 small, discarded logs from native species from second-growth forests of Nothofagus in the Ñuble Region, Chile. The logs were scored after a qualitative and quantitative assessment for small logs, as designed in this study, and processed using a flexible sawing pattern to optimize wood recovery based on random lengths, widths, and thicknesses. Log dimensions varied, with lengths from 31 to 156.2 cm, small end diameters from 11.5 to 25.6 cm, and volumes between 0.001 and 0.092 m³. Key defects in logs included knots (95%), curvature (79%), and checks (46%), among others. A key result is the obtained general yield value of 36%, a considerable value for small-diameter, low-quality logs. The highest sawing yields were achieved with Nothofagus dombeyi (Mirb.) Oerst (42%), Geviuna avellana Molina and Persea lingue Miers ex Bertero Nees (39%), and Nothofagus obliqua (Mirb.) Oerst (34%). The quality of the boards correlates positively with the quality of the logs, and the yields with the log size and quality. The yield achieved in boards coming from such low-quality logs shows a promising possibility of improvement for this kind of process. Further development of the grading process and automation of the sawmill process could be future research steps. Full article

(This article belongs to the Section Wood Science and Forest Products)

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17 pages, 2331 KB

Open AccessArticle

Co-Pelletization of Lavender Waste and Pine-Wood for Sustainable Fuel Pellet Production

by Vasiliki Kamperidou and Paschalina Terzopoulou

Forests 2025, 16(9), 1455; https://doi.org/10.3390/f16091455 - 12 Sep 2025

Abstract

In the current study, lavender plant (Lavandula angustifolia Mill.) waste, as obtained after the essential oils steam distillation process as well as lignocellulose biomass of two of the most common pine species (Pinus nigra L., Pinus brutia L.), was characterized in [...] Read more.

In the current study, lavender plant (Lavandula angustifolia Mill.) waste, as obtained after the essential oils steam distillation process as well as lignocellulose biomass of two of the most common pine species (Pinus nigra L., Pinus brutia L.), was characterized in terms of chemical composition, moisture, ash content, and calorific value, in order of its potential to be used as feedstock material in pellets production to be assessed, studying different materials ratios. The lavender material was introduced at low percentages (0, 5, 10 and 15% w/w) in the feedstock of pellets, in order to maintain the total ash content of the mixed feedstock as adequately low-lying, ensuring the classification of pellets in qualitative categories of A1, A2 and B (residential uses, ENplus). The resultant lavender–pine mixed syntheses were densified in a multi-mold pelletizing machine and the pellets were characterized with regard to physical, morphological, mechanical, hygroscopic, and thermal characteristics, based on the limits set by the respective ENplus standards as benchmarks. The results demonstrated that although lavender waste has a high content of ash and extractives compared to wood, it can be used in a mixture (<15% lavender percentage) with pure wood material to produce pellets of adequate quality for residential use. The lavender waste presence favored pellets’ mechanical strength, dimensions, hydrophobicity, dimensional stability, bulk density (marginally) and resultant quality of the pellets. Lavender slightly decreased the calorific value of pellets, though without recording a significant adverse impact. The lavender material mixed with black pinewood (at 15%) revealed the best pellets’ feedstock performance. The findings exhibited that lavender lignocellulosic residues are suitable for producing high-performance residential pellets, provided that the lavender content does not exceed 15% of the feedstock. Full article

(This article belongs to the Special Issue Integrated Forest Products Biorefinery Perspectives)

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19 pages, 15057 KB

Open AccessArticle

Biochar Application for Soil Carbon Sequestration and Greenhouse Gas Mitigation in Forest Ecosystems: A Bibliometric Analysis Using CiteSpace

by Xiangrui Xu, Zeyu Cao, Yang Guo, Tong Li, Linshen Jiao, Yu Bai and Cheng Liu

Forests 2025, 16(9), 1454; https://doi.org/10.3390/f16091454 - 12 Sep 2025

Abstract

Research on biochar application in forest soil carbon sequestration and greenhouse gas (GHG) mitigation has evolved into a rapidly expanding and increasingly sophisticated field. To address the lack of systematic evaluation, this study employed a bibliometric approach using the Web of Science database [...] Read more.

Research on biochar application in forest soil carbon sequestration and greenhouse gas (GHG) mitigation has evolved into a rapidly expanding and increasingly sophisticated field. To address the lack of systematic evaluation, this study employed a bibliometric approach using the Web of Science database to analyze literature published between 1996 and 2025. The visualization and analysis were conducted using CiteSpace, a bibliometric tool that identifies emerging trends and research frontiers through co-citation networks, keyword mapping, and burst detection. Our analysis reveals a sustained rise in publication output, with China, the United States, and the European Union identified as leading contributors, whose influence continues to grow. Thematic mapping indicates a clear progression from early studies focused on “black carbon” and “soil organic matter” toward mechanism-driven investigations, with the “microbial community” now recognized as a key mediator of biochar’s ecological effects. Keyword clustering and burst analysis further reveal that biochar’s influence on soil fertility and microbial functioning has become central to its role in enhancing soil carbon sequestration and mitigating GHG emissions. While biochar’s capacity to enhance SOC stocks is widely affirmed, its variable impact on GHG fluxes highlights the need for integrated assessments of net Global Warming Potential (GWP). Despite promising advances, critical barriers persist, including the paucity of long-term, landscape-scale field trials and the absence of standardized production protocols, both contributing to inconsistent outcomes across studies. Future research should prioritize mechanistic studies across diverse forest ecosystems and adopt comprehensive life cycle assessments that account for both soil and vegetation-mediated carbon sinks. Full article

(This article belongs to the Special Issue Carbon, Nitrogen, and Phosphorus Storage and Cycling in Forest Soil—2nd Edition)

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20 pages, 1683 KB

Open AccessArticle

Interior Ponderosa Pine (Pinus ponderosa var. scopulorum Engelm.) Genetic Profiles, Chemistry, Growth Rates, and Climate Sensitivity in Relation to Mountain Pine Beetle (Dendroctonus ponderosae Hopkins) Predation

by Diana L. Six and Hannah R. Alverson

Forests 2025, 16(9), 1453; https://doi.org/10.3390/f16091453 - 12 Sep 2025

Abstract

Tree phenotypes vary because of genotype–climate interactions, and this variation influences host selection by tree-killing bark beetles. As climate-driven bark beetle outbreaks intensify, identifying phenotypic traits that best predict resistance or susceptibility is critical. We examined genetic variation, secondary chemistry, growth rates, and [...] Read more.

Tree phenotypes vary because of genotype–climate interactions, and this variation influences host selection by tree-killing bark beetles. As climate-driven bark beetle outbreaks intensify, identifying phenotypic traits that best predict resistance or susceptibility is critical. We examined genetic variation, secondary chemistry, growth rates, and climate sensitivity in interior ponderosa pine (Pinus ponderosa var. scopulorum Engelm.) at two sites in the Black Hills—Devils Tower National Monument (DETO), Wyoming, and Wind Cave National Park (WICA), South Dakota—experiencing low-moderate levels of mountain pine beetle (Dendroctonus ponderosae Hopkins) activity. Genetic structure differed between sites. At DETO, large and small trees formed a single genetic cluster, whereas at WICA, two clusters emerged, one consisting of large trees and another comprising both small and large trees. The concentrations of some terpenes also differed between sites. Compared to beetle-killed trees, surviving trees exhibited distinct lifelong growth patterns and greater sensitivity to climate. Notably, surviving trees showed significant correlations of growth with climate variables, while beetle-killed trees were relatively insensitive. Long-term responsiveness of growth to climate was a stronger predictor of tree susceptibility to beetles than responses in years just before attacks occurred. These findings suggest trees with lower sensitivity to climate may be more vulnerable to beetle attack under changing climatic conditions. Full article

(This article belongs to the Special Issue Impacts of Climate Change and Disturbances on Forest Ecosystems)

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16 pages, 3598 KB

Open AccessArticle

Design and Experiment of the Mold for the Production Process of Natural Arc-Shaped Bamboo Laminated Lumber

by Hu Miao, Rui Gao, Guofu Wang, Xinxin Ma, Changhua Fang and Huanrong Liu

Forests 2025, 16(9), 1452; https://doi.org/10.3390/f16091452 - 12 Sep 2025

Abstract

Natural arc-shaped bamboo laminated lumber (ABLL) is an engineering material made from recyclable and rapidly renewable bamboo. Objectives: to enhance processing mechanization by (i) establishing a fixed-arc dimensional model for bamboo splits, (ii) designing an integrated mold capable of simultaneous shaping and drying, [...] Read more.

Natural arc-shaped bamboo laminated lumber (ABLL) is an engineering material made from recyclable and rapidly renewable bamboo. Objectives: to enhance processing mechanization by (i) establishing a fixed-arc dimensional model for bamboo splits, (ii) designing an integrated mold capable of simultaneous shaping and drying, and (iii) validating its performance through simulation and experiment. Methods: numerical modeling simulated the operational process, and physical tests measured split length, thickness, inner and outer chord lengths, and moisture content. Results: after the mold completes the arc-fixing and drying of bamboo splits, parameters including the splits’ length, chord length, thickness, and moisture content are suitable for subsequent processing. Based on simulation results, the working mechanism of load application and deformation of bamboo during the equipment’s arc-fixing process was analyzed. The cylindrical arc geometry causes uneven material deformation and stress distribution during arc-fixing. Arc-fixing of bamboo splits results in irreversible edge densification. Thus, gluing should be performed promptly to prevent warping. Evaluation metrics for arc length data—including RE ≤ 8.46%, R² ≥ 0.71, and RMSE ≤ 3.61—confirm the reliability of the dimensional model and virtual prototype simulation model. The proposed method was expected to provide a reference for the development of devices specifically designed for ABLL. Full article

(This article belongs to the Special Issue Wood Properties: Strength, Density, Hardness)

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12 pages, 3147 KB

Open AccessArticle

Short-Term Changes in the Soil Respiration of Casuarina equisetifolia L. Plantations After Severe Typhoon Disturbance

by Limin Du, Shaofeng Su, Zhipan Lin, Shouqian Nong, Yiqing Chen, Zongzhu Chen, Xiangling Lei, Junting Jia and Haihui Chen

Forests 2025, 16(9), 1451; https://doi.org/10.3390/f16091451 - 12 Sep 2025

Abstract

Typhoon disturbances significantly influence forest carbon cycling by altering both physical structures and biogeochemical processes. Typhoon-induced fluctuations in soil respiration can substantially affect the carbon balance in forest ecosystems. In this study, we conducted a comparative investigation of soil respiration in plantations of [...] Read more.

Typhoon disturbances significantly influence forest carbon cycling by altering both physical structures and biogeochemical processes. Typhoon-induced fluctuations in soil respiration can substantially affect the carbon balance in forest ecosystems. In this study, we conducted a comparative investigation of soil respiration in plantations of Casuarina equisetifolia L. that were either affected or unaffected by the severe Typhoon Yagi, which ravaged Hainan Island, China, in 2024. The soil respiration and its components in Casuarina equisetifolia L. plantations in the coastal areas of Hainan, China, as well as their responses to environmental factors before and after typhoon disturbance, were investigated based on total soil respiration rate (R_s), heterotrophic respiration rate (R_h), 5 cm soil temperature (T₅), and 10 cm soil moisture (W₁₀) to support the carbon emission estimation in coastal sandy land plantations. The mean R_s and R_h in the typhoon-disturbed plots were (1.82 ± 0.16) and (1.19 ± 0.26) μmol·m⁻²·s⁻¹, respectively, while those in the control plots were (2.62 ± 1.08) and (1.41 ± 0.23) μmol·m⁻²·s⁻¹, respectively, with statistically significant differences (p < 0.05). In both plots, R_s exhibited a significant positive correlation with T₅ (p < 0.01). The T₅ correlation and Q₁₀ values for soil respiration were significantly higher in the typhoon-disturbed plots than in the control plots (p < 0.05). W₁₀ of the soil exhibited significant negative correlations with R_s and R_h in typhoon disturbance plots (p < 0.05). Consequently, typhoon disturbance markedly inhibited soil respiration and its components in the Casuarina equisetifolia L. plantations, indicating substantial impacts of typhoons on soil respiration processes and carbon cycling within the forest ecosystem. This study provides key parameters and empirical evidence to improve the accuracy of soil carbon emission estimates in Casuarina equisetifolia L. plantations on coastal sandy soils affected by typhoon events. Full article

(This article belongs to the Section Natural Hazards and Risk Management)

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31 pages, 8949 KB

Open AccessReview

The Impact of Green Infrastructure on Mitigating Urban Heat Island Effect: Current Status, Trends, and Challenges

by Fengmei Lian, Wei Yi, Guibin Ji, Jun Xia and Huiyu Wang

Forests 2025, 16(9), 1450; https://doi.org/10.3390/f16091450 - 11 Sep 2025

Abstract

In the context of global climate change and rapid urbanization, the urban heat island (UHI) effect has emerged as a critical issue impacting urban sustainability. This study analyzes 945 publications retrieved from the Web of Science Core Collection (2000–2025) and employs VOSviewer and [...] Read more.

In the context of global climate change and rapid urbanization, the urban heat island (UHI) effect has emerged as a critical issue impacting urban sustainability. This study analyzes 945 publications retrieved from the Web of Science Core Collection (2000–2025) and employs VOSviewer and Scimago Graphica to construct and visualize a knowledge map. The findings indicate that, since 2013, there has been a significant increase in research interest in utilizing green infrastructure (GI) to mitigate UHI, with China, the United States, and Europe leading international collaboration efforts. Keyword analysis reveals that early studies primarily focused on thermodynamic manifestations. Recent research has shifted toward more diverse topics, including artificial neural networks (ANNs), environmental justice, and public participation. By constructing a knowledge framework, this study clarifies how GI mitigates UHI while simultaneously promoting carbon reduction, enhancing health benefits, and supporting resilient governance. This research provides a comprehensive overview of the role of GI in mitigating UHI, offering theoretical insights and practical solutions for achieving integrated governance that combines climate resilience, biodiversity conservation, and social equity. These findings have significant theoretical and practical implications for advancing both UHI mitigation and sustainable development. Full article

(This article belongs to the Special Issue Greening Our Cities: Urban Forests as a Nature-Based Solution for Air Pollution and Urban Heat Stress)

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23 pages, 6694 KB

Open AccessArticle

Assessment of Potential Crown Fire Danger in Major Forest Types of the Da Xing’anling (Inner Mongolia) Mountains, China

by Bole Yi, Tong Han, Ang Li, Shufeng Shi, Jing Li and Shuxiang Yang

Forests 2025, 16(9), 1449; https://doi.org/10.3390/f16091449 - 11 Sep 2025

Abstract

Crown fires are a major disturbance in boreal and cold–temperate forests worldwide, threatening both ecosystems and human activities. The Da Xing’anling Mountains of Northeast China exemplify these dangers due to their complex vegetation and high crown fire potential. Crown fire occurrence depends on [...] Read more.

Crown fires are a major disturbance in boreal and cold–temperate forests worldwide, threatening both ecosystems and human activities. The Da Xing’anling Mountains of Northeast China exemplify these dangers due to their complex vegetation and high crown fire potential. Crown fire occurrence depends on vertical fuel continuity, fuel load, heating value, surface fire spread rate, and critical fireline intensity. However, many assessments rely on single-factor metrics or low-adaptability simulations. This study developed a Potential Canopy Fire Danger Index (PCDI) that integrates five parameters—fuel vertical distribution continuity index, fuel loading, heating value, surface fire rate of spread, and critical fireline intensity—based on field surveys and combustion tests. Pinus pumila (Regel, 1861), with its dense shrub layer, showed the highest PCDI values (0.502, 0.583 and 0.527), whereas other forest types generally fell in the low to low–moderate range (0.350–0.450), with ≈75% of plots within these classes. Surface fire spread rate correlated most strongly with PCDI, followed by vertical fuel continuity, heating value, and fuel load; critical fireline intensity had minimal influence. The elevated hazard in P. pumila reflects its structural and fuel characteristics, while other forest types present comparatively lower dangers. Model checks indicated high stability and agreement with BehavePlus 6.0 scenarios, with the PCDI showing the lowest sample SD. The PCDI provides a quantitative framework for assessing crown fire danger in cold–temperate forests and supports targeted mitigation—prioritizing P. pumila while employing cost-effective maintenance in low-danger forest types. Full article

(This article belongs to the Special Issue Fire Ecology and Management in Forest—2nd Edition)

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17 pages, 5331 KB

Open AccessArticle

Stem Water Storage Dynamics of Three Boreal Tree Species Under Short-Term Drought

by Jeanny Thivierge-Lampron, Miguel M. Girona, Christoforos Pappas, Louis Duchesne, Raphaël D. Chavardès, Lorena Balducci, Marc-André Lemay, Richard L. Peters and Fabio Gennaretti

Forests 2025, 16(9), 1448; https://doi.org/10.3390/f16091448 - 11 Sep 2025

Abstract

The predicted increase in drought frequency with climate change and its impact on boreal tree species are growing concerns. In this study, we assessed how three boreal tree species in western Quebec used stem water storage during a three-week drought. We estimated stem [...] Read more.

The predicted increase in drought frequency with climate change and its impact on boreal tree species are growing concerns. In this study, we assessed how three boreal tree species in western Quebec used stem water storage during a three-week drought. We estimated stem water deficit from radial variations using point dendrometers installed on 50 mature trees (10 trembling aspen, 20 jack pine, and 20 black spruce) located on clay (all three species) and sandy sites (only conifers). Air temperature/humidity and soil moisture measurements were used to model their effect on stem water storage. Our results reveal contrasted stem water storage use across species during drought. Before the drought, jack pine maintained higher relative stem water storage at night than both black spruce and trembling aspen (all paired p < 0.05) but became more water-depleted during the drought (all p < 0.1). Similarly, black spruce showed the same pattern as jack pine when compared to trembling aspen, both before and during the drought (p < 0.05). Acclimation of jack pine and black spruce to moderately dry conditions on sandy soils was evident, as relative tree water deficit remained low and stable across 20%–60% relative soil extractable water, but it increased sharply below 20%. Our research highlights that boreal trees may substantially mediate drought stress using water storage pools. Our findings emphasize the need to consider stem water storage when determining which boreal tree species will be more affected by increasingly frequent droughts. Full article

(This article belongs to the Section Forest Ecophysiology and Biology)

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27 pages, 11552 KB

Open AccessArticle

Species-Specific Growth Responses to Climate in a Multi-Site Study, NE Poland

by Agnieszka Tokarska-Osyczka, Marek Ksepko, Magdalena Terlecka, Łukasz Kolendo, Szymon Chmur, Martyna Lasek and Grzegorz Iszkuło

Forests 2025, 16(9), 1447; https://doi.org/10.3390/f16091447 - 11 Sep 2025

Abstract

In the context of intensifying climate change, dendroclimatic research provides insight into tree responses to environmental variability. This study assessed relationships between temperature, precipitation, and radial growth of four major forest species in Central Europe: Scots pine (Pinus sylvestris L.), Norway spruce [...] Read more.

In the context of intensifying climate change, dendroclimatic research provides insight into tree responses to environmental variability. This study assessed relationships between temperature, precipitation, and radial growth of four major forest species in Central Europe: Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst), pedunculate oak (Quercus robur L.), and black alder (Alnus glutinosa (L.) Gaertn.). Analyses were conducted at three independent sites to account for local variability and enhance robustness. We tested three hypotheses: (1) replication improves reliability in dendrochronological studies, (2) multi-species analysis strengthens interpretation of climate–growth relationships, and (3) black alder exhibits distinct precipitation sensitivity. Results showed species- and site-specific responses. The first hypothesis was supported, as replication enhanced the robustness of climate–growth signals in Scots pine, Norway spruce, and pedunculate oak showed broadly consistent responses, while black alder maintained its distinct pattern. Scots pine responded strongly to summer rainfall (June–August, including July of the previous year), Norway spruce to summer rainfall (June–July of the current and previous year), and pedunculate oak to summer rainfall (June–July, with additional effects in August). Black alder exhibited positive correlations with winter precipitation (December–January of the previous year) and negative with summer rainfall (May, June, August; September–November of the previous year), suggesting moisture-related stress. Temperature sensitivity occurred in winter and early spring (December–April, especially February–March) for most species, except black alder, which also responded positively to summer temperatures (May, July–September). These findings highlight the importance of species traits and site conditions in dendroclimatic studies and support replicated multi-species approaches to guide adaptive forest management under climate change. Full article

(This article belongs to the Section Forest Ecology and Management)

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21 pages, 1791 KB

Open AccessArticle

Microbial Community Responses to Nitrogen Addition in Poplar Leaf and Branch Litter: Shifts in Taxonomic and Phylogeny

by Yuan Gao, Yiying Wang, Haodong Zheng, Rongkang Wang, Zimei Miao and Zhiwei Ge

Forests 2025, 16(9), 1446; https://doi.org/10.3390/f16091446 - 11 Sep 2025

Abstract

Poplar (Populus L. species), a fast-growing temperate species, forms plantations with high productivity and biomass, with its litter sustaining key functions in nutrient cycling, microbial diversity, and carbon storage. Litter microbial communities drive decomposition, particularly in early stages, this initial phase is [...] Read more.

Poplar (Populus L. species), a fast-growing temperate species, forms plantations with high productivity and biomass, with its litter sustaining key functions in nutrient cycling, microbial diversity, and carbon storage. Litter microbial communities drive decomposition, particularly in early stages, this initial phase is characterized by the leaching of water-soluble carbon and nutrients from the litter, which creates a readily available resource pulse that facilitates rapid microbial colonization and activation. This process is followed by the activation of microbial enzymes and the immobilization of nutrients, collectively initiating the breakdown of more recalcitrant litter materials. Under rising global nitrogen deposition, we conducted a field randomized block experiment in 13-year-old pure poplar (Populus deltoides L. ‘35′) stands, with three nitrogen addition treatments: N0 (0 g N·m⁻²·yr⁻¹), N2 (10 g N·m⁻²·yr⁻¹), and N4 (30 g N·m⁻²·yr⁻¹). In the initial phase of litter decomposition, we measured the soil properties and litter traits, the litter microbial community composition, and its taxonomic and phylogenetic diversity indices. The results indicate that nitrogen addition altered microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), soil NO₃⁻-N, and accelerated litter decomposition rates. The microbial community in leaf litter responded to nitrogen addition with increased phylogenetic clustering (higher OTU richness and NRI), which suggests that environmental filtering exerted a homogenizing selective pressure linked to both soil and litter properties, whereas the microbial community in branch litter responded to nitrogen addition with increased taxonomic diversity (higher OTU richness, Shannon, ACE, and Chao1), a pattern associated with litter properties that likely alleviated nitrogen limitation and created opportunities for more taxa to coexist. The observed differences in response stem from distinct substrate properties of the litter. This study elucidates microbial taxonomic and phylogenetic diversity responses to nitrogen addition during litter decomposition, offering a scientific foundation for precise microbial community regulation and sustainable litter management. Full article

(This article belongs to the Section Forest Soil)

23 pages, 1452 KB

Open AccessArticle

Green Finance Empowering Forestry New Quality Productivity: Mechanisms and Practical Paths

by Xiran Qiao, Hongmin Li and Xiangyu Wu

Forests 2025, 16(9), 1445; https://doi.org/10.3390/f16091445 - 10 Sep 2025

Abstract

The impact of green fiscal policies on forestry new quality productivity (FNQP) development and the mechanisms behind this are explored in this study. A scientific basis for the promotion of FNQP development through green fiscal policies is intended to be provided. In addition, [...] Read more.

The impact of green fiscal policies on forestry new quality productivity (FNQP) development and the mechanisms behind this are explored in this study. A scientific basis for the promotion of FNQP development through green fiscal policies is intended to be provided. In addition, novel perspectives on the high-quality development of forestry are offered. Panel data from 31 Chinese provinces between 2011 and 2022 are collected and discrepancies between green fiscal policies and the level of FNQP are examined. By constructing a two-way fixed-effects model and employing econometric methods, the significant promotion of FNQP by green fiscal policies is indicated. Indirect promotion of FNQP development through the upgrading of the forestry industrial structure and the intensification of environmental regulation by green fiscal policies is demonstrated by indirect impact analysis results. Furthermore, a positive spatial spillover effect of green finance on forestry new quality productivity is documented. For policy selection, regional economic development level heterogeneity characteristics should be taken into account. Based on the findings of this study, some recommendations have been given for responses to green fiscal policy for forestry new quality productivity in the future. Full article

(This article belongs to the Section Forest Economics, Policy, and Social Science)

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11 pages, 2553 KB

Open AccessArticle

A Multiscale Investigation of Cross-Sectional Shrinkage in Bamboo Culms Using Natural-Speckle Digital Image Correlation During Drying

by Chengjian Huang, Yongjie Bao, Neng Li and Junfeng Hou

Forests 2025, 16(9), 1444; https://doi.org/10.3390/f16091444 - 10 Sep 2025

Abstract

Bamboo cracking is primarily attributed to the influence of moisture on its structure. Natural-speckle digital image correlation (DIC) was employed to characterize tangential shrinkage in cross-sections, using parenchyma cells as intrinsic speckle patterns. Shrinkage behavior during the 24 h drying process at a [...] Read more.

Bamboo cracking is primarily attributed to the influence of moisture on its structure. Natural-speckle digital image correlation (DIC) was employed to characterize tangential shrinkage in cross-sections, using parenchyma cells as intrinsic speckle patterns. Shrinkage behavior during the 24 h drying process at a temperature of 103 °C across the external, middle, and internal layers was comparatively analyzed in bamboo nodal regions (NR), internodal regions (IR), and transitional zones (TZ, i.e., node–internode interfaces). Moisture had the most pronounced effect on NR, which consistently exhibited the highest moisture content and shrinkage ratios during the drying process. Notably, the drying shrinkage of the external layer was significantly greater than that of other layers. Specifically, the drying shrinkage strain ratio of the external layer of NR is 3.02 times higher than that of the internal layer, while for IR, it is 3.60 times higher. Furthermore, the external layer of NR exhibits substantial deformation during the initial stages of drying, with a drying shrinkage strain ratio of 5.96% for 2 h. The results demonstrated that shrinkage deformation in bamboo nodes was significantly greater than in other regions, offering valuable insights for developing strategies to mitigate bamboo cracking. Full article

(This article belongs to the Section Wood Science and Forest Products)

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23 pages, 3052 KB

Open AccessArticle

An Empirical Study on the Effects of the “Sky Window” Policy on Household Income in Rural Communities: Evidence from Wuyi Mountain National Park

by Qi Sun, Yueming Cao, Jingjing Zhang and Jiliang Xu

Forests 2025, 16(9), 1443; https://doi.org/10.3390/f16091443 - 10 Sep 2025

Abstract

The increasing contradiction between ecological conservation and community development is a common challenge faced in most protected areas worldwide. Since 2019, China has used a “sky window” policy to alleviate the dilemma of environmental protection and sustainable production activities in national parks. This [...] Read more.

The increasing contradiction between ecological conservation and community development is a common challenge faced in most protected areas worldwide. Since 2019, China has used a “sky window” policy to alleviate the dilemma of environmental protection and sustainable production activities in national parks. This policy’s impact on household income in national park communities has received little attention. In this study, we aimed to evaluate the impact of the sky window policy on household income in Wuyi Mountain National Park communities in China and explore its mechanism of action in order to provide policy recommendations for achieving the protection goal of the national park and enabling win–win development of the community. Based on a total of 951 samples, which were collected through face-to-face interviews with 518 households in two periods, we used the difference-in-differences (DID) model to obtain consistent results and conducted robustness tests on the model by employing propensity score matching (PSM). The results showed that the “sky window” policy had a significant negative impact on the income of households in national park communities, which was mainly caused by the relaxation of restrictive regulations on farmers’ planting and breeding activities within national parks. The findings indicate that government departments in China need to further improve the laws and regulations regarding national park construction, establish a dynamic evaluation mechanism to regularly review the effects of the “sky window” policy, and make timely adjustments based on changes in the ecological environment of national parks and the development needs of local communities. At the same time, to ensure a stable source of income for residents, it is also necessary to establish a platform for realizing the value of ecological products, strengthen support for livelihood transformation, and establish long-term benefit linkage mechanisms. This study contributes to the research on the effective management of national parks, community welfare improvement, and sustainable development in developing countries. Full article

(This article belongs to the Special Issue Sustainable Wood Market: The Contribution and Challenges of Forest Products for Carbon Neutrality)

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