Forests

22 pages, 8598 KB

Open AccessReview

A Review of Intelligent Identification Technologies for the Collection of Tree-Derived Bio-Based Polymer Materials: Multimodal Perception and Machine Learning Methods

by Hanyun Gao, Meng Xia, Xinhao Feng, Tongtong Li and Xinyou Liu

Forests 2026, 17(6), 727; https://doi.org/10.3390/f17060727 (registering DOI) - 22 Jun 2026

Viewed by 288

Abstract

Tree-derived bio-based polymer materials, including natural rubber, raw lacquer, pine resin, and tree gums, are important renewable resources for sustainable forestry and green manufacturing. However, their collection still largely depends on manual operations, which may cause unstable yield, tree damage, and low operational [...] Read more.

Tree-derived bio-based polymer materials, including natural rubber, raw lacquer, pine resin, and tree gums, are important renewable resources for sustainable forestry and green manufacturing. However, their collection still largely depends on manual operations, which may cause unstable yield, tree damage, and low operational efficiency. This review examines intelligent identification technologies for tree-derived material collection from the perspectives of multimodal perception and machine learning. The collection requirements and recognition targets of typical materials are first analyzed, including trunk localization, tapping line detection, bark feature extraction, tree state assessment, and safe tool–bark interaction. Visual, RGB-D, LiDAR, spectral, force/tactile, and environmental sensing technologies are then reviewed, and their roles in complex forest perception and robotic operation are discussed. Machine learning methods, including traditional classifiers, object detection, image segmentation, point cloud processing, temporal modeling, few-shot learning, transfer learning, and uncertainty-aware evaluation, are further examined. Representative cases in rubber tapping, lacquer collection, and pine resin harvesting are compared to reveal the transition from single-sensor recognition to perception–decision–execution integration. Key challenges are identified in dataset standardization, model generalization, edge deployment, force-aware control, and biological mechanism integration. Future directions are proposed toward autonomous, low-damage, and high-yield intelligent collection systems. Full article

(This article belongs to the Special Issue Advances in Precision Forestry: The Efficacy of Multisource Optical and LiDAR Technologies)

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18 pages, 5166 KB

Open AccessArticle

Delineating Functional Management Zones in Jirisan National Park, South Korea, Using Ecosystem Service Assessment and Self-Organizing Maps

by So-Jin Kim, Hyungjin Cho, Chi Hong Lim and Jin Jang

Forests 2026, 17(6), 726; https://doi.org/10.3390/f17060726 (registering DOI) - 22 Jun 2026

Viewed by 156

Abstract

Protected areas increasingly require functional zoning approaches that integrate biodiversity conservation, ecosystem service provision, and human use. This study developed a data-driven functional zoning framework for Jirisan National Park, South Korea, by combining ecosystem service assessment with Self-Organizing Map (SOM)-based spatial typology. Five [...] Read more.

Protected areas increasingly require functional zoning approaches that integrate biodiversity conservation, ecosystem service provision, and human use. This study developed a data-driven functional zoning framework for Jirisan National Park, South Korea, by combining ecosystem service assessment with Self-Organizing Map (SOM)-based spatial typology. Five ecosystem services—water yield, sediment retention, carbon storage, net ecosystem productivity, and habitat quality—were assessed using InVEST, RUSLE, and locally derived carbon-related coefficients. These indicators were integrated with topographic and anthropogenic disturbance variables, including distances to roads and trails. The SOM analysis classified the park into seven functional spatial types with distinct environmental and ecosystem service characteristics. High-altitude areas near major trails were characterized by strong visitor pressure and mismatches among regulating services, whereas interior forest areas showed high multifunctionality and evenness, indicating stable ecosystem service provision. Low-altitude facility-dense and disturbance-adjacent zones showed relatively low habitat quality or service imbalance, highlighting the need for restoration-oriented management. These results suggest that ecosystem service bundles, multifunctionality, and evenness can provide a useful basis for functional zoning and evidence-based management of mountainous national parks. Full article

(This article belongs to the Special Issue Forest Ecosystem Services and Sustainable Management)

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29 pages, 15702 KB

Open AccessArticle

National-Scale Forest Aboveground Biomass Mapping in Guyana Using Stability-Based Feature Selection and Geospatial Embeddings

by Michael S. Watt, Andrew Holdaway, Jack S. Marchant, Midhun Mohan, Pete Watt and Mahendra Baboolall

Forests 2026, 17(6), 725; https://doi.org/10.3390/f17060725 (registering DOI) - 22 Jun 2026

Viewed by 339

Abstract

Aboveground biomass (AGB) mapping is fundamental to tropical forest carbon monitoring, yet national-scale estimation remains challenging because field plots are sparse and model performance is often sensitive to predictor choice and validation design. This study assessed whether geospatial embeddings improve national AGB mapping [...] Read more.

Aboveground biomass (AGB) mapping is fundamental to tropical forest carbon monitoring, yet national-scale estimation remains challenging because field plots are sparse and model performance is often sensitive to predictor choice and validation design. This study assessed whether geospatial embeddings improve national AGB mapping in Guyana when combined with environmental and topographic predictors. Predictor selection was undertaken using repeated grouped resampling at the plot-cluster level, and model performance was evaluated across 100 independent train–test repeats. Three final random forest models were compared. The environmental baseline model (Env + SRTM-derived elevation; 8 predictors) achieved a mean R² of 0.179, an RMSE of 148.5 Mg/ha and a relative RMSE of 36.1%. A retained 8-predictor model combining environmental variables with a selected embedding subset (Env + Emb*) improved performance slightly, with a mean R² of 0.189, an RMSE of 147.6 Mg/ha and a relative RMSE of 35.9%. The best performance was obtained with a 22-variable full-stack model combining environmental, topographic and embedding predictors, after all Sentinel-2 predictors had been eliminated during feature selection; this model achieved a mean R² of 0.203, an RMSE of 146.3 Mg/ha and a relative RMSE of 35.5%. Across models, isothermality, a measure of how day-to-night temperature variation compares to annual temperature variation, and precipitation of the coldest quarter were consistently the most influential predictors. Mean ensemble coefficient of variation, representing relative model disagreement, ranged from 0.336 to 0.361. These results indicate that geospatial embeddings provide useful complementary information, but predictive performance remained modest overall, with the best model explaining only about one-fifth of plot-level AGB variance. The resulting maps are therefore best interpreted as broad-scale decision-support products rather than high-precision local estimates of AGB. Full article

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

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16 pages, 5465 KB

Open AccessArticle

Forest Quality Gradients Regulate Soil Microbial Carbon Use Efficiency in Subtropical Coniferous Ecosystems

by Feng Wu, Rui Chen, Yujing Yang, Tao Yang, Zhitao Huo, Xin Li, Wubiao Huang and Shuangshi Zhou

Forests 2026, 17(6), 724; https://doi.org/10.3390/f17060724 (registering DOI) - 22 Jun 2026

Viewed by 237

Abstract

Soil microbial carbon use efficiency (CUE) is a pivotal determinant of soil carbon sequestration, yet how forest quality gradients regulate CUE through the interplay of mineral-microbial interactions in subtropical conifer ecosystems remains poorly understood. To address this, we examined the CUE response and [...] Read more.

Soil microbial carbon use efficiency (CUE) is a pivotal determinant of soil carbon sequestration, yet how forest quality gradients regulate CUE through the interplay of mineral-microbial interactions in subtropical conifer ecosystems remains poorly understood. To address this, we examined the CUE response and its drivers across a forest quality gradient (high-quality to poor-quality stands) in subtropical coniferous forests in China. Soil mineral composition (including soil texture and the contents of Fe₂O₃, CaO, and MgO), physicochemical properties, microbial community diversity, and CUE were quantified. The results showed that CUE decreased by 2.7%, from 0.533 in high-quality stands to 0.519 in low-quality stands. Concurrently, soil organic carbon (SOC), nutrient availability, and microbial diversity exhibited consistent declining trends along the forest quality gradient. The CUE showed a significant positive correlation with SOC (r > 0.90, p < 0.001). Structural equation modeling and random forest revealed that microbial diversity was the most dominant correlated factor of CUE (the total effects on CUE = 0.932), followed by SOC. However, soil minerals indirectly influenced CUE via SOC. These findings highlight microbial diversity as the dominant observed correlate of CUE across forest quality gradients. This study not only deepens the understanding of the microbial mechanisms underlying soil carbon dynamics in subtropical forests but also provides key scientific basis for ecological restoration of poor-quality forests and nature-based climate solutions. Full article

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15 pages, 2217 KB

Open AccessArticle

Numerical Study on the Influence of Sheathing Type and Fastener Spacing on the In-Plane Stiffness of LTF and LSF Wall Elements

by Erika Kozem Šilih and Miroslav Premrov

Forests 2026, 17(6), 723; https://doi.org/10.3390/f17060723 (registering DOI) - 22 Jun 2026

Viewed by 232

Abstract

This paper investigates the in-plane bending stiffness of light timber-framed (LTF) and light steel-framed (LSF) wall elements with different sheathing materials (fibre-plaster board (FPB) and oriented-strand board (OSB)), focusing on the influence of the fastener spacing (s) on the wall elements’ structural response. [...] Read more.

This paper investigates the in-plane bending stiffness of light timber-framed (LTF) and light steel-framed (LSF) wall elements with different sheathing materials (fibre-plaster board (FPB) and oriented-strand board (OSB)), focusing on the influence of the fastener spacing (s) on the wall elements’ structural response. The analytical model accounts for bending, shear, and slip deformations in the sheathing-to-frame connection, while boundary conditions are assumed to be rigid in accordance with the Eurocode 5 standard. The results indicate a strong dependence of global stiffness on fastener spacing. Increasing the fastener spacing from 37.5 mm to 300 mm reduced the racking stiffness by approximately 42% in LTF–FPB walls and by 31% in LSF–FPB walls. The highest stiffness was obtained for LSF–FPB wall elements (6514 N/mm), while the lowest stiffness was observed for LTF–OSB elements (1236 N/mm). LSF wall elements generally exhibited stiffness values approximately two times higher than comparable LTF systems, although both framing systems showed similar trends with increasing fastener spacing. This study provides a solid basis for the design and optimization of lightweight wall systems and supports the development of efficient structural solutions in both timber and steel construction. Full article

(This article belongs to the Special Issue Characterization and Numerical Simulation of Solid Wood and Engineered Wood Products)

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13 pages, 5343 KB

Open AccessArticle

SNP-Based Analysis of Genetic Diversity and Genetic Structure in Bursaphelenchus xylophilus Populations from Guizhou Province, China

by Yu Zhou, Jingjing Zhou and Xiongjun Liu

Forests 2026, 17(6), 722; https://doi.org/10.3390/f17060722 (registering DOI) - 22 Jun 2026

Viewed by 222

Abstract

The pinewood nematode (PWN, Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle)), first introduced into China in 1982, has since spread rapidly, posing a serious threat to forest resource security and ecological balance. This study aimed to analyze the genetic diversity and genetic structure of [...] Read more.

The pinewood nematode (PWN, Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle)), first introduced into China in 1982, has since spread rapidly, posing a serious threat to forest resource security and ecological balance. This study aimed to analyze the genetic diversity and genetic structure of PWN in eight geographic populations (60 individuals) of Guizhou Province using single nucleotide polymorphisms (SNPs). Results revealed low genetic diversity (Ho values varied from 0.123 to 0.229; He values ranged between 0.117 and 0.212) across the eight sampled populations, along with low levels of genetic differentiation (pairwise Fst values varied from 0.005 to 0.183) among them. Gene flow was generally high between populations, and no clear geographical clustering was observed based on ADMIXTURE, PCA and phylogenetic analysis. These findings provided a scientific basis for tracking the dispersal and identifying the origins of PWN infestations in China. Full article

(This article belongs to the Section Forest Biodiversity)

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14 pages, 11457 KB

Open AccessArticle

Frankincense Essential Oil Comparison Among Commercial Grades and Harvesting Locations in Ethiopia

by Aytolgn A. Melese, Sisay F. Asfaw, Tekleyohannes B. Tesfu and Duarte M. Neiva

Forests 2026, 17(6), 721; https://doi.org/10.3390/f17060721 (registering DOI) - 21 Jun 2026

Viewed by 488

Abstract

Frankincense is a natural oleo-gum resin obtained from several Boswellia tree species, playing important roles in supporting the spiritual, cultural, and socioeconomic livelihoods of communities across East Africa. Despite their cultural and economic value, the Ethiopian market still lacks scientifically based criteria to [...] Read more.

Frankincense is a natural oleo-gum resin obtained from several Boswellia tree species, playing important roles in supporting the spiritual, cultural, and socioeconomic livelihoods of communities across East Africa. Despite their cultural and economic value, the Ethiopian market still lacks scientifically based criteria to evaluate and properly classify this raw material, with traditional grading relying on gum size, color, collection area, and impurity content. Frankincense-derived essential oil value is much higher than that of gum, making this valorization route very enticing. This work compares the extraction potential and chemical profiles of hydrodistilled essential oils from various commercial grades and also different Ethiopian harvest locations (Afar, Humera, Assosa, Shire, Metema, South Omo, Borena and Jigjiga). The essential oils were extracted using hydrodistillation with a Clevenger-type apparatus, and their chemical composition was identified with GC-MS. The results revealed no substantial quantitative and qualitative differences among commercial grades, showing that essential oils can be obtained indiscriminately from classification. As for harvesting locations, both the extraction yield and essential oil compositions varied substantially. With the economic value of frankincense essential oil around six times that of the raw resin required to obtain it, these results show the importance of revising the commercial grading system to reflect chemical composition and promote the value-added processing of both black and white frankincense, rather than relying mainly on raw resin exports. Full article

(This article belongs to the Special Issue Tree and Shrub Bark: Management, Sustainable Production, and Opportunities in the Forest Bioeconomy)

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18 pages, 12766 KB

Open AccessArticle

Regional Comparison of Atlantic Forest Physiognomies Using GEDI-Derived Structural Metrics

by Marcelo C. S. Bandoria, Hugo T. Seixas, Marcos R. Rosa, Paulo G. Molin and Alfredo P. Queiroz

Forests 2026, 17(6), 720; https://doi.org/10.3390/f17060720 - 20 Jun 2026

Viewed by 485

Abstract

Remote sensing contributes to characterizing forest structure across heterogeneous tropical regions, yet structural parameters used to compare Atlantic Forest phytophysiognomies remain limited, especially in fragmented landscapes affected by multiple drivers of forest loss and degradation. This study used Global Ecosystem Dynamics Investigation (GEDI) [...] Read more.

Remote sensing contributes to characterizing forest structure across heterogeneous tropical regions, yet structural parameters used to compare Atlantic Forest phytophysiognomies remain limited, especially in fragmented landscapes affected by multiple drivers of forest loss and degradation. This study used Global Ecosystem Dynamics Investigation (GEDI) data to compare the structure of old-growth candidate forest polygons in four Brazilian Atlantic Forest phytophysiognomies: Dense Ombrophilous Forest (DOF), Mixed Ombrophilous Forest (MOF), Seasonal Semideciduous Forest (SSdF), and Seasonal Deciduous Forest (SDF). We analyzed canopy height (H), canopy cover (COVER), foliage height diversity (FHD), plant area index (PAI), and aboveground biomass density (AGBD) from GEDI L2B and L4A footprints acquired between 2019 and 2024. Structural differences among phytophysiognomies were significant for all variables (Kruskal–Wallis, p < 0.001), with small-to-moderate effect sizes (ε² ≈ 0.05–0.15). The strongest pairwise contrasts occurred for SDF–SSdF and SSdF–DOF, whereas MOF showed greater overlap with the other groups. Across variables, AGBD and H were the most consistent discriminators, and polygon-level summaries strengthened among-group separation. These findings show that GEDI-derived polygon-level metrics can support regional comparisons of forest structure among Atlantic Forest phytophysiognomies and help identify the strongest contrasts in fragmented landscapes. Full article

(This article belongs to the Special Issue Measurement and Modeling of Forest Vegetation Structures with Remote Sensing Technology)

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16 pages, 3101 KB

Open AccessArticle

Does the Health Condition of the Common Ash Tree Affect Pollen Viability?

by Georgia Kahlenberg, Lisa Buchner, Anna-Katharina Eisen and Susanne Jochner-Oette

Forests 2026, 17(6), 719; https://doi.org/10.3390/f17060719 - 19 Jun 2026

Viewed by 209

Abstract

Pollen viability is a crucial determinant of reproductive success in plants. Given the enormous threat posed to the common ash (Fraxinus excelsior L.) by ash dieback, it is important to investigate the potential disease’s effects on pollen viability and germination. Thus, we [...] Read more.

Pollen viability is a crucial determinant of reproductive success in plants. Given the enormous threat posed to the common ash (Fraxinus excelsior L.) by ash dieback, it is important to investigate the potential disease’s effects on pollen viability and germination. Thus, we conducted an analysis of these pollen characteristics across three distinct forest stands in southern Bavaria, with up to 23 ash trees per study site. These ash trees exhibited varying degrees of ash dieback-related damage symptoms, enabling us to assess differences between mildly and severely affected trees (via Mann–Whitney-U/Wilcoxon tests, complemented by linear mixed-effects modelling). Pollen viability was assessed using the TTC test, while pollen germination capacity was evaluated on a sucrose–agar medium. Our findings revealed no statistically significant differences in pollen viability between mildly affected and severely diseased trees, as indicated by both the TTC test and pollen germination assay when applying non-parametric analyses (Mann–Whitney U and Kruskal–Wallis tests). Nevertheless, a consistent tendency towards higher pollen viability was observed in healthier ash trees. When accounting for the hierarchical structure of the data using linear mixed-effects modes, tree vitality showed a significant effect on pollen viability, whereas a substantial proportion of the observed variation was explained by interannual differences. These results indicate that ash trees generally retain the capacity to produce viable pollen across different levels of disease severity, but vitality-related effects are subtle and context-dependent. However, severely diseased trees produced few or no flowers, substantially reducing the likelihood that their pollen contributes to fertilization. We therefore conclude that ash dieback primarily limits reproductive success in common ash mainly by reducing flower and pollen production, whereas pollen viability itself is strongly driven by interannual differences. Consequently, no consistent pattern of declining pollen viability with increasing disease severity emerged. Full article

(This article belongs to the Section Forest Health)

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19 pages, 3049 KB

Open AccessArticle

Harvester Productivity and Economic Feasibility in Small-Scale Mediterranean Conifer Stands

by Antonio Zumbo, Andrea R. Proto and Salvatore F. Papandrea

Forests 2026, 17(6), 718; https://doi.org/10.3390/f17060718 - 19 Jun 2026

Viewed by 259

Abstract

In Mediterranean small-scale forestry, the adoption of highly mechanized CTL systems remains limited by fragmented forest lots, variable stand conditions, and high machine costs. This case study evaluated the operational productivity and economic feasibility of harvester-based felling and processing in two Mediterranean conifer [...] Read more.

In Mediterranean small-scale forestry, the adoption of highly mechanized CTL systems remains limited by fragmented forest lots, variable stand conditions, and high machine costs. This case study evaluated the operational productivity and economic feasibility of harvester-based felling and processing in two Mediterranean conifer stands in Southern Italy. A harvester was monitored in Calabrian pine and silver fir stands using a time-motion approach. Processing represented the dominant productive phase, while moving accounted for about one-third of productive machine time. Under the observed site conditions, the Calabrian pine showed higher gross productivity and lower unit time consumption than silver fir. The economic analysis indicated that feasibility was strongly dependent on gross productivity, benchmark motor-manual costs, and harvested lot volume, with more favourable break-even conditions in Calabrian pine. Full article

(This article belongs to the Special Issue Harvesting, Processing and Management of Specialty Forest Products and Biomass)

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23 pages, 1884 KB

Open AccessArticle

A Model for Estimating Average Diameter at Breast Height of Pinus yunnanensis Stands Based on Machine Learning Approaches

by Jianming Wang, Nalin Yu, Jiting Yin, Shuangqing Lv and Baoguo Wu

Forests 2026, 17(6), 717; https://doi.org/10.3390/f17060717 - 19 Jun 2026

Viewed by 243

Abstract

The mean stand diameter at breast height (DBH) is a key indicator of stand structure and productivity and is widely used in forest resource inventory and management planning. When using regional inventory data, nonlinear interactions between plot-level conditions and predictor variables can undermine [...] Read more.

The mean stand diameter at breast height (DBH) is a key indicator of stand structure and productivity and is widely used in forest resource inventory and management planning. When using regional inventory data, nonlinear interactions between plot-level conditions and predictor variables can undermine the stability of traditional empirical equations across varying site qualities and stand densities. To improve the accuracy and robustness of inventory-scale predictions of mean stand DBH, this study utilized data from 854 forest plots and employed stand age, site class index (SCI), and stand density index (SDI) as independent variables. The predictive performance of traditional growth equations, machine learning models (Random Forest, XGBoost, LightGBM, and support vector machine), and deep learning models (MLP and CNN, ResNet, RNN) was systematically compared, and ensemble learning strategies were further applied to optimize model performance. The results indicated that the Weibull model based solely on stand age achieved the best fit (R² = 0.669). Incorporating SCI and SDI greatly improved model explanatory capability with R² rising to 0.838. XGBoost and CNN further improved predictive performance (R² = 0.852 and 0.861, respectively), while the ensemble model exhibited the highest goodness-of-fit (R² = 0.893), outperforming all individual models. Compared with linear regression, machine learning models demonstrated superior predictive capability. A feature importance analysis indicated that stand age, site quality and stand density together drive mean stand DBH prediction, among which stand age and stand structural characteristics are the dominant influencing factors, whereas SCI and SDI have comparatively weaker effects. Overall, the ensemble model substantially enhanced the prediction accuracy of mean DBH in Pinus yunnanensis stands, thereby providing for precision forest management and ecological function assessment. Full article

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

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15 pages, 2021 KB

Open AccessArticle

NaOH-Induced Changes in Physical, Mechanical, and Chemical Properties of Artificial Archaeological Wood

by Hui Shen, Zirui Tang and Wei Wang

Forests 2026, 17(6), 716; https://doi.org/10.3390/f17060716 - 18 Jun 2026

Viewed by 262

Abstract

Waterlogged archaeological wood represents a unique cultural heritage but is highly susceptible to physical and chemical degradation, which complicates conservation and restoration. This study aimed to prepare artificial archaeological Cunninghamia lanceolata wood using NaOH vacuum impregnation and systematically evaluate the effects of NaOH [...] Read more.

Waterlogged archaeological wood represents a unique cultural heritage but is highly susceptible to physical and chemical degradation, which complicates conservation and restoration. This study aimed to prepare artificial archaeological Cunninghamia lanceolata wood using NaOH vacuum impregnation and systematically evaluate the effects of NaOH concentration and treatment cycles as two treatment variables on wood degradation. Untreated heartwood specimens were treated with 5%, 10%, 20%, and 30% NaOH solutions for 2, 4, and 6 cycles. The NaOH treatment first induced chemical and structural deterioration, including selective degradation of hemicelluloses, changes in cellulose crystallinity, and progressive damage to the wood cell-wall structure. XRD analysis revealed a significant reduction in cellulose crystallinity from 35.96% to 10.11%, while FTIR confirmed the degradation of hemicelluloses and the relative enrichment of lignin-related structures. SEM observations further showed severe cell-wall erosion, lumen deformation, and local collapse, indicating that alkali treatment effectively reproduced typical microstructural features of degraded waterlogged wood. These chemical and microstructural changes subsequently led to marked changes in physical and mechanical properties. Mass loss increased with NaOH concentration and cycle number, while basic density decreased and maximum water content increased, indicating enhanced deterioration and water-holding capacity. Treated specimens also exhibited increased swelling and shrinkage rates and a substantial reduction in longitudinal compressive strength, with the most pronounced deterioration occurring under higher NaOH concentrations and repeated cycles. The study demonstrates that NaOH treatment can reproducibly simulate the physical, chemical, and microstructural characteristics of waterlogged archaeological wood, providing a reliable experimental model for studying wood degradation mechanisms and supporting conservation strategies. Full article

(This article belongs to the Special Issue Surface Property Evolution and Modification of Wood and Bamboo Products)

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10 pages, 3566 KB

Open AccessArticle

Effects of Timber Stand Improvement Treatments on Tree Growth in Southwestern Virginia

by Richard D. Marshall and Todd S. Fredericksen

Forests 2026, 17(6), 715; https://doi.org/10.3390/f17060715 - 18 Jun 2026

Viewed by 425

Abstract

Non-industrial private forestlands (NIPF) have often been subjected to logging practices that remove the highest quality trees of the highest value species, leaving behind less-desirable stems and species; a practice termed high-grading or selective harvesting. Timber stand improvement (TSI) can be used to [...] Read more.

Non-industrial private forestlands (NIPF) have often been subjected to logging practices that remove the highest quality trees of the highest value species, leaving behind less-desirable stems and species; a practice termed high-grading or selective harvesting. Timber stand improvement (TSI) can be used to correct high-grading practices by removing poorly-formed or low-value tree species in order to promote the growth of higher value trees and species. The felled trees may be removed for biomass fuel or left in place. At study sites in southwestern Virginia, we monitored tree growth across experimental TSI with biomass removal, TSI cut-and-leave felled stems, and control plots in mixed-pine hardwood forests from 2012–2025, measuring diameter at breast height (DBH) for multiple species. Scarlet Oak (Quercus coccinea) and Yellow Poplar (Liriodendron tulipifera) had the largest growth increments during the study period, while Black Gum (Nyssa sylvatica) and Hickory species (Carya spp.) showed consistently low growth. Larger trees tended to grow at faster rates, consistent with allometric expectations. The two TSI treatments had similar growth increments and were 60%–100% higher than control plots over the tree blocks of treatments in this study. Mortality at the longest-term measured block was more than twice as high as TSI plots. These results suggest that TSI can reduce competition for light and nutrients promoting diameter growth, whereas untreated plots may experience resource limitations that suppress growth and increase mortality. The study provides a baseline for understanding forest dynamics and highlights the importance of management interventions in maintaining productivity and structural diversity in selectively-logged forests. Full article

(This article belongs to the Special Issue Forest Management: Silvicultural Practices and Management Strategies)

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23 pages, 10747 KB

Open AccessArticle

How Do Variation and Covariance of Leaf Functional Traits Influence Schinus terebinthifolia Raddi (Anacardiaceae) Acclimation to Light and Water Availability in Tropical Dry Ecosystems?

by Saulo Pireda, Guilherme R. Rabelo, Emilio C. Miguel, Angela P. Vitória and Maura Da Cunha

Forests 2026, 17(6), 714; https://doi.org/10.3390/f17060714 - 18 Jun 2026

Viewed by 285

Abstract

Light availability in tropical forests varies spatially and temporally, strongly influencing plant acclimation. Understanding variation and covariation among functional traits associated with photoacclimation is essential for predicting plant responses to environmental change. Here, we investigated acclimatory responses of Schinus terebinthifolia Raddi (Anacardiaceae), a [...] Read more.

Light availability in tropical forests varies spatially and temporally, strongly influencing plant acclimation. Understanding variation and covariation among functional traits associated with photoacclimation is essential for predicting plant responses to environmental change. Here, we investigated acclimatory responses of Schinus terebinthifolia Raddi (Anacardiaceae), a widespread Neotropical species adapted to heterogeneous light environments. We evaluated variation and covariation in morphological, anatomical, physiological, and nutritional traits under contrasting light conditions. Under high light, plants invested more resources in palisade parenchyma and subepidermal layers while maintaining water-use efficiency, indicated by higher δ¹³C values. Irregular adaxial cuticles and unstacked thylakoid membranes were also observed under high irradiance. The strongest covariation occurred among anatomical traits, especially spongy parenchyma and adaxial and abaxial cuticles. Overall, the relationship between trait variation and covariation was slightly negative but not significant, although patterns differed among functional groups. These findings demonstrate that photoacclimation in S. terebinthifolia involves coordinated functional strategies that optimize light modulation, water conservation, and photosystem II performance under variable tropical light environments. Full article

(This article belongs to the Special Issue Abiotic and Biotic Stress Responses in Trees Species—2nd Edition)

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30 pages, 6497 KB

Open AccessArticle

Heterogeneity in Quantity–Quality Collaboration: Using Geographically Visualized SHAP Interaction Analysis to Explore Relationships Between Multidimensional Urban Green Space Features and Life Satisfaction of Older Adults

by Keju Liu, Dian Zhou, Yingtao Qi and Mingzhi Zhang

Forests 2026, 17(6), 713; https://doi.org/10.3390/f17060713 - 18 Jun 2026

Viewed by 289

Abstract

Urban green spaces (UGSs) are considered crucial for enhancing older adults’ subjective well-being. However, limited studies have explored the synergistic effects of UGS quality and quantity on satisfaction across green spaces, residential environments, and life domains, making it challenging to uncover the multifaceted [...] Read more.

Urban green spaces (UGSs) are considered crucial for enhancing older adults’ subjective well-being. However, limited studies have explored the synergistic effects of UGS quality and quantity on satisfaction across green spaces, residential environments, and life domains, making it challenging to uncover the multifaceted sustainable benefits of UGSs on older adults’ subjective well-being. This study drew on multi-source data and place attachment theory to depict neighborhood-accessible UGS quantity (provision, accessibility, and visibility) and quality (cognition, behavior, and affect). Through the geographical visualization of bivariate SHapley Additive exPlanations (SHAP) interaction values extracted from the trained eXtreme Gradient Boosting (XGBoost) model, and the comparison of bivariate SHAP maps with univariate SHAP maps, the study revealed the nonlinear geographic associations between UGS quantity and quality and three types of satisfaction. The results showed that when UGS quantity and quality coexisted, variations in the impact of quantity on older adults’ satisfaction were associated with quality differences. The gain effect of quality on quantity was more significant in areas with limited green space within a 500 m buffer zone. UGSs made a direct contribution to green space satisfaction, while their indirect association with life satisfaction surpassed that of residential satisfaction due to their provision of emotional qualities. This study calls for neighborhood green planning aimed at improving older adults’ subjective well-being, which should shift focus from quantity to quality and balance the relationship between quantity and quality based on regional characteristics. Full article

(This article belongs to the Section Urban Forestry)

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10 pages, 13474 KB

Open AccessArticle

The Fate of a Wild White Fringetree (Chionanthus virginicus) Population in Ohio 10 Years After Invasion by Emerald Ash Borer (Agrilus planipennis)

by Don Cipollini and Kendra Cipollini

Forests 2026, 17(6), 712; https://doi.org/10.3390/f17060712 - 18 Jun 2026

Viewed by 1099

Abstract

Emerald ash borer (EAB) is an invasive Asian wood borer that has killed hundreds of millions of ash trees across North America. White fringetree is a secondary host of EAB in North America that is generally more resistant and resilient than ash. Past [...] Read more.

Emerald ash borer (EAB) is an invasive Asian wood borer that has killed hundreds of millions of ash trees across North America. White fringetree is a secondary host of EAB in North America that is generally more resistant and resilient than ash. Past studies have mostly focused on ornamentally planted and managed trees over short time scales; the long-term fate of this species in the wild is uncertain. We revisited an unmanaged wild population of white fringetree in Ohio ten years after it was first studied, measuring tree size and health, evidence of EAB attack, and woodpecker activity. We hypothesized that EAB attack would have greater negative effects on this population than previously observed in managed populations. In 2024, 68% of trees showed signs of previous attack by EAB with declining health and 15% had evidence of current-year attack. Thirty percent of trees in the study had died. White fringetrees in managed populations have generally fared well in the aftermath of EAB, but trees in this wild population showed substantial attack and damage, some continuing to host EAB for several years. Wild white fringetrees may meet the same fate as ash trees in the face of EAB, but over longer time scales. Full article

(This article belongs to the Section Forest Biodiversity)

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17 pages, 8212 KB

Open AccessArticle

Short-Term Effects of Thinning on Soil Physicochemical Properties, Microbial Characteristics, and Growth of Middle-Aged Picea koraiensis Forests in Eastern Northeast China

by Qiong Wu, Mengnan Cao, Liuningya Sun, Yuan Lv, Jinmin Wang, Meixuan Chen, Sainan Yin and Zhihu Sun

Forests 2026, 17(6), 711; https://doi.org/10.3390/f17060711 - 17 Jun 2026

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Abstract

Picea koraiensis Nakai is a precious tree species in Northeast China with excellent traits, but research on thinning effects on its growth remains limited, especially regarding soil-thinning–growth interactions. This study focused on a 50-year-old Picea koraiensis plantation in the Mengjiagang Forest Farm, Jiamusi. [...] Read more.

Picea koraiensis Nakai is a precious tree species in Northeast China with excellent traits, but research on thinning effects on its growth remains limited, especially regarding soil-thinning–growth interactions. This study focused on a 50-year-old Picea koraiensis plantation in the Mengjiagang Forest Farm, Jiamusi. Four thinning intensities were set: CK (no thinning), T1 (10%–20%), T2 (20%–30%), and T3 (40%–50%). Short-term (1–3 years) stand growth, soil properties, microbial biomass, and extracellular enzyme activities were measured, with stand volume and large-diameter timber yield estimated via self-established equations. Results showed that T3 significantly promoted average DBH (1.98 × CK) and tree height growth (1.60 × CK). T2 achieved the highest increases in stand volume (38.07 m³/ha) and large-diameter timber yield (56.02 m³/ha), exceeding other treatments by 1.20–7.12 m³/ha and 5.60–11.64 m³/ha, respectively. Stand growth indices were positively correlated with thinning intensity, soil microbial biomass carbon, and soil C/P ratio; DBH and height also correlated with soil catalase activity. Thinning intensity has a direct effect on stand growth. Meanwhile, observational data show that it is significantly correlated with changes in soil organic carbon fractions and soil extracellular enzyme activity, and these correlations may constitute potential pathways that indirectly affect stand growth. Moderate-intensity thinning (20%–30%) is recommended for scientific tending and large-diameter timber cultivation of middle-aged Picea koraiensis plantations in this region. Full article

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

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19 pages, 5124 KB

Open AccessArticle

Greenness, Growth and Productivity in Die-Off Sites Indicate Drought Sensitivity in Semi-Arid Forests and Rapid Recovery

by Arens Pëto, Antonio Gazol, Cristina Valeriano, Michele Colangelo, Manuel Pizarro, Ester González de Andrés, Jie Li, Xiaoxia Li and Jesús Julio Camarero

Forests 2026, 17(6), 710; https://doi.org/10.3390/f17060710 - 17 Jun 2026

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Abstract

Aridification and hotter droughts are triggering forest die-off events characterized by high mortality rates and declines in forest productivity. The western Mediterranean Basin is a climate change hotspot where many of these die-off events have affected several tree and shrub species in recent [...] Read more.

Aridification and hotter droughts are triggering forest die-off events characterized by high mortality rates and declines in forest productivity. The western Mediterranean Basin is a climate change hotspot where many of these die-off events have affected several tree and shrub species in recent decades. Yet, the responses of canopy greenness and cover, radial growth, and gross primary productivity (GPP) to climate in these die-off sites remain poorly understood across species and biomes. Here, we examined 44 sites across Spain, covering humid, dry sub-humid, and semi-arid biomes, and including nine tree and one shrub species. We obtained and correlated monthly climate data, satellite-derived vegetation indices (Normalized Difference Vegetation Index, Enhanced Vegetation Index), tree-ring metrics (basal area increment, ring-width indices), and GPP. We assessed climate trends and relationships between climate, vegetation indices, growth, GPP, and resilience after five extreme drought years in the period 1984–2023. Climate warming impacted all sites, increasing vapor pressure deficit and reducing soil moisture availability, with semi-arid sites warming the most. Vegetation indices and growth showed the largest declines during extreme droughts in dry sub-humid and semi-arid sites. Correlations with climate variables highlighted strong sensitivity to drought stress, particularly regarding growth metrics. During die-off events, GPP significantly declined in the growing season, but no legacy effects were observed afterwards. Vegetation indices and growth partially recovered one year after drought, with resilience peaking for GPP in semi-arid sites. Hotter droughts constrain GPP and growth, especially in dry sub-humid and semi-arid forests. Forests and shrublands experiencing die-off are diagnostic monitors of drought-induced thresholds in ecosystem productivity. Full article

(This article belongs to the Special Issue Forest Die-Off and Mortality: Post-Disturbance Successional Trajectories)

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21 pages, 2246 KB

Open AccessArticle

Wood Modification Using Fast Pyrolysis Bio-Oil (FPBO): Formulation Development, Characterization, and Evaluation of Wood Performance

by Anna Sandak, Faksawat Poohphajai, Amina Selmanović, Rene Herrera-Diaz, Jakub Grzybek, Kelly Peeters, Sasikala Perumal, Edit Földvári-Nagy, Lei Han, Richard Acquah, Joanna Aniśko-Michalak, Mateusz Barczewski, Aleksander Hejna, Marco Fellin, Lex Kiezebrink, Klaas Jan Swager, Hans Heeres, Bert van de Beld and Jakub Sandak

Forests 2026, 17(6), 709; https://doi.org/10.3390/f17060709 - 17 Jun 2026

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Abstract

This study presents a wood modification process using Fast Pyrolysis Bio-Oil (FPBO) as a fully biobased alternative to conventional, fossil-based and potentially toxic preservatives such as copper salts, organic biocides, and creosote. Standard FPBO was used in the development of 10 formulations, which [...] Read more.

This study presents a wood modification process using Fast Pyrolysis Bio-Oil (FPBO) as a fully biobased alternative to conventional, fossil-based and potentially toxic preservatives such as copper salts, organic biocides, and creosote. Standard FPBO was used in the development of 10 formulations, which were systematically characterized in terms of pot life, viscosity evolution, density, and pH. Radiata pine samples were subsequently impregnated using a bench-scale reactor, with specimens prepared in multiple geometries to assess treatment performance across different dimensions. The modified wood was comprehensively characterized with respect to moisture uptake, dimensional stability, density, mechanical strength, fixation efficiency, biological durability, and VOC emissions. Additional screening focused on properties relevant to outdoor applications, including aesthetic appearance and colour uniformity after UV exposure. The results enabled the identification of three top-performing formulations, treatments H, A, and E, which exhibited the most favourable balance between durability, environmental performance, and structural integrity. Overall, the findings demonstrate the strong potential of FPBO-based impregnation as a sustainable, multifunctional, and high-performance alternative for advanced wood protection systems. Full article

(This article belongs to the Special Issue Wood Treatments and Modification Technologies—2nd Edition)

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23 pages, 6093 KB

Open AccessArticle

Quantifying Risk Levels for Active Safety Systems in Autonomous Forest Machinery Using Vision Language Models

by Kengo Usui

Forests 2026, 17(6), 708; https://doi.org/10.3390/f17060708 - 17 Jun 2026

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Abstract

Forestry is recognized as one of the most dangerous industries in the world. To enhance forestry safety, autonomous machinery and safety systems for such machinery are essential. This study aims to introduce large language models (LLMs)—especially their extensions to images, vision–language models (VLMs)—to [...] Read more.

Forestry is recognized as one of the most dangerous industries in the world. To enhance forestry safety, autonomous machinery and safety systems for such machinery are essential. This study aims to introduce large language models (LLMs)—especially their extensions to images, vision–language models (VLMs)—to enable human-like decision-making for autonomous forest machinery. This research focused on VLMs as an active safety system that can adapt to environments and evaluated the effectiveness of a system that quantitatively makes decisions regarding hazard levels using contrastive language–image pretraining (CLIP). The results of industry type, tree state, and road state classification using pretrained models showed that for three tasks—forestry identification, hung-up tree detection, and road collapse sensing—the target classes consistently exhibited higher similarity with disaster texts compared with nontarget classes. Although the F1 scores were 0.693, 0.324 and 0.634, respectively—indicating that the system is insufficient as a direct active safety system—the application of a similarity threshold optimized to maintain a recall of 0.9 yielded F1 scores of 0.291 and 0.584 for tree state and road state, respectively. These results suggest that the system can potentially be used as a quantitative indicator of hazard by setting a threshold on the similarity score. Full article

(This article belongs to the Section Forest Operations and Engineering)

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20 pages, 1899 KB

Open AccessArticle

Variations in Vegetation Cooling Efficiency Across 20 Major Cities Worldwide: The Interplay of Built-Up Fraction and Surface Properties

by Ling Hu, Harald Neidhardt, Andreas Braun and Volker Hochschild

Forests 2026, 17(6), 707; https://doi.org/10.3390/f17060707 - 17 Jun 2026

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Abstract

Urban vegetation is widely regarded as a key strategy for mitigating urban heat, but its cooling performance is not constant and varies across climatic zones and urban structures. Most existing evidence derives from single-city or single-climate studies, leaving the differences in vegetation cooling [...] Read more.

Urban vegetation is widely regarded as a key strategy for mitigating urban heat, but its cooling performance is not constant and varies across climatic zones and urban structures. Most existing evidence derives from single-city or single-climate studies, leaving the differences in vegetation cooling with respect to building density and background climate insufficiently quantified globally. This study examined vegetation cooling efficiency (CE), defined as the absolute slope of the relationship between NDVI and normalized land surface temperature (LST), across 20 major cities spanning tropical, arid, temperate, and continental climate zones during 2000–2020. We combined city-level regression, built-up fraction stratification, and interpretable machine learning to quantify vegetation CE and its variation across climate and urban density gradients. CE varied roughly eightfold across cities (≈0.07–0.60), with the strongest responses in arid and continental cities such as Dubai and Almaty. Increasing built-up fraction systematically weakened the NDVI–LST relationship, turning near-neutral or slightly positive in the most compact temperate cores (80%–100% built-up). The machine learning model reproduced these patterns (out-of-sample R² = 0.757), identifying NDVI and evapotranspiration as dominant drivers. These findings indicate that vegetation cooling is strongly context-dependent, underscoring the need for climate-specific and morphology-based perspectives on urban greening rather than generalized evaluations. 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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7 pages, 565 KB

Open AccessEditorial

Advances in Remote Sensing and GIS Utilization in Monitoring of Forest Ecosystems

by Aleksandar Valjarević, Hang Li, Menglin Qin and Giorgos Mallinis

Forests 2026, 17(6), 706; https://doi.org/10.3390/f17060706 - 16 Jun 2026

Viewed by 241

Abstract

Forest ecosystems are increasingly threatened by climate change, wildfires, droughts, insect outbreaks, and other natural and anthropogenic disturbances [...] Full article

(This article belongs to the Special Issue Advances in Remote Sensing and GIS Utilization in Monitoring of Forest Ecosystems)

21 pages, 1637 KB

Open AccessReview

Research Progress in Efficacy Analysis of Forest Fire Extinguishing Agents and the Environmental Impact Assessment

by Yixin Zhang, Yao Wang and Tongxin Hu

Forests 2026, 17(6), 705; https://doi.org/10.3390/f17060705 - 16 Jun 2026

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Abstract

The prevention and control of forest fires are of vital importance for ecological security. The efficiency and environmental friendliness of fire-extinguishing agents remain the core focus of current research. This paper reviews the research progress and fire extinguishing mechanisms of three types of [...] Read more.

The prevention and control of forest fires are of vital importance for ecological security. The efficiency and environmental friendliness of fire-extinguishing agents remain the core focus of current research. This paper reviews the research progress and fire extinguishing mechanisms of three types of forest-fire-extinguishing agents, namely, foam extinguishing agents, gel extinguishing agents, and fire-resistant barrier materials. These three types of extinguishing agents work together to extinguish fires through three principles: isolating combustibles, reducing the oxygen concentration, and lowering the temperature. This paper systematically summarizes the performance evaluation methods, covering the cooling rate, fire extinguishing time, and re-ignition rate, and combines numerical simulation and field experiments to build a multi-scale verification system. The environmental assessment focuses on biodegradability, the ecological toxicity to soil and water systems, and the impact on plant germination and biodiversity. It clearly indicates that degradability, low toxicity, and low residue are key development directions. The current research still needs to further deepen in aspects such as long-term stability, adaptability to complex terrains, and ecological risk assessment during the life cycle. In the future, priority should be given to promoting green, multi-functional, and precise application technologies to provide solid support for scientific forest fire prevention and ecological protection. Full article

(This article belongs to the Special Issue Fire Ecology and Management in Forest—3rd Edition)

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18 pages, 7321 KB

Open AccessArticle

Microtopography Enhances Surface Runoff Regulation and Plant Growth in Urban Relocation Green Spaces: Evidence from Shanghai Expo Cultural Park

by Aiqing Zhu, Dongmei Zhang, Yulan Luo and Lang Zhang

Forests 2026, 17(6), 704; https://doi.org/10.3390/f17060704 - 16 Jun 2026

Viewed by 234

Abstract

Urban microtopography plays an important role in regulating soil processes and vegetation performance in newly constructed green spaces, yet its effects on surface runoff, soil nutrients, and plant growth remain insufficiently quantified in urban relocation sites. This study investigated how slope gradient, slope [...] Read more.

Urban microtopography plays an important role in regulating soil processes and vegetation performance in newly constructed green spaces, yet its effects on surface runoff, soil nutrients, and plant growth remain insufficiently quantified in urban relocation sites. This study investigated how slope gradient, slope position, and slope curvature influence surface runoff, soil nutrient distribution, and tree growth in Shanghai Expo Cultural Park. Field monitoring was conducted in 36 plots planted with Cinnamomum camphora and Ginkgo biloba in 2017, 2020, and 2024. Microtopographic characteristics were quantified using terrestrial and handheld three-dimensional laser scanning, point-cloud processing, and digital elevation models (DEMs), and plant growth, calculated runoff, and soil physiochemical properties were analyzed using analysis of variance (ANOVA) and regression analysis. Annual DBH increments were greatest on meso slopes (mean = 0.558 cm), followed by gentle slopes (0.513 cm) and abrupt slopes (0.511 cm). Growth was also greater at slope-tail positions than at slope-head positions and greater on concave slopes than on convex slopes. The mean calculated runoff increased from gentle to meso and abrupt slopes, and soil organic matter, total nitrogen, hydrolysable nitrogen, available phosphorus, available potassium, and cation exchange capacity were generally higher at slope-tail positions. These results indicate that micrographic design affects tree growth mainly through runoff-mediated redistribution of water and soil nutrients. These findings provide practical guidance for optimizing microtopographic design, tree species selection, and soil management in urban green spaces established on relocation sites. Full article

(This article belongs to the Section Urban Forestry)

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21 pages, 5378 KB

Open AccessArticle

Post-Tsunami Forest Resilience in a Coastal Forest Ecosystem After the Mega-Tsunami of 2011, Japan

by Anna Trigubenko, Maximo Larry Lopez Caceres, Juan Pedro Ferrio, Tatiana A. Shestakova, Vladislav Bukin and Sergi Garcia Riera

Forests 2026, 17(6), 703; https://doi.org/10.3390/f17060703 - 16 Jun 2026

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Abstract

The Mega-Tsunami of March 2011 in eastern Japan caused severe damage in the coastal black pine (Pinus thunbergii) forests along the Pacific coast. To evaluate post-disturbance forest recovery, tree-ring samples from 30 trees at Ishinomaki coastal forest were analyzed for the [...] Read more.

The Mega-Tsunami of March 2011 in eastern Japan caused severe damage in the coastal black pine (Pinus thunbergii) forests along the Pacific coast. To evaluate post-disturbance forest recovery, tree-ring samples from 30 trees at Ishinomaki coastal forest were analyzed for the period 2006–2020 using tree-ring indices and stable carbon isotope discrimination (Δ¹³C). The results revealed a strong decline in radial growth immediately after the tsunami, indicating severe growth suppression during the years 2011–2014. Simultaneously, Δ¹³C values decreased, suggesting reduced stomatal conductance and acute physiological stress associated with the initial salinity effect at the root zone. Although isotopic signals indicated gradual physiological adjustment in subsequent years, radial growth recovery occurred more slowly. Most trees returned to pre-disturbance growth levels within approximately 3–5 years and later exceeded pre-disturbance growth levels, likely due to reduced competition following the mortality of nearly 40% of trees after the tsunami. However, recovery trajectories differed markedly among individual trees, with some trees showing prolonged growth suppression beyond 6 years. This variability may reflect highly localized or tree-level factors, including intrinsic differences in individual resilience, while spatial autocorrelation analysis did not indicate significant clustering of recovery time across the stand. We conclude that black pine coastal forests show a high degree of resilience, showing physiological recovery in a short period (3–4 years). Although growth recovery took longer, initial tree mortality promoted the growth of the surviving trees beyond pre-disturbance values. Full article

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

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29 pages, 9857 KB

Open AccessArticle

Network Structure Explained the Differences in the Response of Soil Bacterial Community Structure and Functional Structure to Afforestation Types

by Zhenlu Qiu, Jin Liu, Hui Gao, Suying Dong, Xiaojin Zang, Wenxin Kang and Jing Shu

Forests 2026, 17(6), 702; https://doi.org/10.3390/f17060702 - 16 Jun 2026

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Abstract

This study used 16S rDNA high-throughput sequencing and Faprotax functional prediction to analyze the effects of different artificial forests (coniferous forest, conifer–broad-leaved mixed forest, broad-leaved forest) in the Fanggan ecological restoration area of North China on soil bacterial community composition and functional characteristics [...] Read more.

This study used 16S rDNA high-throughput sequencing and Faprotax functional prediction to analyze the effects of different artificial forests (coniferous forest, conifer–broad-leaved mixed forest, broad-leaved forest) in the Fanggan ecological restoration area of North China on soil bacterial community composition and functional characteristics and, based on network topology features, analyzed the potential influencing pathways. Planting broad-leaved forests significantly increased soil bacterial α-diversity indices (ACE, Chao1, Shannon) and induced the greatest heterogeneity in both community and functional composition. Soil bacteria exhibit significant differences in taxonomic structure across forest types but not in functional structure. The classification network and functional network of broad-leaved forests are more complex than those of coniferous and mixed forests, with the former having more nodes and edges, as well as higher weighted degree and betweenness centrality. Zi-Pi analysis indicates that high-abundance taxa involved in carbon and nitrogen cycles dominate the keystone taxa of the taxonomic network, while low-abundance pathogenic, urea-decomposing, and trace element metabolism functional groups dominate the keystone groups of the functional network. Redundancy analysis further revealed that soil available potassium concentration, pH, and tree species composition (importance values of Pinus tabulaeformis and Populus davidiana) were the principal determinants of bacterial functional structure. Collectively, broad-leaved forests achieve higher network robustness via elevated network complexity and functional redundancy, whereas coniferous forests might rely on functional convergence and modular integration to cope with resource limitation. These results indicate that network traits mediate the distinct responses of bacterial communities and their functional potentials, offering practical references for vegetation restoration in limestone mountain areas. Full article

(This article belongs to the Section Forest Soil)

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17 pages, 2296 KB

Open AccessArticle

Plant Resource Acquisition Strategies Bridge Structural Diversity and Ecosystem Multifunctionality in Typical South Subtropical Forests

by Feifan Li, Xinyu Li and Nancai Pei

Forests 2026, 17(6), 701; https://doi.org/10.3390/f17060701 - 16 Jun 2026

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Abstract

Plant functional traits are central to regulating ecosystem multifunctionality (EMF), yet how coordinated above- and below-ground resource acquisition strategies mediate the effects of forest structural diversity on EMF remain insufficiently understood, particularly in typical south subtropical forests. Here, we applied a trait-based framework [...] Read more.

Plant functional traits are central to regulating ecosystem multifunctionality (EMF), yet how coordinated above- and below-ground resource acquisition strategies mediate the effects of forest structural diversity on EMF remain insufficiently understood, particularly in typical south subtropical forests. Here, we applied a trait-based framework to disentangle the pathways linking forest structural diversity to EMF through plant resource acquisition strategies. Typical south subtropical forests were sampled for community-level leaf and root traits, including leaf total nitrogen and total phosphorus content, specific leaf area, leaf dry matter content, root diameter, specific root length, root tissue density, root total nitrogen and root total phosphorus content. EMF was quantified using 13 indicators associated with carbon storage, litter decomposition, primary productivity, and nutrient cycling, evaluated using both averaging and multi-threshold approaches. Principal component analysis was used to summarize trait variation along major functional axes representing the leaf and root economics spectra, and structural equation modeling was employed to quantify direct and trait-mediated pathways linking forest structural diversity to EMF. We found pronounced variation in EMF among forest types, with multifunctionality increasing along the classical fast-slow plant economics spectrum. Communities dominated by fast-growing species exhibited consistently higher EMF than those dominated by slow-growing species, with below-ground traits showing stronger associations with EMF than above-ground traits. In contrast, EMF was unrelated to the root collaboration gradient, suggesting that alternative below-ground foraging strategies contributed little to multifunctionality. Moreover, the positive effects of structural diversity on EMF were indirectly mediated through both leaf and root conservation gradients. Notably, the relative importance of these trait-mediated pathways was threshold-dependent. Root conservation gradients dominated EMF at low multifunctionality thresholds, whereas leaf conservation gradients became increasingly important at higher thresholds. Our findings show that forest structural diversity enhances ecosystem multifunctionality through coordinated leaf and root strategies. By revealing trait-mediated links between biodiversity and EMF, this study clarifies how community composition and species turnover shape multifunctionality in typical south subtropical forests. Full article

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

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17 pages, 2227 KB

Open AccessPerspective

Perspectives on the Future Roles of AI for Forest Health Monitoring

by Qinfeng Guo, Frank H. Koch, Kevin M. Potter, Karun Pandit, Simone Lim-Hing and Elizabeth R. Matthews

Forests 2026, 17(6), 700; https://doi.org/10.3390/f17060700 - 16 Jun 2026

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Abstract

Global forest ecosystems face growing threats from land use change, climate and weather extremes, and insects and diseases. Managing these threats is difficult due to the time, cost, and human error associated with the quality and quantity of data required for research and [...] Read more.

Global forest ecosystems face growing threats from land use change, climate and weather extremes, and insects and diseases. Managing these threats is difficult due to the time, cost, and human error associated with the quality and quantity of data required for research and assessment. While conventional analytical methods are being improved constantly, they are often slow in providing information needed to respond promptly to unprecedented changes driven by both natural and anthropogenic alterations to forest ecosystems. For this reason, potential applications of artificial intelligence (AI) have attracted increasing attention in the field. Here, we examine the benefits and challenges of using AI in near-term forest health monitoring (surveillance, mostly over small scales) and discuss the need for long-term and larger-scale assessment. Abundant evidence shows that existing AI methods already facilitate the rapid collection, compilation, and synthesis of available data from diverse sources. Furthermore, emerging technologies (e.g., agentic AI) are building these capabilities into autonomous systems. However, every AI tool has advantages and limitations. With constant improvements, integrative AI-driven approaches that simultaneously deal with multiple and cross-scale interacting factors are expected to deliver actionable insights about forest health better than any single AI tool. Consequently, they can enhance decision-making processes, reduce monitoring costs, and help mitigate the impacts of forest health threats. As AI continues to evolve, it is essential to circumscribe its role in forest health monitoring. Most importantly, AI should not define what humans value regarding forest health but instead should be applied to help us evaluate data about our chosen value targets. Full article

(This article belongs to the Special Issue Applications of Artificial Intelligence in Forestry: 2nd Edition)

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41 pages, 14242 KB

Open AccessArticle

Assessing Community and Protected Area Exposure to Wildfires in Navarra, Spain

by Fermín Alcasena, Alan Ager, Julia Loján, Isabel Pinto, Ignacio García, Pere Gelabert, Mikel Repáraz and Cristóbal Molina

Forests 2026, 17(6), 699; https://doi.org/10.3390/f17060699 - 15 Jun 2026

Viewed by 521

Abstract

The unprecedented 2022 wildfire season in Navarra, northern Spain, marked a turning point in regional wildfire management, when seven simultaneous large fires during a June heatwave burned more than 17,000 ha in just a few days, overwhelming suppression capacity and highlighting the limits [...] Read more.

The unprecedented 2022 wildfire season in Navarra, northern Spain, marked a turning point in regional wildfire management, when seven simultaneous large fires during a June heatwave burned more than 17,000 ha in just a few days, overwhelming suppression capacity and highlighting the limits of a strategy based primarily on ignition prevention and fire suppression. In this study, we implemented a stochastic wildfire modeling system based on the Minimum Travel Time algorithm, historical ignition patterns, spatial fuel data, and spatiotemporal weather variability to assess community and protected area exposure to wildfire. We simulated more than 50,000 fire season replicates under extreme fire weather conditions, estimating annual burn probability across fire intensity classes at 50 m spatial resolution. We then intersected modeled fire perimeters with building footprints representing residential and industrial structures, as well as protected areas, to assess the spatial distribution of exposure across the region. Results showed strong concentration of community exposure, with three fourths of residential and industrial exposure concentrated in just over one third of the total municipal area. Across Navarra, mean annual modeled exposure summed to 120 residential buildings and 16 industrial structures. Across the protected area network, mean annual burned area summed to 90 ha year⁻¹, including 68 ha year⁻¹ at flame lengths greater than 2.5 m, while burned forest area was 16 ha year⁻¹. Protected areas in southern Navarra and forested protected areas in central and northern Navarra showed the highest modeled exposure, identifying priority landscapes where prevention, restoration, and evaluation of managed fire options could support more resilient ecosystems. This study provides a scientific basis for improving wildfire risk governance and strengthening the resilience of communities and protected areas under increasing wildfire pressure in the region. Full article

(This article belongs to the Special Issue Forest Fire Detection, Prevention and Management)

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18 pages, 2597 KB

Open AccessArticle

Functional Traits of Trees and Shrubs Drive Soil Carbon Storage in Rocky Desertification Areas via Direct and Fungal-Mediated Pathways

by Xi Li, Wanzhi Qiao, Jicun Bao, Yue Li, Jijie Wang, Aluo An, Jiashun Luo and Wen Zhang

Forests 2026, 17(6), 698; https://doi.org/10.3390/f17060698 - 15 Jun 2026

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Abstract

Vegetation restoration is an effective measure to improve soil carbon storage in rocky desertification areas. However, the underlying mechanisms driving differences in soil carbon storage among different vegetation types remain unclear. In this study, we selected four typical vegetation types (monospecific broadleaf plantation, [...] Read more.

Vegetation restoration is an effective measure to improve soil carbon storage in rocky desertification areas. However, the underlying mechanisms driving differences in soil carbon storage among different vegetation types remain unclear. In this study, we selected four typical vegetation types (monospecific broadleaf plantation, mixed conifer–broadleaf plantation, monospecific coniferous plantation, and natural shrubland) from the comprehensive control zone for moderately rocky desertification of Xuyong County in the Chishui River Basin. We investigated the effects of vegetation patterns on soil carbon storage through tree layer functional traits, tree diversity, shrub layer functional traits, shrub diversity, and soil fungal/bacterial diversity. The results showed that soil carbon storage was highest in monospecific broadleaf plantations, followed by mixed conifer–broadleaf plantations, then natural shrubland, and it was lowest in monospecific coniferous plantations. Significant differences were mainly observed in the 0–10 cm and 10–20 cm soil layers, while no significant difference was found in the 20–30 cm layer. Tree layer community-weighted mean of leaf nitrogen content, soil fungal Shannon–Wiener index, and shrub layer community-weighted mean of specific leaf area were the core positive drivers of soil carbon differentiation. Among these, tree layer community-weighted mean of leaf nitrogen content was the most important factor, whereas the regulatory effect of shrub layer community-weighted mean of specific leaf area intensified with increasing soil depth. Furthermore, tree layer community-weighted mean of leaf nitrogen content and shrub layer community-weighted mean of specific leaf area not only directly promoted soil carbon accumulation but also indirectly promoted it by enhancing soil fungal diversity. In contrast, the effects of tree and shrub layer diversity and soil bacterial diversity were negligible. This study demonstrates that increasing soil carbon storage in rocky desertification ecosystems depends on the direct effect of soil fungal diversity, as well as the direct effects of tree and shrub layer functional traits and their indirect effects via regulating soil fungal diversity. We recommend that in moderately rocky desertified areas, priority should be given to tree species with high leaf nitrogen content; on sites unsuitable for afforestation, promoting natural shrublands with high specific leaf area can effectively enhance carbon sequestration capacity. Full article

(This article belongs to the Section Forest Soil)

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