Forests doi: 10.3390/f17111352

Authors: Feng Gao Yan Zhu Bing Shi Yanling Liu Wanqing Chi Qingyun Yuan Tao Bai Yuning Chi Keyi Fu Haiyang Yan

In the Yellow River Delta, the aboveground biomass (AGB) of Tamarix chinensis, Suaeda salsa, and Phragmites australis reflects wetland productivity and carbon sequestration capacity. However, due to redundancy among multi-source remote sensing features, large-scale AGB estimation remains a challenge. Field measurements from sample plots were integrated with multi-source remote sensing features from the Diaokou River and Qingshuigou regions. A machine learning framework combining feature selection, VIF-based multicollinearity assessment was developed. The optimal feature selection strategy varied among machine learning algorithms. The random forest model combined with stepwise regression (RF-STEP) achieved the highest estimation accuracy (R2 = 0.75, RMSE = 116.91 g/m2, RPD = 2.24). SHAP analysis revealed that vegetation indices including TVI and NDVI dominated the prediction. Wetland AGB generally increased during the growing seasons from 2017 to 2024, with mean values of 225.13 g/m2 in the Diaokou River region and 170.15 g/m2 in the Qingshuigou region. A larger proportion of the Qingshuigou region exhibited moderate AGB increase according to pixel-wise fitted slopes, at 50.46%, compared with 38.50% in the Diaokou River region. Areas with negative fitted slopes occupied 23.65% of the Diaokou River region, implying potential localized degradation. These research findings support wetland ecological restoration and sustainable management in the Yellow River Delta.

Forests doi: 10.3390/f17111351

Authors: Zichen Huang Jiannan Wang Lihong Dong Hongling Liang Zhenzhen Zhang Kongshu Ji

Standing-tree biomass carbon stock varies among tree provenances, but its root metabolic correlates remain incompletely characterized. Pinus massoniana is an important subtropical conifer in southern China, and identifying metabolic signatures associated with high carbon stock may provide insights into provenance-related carbon accumulation. We profiled root metabolites from 36 independently sampled trees (six trees per provenance) representing six P. massoniana provenances at a single common-garden site in July 2022. The provenances were classified using provenance-level mean estimated individual-tree carbon stock: SM and AY (high), SW and QJ (medium), and HF and SX (low). Untargeted LC–MS data were evaluated using multiple overlapping provenance contrasts, KEGG pathway mapping, and exploratory weighted correlation network analysis. Of 10,386 detected LC–MS features, 746 met the nominal directional-consensus screening rule, and 199 showed strictly ordered provenance-mean relative-abundance patterns across the three predefined classes; 189 of these followed high < medium < low. Network integration generated 12 exploratory chemical candidates requiring structural confirmation. These findings describe internally consistent root metabolic associations with estimated standing-tree carbon stock rather. Generalization beyond one site and sampling date requires independent validation.

Forests doi: 10.3390/f17111350

Authors: So-Min Lee Kug-Bo Shim

The knot is one of the defects that reduce strength and contribute to performance variability in structural timber. The knot area ratio (KAR) has been widely used to quantify its effects in grading and performance prediction. This review examines the definition of KAR; methods for measuring and estimating knot information; applications of KAR in structural timber performance prediction; and the use and limitations of KAR-based probabilistic models and indicating property (IP)-based models incorporating local fiber deviation. The reviewed studies show that non-destructive techniques can provide information on knot size, position, distribution, and geometry, but this information is often reduced to representative values for specific cross-sections, longitudinal segments, or local regions when used in prediction models. Consequently, three-dimensional knot geometry, longitudinal distribution, clustering, and local fiber deviation are not fully represented. KAR-based probabilistic models are useful for capturing material variability and performance distributions but remain limited in explaining local failure behavior and stress concentration in critical regions. IP-based approaches incorporating local fiber deviation provide complementary information. Future performance prediction models should integrate knot spatial information, local modulus of elasticity (MOE), and local fiber deviation while retaining the practical advantages of KAR.

Forests doi: 10.3390/f17111347

Authors: Junyan Liu Tingfa Dong Jie Du Debit Datta Yu Xie Ye Chen Liling Mo Yan Wu Lei Yu

The Tibetan Plateau plays a vital role in maintaining regional ecological stability across Asia, yet its subalpine forests have been severely altered by past degradation and disturbances. Assessing the potential long-term changes in these forest communities and their consequent impacts on ecosystem service values (ESVs) is critical for regional sustainability, yet remains poorly explored. This study aims to assess long-term ESV changes under future forest landscape dynamics and analyze their driving factors on the eastern Tibetan Plateau. Using the established LANDIS-II–PnET-II modeling approach, we simulated forest landscape dynamics from 2016 to 2096 under a constant-climate, no-disturbance scenario and linked the resulting landscape outputs with an improved value equivalent factor method to quantify ESVs. The results indicate that, under this scenario, secondary succession increased the dominance of late-successional coniferous forests, which became the major contributors to ESVs (>55%). Consequently, total regional ESVs showed a marginal increase of 0.48% by 2096, with distinct spatial heterogeneity. Geographical detector analysis identified human influence as the primary determinant shaping ESV spatial heterogeneity, dominating over natural environmental factors. This study provides a scenario-based assessment of long-term ESV dynamics for the Tibetan Plateau’s vulnerable subalpine forests, demonstrating key indicators to inform proactive ecological protection and adaptive land-use strategies.

Forests doi: 10.3390/f17111349

Authors: Phongsiri Phasi Piyapong Tongdeenok Weeraphart Khunrattanasiri Surachit Waengsothorn Sitthisak Moukomla Pramet Kaewmesri

Tropical dry evergreen forests retain a closed canopy during long dry seasons, yet their carbon exchange remains poorly measured. We analyzed 20 months (April 2024–December 2025) of eddy-covariance observations at Sakaerat, Thailand, including a single-point CO2 storage term, gap filling, and flux partitioning. We assessed whether tower soil measurements and optical, thermal, and Sentinel-1 radar predictors improved daily net ecosystem exchange (NEE), gross primary productivity (GPP), and ecosystem respiration (Reco) estimates beyond tower meteorology. Estimated monthly NEE was negative throughout the record, including the dry season. Cumulative NEE over 1 January–17 December 2025 was −1043 g C m−2 (GPP 2620; Reco 1635 g C m−2). Uptake was stronger in the wetter, cooler second wet season, consistent with directly measured daytime fluxes. In the later held-out period, soil water content and temperature improved NEE and GPP estimates, while cross-calibrated Sentinel-1 backscatter improved GPP estimates. Optical and thermal products did not improve NEE and degraded GPP. These gains mainly tracked the interannual shift in flux level rather than daily variation. Better constraints on nighttime respiration are needed to confirm the magnitude of the carbon sink.

Forests doi: 10.3390/f17111348

Authors: Xin-Chen Hong Jiang Liu Guangyu Wang

The World Health Organization (WHO) has made considerable efforts to reduce citizens’ exposure to community noise in urban and suburban areas [...]

Forests doi: 10.3390/f17111346

Authors: Jurata Buchovska Darius Danusevičius Linas Daugnora Algirdas Girininkas Gediminas Motuza Rūtilė Pukienė Žana Skuratovič Miglė Stančikaitė

This paper presents new ancient DNA (aDNA) results from a Scots pine (Pinus sylvestris L.) megafossil dated to the earliest intervals of the Lateglacial Interstadial (13,786–13,500 cal yr BP (calibrated years before present)). The investigated trunk was discovered between sediment layers at the Pamerkiai Outcrop in southern Lithuania, an area situated within the marginal zone of the Late Weichselian Glaciation. To date, this is the oldest megafossil successfully subjected to aDNA analysis in the eastern Baltic region. Nuclear microsatellite (nSSR) analysis indicates a strong genetic affinity to the northern genetic lineage, supporting the hypothesis of Scots pine expansion from a “Northern Refugium” (50–55° N; 35–45° E) into present-day southern Lithuania during the initial afforestation stages of the Lateglacial Interstadial. Consequently, these findings support a model involving two glacial refuge sources for Scots pine in the eastern Baltic region during the Lateglacial. Furthermore, the aDNA results demonstrate a close genetic association between this ancient sample and present-day Scots pine populations typical of wetland environments, suggesting the prevalence of a wetland palaeoenvironmental regime at the site during the earliest stages of the Lateglacial Interstadial.

Forests doi: 10.3390/f17111345

Authors: Bailing Zhou Ziheng Yu Niejiaying Xie

Vegetation can mitigate courtyard heat stress, but nonlinear and interactive effects of canopy amount, layout continuity, and species composition remain poorly quantified for semi-enclosed courtyards in hot-summer and cold-winter regions. Using a single representative courtyard in Wuhan, this study coupled ENVI-met /RayMan Pro simulation with a Random Forest surrogate and SHAP interpretation to examine how tree canopy coverage (TCC), layout pattern (LP), and evergreen-to-deciduous ratio (ETR) affect physiological equivalent temperature (PET). Twenty greening scenarios were simulated over five representative meteorological days (2400 hourly samples). The surrogate achieved R2 = 0.98 and RMSE = 1.28 °C. Meteorological and solar variables contributed >93% of global SHAP attribution, whereas TCC, LP, and ETR together contributed 6.3%. Vegetation–PET relationships were condition-specific, and SHAP interactions were non-monotonic. Matched-pair simulations holding TCC and ETR constant showed that layout effects involve spatial continuity and orientation relative to building shade and airflow, not canopy amount alone. Relative to the baseline ATCP of 11.33%, the best tested configuration reached 19.80% (+8.47 percentage points), and all configurations reduced absolute PET deviation. These findings provide a case-conditional screening framework; generalization requires multi-courtyard validation.

Forests doi: 10.3390/f17111344

Authors: Anna R. Harris Martin S. Mullett Joan F. Webber

The oomycete Phytophthora pseudosyringae is mainly associated with rhizosphere infections of declining oak, beech, and alder in mainland Europe where it is considered native. However, the species has recently come to prominence in Britain, initially by causing significant damage to the heathland and woodland dwarf shrub Vaccinium myrtillus, then more recently associated with aerial infections on larch (Larix). The emergence of P. pseudosyringae on conifers raises concerns for forestry, particularly of larch in Europe, plus questions about its significance compared to P. ramorum, which has killed millions of plantation-grown larch in Britain since 2009. To understand the drivers underlying the emergence of P. pseudosyringae, we investigated the genetic, morphological, and pathological diversity of P. pseudosyringae isolates obtained from various hosts across Britain. Major gene sequence analyses identified two major genetic lineages within the British population of P. pseudosyringae. Within these lineages, three host-associated groups (Fagus–Nothofagus, Vaccinium and Larix) could be differentiated based on colony morphology, sporangial size, and in vitro growth characteristics. Moreover, pathogenicity varied markedly between groups with Larix-associated isolates producing larger lesions on Japanese larch (L. kaempferi) comparable to those formed by P. ramorum, whereas Fagus-Nothofagus- and Vaccinium isolates caused smaller or negligible lesions, respectively. Our findings suggest that P. pseudosyringae comprises genetically differentiated lineages that differ in host association, morphology, growth characteristics and pathogenicity. The Larix-associated group produced lesions on Japanese larch comparable in size to those caused by P. ramorum, suggesting that it has the potential to be an important pathogen of larch in Britain.

Forests doi: 10.3390/f17111342

Authors: Óscar González-Prieto Andrea R. Proto

High moisture content in unseasoned green wood significantly influences bonding kinetics in moisture-curing systems. This study investigated the in situ viscoelastic 1. C-PUR viscoelastic curing kinetics without compromising ultimate stability. A Two-Way ANOVA confirmed a dominant main effect of moisture condition on the 50% consolidation milestone (t50%, p < 0.001, partial ηp2 = 0.954). Specifically, green moisture reduced t50% from 62.8 ± 4.4 min to 24.0 ± 0.8 min for Adhesive A (61.8% acceleration) and from 89.4 ± 2.3 min to 56.3 ± 8.3 min for Adhesive B (37.1% acceleration). No statistically significant difference occurred for the 120 min storage modulus baseline (E′120 > 6000 MPa, p = 0.166), demonstrating that interfacial free water acts as a stoichiometric promoter rather than a defect, overriding cell-wall plasticization. While these findings validate early viscoelastic screening feasibility for green gluing high-density hardwoods, complete structural joint qualification requires subsequent standardized macro-mechanical shear and durability testing.

Forests doi: 10.3390/f17111343

Authors: Panya Waiboonya Prapatsorn Yodsa-nga Panadda Larpkern Jetsada Wongprom La-ongdao Thaopimai Boontida Moungsrimuangdee

The decline of mangrove forests, including those in Thailand, poses significant threats to ecosystem functions and human livelihoods. This study assessed species composition, diversity, and carbon stocks within the Urban Mangrove Forest Project in Rayong Province, focusing on three stand types: natural mangrove forest (NMF), restoring mangrove forest (RMF), and non-submerged forest (NSF). We surveyed 36 plots (12 plots of 20 × 20 m per stand) to evaluate species composition, diversity, and carbon stocks. The Rhizophoraceae family exhibited the highest species richness (five species). The NSF demonstrated the highest species richness and diversity, while the NMF contained the greatest carbon stock (215.68 tons C ha−1). RMF showed a carbon stock similar to NMF (181.60 tons C ha−1), indicating that restoration efforts contribute to carbon storage. Based on the importance value index, Avicennia marina was dominant in NMF, Rhizophora apiculata in RMF, and Acacia auriculiformis in NSF. Although the NSF had a substantially lower carbon stock (21.02 tons C ha−1), it supported a diverse assemblage of mangrove, associate, and upland species. Preserving this ecological transition zone is recommended, as it enhances biodiversity, serves as a natural buffer, and may increase resilience to climate change and land-use pressures. These findings highlight the importance of restoring and conserving transition zones to sustain mangrove ecosystems.

Forests doi: 10.3390/f17111341

Authors: Nuria Torrescano-Valle Ramiro Chi-Pech Citlali Carrillo-García Fernando Casanova-Lugo Dafne Aceves-Zayas Pablo Jesús Ramírez-Barajas

Wetlands are among the most efficient terrestrial ecosystems for long-term carbon sequestration; however, information on carbon stocks in karst-derived tropical freshwater wetlands remains scarce. We estimated carbon stocks in above-ground and below-ground components of vegetation types associated with the Bacalar lagoon system in southeastern Mexico. We compared different carbon estimation methodologies to assess how methodological choices affect carbon stock estimates at the sample’s sites. Five vegetation types were studied; above-ground biomass was estimated using multiple allometric equations, which were compared in terms of relative variability using coefficients of variation. Below-ground carbon was quantified from root biomass and soil organic carbon using the loss-on-ignition (LOI) and Dumas methods. Gallery forest had the highest above-ground carbon stocks due to larger tree sizes, while mangroves (included petenes) stored greater amounts of below-ground carbon, reflecting the influence of hydrology, clay-rich substrates, and the accumulation of organic matter. The LOI based estimates were higher than Dumas, although both approaches showed similar patterns and high agreement following cross-validation. Our results show that vegetation type, substrate characteristics, and methodological choices significantly influence estimates of carbon stocks. Karst wetlands are important carbon reservoirs, and their conservation contributes to the mitigation of regional climate change.

Forests doi: 10.3390/f17111340

Authors: Tianbiao Bai Wenqi Dong Zhihao Zhu Li Zhang

Pine wilt disease (PWD) has caused extensive damage to pine forests in China. However, large-scale monitoring using high-resolution imagery is constrained by the high cost of hyperspectral data and the annotation requirements of task-specific deep learning models. To address these challenges, this study proposes SMNDO-PWD, a remote sensing framework for detecting PWD-affected trees. First, a pretrained SegFormer (MiT-B5) model removes non-vegetation features such as buildings and bare soil. MST++ then reconstructs statistically plausible hyperspectral bands in the 400–700 nm range from the RGB imagery, and the normalized difference index (NDI) is computed from the reconstructed 670 nm and 550 nm bands. Subsequently, support vector machine (SVM)-based density classification is integrated with density-adaptive dynamic Otsu thresholding to extract PWD-affected trees, requiring only lightweight classifier training and threshold optimization. Results from three reference plots in Shaoguan show that SMNDO-PWD achieves average pixel-level intersection over union (IoU) and F1 scores 51.28% and 32.14% higher, respectively, than YOLOv8s-seg. Further evaluation across eight cities in six provinces yields average IoU and F1 scores of 0.52 and 0.69, respectively, using manual annotations as reference. Ablation experiments confirm the contributions and complementary effects of individual modules. Furthermore, an application covering approximately 900 ha in Zhaoqing demonstrates the potential of SMNDO-PWD for large-scale monitoring. The framework also enables the quantification of the affected area ratio (AAR), affected area, and the relative NDI distribution in the affected areas, providing spatial information to support PWD assessment and management.

Forests doi: 10.3390/f17111339

Authors: Jennifer Yang Gourav Salotra Eugene Pinsky

Cork oak (Quercus suber L.) woodlands are ecologically and economically important and are threatened by a decline syndrome in which the endophytic ascomycete Biscogniauxia mediterranea (De Not.) Kuntze (charcoal canker) and the soil-borne oomycete Phytophthora cinnamomi Rands (root rot and bleeding cankers) play prominent roles. This study investigates whether a small set of real, representative bark images can provide an interpretable, field-oriented aid for classifying bark symptoms. We assembled 968 publicly available source photographs (361 asymptomatic, 434 charcoal-canker and 173 bleeding-canker images) labeled from their source captions as asymptomatic, charcoal-canker symptoms, or bleeding-canker symptoms; the labels describe visible symptoms and were not confirmed by laboratory diagnosis. To balance the classes, 227 geometrically augmented copies of bleeding-canker photographs were added (bringing the total image count to 1195). Features were extracted with a frozen MobileNetV3-Small network, and per-class k-means or k-medoids clustering was used to select the real images closest to the cluster centers (“pseudo-centroids”), which were then used as references for k-nearest neighbors (KNN) classification. In 30 repeated splits that kept each source photograph and all its augmented copies on the same side of the split and tested on source photographs only, the practical configuration with four reference images per class reached a mean accuracy of 73.6 ± 3.4%, and the configuration with ten per class reached 77.8 ± 2.8%. On the original single split of 239 images, in which augmented copies of some training photographs also occur in the test set, the corresponding accuracies were 72.8% (95% CI 66.8–78.1%) and 79.1% (73.5–83.8%). Exact McNemar tests and repeated splits showed no statistically significant differences among the three KNN variants, and geometric or AutoAugment-type augmentation of the minority class did not change accuracy. Swapping the labels of two reference images reduced accuracy by 9.8 ± 3.8 percentage points with four references per class and by 4.8 ± 2.1 points with ten. Bleeding-canker symptoms were the most difficult class, reflecting their high visual heterogeneity, overlap with the other classes, and small sample size. Using all training images as references raised accuracy to 91.1%, quantifying the cost of a compact card set. The reference cards are therefore best viewed as a visual screening and training aid that complements, rather than replaces, established field keys and laboratory confirmation.

Forests doi: 10.3390/f17111338

Authors: Chenjia Xu Yunhao Fang Yao Xiong Zunling Zhu

Urban forests provide diverse ecosystem services that contribute to human well-being, yet the spatial distribution of their perceived social values and their associations with environmental characteristics remain insufficiently understood. This study examines the spatial heterogeneity of social values for ecosystem services (SVES) and their implications for urban forest management. Using Zijin Mountain National Forest Park in Nanjing, China, as a case study, we integrated social media data and participatory mapping surveys with the Social Values for Ecosystem Services (SolVES) model and the maximum entropy (MaxEnt) algorithm to assess eight SVES categories, identify multi-value hotspots, and examine their associations with environmental factors. The results revealed pronounced spatial heterogeneity and multiple centers of social value concentration. Four functional hotspot types were identified, corresponding to ecological conservation, cultural exhibition, recreational activities, and health and wellness. Environmental associations differed across these areas, with roads, pedestrian paths, water bodies, forest edges, buildings, and educational facilities exhibiting distinct relationships with perceived values. Exploratory response curves further suggested nonlinear variations along environmental gradients. These findings highlight the importance of accounting for spatially differentiated social values when coordinating ecological conservation, recreational opportunities, and cultural experiences in urban forest management.

Forests doi: 10.3390/f17111337

Authors: Miaomiao Wang Shaoqiang Wang Weikang Lin Jinghua Chen Hong Chen Yong Liang Jian Zhao

Accurate estimation of the maximum carboxylation rate (Vcmax) and maximum electron transport rate (Jmax) is important for improving the representation of photosynthetic capacity in terrestrial carbon-cycle models. Leaf hyperspectral spectroscopy provides a promising approach for estimating these physiological traits, but the effects of spectral preprocessing and modeling strategy on prediction performance remain insufficiently evaluated, particularly across different forest types. In this study, leaf hyperspectral reflectance (400–2400 nm) and gas-exchange measurements were collected from subtropical evergreen needleleaf forest (ENF) and evergreen broadleaf forest (EBF) samples to systematically evaluate the estimation of Vcmax and Jmax using six spectral preprocessing methods and three machine learning algorithms. ENF and EBF showed broadly similar spectral signatures and comparable distributions of Vcmax and Jmax. Across the tested model configurations, derivative-based preprocessing methods generally improved prediction performance, while random forest (RF) and extreme gradient boosting (XGBoost) generally outperformed partial least squares regression (PLSR). Using 99 leaf samples (36 ENF and 63 EBF samples) and internal leave-one-out cross-validation, the highest predictive performance was moderate, with R2 = 0.45 (RMSE = 9.89, MAE = 8.23) for Vcmax and R2 = 0.57 (RMSE = 15.50, MAE = 12.19) for Jmax. The models were evaluated using internal leave-one-out cross-validation (LOOCV). Although overall prediction performance was broadly comparable between ENF and EBF, spectral importance analyses revealed distinct forest-type-associated patterns in important wavelengths. Important wavelengths in ENF samples were concentrated mainly in the shortwave infrared (SWIR) region (1300–2400 nm), whereas EBFs showed greater importance of wavelengths in the near-infrared (NIR) region (750–1300 nm). These findings highlight the importance of spectral preprocessing when estimating leaf photosynthetic capacity from hyperspectral reflectance and indicate that forest types may exhibit different patterns of spectral importance. The identified patterns provide a basis for further investigation of hyperspectral approaches to photosynthetic trait estimation in subtropical forests.

Forests doi: 10.3390/f17111336

Authors: Paulo Eduardo Barni Liana Oighenstein Anderson Luiz Eduardo Oliveira e Cruz de Aragão Reinaldo Imbrozio Barbosa Philip Martin Fearnside

Selective logging (SL) and forest fires cause disturbances in the forest canopy and are the main vectors of forest degradation in the Amazon. These processes, in conjunction with adjacent disturbances such as falling trees, the use of heavy machinery in SL operations impacting the soil and mortality in the understory, are enhanced by the passage of fire, triggering a series of local dynamics, among them natural regeneration. The main objective of this study was to evaluate the behavior of natural regeneration of vegetation in a dense Amazonian forest impacted by SL and understory fire. We used images from the Landsat-8 (30 November 2015) and 9 (27 October 2023), Sentinel-2 (27 October 2023) and PlanetScope (4 January 2024 and 25 January 2024) satellites. Between 2015 and early 2024, the natural regeneration area increased by a weighted average of 252.3% in SL areas with fire. The results indicate that the highest severity levels of understory fire (strong and very strong) affect the trajectory of natural regeneration originating from SL in the Amazon. The net loss of biomass and carbon stocks from these degradation processes is substantial and indicates the need for changes in government policies to restrict logging and prevent forest fires.

Forests doi: 10.3390/f17111335

Authors: Karolina Anna Gabrysiak Izabela Sondej Rafał Paluch

Research Highlights: Long-term observations reveal a shift in stand species composition and regeneration, including an increasing importance of shade-tolerant species and weak oak recruitment in protected oak–hornbeam forests of northeastern Poland, highlighting the declining role of pedunculate oak. Background and Objectives: Natural forest dynamics and regeneration are important for biodiversity and the conservation objectives of protected areas. We assessed long-term changes in species composition, stand structure, and regeneration in selected nature reserves containing mature oaks (Quercus robur L. and, in Stara Dębina, potentially Q. petraea (Matt.) Liebl.). Materials and Methods: Archival records and repeated field measurements from 1970–2019 were analysed for 14 permanent plots in five nature reserves: Stara Dębina, Grąd Radziwiłłowski, Koryciny, Kalinowo, and Rycerski Kierz. Tree density, basal area, species composition, dead wood, and regeneration of seedlings and saplings were assessed. Changes were evaluated using non-parametric statistical tests. Results: Stand structure generally changed only slightly, while hornbeam (Carpinus betulus L.) increased in importance in several reserves. Oak regeneration was scarce, and the density of upper saplings declined in most reserves, indicating weak recruitment into the advanced regeneration layer. Maple, lime, elm, and hazel frequently became more prominent in younger stand layers. Conclusions: The observed scarcity of advanced oak regeneration suggests limited recent recruitment on many monitored plots but does not establish the long-term fate of oak populations or the causes of regeneration failure. Continued monitoring and assessment of potential limiting factors are needed before site-specific conservation interventions are considered.

Forests doi: 10.3390/f17111334

Authors: Xin Li Bo Wang Xiaodi Zhao Ming Li Yuwei Li Dandan Zhou Chuanqi Wang Nan Lyu Yanan Yu Xuexia Hu Ke Zhao Pingping Zhu Qianqian Qin Pu Li

Global climate change has rendered the ecological environment in China’s arid and semi-arid regions increasingly fragile. Water has emerged as a limiting factor for development in these areas. The current understanding of how soil stoichiometry responds to changes in precipitation remains incomplete. This study utilized meta-analysis to synthesize and organize a substantial body of relevant research data, examining the relationships between precipitation variation, influencing factors, soil nutrients, and stoichiometric ratios. The findings indicate that changes in precipitation significantly affect soil physical and chemical properties. Overall, soil ecological stoichiometry shows a downward trend, suggesting that soils in these regions are highly sensitive to moisture fluctuations. The responses of desert and desert steppe ecosystems exhibit the most pronounced econometric ratio changes, while surface and deep soils demonstrate differing responses to variations in precipitation. Analysis of environmental factors reveals that climate, soil physical and chemical properties, and microbial activities are the primary drivers of changes in metering ratios. Precipitation fluctuations affect the soil C, N, and P equilibrium in arid and semi-arid regions by controlling soil moisture, organic matter, and microbial activity. Consequently, these changes can potentially influence nutrient cycling, vegetation growth, and ecosystem stability. This research demonstrates the sensitivity of soil C:N:P balance in arid regions of China to precipitation variations, offering a foundation for evaluating nutrient cycling in arid ecosystems, the resilience of carbon, nitrogen, and phosphorus reservoirs, and guiding future ecological restoration and climate change adaptation efforts in arid regions.

Forests doi: 10.3390/f17111333

Authors: Chaoqun Du Yun Zhao Yezhou Xu Hui Yuan Yue Cao Aiguo Duan Kebing Du

Cunninghamia lanceolata var. Luotian is a valuable variant of Chinese fir characterized by a weeping branch architecture, a narrow crown, and excellent natural pruning compared with Cunninghamia lanceolata. The weeping branch phenotype is a typical characteristic of Cunninghamia lanceolata var. Luotian; however, the molecular mechanisms potentially associated with this phenotype remain unclear. To investigate the gene expression characteristics associated with this phenotype, terminal buds and basal parts of one-, three-, and six-year-old lateral branches from C. lanceolata var. Luotian and C. lanceolata with comparable growth status were sampled for de novo transcriptome sequencing using the Illumina high-throughput platform. A total of 59,109 unigenes were obtained from transcriptome sequencing. The Q30 values of all samples were above 93.76%, with an average unigene length of 1175 bp and an N50 of 2293 bp. The mapping rates ranged from 68.11% to 79.25%, with an average of 75.65%. Comparative transcriptomic analysis revealed substantial differences in gene expression between C. lanceolata var. Luotian and C. lanceolata, with the largest number of DEGs detected in the terminal buds of three-year-old lateral branches. Differences in DEG numbers were also observed among comparisons involving different branch ages and tissue positions. KEGG enrichment analysis identified phenylpropanoid biosynthesis, plant hormone signal transduction, and MAPK signaling pathway–plant among the top-ranked pathways. Based on the analysis of the top 50 DEGs, several candidate genes, including TRINITY_DN19150_c0_g1, TRINITY_DN27401_c0_g1, and TRINITY_DN14240_c0_g1, were identified as potentially associated with lateral branch development. These findings suggest that signal transduction and secondary metabolism may be associated with the weeping branch phenotype of C. lanceolata var. Luotian. This study provides preliminary transcriptomic evidence and candidate gene resources for further investigation of the weeping branch phenotype, although the specific regulatory roles of these pathways and genes remain to be experimentally validated.

Forests doi: 10.3390/f17111332

Authors: Feng Zhang Yuan Zhou Mingkun Chen Bei Li Linlin Chen Xu Cheng

Urban parks can mitigate surface heat in high-density cities, but their cooling services may not align with population demand or social vulnerability. This study developed an equity-oriented planning framework for central Chengdu, China, linking park-level cooling assessment, cooling supply–demand analysis, social vulnerability, and land-constrained multi-objective optimization. Cooling intensity and effective cooling distance were estimated for existing parks from Landsat-derived land surface temperature (LST) and park-level temperature–distance profiles. Cooling demand was represented by LST, activity-informed population distribution, and building density; distributional inequality and vulnerability-sensitive deficits were assessed separately. The Non-dominated Sorting Genetic Algorithm II (NSGA-II) optimized new-park locations and nominal areas, and a constrained Random Growth Algorithm (RGA) converted the selected allocation into contiguous polygons. A consistent linear distance-decay function was used for baseline and intervention assessments. Cooling demand was concentrated in the dense urban core, whereas relatively high modeled cooling supply occurred around larger peripheral green spaces. The selected solution comprised 71 proposed parks with a nominal target area of 1265.42 ha; 842.06 ha was realized after polygon growth. The realized configuration reduced population-weighted and Social Vulnerability Index (SVI)-weighted cooling-service deficits by 34.93% and 25.54%, respectively. Thirty independent runs and alternative cooling-response scenarios were used to assess optimization stability and model sensitivity. The framework distinguishes theoretical allocation from spatial realization when evaluating equity-oriented cooling provision.

Forests doi: 10.3390/f17111331

Authors: Soongil Kwon Jeongmook Park Hyun Kyu Won

Unused forest biomass is often proposed as a non-food feedstock for lignocellulosic polylactic acid (PLA), but national resource totals alone cannot establish recoverable supply, conversion performance, or comparative environmental and economic viability. This study develops a national screening framework for the Republic of Korea that links a published model-based potential (2,826,381 bone-dry tons, BDT, yr−1) to scenario-based allocation, stoichiometric and process-yield constraints, competing uses, and the evidence required for greenhouse-gas (GHG) and techno-economic assessment, organized as sequential decision gates. Applying assumed allocation fractions of 25%–100% and overall mass yields of 20%–40% gives an illustrative arithmetic output of approximately 141–1131 kt PLA yr−1 (212–848 kt yr−1 at 30% yield); these figures are not estimates of recoverable supply, validated conversion performance, or market demand. The assumed yields are stoichiometrically coherent but require high simultaneous performance across all conversion stages, which has not been demonstrated for Korean forest residues. Reported power-generation use indicates competition for the resource but cannot define a residual-supply ceiling, and published PLA and polypropylene (PP) GHG factors are not harmonized. The study therefore claims neither a verified GHG reduction nor commercial profitability; it specifies the regional supply, conversion, life-cycle, and techno-economic evidence needed before feasibility can be assessed.

Forests doi: 10.3390/f17111330

Authors: Li Gou Lin Zhu Yaning Mu Yunpeng Liu Dongmei Kuang Chunhong Liu

Against the backdrop of intensifying global climate change and increasing water scarcity in arid and semiarid regions, identifying ecological and economically valuable tree species with high water-use efficiency has become essential for vegetation restoration and sustainable management in sandy ecosystems. In this study, 14 cultivars of Amygdalus pedunculata Pall. were investigated along the southwestern margin of the Mu Us Sandy Land. Leaf gas exchange parameters, chlorophyll fluorescence parameters, relative chlorophyll content, and carbon isotope composition (δ13C) of leaves and current-year shoots were measured during the peak growing season from May to July. The relationships between δ13C, intrinsic water-use efficiency (WUEi), and photosynthetic physiological traits were analyzed, and principal component analysis (PCA) was performed to comprehensively evaluate cultivar performance and identify cultivars with high water-use efficiency suitable for the Mu Us Sandy Land. The results showed that net photosynthetic rate (An), stomatal conductance (gs), intercellular CO2 concentration (Ci), transpiration rate (E), and the ratio of intercellular to atmospheric CO2 concentration (Ci/Ca) generally decreased significantly from May to July (p < 0.05), whereas WUEi increased from 64.34 to 169.60 μmol mol−1, indicating changes in the relationship between carbon assimilation and stomatal regulation. Leaf δ13C was significantly and positively correlated with WUEi only in May (r = 0.67, p < 0.01), with no significant correlations observed in June or July. Shoot δ13C showed no significant correlation with WUEi in any of the three months. Significant positive correlations between shoot and leaf δ13C were observed in June and July, with correlation coefficients of 0.63 and 0.82, respectively, suggesting differences in the seasonal dynamics of δ13C and its potential as an indicator of water-use efficiency between organs. PCA identified three principal components that collectively explained 77.43% of the total variance. Cultivars 13065, 13071, and 12037 achieved relatively high comprehensive evaluation scores, indicating favorable overall physiological performance. These findings provide a scientific basis for cultivar screening and site-specific selection of A. pedunculata in the Mu Us Sandy Land.

Forests doi: 10.3390/f17111329

Authors: Gayeon Kim Junsik Ko Sugwang Lee

Increasing forest-trail use requires empirical identification of patterns that conventional surveys may miss, including prolonged stationary periods that may be associated with camping or backpacking. This study examined activity records from the Seonjaryeong section of Korea’s Daegwallyeong Forest Trail, combining GPS movement data with geotagged photographs linked at the activity-record level. Of 6505 GPS records collected in 2021, 3105 remained after cleaning. Stay point detection and K-means clustering identified three user types: short-distance (89.5%), long-distance (9.1%), and long-stay (1.4%). We also analyzed 1410 geolocated photographs using the Google Cloud Vision API. The long-stay type had an exceptionally long mean rest time (930 min) and distinct movement behavior. No significant difference in sex composition was detected, whereas age composition (with a small effect) and seasonal composition differed significantly among types. In the available photographs, forest and vegetation dominated object labels for all three types; second-ranked categories differed but rest on small, untested subsamples, two dominated by single contributors. The long-stay group, identified from GPS trajectories alone and defined by prolonged stationary time rather than verified on-site stays, represents a pattern current management systems do not explicitly address; the photographs add exploratory information on where some records stopped.

Forests doi: 10.3390/f17111328

Authors: He Han Yan Ma Zhichao Lou

Bamboo’s inherent radial gradient gives rise to heterogeneous hygrothermal deformation and mechanical responses, yet the effects of saturated steam softening across the radial thickness of the bamboo culm remain unclear. Eight radial layers of untreated bamboo (UB) and hygrothermally softened bamboo (HSB) were subjected to tests of anatomical structure, water absorption, hygrothermal deformation, and longitudinal and transverse compression in this study. The fraction of the vascular bundle area decreased from 67.67% in the outer layer to 10.08% in the inner layer, and water uptake in UB increased from 19.80% to 77.55%. Softening increased water absorption by 4.30–18.21 per hundred. Tangential and radial swelling coefficients generally decreased inwards, whereas dimensional swelling strains showed different radial trends, and the tangential-to-radial swelling ratio dropped from 1.70 to 0.62 in UB and from 1.46 to 0.59 in HSB; thus, the main direction of swelling had shifted. The most prominent adjacent-layer swelling mismatch occurred at L2–L3, and after softening, the radial mismatch increased by 52.40%. The largest dimensional swelling differences occurred between L1 and L2. Temperature-dependent deformation also varied with direction and radial position. Under longitudinal compression, the peak strain of L8 increased from 1.399% to 2.473%; transverse compression of L1 showed a 31.10% increase in peak strain but a 40.12% decrease in pre-peak work density. These findings highlight the layer-dependent effects of saturated steam softening and provide experimental evidence for assessing deformation compatibility and controlling potential damage during steam-assisted bamboo flattening.

Forests doi: 10.3390/f17111327

Authors: Yufei Huang Bin Zhang Shengchuan Tian Yugang Wang Yan Li Hao Zhang Xinjun Zheng

We assessed 13 desert shelterbelt plots between Wusu and Jimsar using a 25-indicator health index integrating stand structure and growth, soil properties, habitat and climate, and health risks. Soil variables combined mean 0–200 cm profile contents with 0–20 cm nutrient contents. Entropy and analytic hierarchy process (AHP) weights were combined by game-theoretic weighting; obstacle degrees, limitation pathways, and 5000 bootstrap iterations were used to describe relative score deficits and uncertainty. The entropy and AHP coefficients were 0.6034 and 0.3966. Health indices ranged from 0.3159 to 0.6930: ten plots were generally healthy, two unhealthy, and one subhealthy. Six 95% bootstrap intervals crossed a class threshold. Maximum patch-area proportion and crown width had the largest combined weights and mean obstacle degrees of 12.19% and 10.86%, respectively. Point estimates assigned seven plots to structural limitation, five to soil limitation, and one to external pressure; the bootstrap indicated stable pathway dominance at 12 plots. These model-derived patterns identify plot-specific priorities for subsequent field evaluation, rather than measured ecological drivers or temporal trends.

Forests doi: 10.3390/f17111326

Authors: Aihua Yu Mandira Pokharel Marissa “Jo” Daniel John Lancaster Tom Gallagher Tim McDonald Dana Mitchell

Growing demand for renewable energy from biomass has prompted exploration of timber transportation concepts. This study evaluated the operational and regulatory boundaries of whole-tree hauling using a modified log trailer in the southeastern United States. Two designs, a swinging gate and an extendable bolster, were developed to accommodate full-length, unprocessed loblolly pine (Pinus taeda) and contain tree crowns. The swinging gate was selected for field testing due to its lower cost, lighter weight, and structural reliability. Field testing included nine loads evaluated under unprocessed, trimmed, and delimbed trees. Axle weights and net payloads were evaluated with tandem and tridem axle regulations. The modified trailer increased biomass recovery, while processed biomass represented 14% of total load weight. However, the mean trimmed loads exceeded tandem-axle allowances reviewed for the eleven southeastern states considered. Pulpwood-sized timber required less trimming and allowed better crown containment than chip-and-saw timber. Overall, the modified trailer can improve biomass recovery, but practical implementation is strongly constrained by timber characteristics, axle configuration, and state-specific weight regulations.

Forests doi: 10.3390/f17111325

Authors: Gerard Alcoverro Adriano Raddi Daniel Tarrés Gianni Picchi

Electrification of professional forestry operations has been extensively studied in motor-manual operations involving chainsaws. Recent studies have highlighted that the main limitation to the widespread adoption of battery-powered chainsaws in professional forestry work is their limited autonomy. In the present study, this issue was addressed from an economic perspective, with the objective of determining how many years are required to offset the high initial investment in batteries through the lower operating costs associated with electricity compared to petrol. To carry out this study, different battery-powered chainsaws were compared with equivalent petrol-powered chainsaws under identical workloads across different forest types. To assess these comparisons, electricity consumption (Wh) and petrol consumption were measured to determine machine autonomy. The results showed a clear advantage of electricity in terms of energy cost per tree cut, meaning that the high initial investment in batteries (approximately €4000–6000 and 8–10 batteries per working day) can be recovered within 3–4 years. Battery-powered chainsaws proved economically competitive, recovering the initial investment within a relatively short period. However, further studies are necessary to evaluate a wider range of operating conditions, to test chainsaws with different power levels, and to assess the potential impact of future battery developments.

Forests doi: 10.3390/f17111323

Authors: Debin Li Chuan Tian Shisong Lu Hongna Chen Bo Dong Shengwei Jiang

Pine wilt disease (PWD), caused by Bursaphelenchus xylophilus, poses a severe threat to coniferous forests worldwide, yet conventional control measures remain limited. Therefore, identifying resistance genes from resilient species such as Larix kaempferi has become crucial for developing genetic strategies to protect forests. The overexpression of LKF3H2 (LKF3H2-OE) from L. kaempferi in A. thaliana significantly enhanced both plant growth and resistance to B. xylophilu. Compared to wild-type (WT) plants, LKF3H2-OE transgenic lines exhibited a 61.4% increase in plant height, a 61.5% increase in silique number per plant, and accelerated bolting and flowering by 6 days and 5 days, respectively. Following nematode inoculation, the disease incidence in transgenic plants was 40%, significantly lower than that in WT plants (76%). This enhanced resistance was associated with the density- and time-dependent induction of LKF3H2 expression, which reached 2.04-fold under high inoculum pressure and 5.48-fold at 7 days post-inoculation. Furthermore, transgenic plants accumulated higher levels of defense-related metabolites, including flavonoids (up to 3.12 mg/g) and proline (up to 34.35 mg/g). These results demonstrate that LKF3H2 significantly improves nematode resistance by synergistically enhancing growth traits and activating disease-resistant metabolic pathways, highlighting its potential as a key genetic resource for breeding disease-resistant wood plants.

Forests doi: 10.3390/f17111324

Authors: Yuxin Bai Kai Du Guanyue Ma Xufeng Mao Hongyan Yu

Growing stock volume (GSV) estimation in complex mountainous forests is complicated by terrain-induced radiometric distortions and the heterogeneous characteristics of multisource remote-sensing data. This study evaluated the effects of topographic correction and optical–microwave fusion on GSV estimation. Data from 93 field plots in Beishan Forest Farm, northeastern Qinghai Province, China, were integrated with Sentinel-2 imagery, fully polarimetric SAOCOM SAR data, and a digital elevation model (DEM). Seven Sentinel-2 topographic correction schemes were compared, and SAOCOM data before and after radiometric terrain correction (RTC) were evaluated using multiple feature-selection strategies and machine-learning models. SHapley Additive exPlanations (SHAP) were further used to quantify feature contributions. The results showed that the slope-stratified VECA correction achieved the highest mean GSV estimation performance among the Sentinel-2 configurations (R2 = 0.727; RMSE = 49.736 m3·ha−1). The optical–microwave fusion model combining Boruta + RF-RFECV feature selection with random forest achieved the highest mean performance (R2 = 0.734; RMSE = 48.906 m3·ha−1), with a modest 1.67% reduction in RMSE relative to the selected optical model. Cross-validated SHAP analysis further showed that Sentinel-2 features accounted for 92.98% ± 3.54% of the total normalized absolute SHAP contribution, compared with 7.02% ± 3.54% for SAOCOM features. The B5 red-edge band and its multi-window mean-texture features showed the highest SHAP contributions among optical predictors, while the MCSM and An–Yang4 volume-scattering components were among the leading SAOCOM predictors. These findings highlight the potential value of topographic correction for GSV estimation in complex mountainous forests, with the addition of fully polarimetric SAOCOM data providing only a small numerical improvement in predictive performance.

Forests doi: 10.3390/f17111322

Authors: Yeheng Jiang Haiying Su Weicong Qian Ziqian Li

This paper quantifies the rerouting of China’s wood and paper sector value added to the United States over 2016–2022, a period spanning the imposition of U.S. Section 301 tariffs and subsequent supply-chain reorganization. Using OECD ICIO, a three-term value-added decomposition separates direct bilateral from indirect trilateral flows through third-country transit economies. A structural decomposition analysis attributes changes in the trilateral channel to four factors: value-added intensity, China’s domestic supply-chain structure, China’s intermediate export orientation toward transit economies, and transit-economy global value chain output combined with U.S. final demand. The trilateral channel grew by 125.5% in wood and 159.4% in paper over the study period, substantially exceeding bilateral channel growth. China’s active reorientation of intermediate exports toward transit economies emerged as the dominant supply-side driver. Vietnam, Mexico, and Canada are identified as the principal conduit economies. Value-added RCA consistently exceeded gross-trade RCA in both sectors; in paper, the gap widened throughout the tariff period, indicating that China’s upstream international competitiveness strengthened despite bilateral trade barriers. These findings demonstrate that bilateral tariffs are materially less effective than gross-trade statistics imply. Value-added tracking should accompany gross-trade monitoring in trade policy assessment.

Forests doi: 10.3390/f17111321

Authors: Peihong Jia Piaopiao Li Yuxin Zhu Xinyue Wang

Elucidating the spatio-temporal evolution of ecosystem services (ESs) and their complex driving mechanisms is crucial for the restoration and differentiated management of integrated land-use systems in alpine national parks. Sanjiangyuan National Park is characterized by a forest–grassland–wetland mosaic, yet the ecological effects of long-term land-use transitions and their underlying drivers remain insufficiently understood. In this study, the InVEST model was used to evaluate the spatio-temporal dynamics of four key ESs: water conservation (WC), carbon storage (CS), habitat quality (HQ) and soil conservation (SC) from 1990 to 2020. Using the Geographical Detector Model (Geodetector), we quantitatively attributed the interactive effects of physiographical and socioeconomic factors on ES spatial differentiation. The results showed that (1) ESs generally exhibited positive changes over the past three decades, with WC and SC showing the greatest increases. Spatially, ESs exhibited a southeastward increasing gradient. (2) Single-factor detection showed that precipitation and Normalized Difference Vegetation Index (NDVI) were the main explanatory factors for WC, CS and HQ, while slope and precipitation were the main explanatory factors for SC; socioeconomic factors exerted weak but localized effects. (3) Pairwise interactions showed higher q-values than individual factors, primarily exhibiting bivariate enhancement and nonlinear enhancement, while the dominant interaction combinations varied among ESs and over time. This indicates that interactions among multiple physiographical and socioeconomic factors jointly shape the spatial patterns of alpine ES. This study deepens the understanding of ES dynamics in alpine national parks, providing scientific support for ecological conservation assessment, differentiated spatial management, and regional human–nature harmony.

Forests doi: 10.3390/f17111320

Authors: Yuan Yuan Guanrong Huang Wen Lei Yuantao Hu Mengtao Zheng Le Chang

The Qinling Mountains form a major geographical boundary and climatic transition zone in China. This study derived the kernel Normalized Difference Vegetation Index (kNDVI) from Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI data and evaluated it against conventional NDVI and gross primary productivity (GPP) in the Shaanxi section of the Qinling Mountains for 2000–2025, using trend, partial-correlation, variance-partitioning and geographical-detector analyses. (1) Vegetation improved overall: annual kNDVI rose from 0.593 to 0.668 at 0.0027 yr−1 (R2 = 0.90), and 84.55% of the area increased significantly. (2) kNDVI was only slightly better correlated with GPP than NDVI (pixel-wise r = 0.566 versus 0.563; difference 0.0026, 95% CI 0.0025–0.0027), and no pixel differed significantly after false-discovery-rate correction, so local superiority cannot be claimed. (3) Temperature and precipitation promoted growth whereas sunshine duration inhibited it; the three factors uniquely explained 44.3%, 39.2% and 15.9% of the climatically explained variance of kNDVI, and temperature alone 74.2% for GPP. (4) After significance masking, 60.08% of the kNDVI grid and 33.94% of the GPP grid had no significant dominant driver; temperature dominated 64.96% of the area for GPP, whereas precipitation dominated kNDVI in the west and temperature in the east. Annual climate explains only about one-fifth to one-quarter of inter-annual variability, leaving a large, spatially coherent residual trend.

Forests doi: 10.3390/f17111319

Authors: Alessio Santosuosso Giovanna Sala Serena Sofia

This study evaluates whether handheld mobile laser scanning (HMLS) can support the design of canopy consolidation systems for urban Pinus pinea L. trees without climbing into the crown. Fifty stone pines in a historic park in Pistoia (Italy) were surveyed with a SLAM-based handheld laser scanner and assessed with Visual Tree Assessment; five trees were then selected for consolidation design. Tree height, diameter at breast height (DBH), and crown metrics were derived from the point cloud and compared with field measurements, and the scaffold branches were reconstructed as sequences of truncated cones. For each branch, the bending stress generated by self-weight was computed with cantilever-beam theory and compared with the compressive strength of green P. pinea wood; a wind load case and a sensitivity analysis to diameter errors were added. Under self-weight, the safety factor of the vulnerable branches ranged from 1.44 to 37; one branch was below the usual minimum of 1.5 and a second fell to 1.69 under the 27 m/s wind. Anchor positions, rope trajectories, and system classes (4 t or 8 t) were drawn directly on the point cloud. The study is proof of concept: the systems have not been installed, and the mechanical results have not been verified by load tests, but the workflow shows that the data needed for consolidation design can be obtained remotely and non-invasively.

Forests doi: 10.3390/f17111318

Authors: Jia Liu Qingqing Huai Yachao Li Yunfei Yan Peng Wang Shuoshuo Liang Yafei Shi Wendou Liu

Reliable quantification of forest aboveground biomass (AGB) and growing stock volume (GSV) underpins carbon stock assessment and ecosystem monitoring. However, the complex mountainous terrain makes it difficult to estimate forest parameters, and research on the simultaneous estimation of forest AGB and GSV remains limited. To this end, this study proposed an eco-constrained explainable multi-task deep learning framework (Eco-AMT-MLP) that integrated Sentinel-2 data obtained from the Google Earth Engine platform with topographic, soil, and climatic factors to jointly estimate forest AGB and GSV while incorporating an ecological constraint linking the two prediction tasks in the complex mountainous forests of northwestern Yunnan Province. The model’s performance was evaluated against Random Forest (RF), Extreme Gradient Boosting (XGBoost), Categorical Boosting (CatBoost), and K-Nearest Neighbor Regression (KNN), and ablation experiments were conducted to assess the contribution of the ecological constraint module. The Eco-AMT-MLP model demonstrated the best overall predictive performance among the compared models, achieving an R2 of 0.64 ± 0.08 and an RMSE of 132.99 ± 19.96 m3 ha−1 for GSV prediction, and an R2 of 0.58 ± 0.07 and an RMSE of 87.37 ± 13.10 Mg ha−1 for AGB prediction. Compared with the MLP model, Eco-AMT-MLP increased the R2 values for GSV and AGB predictions by 0.04 and 0.11, respectively, while reducing the corresponding RMSE values by 7.46 m3 ha−1 and 10.12 Mg ha−1, respectively. However, the model shows only limited improvement in AGB estimation accuracy, indicating that its enhancement of AGB estimation is less pronounced than its improvement of GSV estimation. SHAP analysis further identified environmental covariates and Sentinel-2 spectral features as important predictors of forest AGB and GSV. By integrating joint estimation of forest AGB and GSV with ecological constraints and interpretable predictor analysis, this framework provides a methodological reference for regional forest carbon-stock assessment, forest resource inventories, and ecosystem monitoring in complex mountainous regions.

Forests doi: 10.3390/f17111317

Authors: Ivan Bazijanec Ernest Goršić Milivoj Franjević Marija Majnarić Mario Božić

European forests face increasing pressure from climate change and a growing number of invasive alien species. This study examines whether growth patterns and climate–growth relationships in pedunculate oak (Quercus robur L.) changed after the appearance of the oak lace bug (Corythucha arcuata; OLB) in the Spačva basin, Croatia. We analyzed 90 cores from 45 trees in young, middle-aged and old stands, comparing growth before and after 2013 (2000–2023). Structural change analysis identified a 2013 breakpoint in all stands, coinciding with the first regional detection of OLB. Growth trends declined significantly in young (p < 0.001) and middle-aged (p < 0.01) stands, but not in the old stand, and increased variability in tree-level slopes indicated heterogeneous individual responses. Declining mean interseries correlation (Rbar) and expressed population signal (EPS) suggested reduced growth synchrony. Positive correlations with precipitation and negative correlations with temperature strengthened in recent years, overlapping the period after OLB appearance. New earlywood signals emerged: a negative correlation with previous December precipitation and a positive correlation with previous October SPEI-3. As the breakpoint also follows the 2011–2012 drought and precedes the 2014 floods, the link to OLB remains correlative. We hypothesize that late-season drought, favoring OLB activity and limiting non-structural carbohydrate (NSC) replenishment, combined with winter waterlogging, may deplete NSC reserves and constrain growth the following year.

Forests doi: 10.3390/f17111316

Authors: Rômullo Oliveira Louzada Rosa Helena da Silva Staci Arielli Caires Correia Rodney Murillo Peixoto Couto Diego Campos Vasconcelos André Nogueira Bozza João Gabriel Chaib Maximiliano Guimarães Sales Renato Maurício Barbosa Tavares

Machine-learning models trained on remote sensing data are widely used to map ecosystem carbon stocks, but their validation often ignores spatial autocorrelation, inflating apparent predictive skill. We tested whether this concern, established for large-scale satellite-based biomass mapping, also holds for UAV-LiDAR carbon estimation at the plot scale, comparing continuous structural metrics, segmentation-derived crown metrics, and Sentinel-2 spectral variables for predicting aboveground biomass (AGB) and soil organic carbon (SOC) across 29 inventory plots in a Cerradão-dominated Pantanal–Cerrado ecotone, Brazil. Random Forest models were evaluated under fourteen predictor scenarios and two allometric formulations. A single spatial partition yielded seemingly reasonable accuracy for AGB (best R2 = 0.27), whereas SOC showed weak apparent skill, even under a single partition (best rRMSE = 33.7%, R2 = −0.14); repeating validation across 20 independent spatial partitions, combined with leakage-free nested variable selection, showed predictive skill collapsing to near-zero or negative R2 for all 98 tested scenario–response combinations (mean R2: −0.44 to −0.003), a pattern statistically indistinguishable from a null model built on permuted response data. Variable selection stability differed from full-dataset importance rankings: raw spectral bands and canopy vertical-complexity metrics were the most consistently retained predictors across partitions for AGB and SOC, respectively, even though a derived spectral index and a lower-canopy structural metric dominated single-model importance for each response. Cross-pool coupling tests showed no meaningful gain from using AGB to predict SOC or vice versa. Empirical variogram analysis further indicated that the spatial blocking scheme adequately separated the two response variables, although residual spatial dependence could not be excluded for a subset of predictors. Validation strategy, rather than sensor combination or vegetation representation, was the primary determinant of apparent predictive skill, cautioning against overinterpreting single-partition accuracy in small, heterogeneous tropical landscapes.

Forests doi: 10.3390/f17111315

Authors: Kasidit Chonmanus Piyapong Tongdeenok Chakrit Na Takuathung Surachit Waengsothorn Sitthisak Moukomla

Dry dipterocarp forests exhibit strong seasonal constraints on carbon uptake, but satellite predictive value remains uncertain. We evaluated a tower-to-satellite framework for daily gross primary productivity (GPP) at Sakaerat, Thailand, combining 698 days of eddy covariance data and meteorology with Sentinel-2 vegetation indices from non-overlapping 10-day median composites within an approximately 90% climatological flux footprint. Composites were assigned to EC days by backward-only matching (maximum age: 45 days). Four algorithms underwent nested purged blocked cross-validation and an independent 184-day holdout (February–August 2026). In 2025, daytime-partitioned (DT) GPP was 2302.62 g C m−2 yr−1, with 79% during the rainy season, whereas nighttime-partitioned (NT) GPP was 60.11% higher. During development, Sentinel-2 reduced error for random forest and XGBoost but increased it for support vector regression (SVR) and ridge regression under DT; under NT, all four improved. M4-SVR had the lowest mean outer-fold RMSE (1.582 vs. 1.586 g C m−2 d−1 for M1-SVR) but a higher pooled OOF RMSE (1.751 vs. 1.649). Holdout performance declined (RMSE = 3.313 g C m−2 d−1; R2 = 0.404), with negative within-season R2 and high-GPP underestimation. These results indicate conditional satellite gains beyond seasonal and meteorological baselines, with limited within-season daily skill; full-year and cross-site generalization remain untested.

Forests doi: 10.3390/f17111314

Authors: Óscar Dorado Dulce María Arias José María De Jesús-Almonte Gerardo Cuevas Patricia Mussali-Galante Efraín Tovar-Sánchez

Natural hybridization can obscure species boundaries and generate morphologically atypical individuals whose taxonomic identity cannot be resolved from phenotype alone. In central Mexico, Mimosa benthamii and M. mollis occur in sympatry with individuals exhibiting unusual combinations of morphological traits. We integrated morphological and molecular evidence to test whether these individuals originated through interspecific hybridization, characterize variation in parental genetic contributions, and evaluate whether they constitute a morphologically diagnosable hybrid entity. We examined 29 leaf, prickle, fruit, and inflorescence characters in 145 plants and analyzed 42 reproducible RAPD bands, including 16 parental-diagnostic markers. The putative parental species were morphologically differentiated and distinguishable by parental-diagnostic RAPD markers, whereas morphologically atypical individuals exhibited heterogeneous combinations of intermediate, parental-like, and transgressive morphological characters and occupied intermediate and partially overlapping positions relative to both taxa. The concordance between morphological and molecular evidence supports natural hybridization between M. benthamii and M. mollis. Hybrid-index analyses revealed heterogeneous parental-marker profiles, including individuals with intermediate values and others showing greater similarity to M. mollis. However, the limited resolution of RAPD markers precluded confirmation of backcrossing events, genetic introgression, or specific hybrid generations. Despite the occurrence of mixed parental-marker profiles, M. benthamii and M. mollis remained morphologically differentiated and distinguishable by parental-diagnostic RAPD markers within the contact zone. The concordance between molecular evidence consistent with hybrid ancestry and a diagnostic combination of morphological characters supports recognition of the hybrid entity as Mimosa × gretheriae nothosp. nov. These findings document natural interspecific hybridization in Mimosa and show that hybridization can generate substantial phenotypic and molecular variation while the parental taxa remain morphologically distinguishable.

Forests doi: 10.3390/f17111313

Authors: Jingli Yan Yuanyuan Zhang Xiuhuan Wu Shan Yin

Traffic emissions contribute to fine particulate matter (PM2.5) exposure near roads. Vegetation barriers (VBs) alter particle transport, but their effects depend on planting design and local airflow. This study simulated 24 planting and wind-speed scenarios for a roadside VB and a downwind building in Shanghai. Vegetation was represented by aerodynamic resistance; foliage deposition was not modelled. Field comparison used 40 locations at 1.5 m, separate from five road-edge locations used for inlet prescription. At a reference wind speed of 2.0 m/s, tree-dominated VBs had 10.52% higher mean concentrations within the barrier than shrub-dominated VBs (33.95 versus 30.72 µg/m3). Mean sidewalk concentrations across vegetated configurations were 14.48% higher than in the vegetation-free control. Along the sampled façade profile from 1.5 to 19.5 m, tree-dominated VBs had lower mean concentrations than the control (28.42 versus 29.47 µg/m3), whereas shrub-dominated VBs had higher concentrations (31.09 µg/m3). Increasing reference wind speed from 1 to 5 m/s decreased mean concentrations within the all-tree VB and along the façade. These results describe simulated concentration redistribution under the prescribed inflow and geometry. Predictions above 1.5 m remain unevaluated, and unquantified mesh sensitivity limits interpretation of small differences among planting arrangements.

Forests doi: 10.3390/f17111312

Authors: Attila Borovics Éva Király Endre Schiberna

Temperate forests face intensifying climatic stress, yet evidence on management-based adaptation remains fragmented. We systematically mapped peer-reviewed evidence on forest management interventions implemented or proposed for adaptation in temperate forests. Web of Science and Scopus searches yielded 130 eligible records, including primary empirical studies, modelling studies and reviews/perspectives. Records were coded for context, interventions, mechanisms, outcomes, monitoring, implementation constraints and trade-offs. Analyses included descriptive statistics, multiple correspondence analysis (MCA) and a sensitivity analysis of 53 records describing experimental or operational interventions. Evidence was concentrated in Europe and North America, predominantly addressing drought. Thinning studies reported benefits from reduced competition alongside trade-offs from canopy opening and microclimatic exposure, highlighting the importance of thinning intensity and gap area. Regeneration studies emphasized balancing light availability with microclimatic protection, while browsing frequently constrained establishment. Species mixing, diversification and continuous cover forestry commonly occurred in records reporting favourable outcomes, although the independent effects of diversification and continuous cover forestry could not be isolated. Assisted-migration outcomes varied with species, provenance and transfer conditions. Of 107 records with assessed outcomes, 96 (89.7%) were classified as successful (n = 58) or partly successful (n = 38) based on the original authors’ conclusions. Observation or monitoring periods were quantified for 64 records (median: 7 years; interquartile range: 4–13.5 years), indicating limited long-term evidence. Knowledge gaps and browsing pressure were the leading implementation constraints, while maladaptation uncertainty and biodiversity loss or species-composition change were the most frequent trade-offs. MCA described intervention–context associations without clear separation by reported outcome. Overall, the map highlights diversified, structurally heterogeneous stands with canopy continuity and site-specific density regulation as promising directions, while underscoring the urgent need for long-term monitoring and the systematic integration of browsing management into adaptive silviculture.

Forests doi: 10.3390/f17111311

Authors: Siqi Hao Yalin Zhai Lei Wang Yanxue Li Mengsi Ding Zishan Huang

The carbon mitigation benefits of urban parks are expanding beyond traditional biological carbon sequestration to encompass the regulation of urban energy demand. Direct carbon sequestration capacity (DCSC), resulting from vegetation carbon fixation, and indirect carbon-saving capacity (ICSC), arising from reductions in building cooling energy consumption induced by summer cooling effects, represent two important pathways for carbon mitigation by urban parks. However, how landscape patterns and morphological spatial patterns jointly regulate DCSC and ICSC, and what nonlinear responses and interactions exist among different spatial indicators remain to be further investigated. Focusing on urban parks in the main urban area of Harbin, this study quantified DCSC and ICSC using multisource remote sensing data and revealed the spatial differences between these two carbon mitigation functions. By developing an analytical framework integrating explainable machine learning and nonlinear response modeling, this study identified the key indicators affecting DCSC and ICSC, the directions of their contributions, and their interactions. It further characterized the nonlinear responses of key indicator combinations and identified favorable ranges for the synergistic enhancement in both carbon benefits. The results showed that: (1) DCSC ranged from 0.96 to 946.75 kg C·day−1, while ICSC ranged from 0.10 to 9,828.50 kg C·day−1. Total ICSC across all parks was approximately 16 times the total DCSC, and both DCSC and ICSC were generally lower in urban parks located within the inner ring. (2) The relative contributions of landscape metrics and MSPA classes to the two carbon benefits differed markedly: landscape metrics made a greater explanatory contribution to ICSC, whereas MSPA classes made a relatively greater explanatory contribution to DCSC. Mean shape index (SHAPE_MN), patch density (PD), and Perforation were identified as key indicators with the potential to enhance both DCSC and ICSC. (3) From a synergistic perspective, interactions involving SHAPE_MN were prominent, with SHAPE_MN × PD ranking among the strongest for both responses, highlighting the importance of boundary complexity and spatial fragmentation. In addition, coordinating green space coverage, spatial continuity, boundary morphology, and the integrity of core spaces can effectively promote the synergistic enhancement in both carbon benefits. These findings provide a new planning basis for optimizing urban park structures in cold-region cities under spatial constraints and advancing the goal of urban carbon neutrality.

Forests doi: 10.3390/f17111310

Authors: Florian Kraxner Dmitry Schepaschenko Georg Kindermann Anatoly Shvidenko Oskar Franklin Colin P. Johnstone Eunbeen Park Andrey Krasovskiy Linda See

Due to climate change, forest growth conditions are changing and may become unfavorable for the tree species currently growing in different regions across the EU. Forest managers can actively plant trees that are better adapted not only to current site conditions but also to those expected in the future. Given the long rotation periods in forestry, consideration of climate projections up to 2100 is crucial. In this paper, we use the Global Forest Model (G4M) to project the future of German forests under different climate pathways (RCP2.6, RCP4.5, RCP6.0, and RCP8.5) and management alternatives (Economic, Societal, and Conservation). Utilizing spatially explicit forest cover and biomass maps with climate and soil data, G4M simulates forest dynamics including species distributions, productivity, growth, and carbon stocks. Our findings reveal substantial variations in forest composition, productivity, and carbon accumulation from growth across the scenarios. The Conservation management alternative, emphasizing broadleaved species and extended rotation times, notably enhances carbon stocks under moderate climate pathways. In contrast, the Economic alternative, focusing on wood harvest maximization, maintains current forest stocks under moderate climate pathways while adapting species composition to optimize productivity. These projections underscore the critical influence of management decisions on species composition, growth, and carbon storage, highlighting the need for adaptive strategies in response to climate change. Our study contributes to the ongoing dialogue on sustainable forest management by providing a comprehensive analysis of future forest dynamics under varying environmental conditions and management regimes.

Forests doi: 10.3390/f17111309

Authors: Zeting Dong Yujia Qin Yanfang Tan Junhua Zhu Wanxing Li Jianbo Li Jinyun Song Xiaoguo Yang Yunxiu Liu Chunmei Wei Lingting Lu Fang Liang Yutong Lin

Barringtonia fusicarpa Hu, an endemic tree species of southern China that is listed as Vulnerable, is increasingly threatened by anthropogenic disturbance and illegal logging, yet its potential distribution remains poorly quantified. Based on 31 occurrence records and 37 environmental variables, we developed an optimized Maximum Entropy (MaxEnt) model to predict the current potential suitable habitat of the species, to identify the dominant environmental drivers, and to project spatiotemporal shifts under three Shared Socioeconomic Pathway scenarios (SSP1-2.6, SSP2-4.5 and SSP5-8.5) across four future periods (2021–2040, 2041–2060, 2061–2080 and 2081–2100). The optimized model exhibited excellent predictive performance, with a mean area under the receiver operating characteristic curve (AUC) of 0.947. The mean temperature of the coldest quarter (Bio11), temperature seasonality (Bio4), precipitation of the driest quarter (Bio17) and isothermality (Bio3) were the dominant drivers, together accounting for 99.2% of the total percent contribution; their optimal ranges were 11.6–26 °C, 134–540, 45–230 mm and 42%–57%, respectively. Under the current climate, the total suitable habitat covered approximately 87.29 × 104 km2 (9.10% of China’s terrestrial area), of which 8.03 × 104 km2 was highly suitable, 29.84 × 104 km2 moderately suitable and 49.42 × 104 km2 marginally suitable, mainly in Guangxi, Guangdong, Yunnan, Hainan and Taiwan, China. Under future scenarios, the total suitable area is projected to expand overall, mainly driven by gains in low- and moderately suitable habitat; the highly suitable zone remains close to its current extent. The distribution centroid shifts northeastwards under SSP1-2.6 and SSP2-4.5, whereas under SSP5-8.5 it shifts southwest of its baseline position by the 2081–2100. These results indicate that temperature-related variables primarily constrain the distribution of B. fusicarpa and that proactive, climate-informed conservation planning—including in situ protection and germplasm collection in southern Yunnan and Hainan—is needed to secure the species’ long-term persistence.

Forests doi: 10.3390/f17111308

Authors: Matheus Azevedo Carvalho Matheus Severo de Souza Kulmann Cristiane Coelho de Moura Dione Richer Momolli Grasiele Dick João Gabriel Missia da Silva Tiago de Oliveira Godinho Gabriel Soares Lopes Gomes Robert Gomes Ítalo Favoreto Campanharo Carlos Henrique Rodrigues de Oliveira Marcos Vinicius Winckler Caldeira

Nutrient removal through timber harvesting can affect the long-term sustainability of forest plantations, particularly when species differ in biomass allocation and nutrient use. Understanding these differences is therefore essential for developing species-specific nutrient management strategies. This study evaluated differences in stem biomass allocation, nutrient and carbon stocks, and nutrient use efficiency (NUE) among 8.6-year-old Khaya grandifoliola, K. ivorensis, and K. senegalensis. This study was conducted in a plantation located at Reserva Natural Vale, Brazil, where five trees per species were sampled. Discs collected from the base, middle, and top of the commercial stem were separated into stemwood and stembark for chemical analyses. Biomass, nutrient and carbon stocks, and NUE were estimated, and differences among species were assessed using univariate and multivariate analyses. Macronutrient concentrations in the stembark followed the order Ca > N > K > Mg > S > P. K. senegalensis had the highest proportion of stembark (24.13%) and accumulated greater stocks of several nutrients and carbon in this compartment, as well as higher N, P, and Mg stocks in stemwood. In contrast, K. ivorensis showed the highest K and Fe stocks in stemwood, whereas K. grandifoliola accumulated the greatest amount of Ca. Stemwood carbon stocks averaged 11.77 Mg ha−1 and did not differ among species. Nutrient use efficiency also differed among species, with K. ivorensis showing greater efficiency for N, Ca, Mg, and Cu, K. grandifoliola for K, Zn, and Mn, and K. senegalensis for Fe. The results revealed species-specific patterns of biomass allocation, nutrient accumulation, and nutrient use efficiency. K. senegalensis, which had the highest proportion of stembark, also accumulated greater stocks of several nutrients and carbon in this compartment, highlighting the potential value of retaining bark after harvesting to support nutrient return to the soil. However, the species-specific patterns of nutrient accumulation indicate that the implications for nutrient export depend on the element considered. These findings can inform species selection and harvesting practices aimed at improving nutrient conservation in Khaya spp. plantations.

Forests doi: 10.3390/f17111307

Authors: Ratu Mutiara Wulandari Lailan Syaufina Imas Sukaesih Sitanggang I Nengah Surati Jaya Asmadi Saad Ferdian Krisnanto Rinaldi Muhammad Askary

Peatland fires in Southeast Asia are strongly influenced by hydrological conditions, yet most studies rely on low-temporal-resolution data, limiting the capture of rapid hydrological dynamics. This study analyzes high-frequency hydrological dynamics in relation to fire occurrence in protected peatlands of Central Sumatra. Real-time monitoring using 12 IoT sensors recorded groundwater level (GWL), soil moisture (SM), and soil temperature (ST). Results show substantial spatial variation, with GWL (−144.30 to 9.00 cm), SM (14.52% to 94.82%), and ST (23.01 to 33.93 °C). Linear mixed-effects models (LMMs) and first-order autoregressive (AR (1)) temporal correlation showed significant associations of GWL with SM (β = 0.460, p < 0.001) and ST (β = −0.516, p < 0.001). GWL decreased by 13.73 cm (−0.54 cm day−1) during the pre-fire period and by a further 6.34 cm (−0.47 cm day−1) during the fire period (27 August 2024–9 September 2024), when the descriptive mean GWL reached −89.43 cm. Post-fire, GWL increased by 41.99 cm (0.82 cm day−1), while SM increased and ST decreased, coinciding with reduced hotspot activity. The fire period was identified using SIPONGI hotspots and SIPP fire records and suppression. These findings show temporal associations between hydrological dynamics and fire occurrence, supporting high-frequency IoT monitoring of peatland hydrology.

Forests doi: 10.3390/f17111306

Authors: Anshelo Stin Salazar-Valqui Leif Armando Portal-Cahuana Katherine Julissa Oyarce-Tafur Ingrid Aracelli Cassana-Huamán

Non-destructive assessment of the internal condition of standing trees is essential for managing high-value species such as Cedrela spp., listed in CITES Appendix II. We evaluated 59 trees from eight localities in Amazonas, San Martín, and Cajamarca, Peru, using acoustic tomography at 1.00 and 1.30 m above ground. We quantified the incidence of internal defects, the percentage of affected area (RH), and wave velocity (WV), and examined their relationships with dendrometric and climatic variables. Incidence ranged from 0% to 100% and decreased from 1.00 to 1.30 m across five localities, never increasing; RH and WV differed by height (p ≤ 0.006). Magdalena showed the greatest deterioration (RH = 60.33%; WV = 977.23 m s−1 at 1.00 m), whereas the remaining localities formed a largely homogeneous group. Incidence was not significantly related to RH but was negatively correlated with commercial height at 1.30 m (ρ = −0.88). Temperature was positively correlated with incidence, as were RH at 1.00 m and precipitation, and RH at 1.30 m (ρ = 0.73–0.78), but neither was significantly correlated with WV. Climate may contribute to internal deterioration but does not fully explain it, and assessment protocols for Cedrela spp. should include the lower stem section.

Forests doi: 10.3390/f17111305

Authors: Rong Zhao Zhao Chen Cairong Xu Yingran Che Ranping Xiong

Image-based forest 3D reconstruction from multi-view imagery can generate stand-level point clouds and provide data support for extracting individual-tree structural parameters, such as diameter at breast height (DBH) and tree height. Three-dimensional reconstruction of forest ecosystems is fundamental to forest resource monitoring and biomass assessment. However, forest scenes are characterized by frequent branch and leaf occlusions, repetitive bark and foliage textures, and complex illumination conditions. These factors often introduce ambiguities into feature matching and cost aggregation in convolutional neural network (CNN)-based multi-view stereo (MVS) methods, resulting in incomplete point clouds and depth estimation errors. To address these challenges, this study proposes CasFormer, a cascaded multi-view 3D reconstruction model designed for near-ground handheld forest imagery. Built upon a cascaded cost-volume framework, CasFormer constructs a Self-and-Cross Attention Feature Pyramid Network (SC-FPN) and incorporates a Positional Encoding Generator (PEG) to inject camera geometric priors into feature representations, thereby enhancing feature discriminability in repetitive weak-texture regions. In addition, a pixel-wise visibility-weighted cost volume is used to adaptively adjust source-view aggregation weights according to matching confidence, reducing the influence of occluded or low-quality source views on the cost volume and improving the stability of depth estimation in forest scenes. Experiments across three forest plots show that CasFormer achieves the highest overall single-tree matching rate (99.14%) and outperforms the competing methods in tree-height accuracy and point-cloud density at all three plots. Its mean DAE is 92.87%, exceeding FS-MVSNet and MVSFormer by 0.97 and 2.78 percentage points, respectively. CasFormer attains the lowest DBH RMSE at Plots 1 and 2; at Plot 3, its RMSE is comparable to those of MVSFormer and FS-MVSNet. Its point-cloud densities are 3.87, 2.17, and 4.87 × 106 points/m2 at Plots 1, 2, and 3, respectively, the highest among the methods evaluated at each plot. These results demonstrate that CasFormer improves plot-scale forest 3D reconstruction using handheld RGB imagery that can be acquired with minimal effort. It provides an effective image-based reconstruction method for extracting individual-tree parameters and supports sustainable smart forestry monitoring.

Forests doi: 10.3390/f17111304

Authors: Zeyu Yang Jingjie Zhang Yingying Li Beibei Tao Shichen Zhu Zhongrui Zhang

Forest soil organic carbon (SOC) and nutrient dynamics are critical for terrestrial carbon cycling, yet full-profile soil property characterization at regional scale remains limited in southern subtropical China. Based on 0–100 cm soil profile data from 443 forest sampling points in Maoming City—6645 field observations aggregated to 2215 point × layer records for statistical modelling—this study investigated vertical distribution patterns of SOC, total N, total P, total K, pH, and molar stoichiometric ratios, and quantified the relative explanatory contributions of stand type and topographic factors using linear mixed-effects models (LMMs), random forest (RF), and geostatistical kriging. SOC and total N exhibited pronounced surface accumulation, declining by approximately 50% and 44% from the surface (12.75 g kg−1 and 941 mg kg−1) to the 80–100 cm layer (6.35 g kg−1 and 530 mg kg−1), respectively. Total P showed minimal vertical variation (≈5%), total K remained broadly stable, and pH increased slightly with depth (4.55 → 4.66). Stand type was significantly associated with SOC, total N, total K, pH, and most stoichiometric ratios (all p < 0.05); surface SOC was higher in broadleaf mixed and coniferous forests than in eucalypt, economic tree species, and litchi/longan plantations. All stoichiometric ratios declined significantly with depth. RF models showed that soil depth had the highest permutation importance for SOC and total N (0.44–0.59), while stand type ranked first for pH and total K (0.40–0.49); however, out-of-bag R2 values were modest (–0.06 to 0.23), indicating that substantial variation remains unexplained by the four measured predictors. All properties exhibited moderate spatial autocorrelation (nugget ratio 0.48–0.67). Total K showed moderate interpolation accuracy under random leave-one-out validation (R2CV = 0.458), whereas spatially structured block cross-validation yielded negative R2 for four of the five properties; the kriging maps accordingly visualise the spatial arrangement of the measured properties. These results provide regional baseline evidence for 0–100 cm nutrient vertical patterns and soil carbon density in southern subtropical China.

Forests doi: 10.3390/f17111303

Authors: Liang Gao Liangjin Yao Xiaodong Jiang Chuping Wu Jiejie Jiao Hong Xiao Chaoran Wen

Biodiversity responses to habitat transformation may differ among taxonomic groups and vary seasonally, yet these dimensions are rarely evaluated simultaneously. We assessed vegetation, butterfly, frog, and bird diversity across forest, farmland, and urban green space in Dongyang, Zhejiang, China, using repeated seasonal surveys. Habitat, season, and their interaction were evaluated using models accounting for repeated observations within sampling plots. Cross-taxon associations were quantified using habitat-specific Spearman rank correlations based on richness, Shannon diversity, Pielou’s evenness, Gini–Simpson diversity, and abundance, with Benjamini–Hochberg correction for multiple comparisons. Species richness showed pronounced taxon-specific habitat associations: vegetation richness was highest in forests, butterflies and frogs were relatively well represented in farmlands, and birds showed the highest richness in urban green spaces. Richness generally increased toward summer and declined toward winter, while significant habitat × season interactions indicated that habitat differences varied temporally. Cross-taxon associations also differed markedly among habitats, demonstrating strong context dependence in the covariation among taxonomic groups. These findings indicate that biodiversity responses along the forest–farmland–urban gradient cannot be adequately represented by a single habitat ranking or a single taxonomic group. Multi-taxon and multi-season assessments, together with habitat-specific analyses, are therefore essential for disentangling biodiversity patterns and cross-taxon associations and for informing landscape-scale conservation in human-dominated landscapes.

Forests doi: 10.3390/f17111302

Authors: Zijian Wu Zhen Ye

Coarse urban green-space assessments often merge tree canopy, low-lying vegetation, and impervious surfaces within large spatial units, failing to resolve fine-scale greening composition in heterogeneous built environments. To address this gap, we evaluated whether centimetre-scale unmanned aerial vehicle (UAV) imagery coupled with SAM3 concept segmentation can quantify sub-hectare urban green structure across functional–morphological scene types within a representative mountainous, ecological medium-sized city in East China characterized by compact built-up spaces constrained by valley geography. Using 746 sub-hectare analytical tiles, we extracted canopy, visible non-canopy green, and canopy-share metrics, applying source-fixed-effects models with source-clustered inference to compare scene types. Primary scene type driven by urban morphological forms accounted for substantial variation in total green cover (35.6%) and tree canopy (17.5%), with planned residential areas exhibiting over twice the total green cover of compact residential areas and industrial/compact residential scenes presenting the lowest coverage. These results reveal that fine-scale greening in compact, valley-constrained ecological cities is highly heterogeneous and strongly governed by morphological layout, demonstrating that combining ultra-high-resolution imagery with vision foundation models provides a scalable tool for identifying micro-greening deficits and guiding context-sensitive urban renewal in such urban contexts.

Forests doi: 10.3390/f17111301

Authors: Bernard T. Bormann Amelia Fitch Courtney R. Bobsin Glenn Ahrens Indroneil Ganguly

Increasing belowground carbon sequestration through forest management has significant potential to mitigate rising atmospheric CO2 but is rarely used in C-credit systems. Difficulty in, and expense of, quantifying changes in soil C, along with large but somewhat ambiguous results in trials, has hindered its use in C-credit systems. Growing N2-fixing trees, however, has been widely suggested to consistently increase soil C. We review evidence from empirical and ecosystem process studies to evaluate whether consistent belowground C sequestration is present in the most widely studied N2-fixing-tree genus Alnus (alder). We searched globally for studies that included measures of change in mineral-soil C, including chronosequence studies and field trials. We found studies that also compared alder effects against non-N2-fixing species, which link to additionality calculations (relative C sequestration). We found that: (1) the empirical evidence of positive soil-C accretion under alder is large and unidirectional for all studies; (2) ecosystem process studies provide multiple mechanisms that can explain the observations; and (3) both empirical and mechanistic evidence persist across a wide array of climate, soils, and disturbance regimes. We suggest that evidence is sufficiently consistent to establish an interim 0.5 Mg ha−1 yr−1 standard when considering C-credits, especially in decisions on whether to include alders to mitigate rising CO2.

Forests doi: 10.3390/f17111300

Authors: Yanan Zheng Jue Wang Peixuan Liu Alia Ambreen Yu Shen

This research aimed to investigate the oviposition preference of Monochamus saltuarius for different host trees and to determine whether it is capable of completing its life cycle in Larix kaempferi and Larix gmelinii subsp. olgensis. Male and female adults were placed in insect cages with the logs of Pinus tabuliformis, P. koraiensis, L. kaempferi, and L. gmelinii subsp. olgensis positioned in the four corners to determine the female beetles’ oviposition preference and the development of their offspring on the different host tree logs. First-instar larvae were also collected and introduced into logs of L. kaempferi and L. gmelinii subsp. olgensis to observe and measure their development. In addition, the phloem thickness, sapwood thickness, heartwood thickness, xylem density, and moisture content of these four host tree species were measured. The results showed that M. saltuarius larvae can develop into adults on L. kaempferi and L. gmelinii subsp. olgensis, but the lifespan and fecundity of adult M. saltuarius were lower than those observed for P. tabuliformis. In the choice test, females preferred P. tabuliformis to oviposit (75.44%), followed by P. koraiensis (12.86%), which showed less preference for L. kaempferi (5.99%) or L. gmelinii subsp. olgensis (5.71%). Phloem thickness and xylem density were significantly greater in the logs of L. kaempferi and L. gmelinii subsp. olgensis than in those of P. tabuliformis and P. koraiensis. M. saltuarius may feed on Larix species when food sources are scarce in forests. However, the likelihood of the beetle feeding on Larix species may decrease in the presence of favorable host species.

Forests doi: 10.3390/f17111299

Authors: Piotr Mędrzycki Artur Obidziński Tomasz Hałatkiewicz Anna Świercz Dorota Panufnik-Mędrzycka Małgorzata Jankowska-Błaszczuk

Thermophilous oak forests are among the most species-rich forest ecosystems of central Europe and a relic of its traditional biocultural landscape. In the absence of grazing, they turned gradually into shaded, mesophilous oak-hornbeam forests. We tested three restoration treatments—annual shrub removal, supervised sheep grazing, and their combination—against a thinned-only control, on twelve 20 × 20 m plots in a Potentillo albae-Quercetum stand in S Poland, surveyed on 50 randomly placed 1 m2 subplots per plot in 2016 and again in 2019. Herb layer composition changed significantly in every variant, including the control. The variance explained by the survey year rose from 2.2% under thinning alone to 5.8% under removal with grazing. At the plot level, the herb layer became more light-demanding and less nutrient- and moisture-demanding, and the frequency of disturbance-tolerant species rose. Differences between the four variants were not statistically resolvable with three replicates each. Both grazed variants converged on the target community markedly more strongly than shrub removal alone and an order of magnitude more than the control, with grazing the component associated with the largest change. The characteristic species gained frequency, indicating that the treatments released formerly suppressed resident herbs rather than recruiting new colonists.

Forests doi: 10.3390/f17111298

Authors: Linyan Qin Hongge Zhu

Promoting the development of non-timber forest products (NTFPs) is of great significance for reconciling the trade-off between environmental protection and economic growth. Given its distinctiveness as a management paradigm capable of sustainably providing ecosystem services, sustainable forest management (SFM) may play a pivotal role in promoting the development of NTFPs and related industries. To investigate the impact and underlying mechanisms of SFM on NTFP development, this study employs a two-way fixed effects panel model, utilizing panel data from 31 provinces, municipalities, and autonomous regions in China over the period 2013–2022. The findings are threefold. (1) The baseline regression results indicate that SFM indeed promotes the growth of NTFPs, remaining robust across a series of robustness checks. (2) Regarding the underlying mechanisms, SFM can effectively reduce the risk of pest and disease outbreaks by enhancing forest ecological resilience, thereby increasing the total output value of NTFPs. Additionally, SFM can boost the total output value of NTFPs by increasing fiscal investment in forestry, thereby accelerating infrastructure improvement in forest regions. (3) Heterogeneity analysis reveals that the positive effect of SFM exhibits regional heterogeneity, being more pronounced in regions with lower forest resource endowments and in non-southern collective forest regions. The findings of this study offer novel insights into promoting the growth of NTFPs, provide empirical evidence for the role of SFM in fostering this sector, and offer policy guidance for governments to formulate regionally differentiated policies.

Forests doi: 10.3390/f17111297

Authors: Guanrong Huang Yuan Yuan Yanqun Liu Min Wang Lifang Li Shuxiao Peng

Atmospheric drought, defined here as days on which vapor pressure deficit (VPD) exceeds its 90th percentile, is usually studied in water-limited regions yet threatens vegetation where water is abundant. Using solar-induced chlorophyll fluorescence (SIF) from the contiguous SIF (CSIF) dataset, MODIS gross primary productivity (GPP), and meteorology in the Nanling Mountains, China, we quantify the dominant climatic signal and vegetation response. Extreme hot days showed no trend, whereas extreme drought days rose nearly tenfold, from 10.6 to 101.8 d yr−1, partly reflecting a 2002–2003 humidity step; both VPD tails widened. Hydrological drought (via the standardized precipitation evapotranspiration index, SPEI-3) showed no regional trend, and the two trend fields were uncorrelated. A counterfactual reconstruction validated the record; humidity alone contributed +1.06 d yr−1 (46% of the rise), temperature alone +0.12 (not significant), and the remainder reflects their joint covariation. Path analysis showed associations consistent with drought suppressing GPP mainly via SIF (indirect effect −0.174; direct effect not significant). Canopy greenness (near-infrared reflectance of vegetation, NIRv) was unresponsive in dry months, topsoil moisture showed no trend, and MODIS GPP moved in the opposite direction to CSIF in dry months (+2.42% versus −2.33%); both declined in the 2022 flash drought, CSIF five times more (−9.6% versus −1.9%).

Forests doi: 10.3390/f17111296

Authors: Yong Zeng Lizhi Liu Ruiheng Lyu

Accurate regional mapping of Populus euphratica remains challenging because of its spectral similarity to co-occurring riparian vegetation and the limited availability of species-level reference data across geographic regions. To address these challenges, we developed a three-season Temporal Transformer that integrates Sentinel-2 spectral bands and vegetation indices from spring, summer, and autumn. In the lower Tarim River source region, the model achieved an overall accuracy (OA) of 92.06% and a Macro-F1 score of 92.25% under stratified random pixel-based evaluation. Under spatial-block evaluation, the model achieved an overall accuracy of 87.16%±0.60% and a Macro-F1 score of 86.39%±0.74% across three training runs. Ablation experiments further demonstrated that combining all three seasons with the complete set of spectral bands and vegetation indices yielded the highest mean classification performance among the evaluated configurations. The source-trained model was subsequently applied to Sentinel-2 imagery over Kuqa City without retraining or fine-tuning, identifying 1173.76 km2 (8.79% of the valid mapping area) as candidate P. euphratica areas. Of the predicted candidate area, 68.36% fell within the high-confidence category, with a mean normalized entropy of 0.213. These findings highlight the value of multi-season spectral–phenological integration for source-region species classification and demonstrate its potential for uncertainty-aware candidate mapping and field-survey prioritization in regions with limited reference data.

Forests doi: 10.3390/f17111295

Authors: Zihan Guo Weijun Gao Yiqing Yu Yiying Zhu Lingxiao Guo Bart Dewancker

High-density built environments raise concerns for mental health, yet most studies rely on macro-scale indicators and overlook the street-level visual environment that pedestrians experience. In dense campuses, depression among young adults is persistently high, but how micro-scale visual features shape perceived depressiveness through nonlinear pathways remains unclear. This study develops a spatially explicit perception–environment framework to examine these effects. Taking Longzihu University Town in Zhengzhou, China, as the study area, we combined large-scale street view imagery (SVI) with multi-source geospatial data: visual features were extracted by DeepLabV3+ semantic segmentation, and a Perceived Depressiveness Index (PDI) was derived from a pre-trained deep-perception model as the dependent variable. Sky View Factor (SVF) and Green View Index (GVI) were the dominant predictors. SVF followed a three-stage gradient in which perceived depressiveness declined continuously as sky openness increased, and GVI a non-monotonic pattern that was protective at low-to-moderate exposure and turned mildly adverse beyond a sign-change threshold of about 26%. Conditional interactions among GVI, SVF, Enclosure Index (ECL), road proportion, and sidewalk proportion revealed further threshold effects and diminishing returns. Perceived wellbeing is thus jointly shaped by micro-scale visual perception and macro-scale context, yielding quantitative thresholds to guide health-oriented campus greening and spatial planning. Methodologically, this study couples an interpretable XGBoost–SHAP framework with bootstrap-based threshold estimation and spatial validation to recover nonlinear thresholds and cross-feature interactions that linear or single-scale models cannot detect; empirically, sky openness (SVF) emerges as the dominant, direction-stable driver. Throughout, PDI denotes the perceived depressiveness of the street scene—an image-based environmental indicator—rather than clinically measured depression of individuals.

Forests doi: 10.3390/f17111294

Authors: Heejae Lee Hyunjin Lee Sol-E Choi Eun-Sook Kim Chan-Ryul Park

Forest type maps require periodic revision, yet field inspection of every stand is impractical. This study tested whether stand-level disagreement between a Sentinel-2 U-Net classifier and the Republic of Korea’s forest type map could support screening for revision. A seven-class U-Net was trained using seasonal Sentinel-2 composites from 2025, and pixel predictions were aggregated to forest stands. Disagreeing stands passing dominance and confidence thresholds were flagged and assessed by blinded interpreters using high-resolution basemaps supplemented by Sentinel-2 composites. Stand-level agreement with the map was 0.69 by stand count and 0.76 when area-weighted. In the primary analysis, high-precision-class flags were mismatched in 41.3% of interpreted stands (29.7% when population-weighted), compared with 7.7% of controls. Test-set class precision, the pre-specified prioritization criterion, did not distinguish more reliable flags in this analysis. An exploratory partition by flag type yielded weighted rates of corresponding mismatches of 80.9% for stocking-status flags and 26.0% for species-dominance flags, representing 12.3- and 2.4-fold enrichment over their respective region-wide baselines. Approximately 35% of flagged stands were estimated to be mismatches, and the flags captured approximately 7.5% of estimated mismatches. These findings support model–map disagreement as a potential tool for prioritizing stand verification in the study region.

Forests doi: 10.3390/f17111293

Authors: Štěpán Beránek Martin Brabec Charalampos Lykidis Jakub Dömény

Due to the limited availability of durable tropical timber species, the development and production of chemically modified wood materials are expanding. Past research has investigated chemical reactions between the hydroxyl groups of wood and carboxylic acid anhydrides. Tropical species exhibit excellent durability, mechanical properties, and low water absorption, making it difficult for domestic species to compete with them. Therefore, this study employed a combination of chemical modification processes (acetylation and propionylation) and densification on two of the most widespread domestic species: European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) H. Karst). The modified samples were compared in terms of water-related properties, specifically sorption and dimensional stability. Both chemical modification methods, when combined with densification, positively influenced the monitored sorption and dimensional characteristics compared to non-densified samples. Unlike the reference samples, the modified domestic species exhibited water-related properties and dimensional stability comparable to the selected exotic species, Jatoba (Hymenaea courbaril). While Jatoba samples generally showed higher density values, densified propionylated beech and reference spruce were statistically comparable, and densified reference beech actually surpassed the density values significantly.

Forests doi: 10.3390/f17111291

Authors: De-Juan Xie Gui-Lin Chen Chun-Jing Wang De-Chao Chen Li He Lei Wang De-Xiang Wang

Forest management regimes are associated with broad-scale variation in relationships among habitat conditions, plant diversity, and biomass carbon stocks, but these relationships remain difficult to compare across management regimes because global datasets differ in resolution, date, and method of construction. We integrated 73,767 forest management locations with raster products for vascular plant richness, terrestrial habitat availability, and biomass carbon density using five forest management categories identified in five analytical fields: F11, F31, F32, F40, and F53. Habitat availability was defined as the fractional coverage or availability of terrestrial habitat types derived from the habitat classification of the International Union for Conservation of Nature, rather than a direct measure of soil fertility, moisture, or site-level microhabitat quality. Habitat availability was weakly associated with ln-transformed plant species richness overall (Pearson r = 0.072, p < 0.001) and moderately associated with ln carbon density (r = 0.427, p < 0.001), whereas ln species richness and ln carbon density were weakly to moderately associated (r = 0.228, p < 0.001). Management-specific correlations differed in strength and direction; the habitat availability–richness relationship was strongest in F32 (r = 0.318, p < 0.001), while the habitat availability–carbon relationship was strongest in F11 (r = 0.320, p < 0.001). Overall, the results support management-dependent, weak-to-moderate global associations rather than causal management effects or site-level thresholds.

Forests doi: 10.3390/f17111292

Authors: Jia Ye Jilin Yan Linfei Chen Yijun Bai Hui Zhang Na Zhang Yu Zhao Ying Liu

This study examined four forest stands (Pseudotsuga gaussenii Flous, Quercus glauca Thunb., Pinus taiwanensis Hayata and Rhododendron simiarum Hance forests) in the Huaiyu Mountain Range at the Jiangxi–Zhejiang border in China and systematically compared their litter stocks, water-holding characteristics, soil hydro-physical properties, and infiltration characteristics through field investigation, the cutting-ring method, and the indoor soaking method. The results were as follows: (1) The total litter stock ranged from 4.64 to 8.35 t·ha−1, being highest in the R. simiarum forest and lowest in the Q. glauca forest. (2) The litter maximum water-holding capacity (2.92–5.92 t·ha−1) and effective water-retention capacity (1.56–3.30 t·ha−1) differed significantly among stands (p < 0.05), with the P. gaussenii forest performing well and the P. taiwanensis forest performing the worst. (3) In the 0–30 cm soil layer, bulk density increased with depth, while total porosity and water-holding capacity decreased significantly (p < 0.05), and the infiltration rate showed a power-function relationship with time (R2 > 0.95); among the four forest types, the R. simiarum forest exhibited the highest maximum and capillary soil water-holding capacities, the Q. glauca forest had the strongest infiltration and runoff-interception capacity, and the P. taiwanensis forest had the weakest overall soil hydrological performance. (4) Semi-decomposed litter had a significantly higher maximum water-holding capacity than undecomposed litter, and litter water-holding capacity and water absorption rate showed logarithmic and power-function relationships with soaking time, respectively (both R2 > 0.90). A comprehensive evaluation using the entropy weight method identified the P. gaussenii and Q. glauca forests as the superior stand types. These results provide scientific guidance for tree species selection in forest transformation and for sustainable forest management in this region.

Forests doi: 10.3390/f17111290

Authors: Jihwi Jang Yongkyu Lee Byung-Jun Ko Sang-Tae Lee

This research aimed to provide fundamental growth data to support efficient afforestation and forest management, analysing the early growth of Korean red pine (Pinus densiflora Siebold & Zucc.) and Japanese larch (Larix kaempferi (Lamb.) Carr.) at varying planting densities in Korean slope plantation forests (30%–35% slope). Therefore, P. densiflora and L. kaempferi (both 2-year-old (1 + 1) seedlings) were planted in the Gwangneung Experimental Forest, Korea in April 2020, according to three different densities (i.e., P. densiflora: 2500, 3000 and 5000 trees ha−1; L. kaempferi: 2000, 2500 and 3000 trees ha−1). The highest net diameter at breast height (DBH) growth and DBH class (8 cm) of P. densiflora were observed at 2500 and 3000 trees ha−1 groups, while the highest net DBH growth and DBH class (>5 cm) of L. kaempferi trees were observed at 2000 trees ha−1 group. Meanwhile, the planting density of 3000 trees ha−1 did not affect the reduction in the net growth of DBH and stem volume in P. densiflora. Conversely, the net growth of stem volume in L. kaempferi was the lowest in the 2500 trees ha−1 group rather than the 3000 trees ha−1 group. This study indicates that the lowest or highest density does not always equate to the highest or lowest stem volume obtainment and provides useful information for initial setup and optimal density when planting two different species, P. densiflora and L. kaempferi afforestation. Results can be utilized to support the planning of post-reforestation management.

Forests doi: 10.3390/f17111289

Authors: Lingyun Tong Huiyu Zhong Ruoshi Zhang Fanguo Zeng Lei Wang

While the cross-sectoral development of forest wellness has given rise to studies on individual physiological–psychological benefits and rural development, the evolution of its policy goals and instruments remains largely unexplored. This paper examines how forest wellness policy goals and instruments have evolved in China, and how changes in instrument configurations have corresponded with emerging policy goals, by adopting a longitudinal perspective and an integrated goal–instrument analytical framework. A dual-stream thematic analysis was conducted, combining manual qualitative thematic analysis and Structural Topic Modeling, using available excerpts from 74 identifiable national-level policy documents related to China’s forest wellness sector over approximately three decades. The findings reveal a three-stage evolutionary trajectory of policy goals and policy instruments. The analysis also identifies three manifestations of potential institutional friction: goal–instrument misalignment, instrument structural bias, and cross-sectoral coordination problems. Empirically, this study provides a longitudinal account of forest wellness policy development. Theoretically, it offers an institutional understanding of uneven goal–instrument evolution and contextualizes the Policy Instrument Theory by identifying sector-specific instruments across environment-side, supply-side, and demand-side dimensions to inform their operationalization in future research. Policy designers are advised to further improve goal–instrument alignment, rebalance the policy instrument configurations, and institutionalize cross-sectoral coordination mechanisms in a more sustainable manner.

Forests doi: 10.3390/f17111288

Authors: Jeongwan Lee Jinmun Hwang Sungyong Kim Hyunseok Lee

Thermal stress induces physiological changes in forest tree seedlings, and multispectral imaging offers a non-destructive approach for monitoring associated changes in spectral reflectance. This study evaluated the responses of Pinus densiflora seedlings to sustained high-temperature stress and short-term extreme thermal exposure using multispectral vegetation indices, photosynthetic pigments, and soil environmental measurements. Seedlings were subjected to four thermal treatments: 38 °C at 60% relative humidity (RH), 38 °C at 40% RH, 45 °C at 60% RH, and short-term exposure to 90 °C. Spectral responses were assessed using NDVI, GNDVI, NDRE, and CIRE. Temporal changes in vegetation indices and soil variables were evaluated using linear mixed-effects models, while pigment contents were analyzed using linear models. NDVI and GNDVI generally declined under sustained heat exposure, whereas NDRE remained comparatively stable and CIRE exhibited treatment-dependent responses. Photosynthetic pigment contents also varied among treatments, with total chlorophyll increasing under 38 °C at 60% RH but decreasing under 38 °C at 40% RH, while carotenoid contents increased under both conditions. Soil temperature and moisture changed significantly over time under all treatments (all p<0.001). Soil moisture reached a recorded value of 0% under both sustained 38 °C treatments, whereas relative reductions of 88.7% and 37.0% were observed under the 45 °C and short-term 90 °C treatments, respectively. Time-adjusted association analyses identified only one statistically significant relationship after false discovery rate correction, between GNDVI and soil temperature under 38 °C at 40% RH (FDR-adjusted p = 0.0499). Nevertheless, the observed temporal changes in vegetation indices indicate that multispectral imaging can capture spectral responses of seedlings to thermal stress, although the associations between vegetation indices and physiological or environmental variables were limited.

Forests doi: 10.3390/f17111287

Authors: Mei Wang Bin Liu Xianbin Liu Ju Yuan Ruibin Wang Xiaomeng Yang

Soil microbial biomass and labile organic carbon (LOC) are pivotal regulators of carbon and nutrient cycling in forest ecosystems. However, the interactive effects of plant roots and forest litter on the seasonal dynamics of soil microbial biomass and LOC still remain poorly quantified, particularly in nutrient-poor subtropical forest ecosystems under monsoon climates. We performed a three-year (2022–2025) factorial experiment in a montane subtropical moist evergreen broad-leaved forest in central Yunnan, southwestern China. We manipulated plant roots (present vs. removed) and forest litter (present vs. removed) in a fully crossed design within the control and fertilized plots, and measured soil moisture, microbial biomass carbon (MBC) and nitrogen (MBN), MBC/MBN ratio, and LOC and its turnover time at monthly intervals. The study results showed that litter presence exerted a stronger positive influence on soil MBC, MBN, and LOC than root presence. The combined presence of roots and litter (i.e., R+L+) produced the highest soil microbial biomass and LOC, indicating an interactive root-litter effect. Fertilization significantly elevated soil moisture, MBC, MBN, and LOC across all experimental treatments, and shortened turnover time of soil LOC. However, fertilization did not significantly alter the monthly dynamics of any measured variable. Soil MBC/MBN ratio exhibited greater temporal variability in R−L+ treatment than the other three treatments, highlighting the important role of forest litter in structuring the composition of soil microbial community. These results reveal a “quantity-rhythm decoupling” in soil microbial responses to nutrient enrichment: fertilization regulates the magnitude of microbial biomass and LOC but not alters their seasonal periodicity. The seasonal rhythm of soil microbial biomass and LOC appears governed by plant phenology and monsoon-driven hydrothermal cycles. Our findings provide mechanistic insights into plant-microbe intense competition for nutrients in nutrient-poor subtropical forests and have positive implications for modeling soil carbon and nutrient dynamics under global climate change.

Forests doi: 10.3390/f17111286

Authors: Andrés Flores Tomás Pineda Ojeda Enrique Buendía Rodríguez Jonathan Hernández Ramos Carlos Román Castillo Martínez Jesús Antonio Buenaventura Francisco

Seed germination is a key factor in the success of forest regeneration and nursery production; however, its performance depends on the interactions among seed physiology, pre-germination treatments, and environmental conditions. We evaluated how eight pre-germination treatments and two contrasting environments affected germination capacity, vigor, and kinetics in seed lots (provenances) of Pinus hartwegii, P. montezumae, and P. pseudostrobus. The seeds were subjected to hydration, H2O2, mechanical scarification, or GA3 treatments and were germinated in a controlled chamber and a greenhouse; the responses were analyzed using generalized linear mixed models. Species × environment interactions were significant for all germination parameters. Final germination was higher in the greenhouse than in the chamber (81% vs. 72%), while germination was faster in the chamber. P. pseudostrobus achieved the highest germination rate (96%), P. montezumae showed the greatest stability across environments, and P. hartwegii exhibited a relatively stable final germination capacity across environments but greater kinetic sensitivity. Among the treatments evaluated, 2% H2O2 and 200 mg L−1 GA3 showed the most favorable balance between germination capacity and rate, while scarification accelerated germination but reduced its final percentage.

Forests doi: 10.3390/f17111285

Authors: Shihao Zhang Kangning Xiong Xiaoying Min Xuewei Ma Youze Ning Lei Fang

Vegetation restoration following cropland abandonment is commonly accompanied by soil organic carbon accumulation. However, the relationships among rural depopulation, land-use transition, ecological restoration, and regional soil carbon dynamics remain insufficiently quantified. Focusing on the South China Karst, this study integrated long-term remote-sensing data, the Revised Universal Soil Loss Equation, structural equation modelling, and random forest analysis to evaluate the statistical relationships and predictive importance linking rural depopulation, cropland abandonment, vegetation restoration, and surface processes to changes in soil organic carbon storage (SOCS) in the upper 0–20 cm of soil. During the study period, the rural population share declined from 82.89% to 48.91%, while cumulative net cropland abandonment during 1991–2019 reached 4.45 × 104 km2. Over the same period, forest aboveground biomass and tree cover on abandoned cropland increased at rates of 1.79 Mg ha−1 yr−1 and 1.27% yr−1, respectively. Structural equation modelling showed that rural depopulation and the abandonment of sloping cropland were associated with vegetation restoration. Vegetation restoration was, in turn, associated with reduced soil erosion, changes in soil sand content, and increased net primary productivity (NPP), which were further associated with increased SOCS. Random forest analysis identified NPP and tree cover as the principal predictors of SOCS change, with the strongest responses occurring on moderate and steep slopes above 15°. These findings indicate that rural depopulation and the accompanying withdrawal of marginal sloping cropland and vegetation restoration were closely associated with increased SOCS on karst slopes, providing statistical evidence for understanding regional soil carbon dynamics in the context of rural demographic transition.

Forests doi: 10.3390/f17111284

Authors: Huichao Zheng Xingyu Wang Kaihang Xu Shuzhan Fan Yuhong Tian

The health benefits of park green spaces are widely recognized, yet how multidimensional nature contact (nature contact frequency, nature contact duration, nature contact quality) is associated with these benefits through nature connectedness remains unclear. Based on 1049 valid questionnaires from comprehensive and community parks in Haikou and Taiyuan, we constructed a quality evaluation system and used structural equation modeling with Bootstrap mediation tests. Results show that nature contact quality has significant spatial and typological differences. Taiyuan scored higher than Haikou, and comprehensive parks performed significantly better than community parks, with the latter facing the bigger supply–demand gap. Nature contact frequency was positively associated with health benefits, with nature connectedness playing a partial mediation effect (39.3% of total). Nature contact quality showed a direct positive association, while nature contact duration shows no significant effect. Multi-group analysis reveals different pathways: In Haikou, both nature contact frequency and quality showed significant indirect associations with health benefits through nature connectedness, whereas in Taiyuan, both nature contact duration and frequency show significant indirect effects through nature connectedness, with the duration pathway being negative. Within the comprehensive park group, the pathway from nature contact frequency to nature connectedness to health benefits was significant. Within the community park group, direct associations involving nature contact quality and nature connectedness with health benefits were observed. Childhood living environment and physical activity types were also associated with variation in these pathways. These findings indicate that nature contact frequency and quality were positively associated with perceived health benefits. To enhance health benefits, differentiated strategies should be adopted based on city contexts, park types, and population characteristics.

Forests doi: 10.3390/f17111283

Authors: Gianmarco Goycochea Casas Zool Hilmi Ismail Abdulaziz Seraj Alnori Silas Tadin Sardinha Pedro Henrique Fontes dos Santos Gilciano Saraiva Nogueira Helio Garcia Leite

Ground robots are proposed for inventory in commercial eucalypt plantations, where inter-row corridors leave a platform about one metre of lateral room for error. This study asked, entirely in simulation with parameters plausible rather than calibrated to a platform or stand, when controller tuning changes the outcome. Three tuning algorithms (finite-difference descent, Bayesian optimisation and covariance matrix adaptation evolution strategy) and two robust controllers (sliding-mode and active disturbance rejection) were compared across two commercial spacings and a factorial ablation of state estimation and terrain disturbance. In 1440 simulated missions, the success rate was 0.999. Intermittent satellite positioning consumed 18% of the lateral error budget and underlay every stem contact, whereas terrain disturbance cost 18% of traversal time and 2% of the budget; a filter matched to the plant left this unchanged. Tuning the algorithm and control law moved clearance by at most 2% of the budget. Over 64,512 missions under amplified disturbance, breakdown was predicted by integral action rather than the stability margin, and an anti-windup clamp showed this effect to be mostly integrator windup. Within this model, safety is bounded by localisation rather than the control loop; the magnitudes depend on the simulated parameters and are hypotheses for field testing.

Forests doi: 10.3390/f17111282

Authors: Juanjuan Cao Ting Zhou Tianchen Peng Rongxue Zhang Ziwei Zhao

Forest ecological products (FEPs) embody both marketable outputs and critical ecosystem services, yet how their value realization coordinates with regional high-quality development (RHQD) remains insufficiently documented at the provincial level. This study constructs a forest-specific measurement framework that distinguishes the FEP value level from FEP value-realization efficiency, synthesizes them into a comprehensive FEP index, and couples it with an RHQD index for 30 Chinese provinces over 2014–2024. Coupling-coordination degree models, Dagum Gini decomposition, kernel density estimation, spatial autocorrelation and σ/β-convergence tests are applied as descriptive tools. The results show that: (1) the national coupling-coordination degree rose from 0.528 (2014) to 0.637 (2024), entering the primary-coordination stage, with a Central > East > West gradient formed by 2024; (2) global spatial clustering is significantly positive throughout (Moran’s I ranging from 0.396 to 0.546), with high–high agglomeration contracting from seven southern provinces in 2014 to four in 2024; (3) inter-regional disparities contribute about 64% of total inequality, and national polarization has gradually mitigated; and (4) absolute and conditional β-convergence are both significant, whereas σ-convergence is absent, indicating conditional catch-up without an absolute narrowing of gaps. As a pattern-oriented descriptive analysis rather than a causal identification, this study provides verifiable forest-oriented evidence for region-differentiated forest economy policies in China.

Forests doi: 10.3390/f17111281

Authors: Hung-Kai Chen Tzu-I Tseng Jia-Kun Chen Po-Hsiung Lin

In tree risk assessment, visual tree assessment (VTA) commonly involves tapping the trunk or branches to detect abnormal sounds as a basis for further assessment. However, interpreting tapping sounds typically requires extensive professional experience and may be subject to subjective judgment. Therefore, research on the classification of tapping sounds may provide valuable supplementary information for assessing local decay in trees. Tapping sounds from a tree trunk can provide cues to the local internal condition, but their classification performance must be evaluated on trees not seen during training. This study examined 30 sweetgum (Liquidambar formosana) trees at a private nursery on the outskirts of Taipei, using mallet taps recorded with a smartphone, with reference labels established by directly sawing open the trunk cross-section after sampling. Each tap point was assigned to one of three original labels—healthy (L0), mildly decayed (L1), and decayed (L2); the binary classification merged L1 and L2 into an “affected” class for comparison with the healthy class (L0), covering all 966 recordings (449 healthy, 517 affected) without excluding any measurement position. The model comparison included a support vector machine, a random forest, and extreme gradient boosting using a 611-dimensional acoustic feature vector, together with a convolutional neural network (CNN) using log-mel spectrograms, with a deeper classification head and feature fusion serving as robustness checks; all per-fold epoch budgets and decision thresholds were chosen by nested cross-validation (tree-grouped inner validation within each outer training fold), and evaluation used five-fold cross-validation grouped by tree. The four main models performed comparably, with five-fold-averaged macro-F1 between 0.6288 and 0.6548 (highest for XGBoost, lowest for the CNN) and ROC-AUC up to about 0.73; no model was decisively superior, and the deep CNN did not outperform the conventional feature-based classifiers, while neither a deeper head nor feature fusion produced a stable improvement. The fold-to-fold variation of every model exceeded its seed-to-seed variation, and all models were lowest on the same fold, indicating cross-tree generalization as the primary source of variation. Although the pooled area under the curve on the 24 mixed-label trees was comparable to that on the full dataset, the median within-tree ROC-AUC (for the RF model) was only 0.511, close to chance, indicating that the pooled metric mainly reflects between-tree differences rather than within-tree discrimination of local decay; the approach therefore cannot reliably localize decay within an individual tree. An exploratory threshold analysis showed that, because the affected class is the majority and the default threshold is already near-optimal, threshold tuning offers limited benefit. Overall, the results provide preliminary support for the feasibility of using tree-trunk tapping sounds as auxiliary information for population-level decay screening; the approach cannot yet identify decayed locations within a single tree, and validation using additional independent trees and external sites is still needed.

Forests doi: 10.3390/f17111280

Authors: Jing Wang Caiyao Xu Jun Zhai Can Tang Fanbin Kong

The value realization of forest ecological products in mountain areas represents a critical pathway for China to reconcile ecological protection with rural prosperity. This study develops a conceptual framework integrating new economic geography, information economics, transaction cost theory, and Schumpeterian innovation theory to examine the potential complementarities between the Four Good Rural Roads initiative and digital village construction, their underlying mechanisms, and relevant boundary conditions. The analysis proposes that: (1) transportation accessibility and digital connectivity may facilitate forest ecological product value realization through distinct but complementary mechanisms by reducing spatial barriers, information asymmetries, and transaction costs; (2) their interactions may promote resource reallocation and business model innovation through the progressive analytical framework of “physical connectivity–digital value enhancement–ecological efficiency restructuring”, potentially improving value realization efficiency; and (3) potential transportation–digital policy synergies face institutional, spatial, governance, and market constraints, which may limit their effectiveness in improving value realization efficiency. Based on these theoretical insights, the study identifies four interrelated policy directions: improving physical and digital accessibility, supporting value discovery, strengthening institutional coordination, and promoting sustainable market formation and business model innovation. This study advances the theoretical understanding of transportation–digital policy complementarities in forest ecological product value realization and provides a basis for context-dependent policy implications in mountainous regions.

Forests doi: 10.3390/f17111279

Authors: Shanwen Ye Changyang Cai Dongliang Lin Wenkai Li Rong Zheng

Soil-covering and light-exclusion are vital silvicultural practices in bamboo-stand management for improving bamboo-shoot palatability, yet their underlying molecular regulatory mechanisms remain largely unclear. This study aimed to decipher how soil covering modulates flavor and texture in Dendrocalamus latiflorus shoots. Shoots under covered-soil (CSE) and uncovered-soil (USE) conditions were subjected to physicochemical determination of soluble sugar, cellulose, soluble protein and total amino acids, combined with transcriptome sequencing; eight key genes were further validated by RT-qPCR. CSE shoots exhibited significantly elevated soluble sugar and cellulose contents, significantly reduced soluble protein levels, and comparable total amino acid concentrations. In total, 5233 differentially expressed genes were detected. Transcriptomic profiling revealed down-regulation of key synthase genes for tannin and oxalate biosynthesis, implying reduced accumulation of these astringent compounds, alongside repressed lignin and hemicellulose modification pathways and activated cellulose-related soluble-sugar metabolism. Our results suggest that soil-covering and light-exclusion coordinately reprogram multiple metabolic pathways to enhance shoot quality, offering candidate genes and theoretical references for the cultivation of high-quality shoots in managed bamboo forests and flavor-oriented molecular breeding.

Forests doi: 10.3390/f17111278

Authors: Emelyne Ineza Kayisire Aureliu-Florin Hălălișan

Forest certification is promoted as a market-based mechanism for strengthening sustainable forest management; however, evidence on stakeholder-perceived benefits and challenges remains limited in Rwanda. In this study, we assessed stakeholder perceptions of certification, focusing on awareness, environmental, economic, and social benefits, implementation challenges, and differences among stakeholder groups. A descriptive survey design was used, with structured questionnaires administered between February and April 2026 to 20 local community members, 5 Rwanda Forestry Authority (RFA) officials, and 1 representative of an FSC-certified forest management company. Quantitative responses were analyzed using frequencies, percentages, means, and standard deviations, while responses to open-ended questions were descriptively interpreted according to recurring issues. Awareness was highest among institutional and organizational stakeholders; the certified company reported a mean awareness score of 5.00 and a mean perceived impact on forest management of 3.56, while RFA respondents reported a mean perceived benefit score of 5.00. Among community respondents, 75% were aware of forest certification. Communities associated certification with improved forest protection, employment, company–community relationships, infrastructure or services, and participation but reported weaker direct livelihood benefits. Major challenges were limited information sharing (80%) and perceived unfair benefit distribution (87%). Overall, the respondents’ perceptions suggest that forest certification has potential to support sustainable forest management in the Nyungwe buffer-zone context. However, its perceived effectiveness depends on improved community information, meaningful participation, equitable benefit sharing, and livelihood opportunities.

Forests doi: 10.3390/f17111277

Authors: Haoxian Qin Hongrui Liu Xinyue Wang Jianli Wang Qingqing Huang

As an underactuated, heavy-load attachment mounted at the end of an external crane boom, a forest harvester head exhibits coupled active motion and passive swing, making its attitude difficult to observe directly during operation. This study considers an underactuated harvester-head system with an undamped suspension link and proposes a hydraulic–inertial multi-source information fusion cubature Kalman filter (MCKF) for monitoring the head’s active attitude and passive swing. First, a multibody dynamics model of the harvester head, including friction terms, is established from the Lagrange equations. Second, a hydraulic observation model is constructed from the fluid-continuity equations to estimate the active joint variables from pressure and flow-rate measurements. On this basis, the resulting MCKF incorporates segmented geometric-constraint mapping to combine hydraulic and dual-IMU information, thereby providing an integrated observation of active attitude and passive swing. Tilt-up and rotation tests are then conducted with the chassis and external crane boom held stationary. For the tested sequences, the mean absolute errors were 1.03° for active tilt, 0.99° for body motion expressed in the base frame, 0.679° for passive swing, and 1.60° for active rotation; the corresponding maximum absolute errors were 2.07°, 2.22°, 1.469°, and 3.84°. The results show that the complete observer can track the active and passive motion components under the tested conditions and provide a methodological basis for subsequent harvesting-head attitude monitoring and control studies.

Forests doi: 10.3390/f17111276

Authors: Hichem Chenaker Akram Hezil Wafa Saleh Alkhuraiji Yahia Ouchene Mohamed Bellaa Rami Khoucha Youssef M. Youssef Heba Bedair

Wildfires can rapidly alter soil physicochemical and biological properties, but short-term paired field evidence from North African forests remains limited. We assessed changes in 14 soil indicators at ten forest sites in northeastern Algeria and interpreted these field observations within a regional GIS analysis of Mediterranean wildfire exposure. The same locations were sampled in March 2026, before the seasonal fire period, and revisited in August 2026. The measured variables comprised soil pH, electrical conductivity (EC), soil organic carbon (SOC), total nitrogen (TN), available phosphorus (P), C:N ratio, microbial biomass carbon (MBC), basal respiration, dehydrogenase activity (DHA), MBC:SOC ratio, gravimetric soil moisture, bulk density, water-stable aggregates, and surface litter biomass. Within-site changes were evaluated using exact paired Wilcoxon tests with Holm correction and paired-bootstrap confidence intervals. Across the ten sites, pH increased by 0.60 units, EC by 112.9%, and available P by 79.6%. In contrast, SOC, TN, MBC, basal respiration, soil moisture, water-stable aggregates, and litter biomass decreased by 26.7%, 36.8%, 49.4%, 44.2%, 40.5%, 37.1%, and 71.0%, respectively. Bulk density and C:N increased by 11.2% and 11.3%, while DHA increased by 29.8%. All 14 paired comparisons remained significant after Holm adjustment (adjusted p = 0.027). PCA accounted for 96.2% of the total variance and separated the March and August profiles. At the regional scale, the complementary EFFIS analysis identified 800,540 ha of mapped wildfire exposure through 6 August 2026, with substantial concentration in Spain, Algeria, France, Italy, and Portugal. Collectively, the paired observations indicate a post-fire-period shift characterized by an ash-associated increase in soluble ions and available phosphorus alongside losses of organic matter, microbial biomass, moisture, aggregate stability, and surface litter. Because contemporaneous unburned control plots and independent plot-level burn-severity measurements were unavailable, the observed changes cannot be attributed exclusively to wildfire and may also reflect seasonal environmental variation.

Forests doi: 10.3390/f17111275

Authors: Jasmyn Tognere Vinicius de Souza Oliveira Deivid Garbrecht Feltz Édlen dos Santos Bonelá Sara Dousseau-Arantes Edney Leandro da Vitória Enilton Nascimento de Santana Alcinei Mistico Azevedo Edilson Romais Schmildt

The coefficient of variation (CV) is widely used to evaluate experimental precision; however, generic classifications may fail to capture the variability in clonal eucalyptus seedlings. This study aimed to propose a reclassification of CV values for morphological traits of Eucalyptus sp. seedlings at the dispatch stage, considering different plot sizes (PS). Data from 8200 seedlings were analyzed across six commercial clones and 41 evaluations of 200 seedlings each. Traits evaluated included plant height, stem diameter, shoot, root, and total dry mass, leaf number, leaf area, and slenderness index. Using bootstrap simulation, CV values were estimated for PS ranging from 1 to 100 seedlings. The relationship between CV and PS was fitted using a power model to estimate updated CV values and reclassify them. CV classification limits decreased progressively as plot size increased from 1 to 10 seedlings. Rather than defining a single optimal plot size, the proposed framework provides dynamic, trait-specific CV benchmarks tailored to the chosen PS. The proposed reclassification was more sensitive and appropriate than traditional criteria. In conclusion, adopting trait-specific CV intervals combined with PS provides more consistent evaluations of experimental quality, contributing to technical standardization in forest nurseries and eucalyptus breeding programs.

Forests doi: 10.3390/f17111273

Authors: Anming Zhu Jingjing Du Rongxian Zhu Jieyu Wu Naping Shen Zhihua Peng Guguo Zhou Qi Gao Xin Wang Nan Huang Junyue Shan Yahui Zhang Wenji Yu Qiuqin Lin

Small-diameter bamboo is a promising raw material for high-performance composites used in outdoor construction. This study aimed to compare the raw-bamboo characteristics of Bambusa textilis (BT) and Bambusa emeiensis (BE), evaluate processing conditions for BT composites, and assess mold resistance and dimensional stability. BE provided a reference for raw-material characterization and a selected flexural comparison. The tested BT material had a denser vascular-bundle distribution and higher isolated-fiber tensile properties. At a target density of 1.35 g/cm3 and 10% phenol-formaldehyde (PF) loading, BT composites reached a flexural strength of 324 MPa, compared with 234 MPa for BE, a flexural modulus of 33 GPa, and a tensile strength of 358 MPa. Thickness swelling was 3.3% and water absorption approximately 16% after 18 days of room-temperature immersion. In a separate BT series at 1.20 g/cm3 and 20% PF, 21% nominal CMIT/MIT formulation retention prevented visible Botryodiplodia theobromae growth on both evaluated faces and Aspergillus niger growth on the front face; side-face A. niger coverage was 35% at day 28. These results support further development of high-strength BT composites with improved mold resistance.

Forests doi: 10.3390/f17111274

Authors: Muhammad Qasim Irfan Haidri Mollah Naimuzzaman Thanet Khomphet Nadir Ayrilmis Thirukkumar Subramani V. R. Mageshen Sivasankari Ruckmanganathan

Soil biogeochemistry differs between tropical and temperate zones and influences the dynamics of soil carbon, nutrients and water. Earth system models used to project future climate change are largely based on a temperate climate framework that does not adequately capture tropical soil processes. In comparison with many temperate soils where 2:1 phyllosilicate clays and nitrogen limitations are often major controls, highly weathered tropical soils (Oxisols and Ultisols) tend to be dominated by kaolinite and Fe/Al oxides. Short-range-order Fe and Al phases play a major role in the organic carbon stabilization, although crystalline iron oxides can also be the dominant stabilization mechanism, because of ligand exchange and nanopore protection. Additionally, these soils have high phosphorus (P) sorption capacity and are highly micro-heterogeneous, even in upland locations. Based on this narrative review, a new conceptual and mechanism-based Tropical Soil Multifunctionality Index (TSMI) is proposed. It integrates soil properties associated with carbon (C) persistence, delivery of P, buffering of hydrological processes and regulation of greenhouse gas fluxes, including N2O flux to the subsoil, and an explicit domain that clearly includes the long-term effects of anthropogenic legacies. The TSMI connects microscale processes such as nanopore protection, oxide-associated biofilms, fungal networks, and rhizosphere P mining with macroscale soil ecosystem functions, thereby supporting improved representation of tropical soils in models. The proposed index remains conceptual and requires regional validation and calibration. To improve the accuracy of climate and food system models and related policies, it is crucial to address scientific mismatches and epistemic inequalities.

Forests doi: 10.3390/f17111272

Authors: Cristiano Foderi Francesco Neri Fabio Fabiano Simone Calamai Andrea Laschi Marco Togni

Motor-manual tree felling by chainsaws remains a widespread but hazardous forestry practice. This operation consists of executing a directional notch followed by a felling cut that releases a hinge. The hinge geometry (defined by its height, width, and alignment relative to the directional notch) is a critical determinant of safe felling, controlling the direction and stability of the falling tree. Although hinge geometry is prescribed in felling guidelines on the basis of field experience, its effect on the mechanical response of the hinge has not been quantified. This study evaluates variations in hinge flexibility and bending stiffness using wooden square beams of European beech (Fagus sylvatica) and silver fir (Abies alba) in a rig reproducing the classical felling cuts, varying hinge geometry combinations. Two geometric parameters, back-cut height (S) and hinge width (C) were examined. Mechanical testing was performed using a universal testing machine, and load–deformation curves were smoothed with a Savitzky–Golay filter; the Critical Bending Angle and Yield Point were determined by using the 0.02° offset method and absorbed energy by Simpson integration. Results reveal different mechanical behavior between the two dimensions: hinge width primarily determines yield force, whereas back-cut height governs flexibility, showing a strong negative correlation with the critical bending angle. Significant species-specific differences were observed for both response variables. Hinge toughness, expressed as absorbed energy per unit hinge cross-section, was found to be independent of back-cut height and about 1.8 times higher in beech (0.39 kJ·m−2) than in fir (0.22 kJ·m−2).

Forests doi: 10.3390/f17111270

Authors: Chenqin Lian Zhiming Feng Víctor Fernández-García

Southwest Europe is experiencing an escalating wildfire crisis driven by climatic warming, with summer megafires generating severe socio-ecological hazards. To systematically quantify how the unprecedented wildfire event in the summer of 2026 deviated from long-term fire regimes, this study used MODIS Collection 6.1 active fire data and adopted fire occurrence frequency and Fire Radiative Power (FRP) as core metrics. Combining global Moran’s I, Getis-Ord Gi* hotspot statistics, median-centre and standard-deviational ellipse approaches, we compared the spatio-temporal patterns of historical wildfires (2003–2025) in Spain, Portugal, France and Italy with the extreme 2026 fire season. The key findings include: (1) There were notable differences in wildfires in Southwest Europe: Portugal and Spain are characterized by low-frequency and high-intensity fires, while Italy has frequent fires with low intensity. (2) The 2026 fire season was unprecedented in the past 20 years: by the end of July, Southwest Europe’s cumulative FRP reached 3.1 times the 23-year average, with Spain and France showing the most pronounced anomalies—4.3 and 5.7 times the average, respectively. (3) July constituted the catastrophic peak, where spatially clustered high-intensity fires converged over central Spain and southwestern France at the 99% confidence level. (4) The intensity of individual fires in Southwest Europe has continued to rise, indicating that the region is gradually shifting toward a fire regime dominated by extreme wildfires. The spatially and temporally specific analyses obtained in this study can provide a foundation and relevant reference for wildfire management and the formulation of related policies.

Forests doi: 10.3390/f17111271

Authors: Wen Ying Hongge Zhu Linyan Qin

Sustainable forest management in China has entered a stage of quality improvement, yet its ecological, economic and social objectives remain insufficiently coordinated. This study adopts a scoping review approach and follows the PRISMA-ScR guidelines to analyse 190 Chinese- and English-language publications from 2000 to 2026, comprising 118 primary empirical studies, 52 review articles, and 20 theoretical/policy analysis articles. The included literature indicates that the ecological dimension faces a spatial mismatch between global carbon sink benefits and local water costs, alongside structural and quality imbalances in planted forests, including high shares of pure forests, young and middle-aged stands, and productivity below potential. The economic dimension suffers from inadequate value transformation and compensation mechanisms, while the social dimension is characterised by weak community participation and institutional fragmentation. However, the social dimension is supported by only 16 core publications, and these findings should therefore be treated as preliminary, with conclusions involving social–ecological and social–economic relationships being less robust. Cross-dimensional synergies depend on compensation design, tenure security, alternative livelihoods, and the coordinated evolution of institutional, technological, and cross-scale governance. These relationships are conditional rather than fixed, and the reported frequency of a theme reflects research attention rather than its actual prevalence. The study recommends promoting cross-sectoral integration, introducing multi-criteria decision-making tools, building decision-support big data platforms, and implementing differentiated regional forest management.

Forests doi: 10.3390/f17111269

Authors: Jelena Nedeljković Daliborka Đukić Pavle Milošević Dragan Nonić Ivana Živojinović

Although heterogeneity among non-wood forest product (NWFP) collectors is well established, less is known about how collectors’ expected benefits from association can be translated into operational support profiles. This study aims to operationalize NWFP collectors’ expected benefits from association into support-priority groups and to assess whether these groups differ in collectors’ stated willingness to participate in establishing an association, with implications for planning institutional support in Serbia. Data were collected through a 2022 survey of 639 NWFP-collecting households, of which 465 households with complete service-item data and at least one named service formed the primary analytical sample. Ten services were grouped into three indices (administrative, information and education, and market and infrastructure) and classified using a complete 27-rule framework implemented through fuzzy inference. The framework generated low (14.8%), medium (54.4%), and high (30.8%) support-priority groups. The medium support-priority group was characterized by a mixed pattern of expected benefits, while the high support-priority group reflected stronger expectations across complementary support domains. Stated willingness to participate in establishing an association, which was not used to construct the classification, was reported by 68.2% of the low, 73.0% of the medium, and 90.7% of the high support-priority group. The overall association was statistically significant (χ2(2) = 19.03, p = 7.38 × 10−5; Cramer’s V = 0.21), with higher adjusted odds of stated willingness in the high group than in either other group, whereas the low–medium contrast was not statistically significant. In a sensitivity analysis (N = 615), assigning 150 households with no recorded service selections to Low under a zero-score assumption reduced willingness in that group to 25.6%. Fuzzy and crisp implementations classified all 80 possible input profiles identically; the rule-based groups were not more strongly associated with willingness than alternative classifications. These findings show how expected association benefits can be translated into interpretable model-generated groups that may serve as exploratory input for planning differentiated association-based institutional support in Serbia.

Forests doi: 10.3390/f17111268

Authors: Xin Shu Jiongkun He Yichao Zhang Erfan Akberjan Pingping Xu Zhipeng Zhao Shunyao Xu Dayong Han Wenge Zhang Xiaolong Shi Chao Yang Arken Arxidin

Fallen wood is widely recognized as an important micro-habitat that facilitates forest regeneration in certain forest environments, yet how its facilitative role varies across ontogenetic stages and what constraints govern its spatial effectiveness throughout the tree life cycle remain poorly understood. This study investigated the spatial associations between Picea schrenkiana (Fisch. & C.A.Mey.) populations and fallen wood across four ontogenetic stages in a 6-ha (6 hm2) permanent plot in the West Tianshan Mountains, China. Our results revealed that fallen wood serves as an irreplaceable regeneration substrate throughout the entire life history: 99.6% of seedlings were established on fallen wood, and this dependency remained remarkably high (>78%) even at the adult stage. Spatial point pattern analyses demonstrated stage-specific shifts in tree–fallen wood associations: strong positive correlations at the seedling stage, significant negative correlations at the sapling stage driven by light limitation, multiscale fluctuating associations at the sub-adult stage, and positive correlations at the adult stage—indicating a functional transition from micro-habitat sheltering to historical legacy. Furthermore, after accounting for environmental heterogeneity using heterogeneous Poisson process models, we identified an environmental action scale (EAS)—the critical spatial distance at which environmental filtering overrides the fallen-wood micro-habitat effect—which expanded systematically with ontogeny: from 3.94 m at the seedling stage to 4.3–8.61 m at the sapling stage and to approximately 16 m at both the sub-adult and adult stages, reflecting a cascading control mechanism in which local environmental filters and fallen wood micro-habitat interact across ontogenetic stages, driving enhanced physiological tolerance and crown expansion that increase the EAS and ultimately shape population spatial patterns. Notably, EAS exhibited a strict proportional scaling relationship with maximum crown diameter (R2 = 0.9839), revealing that population spatial structure is intrinsically constrained by species-specific morphological conservatism. These findings advance our understanding of fallen wood dynamics beyond early recruitment and provide a mechanistic framework for assessing regeneration resilience in montane coniferous forests under climate change.

Forests doi: 10.3390/f17111267

Authors: Siyuan Ren Yan Zhu

The mechanisms controlling plant growth are important to understand as they are key to forest carbon sequestration. Growth is species-specific and depends on mycorrhizal associations, resource availability, and neighbor competition. However, the difference in conspecific negative density dependence (CNDD) on growth between arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) species across life stages needs exploration. Using data from a 20 ha warm temperate deciduous broad-leaved forest in Donglingshan, China, we measured growth of established individuals. Using linear mixed-effects models, we assessed the combined effects of neighbor density, soil factors, and light availability on growth across life stages and mycorrhizal types. We observed reduced growth with increasing conspecific density, but effects varied between AM and EM species and between saplings and trees. Conspecific neighbor density had stronger negative effects on AM than EM saplings. For mature trees, conspecific density had weaker negative effects on AM species and no significant effect on EM species. Additionally, soil factors promoted AM sapling growth, while light promoted EM sapling growth. For trees, light promoted growth in both AM and EM species, whereas soil factors inhibited EM tree growth. Conspecific crowding, light and soil act jointly on growth, with CNDD strength set by mycorrhizal type and life stage.

Forests doi: 10.3390/f17111266

Authors: Yinfan Zhao Xuelong Yang Jun Zhang Haisheng Cai Han Zhang Xi Guo

Identifying ecosystem service (ES) trade-offs and synergies (ESTSs) and their effects provides a critical scientific basis for ecological management. However, the effects of ESTSs are not always direct. To compensate for the limited research on the multidimensional heterogeneity and mediating effects of ESTSs, Jiangxi Province was used as a case study for the analysis of spatiotemporal patterns and heterogeneity in ESTSs. Data from 1990–2020 were assessed from static and dynamic perspectives and from multiple dimensions. The direct and indirect effects of the normalized difference vegetation index (NDVI) and land use intensity (LUI) on ESTSs were also identified. We found that ESTSs were characterized by short-term fluctuations, dynamic changes, and long-term stability. Overall, ESTSs were stronger according to a static perspective than to a dynamic perspective and ESTSs were stronger at a small scale than at a large scale. Spatial heterogeneity in the relationships between and the degrees of ESTSs occurred across different multidimensional zones. The effects of the NDVI on ESTSs were significant, and the heterogeneity of these effects was significant across different dimensions. The influence coefficients were ranked as follows: functional control dimension > horizontal development circle dimension > vertical topographic position dimension. LUI can function as a vital mediator in the influence chain connecting the NDVI and ESTSs and manifests as a significant partial mediating effect. The goal of this study was to explore the empirical application of econometric statistical methods to the impact of ESTSs, thereby providing a foundation for targeted and differentiated ecological management policies and a reference for the governance of ESs in similar regions.

Forests doi: 10.3390/f17111265

Authors: Rong Yu Jingxia Chen Lixia Yue Qian Ma Alison Donnelly Tingting Mei Zihang Chen Linmin Liu Sushu Qiu Jiacheng Chen

Subtropical forests serve as globally significant carbon sinks, yet how climate–CO2 flux coupling pathways respond to hydroclimatic extremes across multiple timescales remains poorly understood. Conventional flux-based approaches can detect changes in CO2 flux magnitudes but may miss underlying shifts in the directed relationships between meteorological drivers and ecosystem CO2 exchange processes. Dynamic Process Network (DPN) analysis provides an information-theoretic approach for resolving how directional climate–CO2 flux coupling reorganizes across seasons and hydroclimatic conditions. We adapted the DPN approach into a high-resolution, daily-sliding framework to quantify the time-varying, directed information flow from air temperature (Ta) and precipitation (P) to gross primary productivity (GPP), ecosystem respiration (RE), and net ecosystem exchange (NEE) in a subtropical mixed coniferous-broadleaved forest at Dinghushan, southern China (2003–2010). By coupling the DPN with multi-timescale Standardized Precipitation Evapotranspiration Index (SPEI-30, -90, and -360), we diagnosed how climate–CO2 flux coupling pathways reorganize under drought, normal, and wet conditions across meteorological, ecological, and hydrological timescales. Three main patterns emerged. First, although CO2 fluxes remained apparently stable across most hydroclimatic states, the DPN analysis revealed pathway-specific shifts in directed climate–CO2 flux coupling, indicating that climate–CO2 flux coupling pathways can reorganize even when changes in flux magnitude remain limited. Second, temperature and precipitation exhibited strongly asymmetric coupling modes: temperature coupling persisted year-round, whereas precipitation coupling was largely confined to the wet season and remained much weaker. Within this seasonal structure, ecosystem respiration emerged as the principal flux component associated with seasonal variation in net CO2 uptake; the stronger dry-season net CO2 uptake (~64% of annual NEE) was driven mainly by reduced RE rather than enhanced GPP. Third, drought-associated responses varied across SPEI accumulation timescales: wet-season TE under drought was significantly lower than under normal conditions for five of six pathways at SPEI-30 and all six at SPEI-90. In contrast, wet conditions at SPEI-360 were associated with enhanced wet-season net CO2 uptake through concurrent GPP enhancement and RE suppression, with a significantly more negative NEE anomaly than under drought conditions (−0.674 vs. +0.118 gC m−2 d−1; p < 0.001). These findings demonstrate that information-theoretic diagnostics can detect changes in ecosystem climate sensitivity that remain invisible to conventional flux-magnitude analyses, offering a complementary diagnostic framework for assessing changes in ecosystem CO2 exchange sensitivity under intensifying hydroclimatic extremes.

Forests doi: 10.3390/f17111264

Authors: Joana Gonçalves Martins Paulo Neves Firmino Joana Amaral Paulo

Cork oak (Quercus suber L.) is a key Mediterranean species whose sustainable management depends on balancing cork production with tree vitality. Debarking intensity is regulated through the debarking coefficient (dcoef), which expresses debarking height relative to tree perimeter at breast height, but its long-term effects on tree growth, cork thickness, mortality and vitality remain insufficiently understood. This study evaluated the effects of increasing debarking intensity in a long-term experimental trial established in 2003 at Herdade da Contenda, southern Portugal, under dry Mediterranean conditions. Three dcoef trajectories were considered, corresponding to increasing debarking intensities relative to the legal limits established by Portuguese legislation. Cork oak trees were monitored between 2003 and 2023. Over this period, diameter growth, mature cork thickness in 2023, tree mortality and tree vitality indicators—including crown dieback symptoms and debarking-related wounds—were assessed. Full and restricted datasets were analysed to distinguish population-level responses from the response of trees that maintained the planned debarking trajectories. Linear mixed-effects models and Cochran–Armitage trend tests were used to evaluate the effects of increasing debarking intensity. Increasing debarking intensity was not associated with significant reductions in diameter growth, which was mainly correlated to tree diameter and total height variables. Some debarking intensity variables showed weak positive correlations with cork thickness. No significant differences in tree mortality were detected among the established trial dcoef trajectories. By 2023, mortality alone still did not show a significant increasing trend across debarking intensity trajectories. However, when mortality and reduced tree vitality were analysed jointly, a significant increasing trend was detected with increasing debarking intensity. The results obtained from both datasets showed no statistically significant reductions in diameter growth or cork thickness among trees that maintained the planned debarking trajectories. Nevertheless, increasing debarking intensity may increase the long-term risk of vitality loss through crown dieback symptoms and/or debarking-related wounds. These findings should be interpreted in light of the selection effect associated with the restricted dataset, as higher debarking intensities were maintained only in trees that remained sufficiently vigorous to sustain the planned trajectories. Consequently, the absence of detectable negative effects on growth or cork thickness in this subset may not reflect the response of the entire initial population. By combining full and restricted datasets with mortality and vitality assessments, this study provides a comprehensive evaluation of the long-term responses of young cork oak trees to increasing debarking intensity in dry Mediterranean conditions.

Forests doi: 10.3390/f17111263

Authors: Wai In Ho Yifen Yin Yuanyuan Yu Chunning Wang

Chinese provinces combat forest fires and pest outbreaks largely by issuing policy documents, yet whether document strength corresponds to lower disaster losses—and which instruments work—remains untested at the province level. We coded the full text of 4503 fire prevention and pest control policies (estimation window 1998–2024), scoring issuing authority, genre force, and instrument strength, and aggregated scores into province-year policy stocks by dominant type: coercive mandates, incentives, and capacity-building. Linking these stocks to forest-masked MODIS active fires and yearbook pest records in two-way fixed-effects models, we found no average association between overall strength and losses. The null masked sharp type differences: a one-standard-deviation increase in incentive strength was associated with about 7% fewer fire points, robust under wild cluster bootstrap inference and Monte Carlo simulation—although not after multiple-comparison correction across the pre-specified family; capacity-building showed weaker, inference-sensitive associations; and coercive mandates—equaling three quarters of the documents—showed none. Associations emerged with a one-year lag and tracked sustained accumulation rather than issuance. For pest losses, results were directionally consistent but weaker. After the forest chief system rollout in 2021, the overall association turned significantly negative. These results help explain why aggregate policy measures often miss policy effects.

Forests doi: 10.3390/f17111262

Authors: Yuhua Ma Yichen Fan Haotian Zhu Fasih Ullah Haider Cheng Huang Xiaowan Geng Zhen Wu Xing Sun

Forest enclosure is widely used for degraded forest restoration; however, microbial functional recovery across enclosure durations in subtropical deciduous secondary broadleaved forests remains poorly understood. This study evaluated microbial carbon metabolic recovery and associated environmental factors across a chronosequence of forests enclosed for 0–1, 5–6, 11–12, 20–24, and 28–34 years, with an old-growth forest as the reference. Forest enclosure significantly enhanced microbial carbon metabolic capacity and functional diversity. Average Well Color Development (AWCD) and Shannon, Simpson, and McIntosh indices increased with enclosure duration, with the lowest values in 0–1 year stands and the highest values in old-growth forests. Enclosure duration significantly altered carbon source utilization patterns, particularly amino acids and carboxylic acids, with carboxylic acids becoming the dominant utilized carbon source category after 5–6 years of enclosure. Furthermore, Bray–Curtis distance analysis revealed progressive convergence of microbial carbon-use profiles toward the old-growth reference state with increasing enclosure duration (Spearman’s ρ = −0.61, p = 0.0155). Soil carbon, nitrogen, moisture, bulk density, pH, and microbial diversity were significantly associated with these functional changes. These findings highlight microbial carbon-use profiles as effective indicators of soil functional recovery and provide insights for incorporating microbial traits into future forest restoration and management strategies.

Forests doi: 10.3390/f17111261

Authors: Deok-Ryong Kim Min-Ji Kim Ji-Hyeon Sung Dong-Gil Cho

Successful establishment of planted trees is critical for forest restoration, particularly when post-outplanting drought occurs. We evaluated associations of planting stock size, wood-chip mulch depth, and relative planting density with the soil microenvironment, survival, and growth of Quercus acutissima over 43 months in a single-site field experiment in southern South Korea. A total of 132 trees were planted in 36 plots, with one plot per treatment combination. Survival was analyzed using interval-censored proportional-hazards models, and growth was assessed among surviving trees using relative growth rates and absolute growth increments. Of 49 final mortality episodes, 43 were first recorded during the first growing season. Relative to R2, mortality hazards were higher for R6 (HR = 5.49, 95% CI: 1.26–23.88) and R8 (HR = 5.10, 95% CI: 1.05–24.86). Relative to no mulch, hazard estimates were lower for 5 cm (HR = 0.36, 95% CI: 0.08–1.60) and 10 cm mulch (HR = 0.19, 95% CI: 0.05–0.83), with clearer evidence for 10 cm. Mulching was also associated with reduced early soil-moisture variability. Relative planting density showed no detectable association with survival, but high relative density was associated with lower early soil moisture and reduced root collar diameter growth. These findings suggest that planting treatments should be considered in relation to site conditions.

Forests doi: 10.3390/f17111260

Authors: Chengzheng Zhao Lichao Fan Yixin Zheng Hailun Du Benhua Sun Hao Feng

Green manure cultivation is recognized as a viable measure for mitigating agro-environmental degradation. However, it remains unclear whether diversified cropping can further enhance the environmental benefits of green manure systems, which impedes the full exploitation of their ecological benefits for sustainable agriculture. Here, we conducted a three-year field experiment in mountainous apple orchards of China’s Loess Plateau, and employed a life cycle assessment to evaluate the effects of five green manure cropping systems (clear tillage (CK); hairy vetch monoculture; oil rapeseed monoculture; hairy vetch intercropped with rapeseed; hairy vetch mixed with rapeseed). Green manure planting significantly improved the soil quality index and comprehensive evaluation index, with the highest soil quality and comprehensive evaluation indices observed in the hairy vetch intercropped with rapeseed. The hairy vetch intercropped with rapeseed can enhance the comprehensive benefits of green manure while reducing carbon and nitrogen footprints. Compared with the control, all green manure treatments except for the hairy vetch monoculture significantly reduced the carbon footprint by 9.39%–30.37%, the nitrogen footprint by 14.23%–22.70%, and environmental damage costs by 16.36%–25.86%. The carbon footprint was primarily regulated by N2O emissions and soil organic carbon sequestration rate, with contribution rates of 31.36% and 62.46%, respectively. The nitrogen footprint was mainly associated with NO3–N and N2O emissions, with contribution rates of 46.88% and 36.79%, respectively. Therefore, the diversified cropping (i.e., the hairy vetch–rapeseed intercropping) system exceed the monoculture for sustainable apple orchard production.

Forests doi: 10.3390/f17111259

Authors: Dian Jin Yancun Yan

Remote sensing and deep learning are increasingly used across the forest-fire management lifecycle in China, but the evidence differs substantially in task, sensor, model, and validation design. We screened 146 candidate records published during 2015–2025 using predefined criteria requiring a China-specific empirical component, forest/wildland-fire relevance, substantive remote-sensing input, substantive deep learning, and primary empirical evaluation. Thirty-four studies met all criteria, and 82.4% were published during 2023–2025. Active-fire detection and monitoring represented 38.2% of the evidence, followed by pre-fire risk and preparedness (32.4%), post-fire assessment (23.5%), and spread/behaviour modelling (5.9%). Sensor use was strongly task-dependent: UAVs supported fine-scale detection and fuel assessment, geostationary satellites supported frequent active-fire monitoring, and multisource satellite/geospatial inputs supported risk and post-fire analysis. Operational evidence remained limited: 11.8% of studies reported multi-region or multi-country validation, 8.8% runtime or latency, 11.8% false-alarm information, 5.9% interpretability, and none reported explicit uncertainty in the study-level evidence extracted for this review. The evidence does not support one universally superior architecture. Progress will depend more on task-matched sensing, independent geographic and event validation, calibrated uncertainty, false-alarm control, and clearer links between model outputs and management decisions. These priorities are relevant beyond China wherever remote-sensing fire systems must transfer across heterogeneous landscapes, sensors, and operating conditions.

Forests doi: 10.3390/f17111258

Authors: Huiwen Tian Kaiwei Zhang Xinxin Zhang Jiaxiang Guo Rutian Bi

Quantifying current topsoil organic matter (SOM) differences associated with cropland retirement is challenging because soil observations are spatially uneven and historical SOM maps are scarce. We integrated 10,262 measurements of 0–20 cm SOM collected in 2023 with remote sensing and environmental covariates and annual land-cover histories from 1999 to 2023 in western Shanxi, China. Random forest (RF), support vector regression, and multiple linear regression were compared using five-fold cross-validation. Ten bootstrap RF prediction runs were used to derive a mean SOM map and a pixel-wise standard deviation layer representing between-run prediction variability. RF achieved the best performance (R2 = 0.52; RMSE = 5.43 g kg−1; MAE = 3.41 g kg−1). Strict one-to-one matching showed that predicted SOM was 3.084 g kg−1 higher in converted croplands than in cropland reference areas. The mean difference was larger for forestland-covered converted croplands (4.960 g kg−1) than for grassland-covered converted croplands (3.019 g kg−1). Earlier conversion cohorts generally showed larger spatial contrasts. A complementary local comparison yielded a mean difference of 3.004 g kg−1 and revealed substantial spatial heterogeneity. These results represent current predicted spatial differences associated with reconstructed land-cover histories rather than directly measured temporal SOM gains or causal effects of the Grain-for-Green Program.

Forests doi: 10.3390/f17101257

Authors: Vahid Nasiri

Forest greening may vary considerably within the growing season, particularly in seasonally water-limited ecosystems. This study examined how long-term greening varies from spring to summer across the Zagros forests of western Iran and whether its environmental associations change seasonally. MODIS NDVI time series (2003–2024) were analyzed for March–August and separately for March–April, May–June, and July–August. Trends in land surface temperature, precipitation, and soil moisture were assessed, and generalized additive models were used to examine their associations with seasonal NDVI trends and topography. More than 93% of the forest area showed increasing NDVI during March–August, but greening weakened markedly from spring to summer. Mean NDVI trends declined from 0.0293 decade−1 in March–April to 0.0121 in May–June and 0.0101 in July–August. Model explanatory power also declined from 45.4% to 34.0% and 28.2%, respectively. Temperature-related effects were more prominent early and mid-season, while topographic influences became relatively more important toward summer. Although increasing heat and water limitation later in the season is consistent with other seasonally dry ecosystems, our results show that widespread Zagros greening masks substantial within-season differences in both trend magnitude and environmental associations, which are not apparent from growing-season trends alone.

Forests doi: 10.3390/f17101256

Authors: Halam Kang Ho-Kwon Kwak Yoo-Jung Park Hye-Yeon Kim Ji-Eun Park Jae-Eun Choi Jaeyun Jo Hee-Young Gil Kyeong-Sik Cheon

This study evaluated the genetic diversity and population structure of Rhododendron micranthum Turcz., a rare plant with a restricted distribution in the Republic of Korea, using genotyping-by-sequencing (GBS). A total of 121 individuals from 11 populations covering the entire distribution range of the species in the Republic of Korea were analyzed using 3330 single-nucleotide polymorphism (SNP) markers. Genetic diversity analysis revealed a mean expected heterozygosity (He) of 0.266, which was lower than that reported for typical perennial plants and other congeneric taxa. Among the populations, the Jecheon (JC) population exhibited the highest genetic diversity (He = 0.297), whereas the Bonghwa (BH) and Yeongwol (YW) populations showed relatively low genetic diversity. Analysis of molecular variance (AMOVA) indicated that 88% of the total genetic variation occurred within populations, and the level of genetic differentiation among populations was moderate (FST = 0.100). Population genetic structure analyses identified three genetic groups, with clear genetic differentiation between the eastern and western populations, which are separated by the Baekdudaegan range. In particular, the YW population exhibited a distinct genetic composition that differentiated it from the other populations, whereas the Yeongju (YJ) population contained ancestry components representing all three genetic clusters observed across the other populations, suggesting that it may represent a central population in the range expansion of R. micranthum in the Republic of Korea. These results are expected to provide important baseline data for establishing effective conservation strategies for R. micranthum in the Republic of Korea.

Forests doi: 10.3390/f17101255

Authors: Rui Liu Cheng Hu Shuxia Yao Jing Li Yulong Han Zhongbao Zhao

Soil organic carbon (SOC) is an important component of forest ecosystem carbon storage, and its distribution may vary with plantation stand composition. However, information on the vertical distribution of SOC stocks among different plantation types on the Bashang Plateau remains limited. In this study, we investigated the vertical distribution of SOC concentration and SOC stock and their relationships with continuous vegetation and soil variables in three mid-aged plantation types: pure Larix principis-rupprechtii stands (LP), mixed Larix principis-rupprechtii–Betula platyphylla stands (LBM), and pure Betula platyphylla stands (BP). Three independent 25 × 25 m plots were established for each stand type, and soil samples were collected from five depth intervals (0–10, 10–20, 20–30, 30–50, and 50–70 cm). SOC concentration, bulk density, soil moisture, pH, sucrase activity, and catalase activity were determined, together with understory aboveground biomass, litter biomass, and fine-root biomass. SOC concentration (g/kg) and SOC stock (t C/ha) generally decreased with increasing soil depth, and more than 50% of the total 0–70 cm SOC stock occurred within the upper 0–30 cm. One-way ANOVA showed that total SOC stock differed significantly among stand types (p < 0.05), with 202.50 ± 4.82 t C ha−1 in BP, 190.25 ± 4.51 t C ha−1 in LBM, and 109.75 ± 4.64 t C ha−1 in LP. Pearson correlation analysis among continuous variables showed that SOC stock was positively associated with understory aboveground biomass, soil moisture, and sucrase activity, whereas bulk density was negatively associated with SOC stock. Neither litter biomass nor fine-root biomass showed significant associations with SOC stock. These results indicate that stand type significantly affected SOC stock on the Bashang Plateau, and broadleaf-containing stands had higher SOC stocks than the pure larch stand under the conditions examined. The findings provide field-based evidence for considering stand composition in forest soil carbon management and ecological restoration in semi-arid plateau ecosystems.

Forests doi: 10.3390/f17101254

Authors: Min Liu Ying Zhang

Forest management objectives have shifted from timber-only production to multifunctional management. From this, a divergence has emerged between the private and social optimal rotation decisions pursued by forest farmers and the government, respectively. Identifying this divergence and improving eco-compensation mechanisms accordingly are critical to promoting multifunctional plantation management. Based on a constructed multi-service Faustmann–Hartman model, this study uses the examples of Picea asperata, Pinus yunnanensis, and Pinus massoniana in Sichuan Province to compare changes in the optimal rotation period and land expectation value (LEV) across three progressive scenarios: timber management, carbon sink management, and multi-objective management. It also estimates eco-compensation needs based on staged opportunity costs. The results show that incorporating non-market ecosystem services delays the optimal rotation period and increases LEV. These systems’ contribution to rotation extension exceeds that of the carbon sink. Sensitivity analysis indicates that timber price and discount rate are important parameters affecting LEV and the optimal rotation period, with the discount rate exerting the most pronounced effect; by contrast, although carbon price increases LEV, its effect on extending the rotation period is relatively limited. Based on management feasibility boundaries, Picea asperata, Pinus yunnanensis, and Pinus massoniana are classified as ecological value-dependent, carbon-enhanced, and management-robust types, respectively. Staged compensation estimates show that carbon sink revenues cover the opportunity costs of switching from timber management to carbon sink management; however, transitioning further to multifunctional management still requires fiscal compensation. Using the existing compensation standard for eligible non-state-owned public welfare forests in Sichuan Province as a policy benchmark, the estimated annual compensation requirements for Pinus yunnanensis and Pinus massoniana exceed this standard by 81.46 and 12.99 CNY/(ha·year), respectively, whereas the requirement for Picea asperata is lower than the benchmark. Therefore, plantation eco-compensation policies should shift from uniform compensation to differentiated mechanisms that account for species heterogeneity and the transition stages included in management objectives.

Forests doi: 10.3390/f17101253

Authors: Jeman Lee Minwoo Roh Sujung Heo Ye-Eun Lee Sujung Ahn

Litter fuel moisture governs the ignition and early spread of forest fires, yet its meteorological controls in Korean conifer and broadleaf stands, and the correspondence of existing fire-weather index classes to locally observed moisture, remain poorly characterised. We directly measured litter fuel moisture in paired conifer and broadleaf stands at four regions in Korea during one spring fire season and classified moisture class (Dry/Intermediate/Moist) from 26 meteorological and soil predictors under time-blocked, nested cross-validation. Five classifiers performed moderately and indistinguishably (macro-F1 0.39–0.51; quadratic weighted kappa 0.20–0.47), all above naive baselines, and performance declined under leave-one-region-out transfer. A multiple-testing-corrected interaction test detected a forest-type-dependent response only for soil water content, and neither a forest-type indicator nor separate per-type models improved prediction over a single pooled model. The Fine Fuel Moisture Code (FFMC) was significantly correlated with measured litter moisture (r = −0.57 conifer, −0.48 broadleaf) and was more sensitive to Dry conditions than any classifier, but its ignition-probability-derived class boundary corresponded weakly to the observed classes, and a moisture-equivalent boundary produced a complementary rather than superior error pattern. Meteorological data provide site-calibrated discrimination of litter-moisture class; forest-type differences are present but narrow, and FFMC class boundaries require local calibration before operational use.