Forests

15 pages, 368 KiB

Open AccessArticle

Effective Wood Veneer Densification by Optimizing Key Parameters: Temperature, Equilibrium Moisture Content, and Pressure

by Tolgay Akkurt, Anti Rohumaa and Jaan Kers

Forests 2025, 16(6), 969; https://doi.org/10.3390/f16060969 (registering DOI) - 7 Jun 2025

Abstract

Due to increasing environmental concerns and the scarcity of high-quality hardwood resources, enhancing wood properties—such as strength, surface smoothness, and impact resistance—has become essential, especially for veneer-based products. Wood densification is a promising method for such improvements, typically involving mechanical, thermo-mechanical, or hygrothermal-mechanical [...] Read more.

Due to increasing environmental concerns and the scarcity of high-quality hardwood resources, enhancing wood properties—such as strength, surface smoothness, and impact resistance—has become essential, especially for veneer-based products. Wood densification is a promising method for such improvements, typically involving mechanical, thermo-mechanical, or hygrothermal-mechanical processes. However, most prior studies examined only one densification parameter at a time. This study systematically investigates the combined effects of equilibrium moisture content (EMC), pressing temperature, and pressure on birch veneer densification. Birch veneers were densified radially using four temperatures (90–210 °C), three pressures (1.8–5.4 MPa), and three EMC levels (5%–20%) for a fixed pressing time of 8 min, resulting in 36 unique combinations. Results showed that higher pressing pressure and higher initial EMC consistently led to greater veneer densification. Optimal outcomes were achieved under two distinct conditions: (1) 90 °C with high EMC and high pressure, and (2) 210 °C with the same high EMC and high pressure. Intermediate temperatures (130–170 °C) were less effective. Temperatures above 200 °C were found critical due to lignin softening beyond its glass transition temperature. These findings highlight the interactive role of key parameters and provide practical guidance for upgrading low-quality veneers into high-performance engineered wood products in a sustainable and resource-efficient manner. Full article

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

14 pages, 4913 KiB

Open AccessArticle

Exploring Fungal Communities in the Needles of Marginal Conifer Tree Populations

by Jelena Lazarević and Audrius Menkis

Forests 2025, 16(6), 968; https://doi.org/10.3390/f16060968 (registering DOI) - 7 Jun 2025

Abstract

In Montenegro, coniferous forests play a key ecological role in maintaining ecosystem stability. Root-associated mycorrhizal fungi and saprotrophic fungi inhabiting forest soils are well known for their roles in nutrient cycling, organic matter decomposition, and supporting host tree health. In contrast, the fungal [...] Read more.

In Montenegro, coniferous forests play a key ecological role in maintaining ecosystem stability. Root-associated mycorrhizal fungi and saprotrophic fungi inhabiting forest soils are well known for their roles in nutrient cycling, organic matter decomposition, and supporting host tree health. In contrast, the fungal communities residing within conifer needles, despite potentially important ecological functions, remain largely underexplored, particularly in natural and marginal forest ecosystems such as those in the Balkans. This study aimed to investigate the diversity and community composition of needle-associated fungi in three native conifers: Picea abies and Abies alba (at the edge of their native range), and the endemic Pinus heldreichii, from different mountainous regions in Montenegro. High-throughput sequencing was conducted to assess fungal diversity and community composition. Dothideomycetes dominated fungal communities in all three tree species, followed by Leotiomycetes and Tremellomycetes. Multivariate analysis revealed distinct fungal communities in P. heldreichii, whereas fungal communities in A. alba and P. abies were partially overlapping. Functional classification showed a dominance of saprotrophic, pathogenic, and endophytic fungi, with P. heldreichii exhibiting the highest proportion of saprotrophs, while A. alba and P. abies showed a considerable proportion of pathogens. The findings highlight strong host specificity, biogeographical influences, and the ecological importance of fungal communities in coniferous forests. This study provides new insights into the diversity and functional roles of needle-associated fungi, emphasizing the need for conservation efforts to maintain microbial biodiversity in native forests of Montenegro. Full article

(This article belongs to the Special Issue Recent Scientific Developments in Forest Pathology)

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28 pages, 2448 KiB

Open AccessArticle

Influence of Increasing Fires on Mixed Conifer Stand Dynamics in the U.S. Southwest

by Simon D. Baker, Kristen M. Waring, David Auty and Nicholas Wilhelmi

Forests 2025, 16(6), 967; https://doi.org/10.3390/f16060967 (registering DOI) - 7 Jun 2025

Abstract

(1) Stand-replacing fires may threaten the continued stability of mixed conifer forests in the U.S. Southwest. Increasing fire frequency and severity have made post-fire forest recovery trajectories uncertain for many coniferous species, potentially leading to long-term shifts in forest structure and composition. (2) [...] Read more.

(1) Stand-replacing fires may threaten the continued stability of mixed conifer forests in the U.S. Southwest. Increasing fire frequency and severity have made post-fire forest recovery trajectories uncertain for many coniferous species, potentially leading to long-term shifts in forest structure and composition. (2) The purpose of this study was to examine post-fire stand dynamics over a 10-year period, using a network of permanent plots established prior to wildfire events across Arizona and New Mexico. We assessed changes in overstory composition, regeneration, and fuel loading across different fire severities. (3) High severity fire caused near-total overstory mortality, with little to no conifer regeneration and abundant sprouting hardwood regeneration. Lower severity fire was more favorable to fire-tolerant conifer species; however, mortality among mature trees was high, and fire-intolerant conifers were either diminished or extirpated completely. (4) In high severity fires, changes in overstory and understory structure and composition may be long-lasting. Additionally, increased fuel loads following high severity fire suggests a heightened risk of reburns, potentially perpetuating ecotype conversion. Our findings highlight the need for active management strategies, including reforestation and fuel reduction treatments, to support forest resilience for mixed conifer ecosystems in the US Southwest and similar forest types in other regions in the face of ongoing climate and fire regime changes. Full article

(This article belongs to the Special Issue How Natural and Anthropogenic Disturbances Affect Plant Communities in Actively Managed Temperate Forests)

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19 pages, 20565 KiB

Open AccessArticle

Mapping Commercial Forests Infected by the Novel Variant of Elsinoë masingae, Using Unmanned Aerial Technology in Southern Africa

by Kabir Peerbhay, Nishka Devsaran, Romano Lottering, Naeem Agjee and Mikka Parag

Forests 2025, 16(6), 966; https://doi.org/10.3390/f16060966 (registering DOI) - 7 Jun 2025

Abstract

Eucalyptus scab disease (Elsinoë) is a harmful plant fungus that can disrupt various ecological and economic services provided by commercial forests. To effectively control and monitor the occurrence of forest pathogens, it is important to understand their spatial distribution within the [...] Read more.

Eucalyptus scab disease (Elsinoë) is a harmful plant fungus that can disrupt various ecological and economic services provided by commercial forests. To effectively control and monitor the occurrence of forest pathogens, it is important to understand their spatial distribution within the infected area. Consistent monitoring, together with high-resolution imagery obtained from unmanned aerial vehicles (UAVs), has become important in forest management. Therefore, this study focuses on detecting and mapping the spatial distribution of E. masingae within commercial forests using image texture and vegetation indices (VIs) computed from a UAV sensor with machine learning (ML) and deep learning (DL) models. The fast large margin (FLM), random forest (RF), and deep learning (DL) models were used to determine which model effectively mapped the spatial distribution of the disease. The results indicated that image texture significantly increased the model accuracies (FLM = 94.8%; RF = 98.9%; DL = 98.9%) as opposed to the results without the use of image texture (FLM = 84.4%; RF = 76.1%; DL = 81.7%). Since the DL model obtained the fastest model run time and was proven to be the most significant model, it selected the mean, homogeneity, second moment, and correlation texture parameters which were predominantly determined from the red and blue bands of the UAV sensor containing visible bands. Additionally, the 3 × 3 moving window size was ideal for detecting E. masingae since the estimation of texture parameters was reduced efficiently. Overall, this study showcases the ability of UAVs to effectively map forest disease. Together with that, it has proven that the DL model outperformed the conventional ML models. Full article

(This article belongs to the Section Forest Health)

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18 pages, 5154 KiB

Open AccessArticle

Monitoring Nitrogen Nutrition in Ginkgo Using Unmanned Aerial Vehicle RGB Imagery and the Gaussian Process Regression Model

by Xinyu Tao, Fuliang Cao, Guibin Wang, Hao Liu, Saiting Qiu, Tingting Dai, Jimei Han, Sinong Yu and Kai Zhou

Forests 2025, 16(6), 965; https://doi.org/10.3390/f16060965 (registering DOI) - 7 Jun 2025

Abstract

Nitrogen nutrition monitoring is crucial in agriculture and forestry. With the development of Unmanned Aerial Vehicle (UAV) imaging technology, its application in nitrogen nutrition monitoring has gained attention. Traditional regression methods often struggle to accurately capture the nonlinear relationships between image features and [...] Read more.

Nitrogen nutrition monitoring is crucial in agriculture and forestry. With the development of Unmanned Aerial Vehicle (UAV) imaging technology, its application in nitrogen nutrition monitoring has gained attention. Traditional regression methods often struggle to accurately capture the nonlinear relationships between image features and nitrogen nutrition parameters. This study introduces Gaussian regression models to better model the relationship between UAV image features and nitrogen nutrition in Ginkgo. UAV RGB imagery of three-year-old Ginkgo biloba L. seedlings was used to extract nitrogen-related image features. Gaussian regression models were employed to select and model these features, creating regression models for nitrogen accumulation and nitrogen content in Ginkgo. The accuracy of the models was validated. Results indicated that the optimal canopy type for monitoring nitrogen accumulation in Ginkgo was the shadowed canopy, with the color feature BMR being the most important feature. For monitoring nitrogen content, sunlight and shadow canopy types were suitable, with BMR and b* being the key features. Gaussian regression demonstrated superior accuracy and robustness compared to traditional regression models. This study emphasizes the potential of Gaussian regression models to improve nitrogen monitoring through UAV imagery, offering valuable applications in precision agriculture and forestry management, particularly in supporting nitrogen fertilization and nutrition management for Ginkgo. Full article

(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)

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13 pages, 1679 KiB

Open AccessArticle

Hydrogen Peroxide Bleaching Induces a Dual Enhancement of Liquid Permeability and Fungal Resistance in Bamboo Through Microstructural Engineering

by Dandan Xu, Sheng He, Weiqi Leng, Yuhe Chen and Haiyang Quan

Forests 2025, 16(6), 964; https://doi.org/10.3390/f16060964 - 6 Jun 2025

Abstract

Bamboo, as a sustainable and renewable biomass resource, possesses significant application prospects along with underutilized potential. However, challenges such as mildew infestation, insect damage, and discoloration during processing and utilization negatively impact its service life and economic value. This study proposes a simplified [...] Read more.

Bamboo, as a sustainable and renewable biomass resource, possesses significant application prospects along with underutilized potential. However, challenges such as mildew infestation, insect damage, and discoloration during processing and utilization negatively impact its service life and economic value. This study proposes a simplified hydrogen peroxide bleaching method for bamboo processing, resulting in bleached materials with uniform coloration and improved mildew resistance. The scanning electron microscopy (SEM) analysis of bleached bamboo showed significantly reduced starch and protein inclusions, expanded intercellular spacing, partial fiber detachment, and localized structural deformation in treated bamboo. The X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analyses revealed substantial lignin degradation in hydrogen peroxide-treated samples. The color difference (ΔE) was measured at 13.65 between treated and untreated samples, confirming effective bleaching efficacy. The mercury intrusion porosimetry (MIP) analysis revealed enhanced porosity accompanied by diameter enlargement in treated bamboo. Antifungal assessments indicated that hydrogen peroxide bleaching delayed the onset of mold colonization and significantly enhanced the mildew resistance of bamboo substrates. Full article

(This article belongs to the Special Issue Ecological Research in Bamboo Forests: 2nd Edition)

24 pages, 1274 KiB

Open AccessArticle

An Analysis of National Park Financing Mechanisms in Serbia

by Ilija Đorđević, Goran Češljar, Jelena Tomićević-Dubljević, Nevena Čule, Sabahudin Hadrović, Sonja Braunovic and Ivana Živojinović

Forests 2025, 16(6), 963; https://doi.org/10.3390/f16060963 - 6 Jun 2025

Abstract

Protected areas are essential for biodiversity conservation, ecosystem services, and protecting different cultural heritage. They are legally designated and managed to safeguard habitats, species, and ecological processes. The EU aims to protect 30% of its land by 2030, while in Serbia 9.74% of [...] Read more.

Protected areas are essential for biodiversity conservation, ecosystem services, and protecting different cultural heritage. They are legally designated and managed to safeguard habitats, species, and ecological processes. The EU aims to protect 30% of its land by 2030, while in Serbia 9.74% of land is under protection. One of the important categories of protected areas represents national parks, which cover 17.3% of all protected areas in Serbia. In order to understand the mechanisms of financing national parks in Serbia, the period from 2008 to 2022 was analyzed. The 15-year period was selected due to the availability of data and the necessity for long-term analysis. All revenues are divided in four groups: business, fee, grant and other business revenues. The results of regression analysis show that the growth rate of business revenue is the most significant contributor among the revenue sources, with a very strong positive impact on the growth rate of total revenue in all four national parks. The growth rate of grant revenue also contributes positively to the growth rate of total revenue. However, its impact is much smaller than the growth rate of business revenue and fee revenue but still highly significant. A strong negative correlation (−0.82) is present between the growth rate of business and fee revenue in National Park Kopaonik. This suggests that with an increase in fee revenues, business revenues decrease. The results of this research show that business revenues are the most important, followed by fee and grant revenue. Full article

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

27 pages, 3752 KiB

Open AccessArticle

Responses of Water Use Strategies to Seasonal Drought Stress Differed Among Eucalyptus urophylla S.T.Blake × E. grandis Plantations Along with Stand Ages

by Zhichao Wang, Yuxing Xu, Wankuan Zhu, Runxia Huang, Apeng Du, Haoyang Cao and Wenhua Xiang

Forests 2025, 16(6), 962; https://doi.org/10.3390/f16060962 - 6 Jun 2025

Abstract

Water use strategies reflect the ability of plants to adapt to drought caused by climate change. However, how these strategies change with stand development and seasonal drought is not fully understood. This study used stable isotope techniques (δD, δ¹⁸O, and δ [...] Read more.

Water use strategies reflect the ability of plants to adapt to drought caused by climate change. However, how these strategies change with stand development and seasonal drought is not fully understood. This study used stable isotope techniques (δD, δ¹⁸O, and δ¹³C) combined with the MixSIAR model to quantify the seasonal changes in water use sources and water use efficiency (WUE) of Eucalyptus urophylla S.T.Blake × E. grandis (E. urophylla × E. grandis) at four stand ages (2-, 4-, 9- and 14-year-old) and to identify their influencing factors. Our results showed that the young (2-year-old) and middle-aged (4-year-old) stands primarily relied on shallow soil water throughout the growing season due to the limitations of a shallow root system. In contrast, the mature (9-year-old) and overmature (14-year-old) stands, influenced by the synergistic effects of larger and deeper root systems and relative extractable water (REW), exhibited more flexibility in water use, mainly relying on shallow soil water in wet months, but shifting to using middle and deep soil layer water in dry months, and quickly returning to mainly using shallow soil water in the episodic wet month of the dry season. The WUE of E. urophylla × E. grandis was affected by the combined effect of air temperature (T), vapor pressure deficit (VPD), and REW. WUE was consistent across the stand ages in the wet season but decreased significantly with stand age in the dry season. This suggests that mature and overmature stands depend more on shifting their water source, while young and middle-aged stands rely more on enhanced WUE to cope with seasonal drought stress, resulting in young and middle-aged stands being more vulnerable to drought stress. These findings offer valuable insights for managing water resources in eucalyptus plantations, particularly as drought frequency and intensity continue to rise. Full article

(This article belongs to the Special Issue Advances in Forest Carbon, Water Use and Growth Under Climate Change)

22 pages, 4944 KiB

Open AccessArticle

Developing Diameter Distribution Models of Major Coniferous Species in South Korea

by Sanghyun Jung, Daesung Lee and Jungkee Choi

Forests 2025, 16(6), 961; https://doi.org/10.3390/f16060961 - 6 Jun 2025

Abstract

This study developed diameter distribution models using the Weibull function for Korean red pine (Pinus densiflora), Korean white pine (P. koraiensis), and Japanese larch (Larix kaempferi). The study data were collected from 49 Korean red pine stands, [...] Read more.

This study developed diameter distribution models using the Weibull function for Korean red pine (Pinus densiflora), Korean white pine (P. koraiensis), and Japanese larch (Larix kaempferi). The study data were collected from 49 Korean red pine stands, 54 Korean white pine stands, and 49 Japanese larch stands located in national forests in Gangwon and North Gyeongsang Provinces, South Korea. To identify the optimal method for modeling the diameter distribution of these three species, parameter recovery methods and parameter prediction methods were analyzed. To identify the optimal parameter recovery method for presenting the diameter distribution of these three species, ten parameter recovery methods were compared using moment-based, percentile-based, and hybrid approaches. For parameter prediction methods, major stand characteristics were used as independent variables to develop the models for the parameters a, b, and c of the Weibull function. For estimating the Weibull parameters, two methods—the estimated parameter recovery method and the parameter prediction method—were compared and analyzed. The optimal parameter recovery method was the one using the minimum DBH, the mean DBH, and the DBH variance. The coefficient of determination (R²) for the models predicting the minimum DBH, the mean DBH, and the DBH variance ranged from 0.7186 to 0.9747, and the R² for the models directly predicting parameters ranged from 0.7032 to 0.9374, indicating high explanatory power and unbiased results. When comparing the two methods, the parameter prediction method showed higher accuracy and lower bias. In addition, paired t-tests were conducted to assess differences from the observed Weibull parameters. The results showed a significant difference for the estimated parameter recovery method, whereas no significant difference was found for the parameter prediction method, further supporting its reliability. Full article

(This article belongs to the Special Issue Silviculture and Management Strategy in Coniferous Forests)

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28 pages, 8742 KiB

Open AccessArticle

The Effects of Fungal Infection Combined with Insect Boring on the Induction of Agarwood Formation and Transcriptome Analysis of Aquilaria sinensis

by Jianglongze Yang, Peng Chen, Libao Zhang, Ruiling Yuan, Dan Feng and Jin Xu

Forests 2025, 16(6), 960; https://doi.org/10.3390/f16060960 - 6 Jun 2025

Abstract

This study investigates the main insects and endophytic fungi that promote the formation of agarwood in Aquilaria sinensis (Lour.) Spreng. and elucidates the effects and mechanisms of different ‘insect + fungus’ combinations on agarwood formation. The results showed that 16 strains of endophytic [...] Read more.

This study investigates the main insects and endophytic fungi that promote the formation of agarwood in Aquilaria sinensis (Lour.) Spreng. and elucidates the effects and mechanisms of different ‘insect + fungus’ combinations on agarwood formation. The results showed that 16 strains of endophytic fungi were isolated from A. sinensis. Fusarium solani, Penicillium chrysogenum, Fusarium equiseti, and Phaeoacremonium alvesii were identified as dominant fungi promoting agarwood formation, while Nadezhdiella cantori was recognized as the dominant insect facilitating this process. The optimal ‘insect + fungus’ combination was Nadezhdiella cantori + Fusarium equiseti. The average agarotetrol contents were 0.046% and 0.054% in February and June, respectively, which were significantly higher than those in cold drilling, fungal-only, and insect-only treatments. RNA sequencing revealed 23,801 differentially expressed unigenes in cjYB1Z4 (optimal combination) versus control BMZ. Upregulated unigenes were enriched in isoflavone biosynthesis, flavonoid biosynthesis, and sesquiterpenoid and triterpene biosynthesis. Fifty sesquiterpene-related differential unigenes encoded seven key enzymes in the MVA pathway, seven key enzymes in the MEP pathway, and seven terpene synthases. Co-expression network analysis indicated that transcription factors (e.g., WRKY33, ABF, WRKY2) potentially regulate agarwood sesquiterpene formation. This work elucidates preliminary effects and molecular mechanisms of insect- and fungi-induced agarwood formation in A. sinensis, advancing agarwood induction technology. Full article

(This article belongs to the Section Forest Health)

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19 pages, 1297 KiB

Open AccessArticle

Genetic Parameters and Family Selection of Pinus pseudostrobus var. apulcensis Through Growth and Stem Quality in Mixteca Oaxaqueña Region, Mexico

by Bertario Sánchez-Rosales, Mario Valerio Velasco-García, Adán Hernández-Hernández, Martín Gómez-Cárdenas and Leticia Citlaly López-Teloxa

Forests 2025, 16(6), 959; https://doi.org/10.3390/f16060959 - 6 Jun 2025

Abstract

The Mixteca Oaxaqueña region has historically suffered from soil and vegetation loss. However, since the last decade of the previous century, successful reforestation efforts have been carried out in many areas. As a result, there is now a need to select phenotypes with [...] Read more.

The Mixteca Oaxaqueña region has historically suffered from soil and vegetation loss. However, since the last decade of the previous century, successful reforestation efforts have been carried out in many areas. As a result, there is now a need to select phenotypes with superior growth and good wood quality. This study aimed to estimate genetic parameters and identify superior families of Apulco pine (Pinus pseudostrobus var. apulcensis (Lindl.) Shaw) based on growth and stem quality traits. After four years, growth and stem quality traits were evaluated in 64 open-pollinated families. Different selection intensities were tested using two evaluation methods. All traits showed significant differences among families (p ≤ 0.0016), with genetic coefficients of variation ranging from 8.01% to 18.84%. Heritability estimates for growth traits were high (

h_{i}^{2}

= 0.42−0.66;

h_{f}^{2}

= 0.55−0.63), whereas heritability for stem quality traits was slightly lower (

h_{i}^{2}

= 0.01−0.38;

h_{f}^{2}

= 0.01−0.38). Genetic correlations (r_g) among growth traits were high and positive (r_g ≥ 0.857), while correlations among stem quality traits and between quality and growth traits were more variable (r₉ = −0.498 to 0.899). Based on both evaluation methods and a 25% selection intensity, sixteen superior families were identified, showing estimated genetic gains of approximately 4% for growth-related traits. These families are recommended for use in timber plantations, whereas a broader set is suggested for reforestation efforts in order to maintain genetic diversity. Full article

(This article belongs to the Special Issue Forest Tree Breeding, Testing, and Selection)

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2 pages, 525 KiB

Open AccessEditorial

Forest Soil and Water Biogeochemistry

by Jiří Kaňa and Snežana Belanović Simić

Forests 2025, 16(6), 958; https://doi.org/10.3390/f16060958 - 5 Jun 2025

Abstract

For us as editors, the whole-ecosystem approach is undoubtedly the most compelling way to study forests [...] Full article

(This article belongs to the Special Issue Forest Soil and Water Biogeochemistry)

24 pages, 5305 KiB

Open AccessArticle

Noninvasive Sonic Tomography for the Detection of Internal Defects in Relict Woodlands of Polylepis in Peru

by Yakov Quinteros-Gómez, Abel Salinas-Inga, Jehoshua Macedo-Bedoya, Enzo Peralta-Alcantara, Marcel La Rosa-Sánchez, Fernando Camones Gonzales, Alexandra Yamunaque, Franco Angeles-Alvarez, Doris Gómez-Ticerán and Olga Lidia Solano Dávila

Forests 2025, 16(6), 957; https://doi.org/10.3390/f16060957 - 5 Jun 2025

Abstract

Polylepis woodlands, endemic to the Andean Mountains, are critical for biodiversity and ecosystem services but face threats from anthropogenic disturbances and climate change. This study employed sonic tomography (ST) to assess the structural integrity of three relict Polylepis stands on the western slopes [...] Read more.

Polylepis woodlands, endemic to the Andean Mountains, are critical for biodiversity and ecosystem services but face threats from anthropogenic disturbances and climate change. This study employed sonic tomography (ST) to assess the structural integrity of three relict Polylepis stands on the western slopes of the Peruvian Andes. A total of 192 tomograms from 48 trees across three sites revealed substantial variation in internal decay (2.5–70%), with mean decay levels of 11.6% (Z1), 16.6% (Z2), and 10.5% (Z3). Although the initial generalized linear mixed models (GLMMs) suggested tree diameters at breast height (DBH) as a potential predictor of decay, subsequent non-parametric Spearman’s correlation analysis found no significant relationship between DBH and decay (r < 0.001, p > 0.05) or between altitude and decay (r = 0.187, p = 0.204). No significant differences were detected among species or zones. The study demonstrates the efficacy of ST for noninvasive health assessment in high-altitude ecosystems and underscores the need for long-term monitoring to guide conservation strategies. Full article

(This article belongs to the Section Forest Health)

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18 pages, 1677 KiB

Open AccessArticle

Restoration of Understory Plant Species and Functional Diversity in Temperate Plantations Along Successional Stages

by Weiwei Zhao, Yanting Chen, Muhammad Fahad Sardar and Xiang Li

Forests 2025, 16(6), 956; https://doi.org/10.3390/f16060956 - 5 Jun 2025

Abstract

Context: Planting forests is an important strategy to combat biodiversity loss and ecosystem service degradation, but its effects on biodiversity and ecosystem services remain uncertain. Objectives: This study aimed to investigate the restoration of plants along successional and environmental gradients in [...] Read more.

Context: Planting forests is an important strategy to combat biodiversity loss and ecosystem service degradation, but its effects on biodiversity and ecosystem services remain uncertain. Objectives: This study aimed to investigate the restoration of plants along successional and environmental gradients in planted forests by examining how understory plant diversity (species richness, composition, functional diversity), functional diversity—the range of species’ traits influencing ecosystem functions and services and their environmental drivers—evolve in temperate plantations over time. Methods: We examined a total of 36 plots with different stand ages in Chongli District, China, and compared the differences in species richness, biodiversity, composition, and functional diversity across different successional stages and over time. We also analyzed the response mechanisms of species richness and functional diversity to environmental factors at both the local and landscape scales. Results and Discussion: Our results showed species diversity, species richness, and functional diversity tended to increase with time in most plots and stabilized after 45 years. Although species richness was lower in mature plots (>100 years), functional diversity was higher, and species composition was significantly differentiated. This trade-off reflects environmental filtering selecting for competitively dominant species with distinct functional traits, while continuous species turnover prevents compositional convergence. The increase in functional diversity was not directly related to the rise in species richness, but it depended on the relative dominance of several species with different functional characteristics in the ecosystem. Simulation analysis confirmed this pattern aligns with a Simpson’s index-driven trait complementarity mechanism. At the local scale, stand age was the most significant positive factor influencing species richness and functional diversity. Soil total nitrogen and organic matter only negatively affected species richness in interactions. At the landscape scale, landscape heterogeneity plays an important role in restoring functional diversity. Historical afforestation since the 1950s restricted comparisons to secondary forests, lacking primary forest baselines. Conclusions: The results suggest that the effects of the successional stage and multiscale environmental factors should be comprehensively considered in the restoration strategy of restored forests. Full article

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

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27 pages, 14684 KiB

Open AccessArticle

Agroforestry in the Soil and Water Conservation of Karst Can Improve Rural Eco-Revitalization: Evidence from the Core Area of the South China Karst

by Yuwen Fu, Min Zhang, Zuju Li, Kangning Xiong, Qi Fang, Wanmei Hu, Liheng You and Zhifu Luo

Forests 2025, 16(6), 955; https://doi.org/10.3390/f16060955 - 5 Jun 2025

Abstract

Agroforestry (AF) effectively enhances ecological restoration and soil–water conservation (SWC), yet the relationship among soil and water conservation agroforestry (SWCAF) in karst soil, water loss (SWL) and rural eco-revitalization (RER) remains unclear, which may hinder the ecological restoration process around the world. This [...] Read more.

Agroforestry (AF) effectively enhances ecological restoration and soil–water conservation (SWC), yet the relationship among soil and water conservation agroforestry (SWCAF) in karst soil, water loss (SWL) and rural eco-revitalization (RER) remains unclear, which may hinder the ecological restoration process around the world. This study aims to reveal whether SWCAF in karst areas improves RER through SWC benefits, ecosystem service (ES) enhancement and rural ecological environment quality (REEQ) improvement. We take Guizhou Province, the core area of the South China Karst (SCK), as the study area and 2010–2020 as the study period. By using the equivalent factor method, the remote sensing ecological index (RSEI) model, bivariate spatial autocorrelation and the panel vector autoregressive (PVAR) model, the study reveals SWCAF’s ecological benefits and its interaction mechanism with RER. Key findings reveal the following: (1) SWCAF reduced the area of SWL by 14.93% by converting cropland into forests. (2) The AF ecosystem service value (AFESV) increased by CNY 9.181 billion, and the forest-related AFESV increases represented 184% of the total AFESV, while REEQ showed an overall positive trend in the western SWC area. (3) The AFESV has an obvious synergistic effect with REEQ (r = 0.60) and obvious positive synergy with SWL (r = 0.69), and its spatial correlation increases over time. (4) The PVAR model verified that there is a bidirectional Granger causal relationship between the AFESV and RER, showing dynamic positive and negative alternating influences. This research study reveals that SWCAF drives RER through the dual path of SWL control and value-added ecological services, among which the forest ecosystem plays a core role. In the future, it is necessary to optimize the diversity of AF structures to avoid ecological service trade-offs. This research study provides a scientific basis for decision making and the ecological management of SWC in karst soils globally. Full article

(This article belongs to the Special Issue Contribution of Forestry Ecological Restoration Projects to the Realization of Sustainable Development Goals)

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19 pages, 2903 KiB

Open AccessArticle

Characteristic and Adaptive Strategy in Leaf Functional Traits of Giant Panda (Ailuropoda melanoleuca) Staple Bamboo Species

by Xiong Liu, Yilin Zhou, Xingcheng Zou, Weiyu Zhu, Renping Wan, Zhengchuan Liang, Junxi Hu, Liehua Tie, Xinglei Cui, Yuanbin Zhang, Shixing Zhou, Jordi Sardans, Congde Huang and Josep Peñuelas Reixach

Forests 2025, 16(6), 954; https://doi.org/10.3390/f16060954 - 5 Jun 2025

Abstract

Leaf functional traits are important indicators that reveal plant adaptation and response to environmental changes. Characteristics and adaptive strategies of leaf functional traits of staple bamboo species (SBSs) for the giant panda (Ailuropoda melanoleuca) remain unclear, which limits conservation management of [...] Read more.

Leaf functional traits are important indicators that reveal plant adaptation and response to environmental changes. Characteristics and adaptive strategies of leaf functional traits of staple bamboo species (SBSs) for the giant panda (Ailuropoda melanoleuca) remain unclear, which limits conservation management of the giant panda and its habitat. Here, this study investigated 10 SBSs in 15 nature reserves across 36 counties, measured eight leaf functional traits, analyzed trait characteristics, variation, and drivers of variation, and examined trait-based strategies and strategy–environmental constraint relationships. Our results indicate that: coefficients of variation in leaf functional traits spanned from 9.58% to 79.16%, and significant differences were found among SBSs for leaf functional traits except chlorophyll concentration. The linear mixed-effects models revealed that the taxonomic factors explained 20.16 to 77.94% of variation, and environmental factors explained 17.03 to 29.12%. Leaf functional traits exhibited distinct environmental associations, primarily driven by geographic location, topography, and soil phosphorus availability. Hierarchical clustering and principal component analysis revealed 10 SBS clustered into two groups, corresponding to conservative and acquisitive resource-use strategies. Canonical correspondence analysis revealed that SBSs with conservative strategies were distributed in warm and moist habitats, and SBSs with acquisition strategies were distributed in habitats with high solar radiation. Our results reveal the key trait characteristics of SBSs and the strategy-environmental constraint model based on traits, which can provide scientific basis for the ecological management practice of SBSs. Full article

(This article belongs to the Special Issue Advancements in Bamboo and Rattan: Insights into Molecular Biology, Physiology, Ecology, and Applications)

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25 pages, 2656 KiB

Open AccessReview

Assessing Forest Degradation in the Congo Basin: The Need to Broaden the Focus from Logging to Small-Scale Agriculture (A Systematic Review)

by Timothée Besisa Nguba, Jan Bogaert, Jean-Remy Makana, Jean-Pierre Mate Mweru, Kouagou Raoul Sambieni, Julien Bwazani Balandi, Charles Mumbere Musavandalo and Jean-François Bastin

Forests 2025, 16(6), 953; https://doi.org/10.3390/f16060953 - 5 Jun 2025

Abstract

While the methods for monitoring deforestation are relatively well established, there is still no compromise on those for forest degradation. We propose here a systematic review on studies about forest degradation in the Congo Basin. Our analysis focused on seven key anthropogenic causes [...] Read more.

While the methods for monitoring deforestation are relatively well established, there is still no compromise on those for forest degradation. We propose here a systematic review on studies about forest degradation in the Congo Basin. Our analysis focused on seven key anthropogenic causes of forest degradation. Shifting agriculture emerged as the most significant driver, accounting for 61% ± 28.58% (mean ± SD) of canopy opening, 73.16% ± 16.88% aboveground carbon loss, and 30.37% ± 30.67% of tree species diversity loss over a 5–60-year period. Our analysis reveals a significant disconnect. Only 29% of the reviewed studies address this driver, while over 64% focus primarily on the consequences of industrial timber harvesting. Despite its comparatively minor contribution to degradation, with effects range from only 8.98% ± 13.63% of canopy opening, 14.79% ± 22.21 aboveground carbon loss, and 4.27 ± 21.07 tree species diversity loss over 1–20 years. Indeed, most of the methods focus on detecting changes in canopy structure associated with forest logging over a short period (0–5 years). These illustrate the need for a shift in focus in scientific research towards innovative methods, which can be developed over time, to monitor the various impacts of all causes of forest degradation. Full article

(This article belongs to the Special Issue Forest Disturbance and Management)

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17 pages, 772 KiB

Open AccessArticle

Analysis of the Impact of RCEP Implementation on Forest Product Exports Among Member Countries Based on a Double Machine Learning Model

by Wanhua Cai, Yongwu Dai, Bo Jiang and Yunfeng Zheng

Forests 2025, 16(6), 952; https://doi.org/10.3390/f16060952 - 5 Jun 2025

Abstract

In 2025, the U.S. reciprocal tariff policy destabilized global multilateral trade and accelerated the advance of regional trade cooperation. As the world’s most populous regional trade agreement, the Regional Comprehensive Economic Partnership (RCEP) plays an important role in regional economic and trade integration. [...] Read more.

In 2025, the U.S. reciprocal tariff policy destabilized global multilateral trade and accelerated the advance of regional trade cooperation. As the world’s most populous regional trade agreement, the Regional Comprehensive Economic Partnership (RCEP) plays an important role in regional economic and trade integration. In this paper, the RCEP’s signing is considered a quasi-natural experiment, and a double machine learning (DML) model is used to analyze the impact of the RCEP’s implementation on the export of forest products among member countries. The sample used for the empirical analysis is product dimension panel data of RCEP member countries from 2012 to 2023. We found that the implementation of the RCEP agreement has facilitated the growth of forest product exports among member countries, as evidenced by the synchronized growth in the quantity, type, and price of forest product exports. Heterogeneity analysis reveals that the positive effects of RCEP implementation vary significantly across product categories and across countries. Our study provides evidentiary support for scholars to more fully understand the policy effects of the RCEP and may also serve as a policy reference for RCEP member countries to expand intra-regional forest product exports. Full article

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

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19 pages, 1508 KiB

Open AccessArticle

Phytochemical Composition, Antioxidant, Anti-Inflammatory Activity, and DNA Protective Capacity of Moss Hypnum cupressiforme Hedw. from Bulgaria

by Zhana Petkova, Mina Todorova, Ivayla Dincheva, Manol Ognyanov, Samir Naimov, Elena Apostolova, Olga Teneva, Ginka Antova and Gana Gecheva

Forests 2025, 16(6), 951; https://doi.org/10.3390/f16060951 - 5 Jun 2025

Abstract

Hypnum cupressiforme Hedw. is a widely distributed moss species with significant bioactive potential, but the phytochemical composition and biological activity of this species are not well documented yet, particularly in Bulgaria. The current study aimed to investigate the amino acid composition, free sugars, [...] Read more.

Hypnum cupressiforme Hedw. is a widely distributed moss species with significant bioactive potential, but the phytochemical composition and biological activity of this species are not well documented yet, particularly in Bulgaria. The current study aimed to investigate the amino acid composition, free sugars, sterol profile, total polyphenol content, antioxidant activity, DNA-protective effect, and the anti-inflammatory activity of ethanolic extracts of H. cupressiforme. Amino acid analysis revealed that proline (2.282 g/100 g), isoleucine (2.047 g/100 g), and glutamic acid (1.746 g/100 g) were the dominant constituents. The moss contained mannose (1.76 g/100 g) and fructose (1.43 g/100 g) as major free sugars and a diverse sterol profile containing stigmasterol (4.37 mg/g), β-sitosterol (4.29 mg/g), and campesterol (3.34 mg/g) as major phytosterols, which are known for their potential health benefits, such as cholesterol regulation and anti-inflammatory effects. The antioxidant activity of the extracts was determined by DPPH and ABTS assays and expressed moderate free radical scavenging ability (2.56 and 4.15 mM TE/g DW). Furthermore, the extracts also exhibited a potent DNA-protective effect against oxidative damage and anti-inflammatory activity. These findings contribute to the phytochemical knowledge of H. cupressiforme and suggest that Bulgarian specimens may be worth further investigation for pharmaceutical, nutraceutical, and cosmetic applications. Full article

(This article belongs to the Special Issue Medicinal and Edible Uses of Non-Timber Forest Resources)

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