Forests doi: 10.3390/f17060637

Authors: Hanyu Feng Xiaoxu Wang Dianguang Xiong Chengming Tian

Wood vinegar is a naturally acidic liquid produced during the pyrolysis of agricultural and forestry residues, which contains a complex mixture of bioactive components, including organic acids, phenolics, ketones and so on. As a multifunctional biomass-derived product with considerable potential, wood vinegar has attracted widespread attention in agroforestry and environmental research. This review summarizes recent research progress on the roles of wood vinegar in plant disease resistance, plant growth promotion, and soil improvement. The inhibitory effects of wood vinegar against various plant pathogens and the potential mechanisms involved are discussed, as well as two major pathways through which wood vinegar promotes plant growth. In addition, the roles of wood vinegar in improving soil fertility are examined, particularly through regulating soil salinity and enhancing soil chemical and biological properties. Recent advances in its practical applications across different agricultural fields are also summarized, and safety considerations associated with its use are analyzed. Despite these advances, current studies remain largely focused on phenomenological observations, with limited investigation in forestry applications. Furthermore, the molecular mechanisms underlying the biological activities of wood vinegar and the long-term ecological risks associated with repeated applications remain insufficiently understood. This review provides perspectives on further exploration of the mechanisms of action of wood vinegar and the potential risks associated with its long-term application, with the aim of providing a scientific reference for the safe and efficient utilization of wood vinegar in sustainable agriculture and ecological restoration.

Forests doi: 10.3390/f17060636

Authors: Željko Škvorc Saša Bogdan Ida Katičić Bogdan Daniel Krstonošić Krunoslav Sever

Forest tree provenances have evolved diverse and complex mechanisms to acclimate to changes in environmental conditions. Pedunculate oak (Quercus robur L.), along with other European tree species, is increasingly exposed to the adverse effects of climate change, particularly prolonged drought periods and severe drought stress. Understanding the species’ capacity to acclimate to expected environmental changes requires knowledge of key functional traits linked to drought tolerance, such as leaf structure and gas exchange. To explore the acclimation mechanisms of pedunculate oak provenances to repeated drought events, a study was conducted under controlled conditions with plants from nine provenances spanning a north–south gradient across eastern Europe, from Estonia to Italy. The study consisted of two parts: first, leaf structural traits were analyzed after three years of experimentally induced drought by comparing drought and control treatments; second, both treatments were subjected to subsequent drought to analyze differences in gas exchange trait responses. Results demonstrated ecotypic differentiation among provenances in morphological, but not in gas exchange traits, suggesting that provenance adaptedness to drier habitats is more closely associated with structural than physiological traits. Provenances originating from drier habitats showed lower specific leaf area but also different acclimation to repeated drought events, including a stronger reduction in stomatal density and a smaller increase in leaf dry matter content, compared to provenances from more humid habitats. Gas exchange acclimation occurred through a shift in the strategy of photosynthesis down-regulation. These findings emphasize the importance of investigating multiple functional traits rather than focusing solely on individual key traits.

Forests doi: 10.3390/f17060635

Authors: Haocheng Zhao Weikai Tan Jialiang Zhuang Mei Wang Dong Ren

Acantholyda posticalis (Hymenoptera: Pamphiliidae) is a forestry pest in China. They primarily infest pine trees, causing serious ecological damage. The research aims to identify the key environmental factors influencing the suitable distribution area of Acantholyda posticalis and their optimal conditions, and investigate the impacts of climate change and possible impacts of its main host plants on the distribution of Acantholyda posticalis. By utilizing the MaxEnt model, we predict the potential distribution of Acantholyda posticalis and its main host plant, Pinus tabuliformis, under current and future climatic conditions. The results indicate that under current climatic conditions, the suitable areas for Acantholyda posticalis in China are extensive in the Loess Plateau and North China Plain regions and have extensive overlapping area with the distribution of Pinus tabuliformis. The dominant environmental factors influencing the distribution of suitable areas for Acantholyda posticalis are the Minimum Temperature of the Coldest Month, Precipitation of the Wettest Quarter, Altitude and Temperature Seasonality. Under the SSP126 and SSP585 climate scenarios for the period 2081–2100, the overall suitable area for Acantholyda posticalis is projected to follow a decreasing trend, exhibiting a tendency to extend toward the southern and eastern regions. Meanwhile, the moderately and highly suitable areas are more concentrated and extensive. The research provides a theoretical foundation for the control of Acantholyda posticalis and the protection of the ecological environment.

Forests doi: 10.3390/f17060634

Authors: Yushuang Shang Jiayu Meng Xiang Li

Whether compact urban development can achieve a spatial balance in the supply and demand of ecosystem services remains unclear amidst rapid urbanization. Understanding this relationship is critical for territorial spatial planning. Using Guanzhong Plain Urban Agglomeration as a case study, we applied local spatial autocorrelation to reveal spatial trade-offs and synergies, and employed ordinary least squares and geographically weighted regression models to analyze the underlying mechanisms. Results demonstrate that urban compactness is significantly negatively correlated with supply–demand gaps for carbon storage (r = −0.66), habitat quality (r = −0.58), recreation services (r = −0.60), and water yield (r = −0.63), while positively correlated with gaps for grain production and soil conservation. The GWR model outperformed the ordinary least squares model, with improvements in adjusted R2 ranging from 0.0019 to 0.13. Land use intensity and GDP emerged as the dominant drivers of spatial heterogeneity in the ecosystem service supply–demand ratio, accounting for 66.21% and 51.08% of the variance, respectively. These findings provide a scientific basis for integrating compact urban form with ecosystem management in sustainable landscape planning.

Forests doi: 10.3390/f17060633

Authors: Doris Gómez-Ticerán Abel Salinas-Inga Jehoshua Macedo-Bedoya Marcel La Rosa-Sánchez Fernando Camones-Gonzales Franco Angeles-Alvarez Marco Carbajal-Bellido Bruno Padilla-Torres Paola Morosini-Inga Luis Alberto León-Bañuelos Yakov Quinteros-Gómez

Palms of the genus Ceroxylon constitute a key component of Andean tropical montane forests; however, their internal structural integrity has been scarcely studied in Peru. The present study assessed the internal structural condition of natural populations within the Private Conservation Area (PCA) Bosque de Palmeras of the Taulía-Molinopampa (Amazonas, Peru) using sonic tomography. A total of 64 individuals distributed across four zones with differing degrees of anthropogenic disturbance—Mixed Forest (MF),

Forests doi: 10.3390/f17060632

Authors: Lixing Guo Zhe Xu Tianxiang Yue

This study refines the application of unmanned aerial vehicle light detection and ranging (UAV-LiDAR) for forest parameter extraction, focusing on calibration aspects of random forest models within subtropical mixed forests. A notable inverse correlation was identified between high-density LiDAR-derived intensity percentiles and stand volume of 20 m × 20 m plots. Using a random forest model with a 20% validation proportion (30 plots), we achieved a validation coefficient of determination (R2) of 0.61 and root mean square error (RMSE) of 27.2%. Key variables included radar echo intensity and forest gap fraction, emphasizing their importance in volume estimation. Additionally, analyses highlighted forest gap fraction as an important variable in model construction, suggesting careful consideration of its distribution in sample plot selection.

Forests doi: 10.3390/f17060631

Authors: Isabella Imakawa Araújo Clara Gaspar Fossi de Souza Tiago Hendrigo Almeida André Luis Christoforo Francisco Antonio Rocco Lahr

Wood-based panels such as oriented strand board (OSB) have gained increasing relevance in sustainable construction due to their favorable mechanical performance and efficient use of raw materials. This study evaluates the physical and mechanical properties of OSB panels manufactured from residues of five Brazilian tropical species, namely Cambará (Erisma sp.), Caixeta (Simarouba sp.), Cedroarana (Cedrelinga catenaeformis), Tatajuba (Bagassa guianensis), and Tauari (Couratari oblongifolia) bonded with castor oil-based polyurethane resin (12% by dry weight; 3-layer ratio 20:60:20). Seven formulations were tested (five monospecies; two mixed species) and characterized in accordance with EN 300, EN 310, EN 317, EN 319, EN 322, EN 323, ABNT NBR 14810-2, and ASTM D2719. Panel densities ranged from 0.685 to 0.813 g/cm3. Cedroarana and Caixeta panels achieved the highest mechanical performance: MOR of 44.04 MPa and 40.96 MPa, and MOE of 6741 MPa and 6287 MPa, respectively (parallel direction), both exceeding EN 300 OSB/4 thresholds. All panels met internal bond requirements (≥0.5 MPa). Compaction ratio emerged as the primary determinant of mechanical behavior. Mixed species panels performed comparably to monospecies configurations, confirming the viability of residue valorization without species segregation. The castor oil-based resin provided adequate bonding and moisture resistance, supporting its use as a formaldehyde free renewable alternative for structural-grade OSB.

Forests doi: 10.3390/f17060630

Authors: Yu Zhu Zhaoyan Cui Yujie Huang Ernian Zhao Ming Xu

Bamboo, as a rapidly renewable and sustainable material, has gained increasing attention in the construction, furniture, automotive interiors, and packaging industries due to its excellent mechanical properties, light weight, and environmental friendliness. However, the inherent flammability of bamboo, characterized by its porous structure and high hemicellulose content, poses a significant fire hazard that severely limits its wide application. This review systematically synthesizes recent advances in the fire performance and flame-retardant modification of bamboo-based materials. First, the thermal degradation behavior and combustion mechanisms of bamboo are discussed in relation to its primary chemical constituents, including cellulose, hemicellulose, and lignin. Subsequently, various flame-retardant strategies are reviewed, including inorganic flame retardants, phosphorus–nitrogen systems, nanomaterial-based additives, and bio-based flame-retardant approaches. The effectiveness of different modification techniques, such as impregnation treatment, adhesive modification, and surface coating, is also analyzed. Future research directions are proposed, emphasizing the development of environmentally friendly flame-retardant systems, multifunctional modification strategies, and the design of high-performance flame-retardant bamboo-based materials. This review aims to provide a comprehensive framework for advancing the fire safety design and sustainable application of bamboo-based materials.

Forests doi: 10.3390/f17050629

Authors: Ling Xia Peichun Li Wenxiu Li Meng Wang Xiaoyu Liang Yu Zhang

Anthracnose, caused by Colletotrichum spp., is a major foliar disease limiting rubber tree (Hevea brasiliensis) productivity. To uncover resistance mechanisms, we compared resistant and susceptible germplasm using an integrated framework combining leaf structural analysis, physiological defense profiling, and transcriptome sequencing. Resistant germplasm exhibited lower stomatal density and more compact mesophyll, likely restricting pathogen entry and within-leaf spread. Following inoculation, resistant accessions showed stronger antioxidant responses, with higher activities of superoxide dismutase (SOD) and peroxidase (POD), and elevated phenylpropanoid-related enzymes, including polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL), peaking at 24–48 h post inoculation. These responses were accompanied by enhanced reactive oxygen species (ROS) accumulation (H2O2) but reduced lipid peroxidation (malondialdehyde), indicating efficient oxidative stress regulation. Microscopic observation revealed delayed infection progression and postponed differentiation of infection structures in resistant germplasm. Transcriptomic analysis further demonstrated that differentially expressed genes were mainly enriched in pathways related to signal transduction and secondary metabolism, particularly phenylpropanoid metabolism and related secondary metabolic pathways. Together, these results suggest that anthracnose resistance is mediated by coordinated structural barriers, redox homeostasis, and transcriptional regulation of defense networks. This study provides a mechanistic framework for resistance-oriented breeding and the utilization of resistant germplasm in rubber tree.

Forests doi: 10.3390/f17050628

Authors: Cao Sun Kong Han Wei Li

Dendroctonus valens LeConte represents a major invasive pest species in China. Both larvae and adults primarily feed on the phloem of the tree trunk base and roots, disrupting nutrient transport and leading to host tree mortality, which poses a severe threat to forest ecosystems and the forestry economy. Juvenile hormone acid methyltransferase (JHAMT) is a key enzyme in insect juvenile hormone (JH) biosynthesis. In this study, we identified a JHAMT-encoding gene, DvJHAMT, in D. valens via bioinformatic analysis. RT-qPCR analysis revealed that DvJHAMT is predominantly expressed during the egg and larval stages. In the fourth-instar larvae, the highest expression levels were observed in the head and epidermis, suggesting a central regulatory role during this critical developmental period. To investigate its function via RNA interference (RNAi), a nanomaterial, star polycation (SPc), was employed for the transdermal delivery of dsRNA into the fourth-instar larvae. The results demonstrated that DvJHAMT knockdown significantly downregulated mRNA levels, resulting in marked decreases in larval survival, pupation, and eclosion rates. Notably, treatment with 0.7 µg dsDvJHAMT-SPc resulted in a 96.67% mortality rate and a reduced pupation rate of 41.67% at 34 days post-treatment. Furthermore, RNAi led to developmental deformities and significant weight loss in larvae. ELISA assays confirmed that DvJHAMT silencing led to reduced JHAMT enzyme activity and JH III titers in a dose-dependent manner. In conclusion, our findings demonstrate that DvJHAMT plays a vital role in JH biosynthesis and that its suppression exhibits potent lethal effects, suggesting that DvJHAMT is a promising candidate for RNAi-based management of D. valens.

Forests doi: 10.3390/f17050625

Authors: Niccolò Conti Gianni Della Rocca Sara Barberini Cecilia Brunetti Roberto Danti Giovanni Emiliani Arcangela Frascella Valentina Lazazzara

Clonostachys rosea is a promising biological control agent (BCA) against several plant pathogens, but its sensitivity to solar radiation limits its field efficacy. The biochemical changes occurring in C. rosea under light are still unknown, and no studies have assessed its antagonistic potential against Phytophthora cinnamomi and Phytophthora × cambivora, the main causal agents of ink disease in sweet chestnut. In this study, C. rosea was isolated from asymptomatic sweet chestnut plants in a forestry area affected by ink disease. We evaluated its in vitro antagonistic capacity against both oomycetes under dark and light conditions and investigated the metabolomic and volatilomic changes through HPLC-QToF-MS and GC-MS analyses. Under dark conditions, C. rosea exhibited remarkable inhibitory activity against both oomycetes in a dual-culture assay and through secreted secondary metabolites, including sorbicillinol and vertinolide, derivatives known for their biological activities. Light exposure significantly reduced antagonistic efficacy and secondary metabolite diversity. Volatilomic analyses revealed moderated differences between conditions, with volatile compounds whose biological roles remain uncharacterized and warrant further investigation. These findings indicate that light conditions critically affect the antagonistic potential of C. rosea, highlighting the importance of environmental factors in optimizing its use for the biological control of ink disease in chestnut.

Forests doi: 10.3390/f17050626

Authors: Yuzhe Kong Binbin Jiao Size Dai Chun Yang Qing Chen Tingting Dai

Despite the growing threat of Pythium helicoides to forest plantations in China, a nationwide assessment of climatic suitability remains unavailable, limiting the development of preventive strategies. This study applied the Maximum Entropy model combined with geographic information system analysis to predict the potential distribution and suitable habitats of the pathogen across China. The model was constructed using occurrence records from the Global Biodiversity Information Facility and published literature, together with bioclimatic, topographic, and soil variables. Simulations were performed under current and future climate conditions throughout the twenty-first century across low, medium, and high emission scenarios. The model performed reliably, with Area Under the Curve values indicating favorable predictive accuracy across all periods. Habitat suitability was governed primarily by precipitation of the driest month, temperature annual range, and elevation. Under current conditions, highly suitable areas are concentrated in tropical and subtropical monsoon regions, particularly eastern Hainan and Taiwan. Under future scenarios, suitable habitats are projected to shift toward warm temperate regions while contracting overall, with plains, basin floors, and valleys retaining high suitability due to favorable moisture retention. Windward mountain slopes are generally unsuitable, although scattered medium-suitable habitats may form in lower-lying depressions with gentler slopes.

Forests doi: 10.3390/f17050627

Authors: Elisa Pecoraro Nicola Macchioni Giorgia Musina Emma Cantisani Sveva Longo Marta Novello Benedetto Pizzo

The Iulia Felix is a 2nd-century AD Roman shipwreck that was discovered off the coast of Grado in 1986. Following its recovery, the hull was dismantled and treated with high concentrations of PEG 4000 at elevated temperatures. This process was completed in 2003. The elements were then stored for over 20 years. During this prolonged storage period, salt efflorescence developed on some surfaces, raising concerns about ongoing degradation and prompting an investigation into the composition of the wood and how environmental conditions influence it. The efflorescence was analysed using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), X-ray powder diffraction (XRPD) and Fourier transform infrared spectroscopy (FTIR). To evaluate the impact of environmental factors, samples were exposed to controlled humidity levels of 35% and 85% until equilibrium was achieved. The analyses identified iron- and sulphur-based compounds, including hydrated ferrous sulphates, calcium sulphate and hydrated iron oxides. These findings suggest a corrosion-related degradation process that originates in a marine burial environment and progresses in humid, oxygen-rich conditions after recovery. The presence of PEG within the efflorescence indicates that environmental conditions after treatment promoted its gradual migration to the surface. Climate testing revealed that PEG 4000 significantly reduced hygroscopic exchange with the environment. Under dry conditions, dimensional changes were minimal, with less than 1% variation in mass and surface area. In contrast, prolonged exposure to high humidity resulted in a 11% increase in mass due to moisture uptake, as well as a roughly 5% increase in surface area. This was accompanied by minor cracking and, in some cases, structural failure. This study highlights the long-term conservation challenges posed by waterlogged archaeological wood treated with high-molecular-weight PEG. It emphasises the importance of continuous environmental monitoring to mitigate degradation processes and preserve structural integrity, providing valuable insights for future museum conservation strategies.

Forests doi: 10.3390/f17050624

Authors: Ying Lu Menglan Shang Zhe Li Yongfeng Lu Yu Long Wangdong Xu Qinghua Zhang

Botrytis cinerea is a globally distributed phytopathogenic fungus that causes gray mold in eucalyptus seedlings, posing a severe threat to eucalyptus nursery production. Pseudomonas eucalypticola Liu et al. NP-1 is an endophytic bacterium isolated from eucalyptus with broad-spectrum antifungal activity. In this study, the fermentation broth extract of strain NP-1 was prepared using the organic solvent extraction method. The inhibitory effects, antifungal mechanisms, and biocontrol efficacy of the extract against B. cinerea were investigated. The results suggested that the NP-1 extract effectively inhibited mycelial growth, conidial germination, and germ tube development of B. cinerea. The EC50 and EC90 values for mycelial inhibition were 110 μg/mL and 332 μg/mL, respectively, while those for conidial germination inhibition were 126 μg/mL and 310 μg/mL. Microscopic and ultramicroscopic observations indicated that while the mycelial structures in the control and EC50 groups remained intact, the EC90 treatment significantly was associated with protoplasmic aggregation, leakage, and cavitation, suggesting potential structural damage to the fungal cells. In vitro and in vivo biocontrol assays showed that the control efficacy against gray mold reached 90.0% on detached eucalyptus leaves and 93.3% on eucalyptus seedlings. These findings elucidate the biocontrol potential of NP-1 and lay a foundation for the development of bio-based pesticides.

Forests doi: 10.3390/f17050623

Authors: Hongru Qiu Liangping Zhang Yunqi Cui Tao Ding Nanfeng Zhu

This study utilized three controlled Sitika spruce beam specimens and established a parameterized transfer-function model based on force–acceleration frequency response functions (FRFs) to characterize and reconstruct the frequency-domain modal response of beam specimens. The specimens were tested using non-contact magnetic swept-sine excitation, laser Doppler vibration measurement, and synchronous FFT analysis methods under free–free boundary conditions. In the experiment, one specimen was used for modeling and the other two specimens were used for consistency verification. Based on the measured complex FRF, a 1st–5th order modal transfer-function model was established in the frequency range of 0–1000 Hz. The experiment identified five resonance frequencies of the specimen, which were 65.0, 198.5, 370.5, 620.0, and 930.0 Hz, respectively. The model can reconstruct the measured magnitude and phase responses, with magnitude residuals within ±5 dB, resonance-peak magnitude errors of 0.03–0.73 dB, and wrapped-phase deviation around the poles of 0.20–5.08°. The Nyquist trajectory was continuous and smooth, with all poles located in the left half-plane, indicating that the model has stable pole behavior. The research results support the specimen vibration response as an approximate linear time-invariant system under small-magnitude and controlled testing conditions. The model can provide a physically interpretable and reconstructable modal-parameter expression for evaluating frequency-domain vibration responses of controlled wooden beam specimens.

Forests doi: 10.3390/f17050622

Authors: Qiangqiang Lu Xinping Cai Xiaomin Zeng Ji Chen Fan Chang Guanghua Jing Jiaqi Guo Sha Zhou Zhikun Chen Lili Jia Jun Liu Tianjiao Liu

Litter decomposition is a key regulator of soil carbon formation and nutrient cycling in the plant–soil continuum. However, the utility of structural chemical indicators for capturing the relationship between litter decomposition and environmental factors under nitrogen (N) enrichment remains unclear. We conducted a two-year in situ decomposition experiment with different N addition treatments in a pure Quercus variabilis forest on the Qinling Mountains, China. During the active six-month growing season, we investigated the stoichiometric ratios of typical organic acids in litter and soil layers and their responses to soil environments. The total relative content of the four organic acids showed the most pronounced nonlinear shift along the N addition gradient, peaking at N75 (7.5 g N m−2) then declining. The stoichiometric ratios of some typical organic acids varied analogously to soil physicochemical properties, microbial diversity and abundance. This inter-annual response was particularly pronounced in the warmer and wetter year of 2023. Structural chemical analysis revealed that steric hindrance and molecular symmetry are key factors regulating the decomposition efficiency of typical organic acids in litter. Notably, phenolic acid and butyric acid isomer ratios exhibited significant subgroup-specific responses to soil physicochemical factors, enzyme activities, and microbial abundances. Collectively, these ratios may indicate N addition impacts on litter decomposition, hold potential for predicting climatic variability responses, and provide conceptual support for an integrated framework linking N enrichment, litter chemistry, and soil carbon dynamics in temperate forests.

Forests doi: 10.3390/f17050621

Authors: Seda Sönmez Halil Özekicioğlu Marina Danilina Yılmaz Bayar

Global warming and climate change have considerably enhanced worldwide environmental concerns since the 1970s. Therefore, researchers have extensively researched the nexus between renewable energy utilization and CO2 emissions in the literature. However, the influence of afforestation and energy productivity along with renewable and nuclear electricity generation on CO2 emissions has not been explored sufficiently in the associated literature regarding the multiple effects of these actors on the decarbonization process. Thus, this article analyzes the short- and long-term effects of afforestation, energy productivity, renewable and nuclear electricity production on CO2 emissions in the BRICS states over the 1993–2021 term via robust bootstrap cointegration and causality tests. The findings confirm a cointegration interplay among CO2 emissions, afforestation, energy productivity, renewable and nuclear electricity generation. Further, the cointegration coefficients demonstrate a negative influence of afforestation, energy productivity, renewable electricity generation on CO2 emissions in most of the BRICS states in the long term, but a negative effect of nuclear electricity production only in China and the Russian Federation. The findings of causality examination also uncover that afforestation, energy productivity, and generation of renewable and nuclear electricity are effective tools in reducing CO2 emissions, but their long-term effects are found to be relatively higher than short-term effects. These findings indicate that promotion of afforestation, along with energy productivity and electricity from renewables and nuclear sources is highly useful for curbing CO2 emissions in the short and long term.

Forests doi: 10.3390/f17050620

Authors: Susannah B. Lerman Corinne G. Bassett Daniel E. Crane David J. Nowak Alexis Ellis Jason Henning

Urban forests support wildlife populations across North America and the world. Yet, challenges remain for research and practice to integrate wildlife habitat as a core component of the myriad objectives that urban foresters manage. Ecosystem services have been adopted as a dominant paradigm in urban forestry for both advocacy and management, yet accounting for contributions to wildlife habitat does not fit squarely within typical ecosystem service frameworks. The i-Tree program, a suite of urban forest ecosystem service models and tools developed by the US Forest Service, presented an opportunity to link widely used urban forest assessment field protocols with indicators of suitable habitat. In this reflection piece, we demonstrate how the i-Tree Wildlife project assessed whether urban forest structural assessment methods could be applied to assess wildlife habitat provision, operationalizing the fundamental question “How do urban forests support wildlife?” We describe the development process for integrating bird habitat suitability models for 12 species present in the northeastern US, ten native and two non-native birds, into the flagship i-Tree Eco tool. We offer reflections, challenges, and opportunities from this process. Ultimately, the improvement of ecosystem assessment tools like i-Tree can assist practitioners who aim to manage healthy and productive urban forests that benefit people and wildlife.

Forests doi: 10.3390/f17050619

Authors: Hasan Tezcan Yıldırım Pınar Topçu Özlem Yavuz Nilay Tulukcu Yıldızbaş Dalia Perkumienė Mindaugas Škėma Marius Aleinikovas Benas Šilinskas

Non-timber forest products (NTFPs) constitute an important component of forest-based production systems and biomass supply chains in Türkiye. Despite their growing economic and ecological significance, the long-term structural dynamics of NTFP production remain insufficiently understood. This study examines temporal and structural changes in NTFP production in Türkiye during the period 1988–2024 using official production statistics and production support data. The analysis applies a quantitative framework that combines linear trend analysis, Shannon diversity and Herfindahl–Hirschman concentration indices, volatility measures based on the coefficient of variation, and regression models to evaluate production trends, structural transformations, stabilization patterns, and the effectiveness of production support mechanisms. The findings reveal a non-linear and multi-phase development pattern characterized by diversification and production growth after 2000, followed by increasing concentration and greater production volatility after 2018. Although total production volume increased substantially, portfolio diversity declined over time, and dependence on a limited number of high-volume products intensified, indicating growing structural vulnerability within the system. In addition, production support mechanisms showed a weak and heterogeneous relationship with production outcomes. A limited contextual comparison with Lithuania’s multifunctional NTFP system is also included to position the findings within a broader European context. Overall, the results suggest that increasing production alone is insufficient to ensure long-term system stability. Instead, diversification-oriented and risk-sensitive resource management strategies that account for production risks, regional disparities, and product heterogeneity are essential for developing sustainable and resilient NTFP production systems.

Forests doi: 10.3390/f17050618

Authors: Jiaxing Guo Julie Cool Chaoguang Luo Yan Zhong Fengfeng Ji Kuanjie Yu Ruixia Qin Huadong Xu Yanbo Hu

A nondestructive, rapid, and portable detection method for moisture content (MC) in living tree trunks remains unavailable. Tree radar, developed based on ground-penetrating radar (GPR) technology, represents a promising approach for tree trunk MC detection owing to its high penetration depth and low susceptibility to environmental interference. However, its application to living tree MC detection is constrained by curvature-induced wave propagation complexity, interspecific structural heterogeneity and the limited availability of labeled MC samples obtained through destructive coring, collectively resulting in poor model performance. The study proposed a novel GPR-based MC detection method employing a multi-scale one-dimensional convolutional neural network integrated with an attention mechanism and mixed data augmentation (mixed-MS1DCNNAM). GPR amplitude data extracted from the first 6.5 ns of B-scan signals were used to capture MC-related features via a custom program developed in MATGPR. A mixed model for four tree species with 15–30 cm diameters at breast height (DBH) achieved an R2 of 0.7908 and an RMSE value of 0.1059, outperforming traditional models, with test metrics calculated at the tree level by averaging predictions from five directional GPR scans per tree. Furthermore, three DBH-specific sub-models (15–20 cm, 20–25 cm, and 25–30 cm) and four single-species sub-models were developed, yielding improved performance (R2 ≥ 0.7246, RMSE ≤ 0.1033; RMSE ≤ 0.0959, MAE ≤ 0.0626, except for European white birch). These results highlighted the effectiveness of stratification by DBH class and tree species. Overall, this study effectively addresses aforementioned challenges and establishes a generalizable nondestructive approach for living trees under field conditions, facilitating sustainable forest management in tree growth monitoring, forest disaster monitoring, harvested timber storage and wood quality assessment.

Forests doi: 10.3390/f17050617

Authors: Debra A. Hamilton Victorino Molina Rojas Therese M. Donovan

Tropical forest restoration has increased in the past decades, with possible advancements given the UN declaration of the “Decade of Ecosystem Restoration”. However, robust assessments to compare ecosystem functions among restored forest stages are essential. We evaluated 13 actively restored forest stands ranging from 3 to 21 years of age and compared measures of forest biodiversity, structure, and ecosystem function to four 70+ year old “reference” stands that serve as restoration “targets” in the study region of the Premontane wet forest of Costa Rica. The restored stands were planted with an average of 13 tree species on abandoned pastures that were fallow for at least two years. Sixteen tree-stand attributes and six ecosystem function estimates were assessed, including: annual biomass (C) accumulation, N-fixation potential, threatened species conservation, and the provision of avian frugivore forage, insect habitat, and insect pollination. Using Principal Component Analysis, linear modeling, and Mahalanobis distance analyses, we learned that planting a diversity of tree species sets the stage for forest recovery at early restoration ages, with an inflection point at 15 years towards older reference forest characteristics and functions. Given that all restoration ages provided tree diversity and some level of ecosystem functions, the value of all restored stands in the landscape is notable. The assessment methods are easily employed, thereby providing an accessible tool to restoration practitioners.

Forests doi: 10.3390/f17050616

Authors: Xin Zhao Jianan Li Xiaohui Rao Dong Li Xueyu Liu Rongrong Zhang Jianbing Liu Jindong Yan

Poor seed germination severely limits the propagation and conservation of Zelkova schneideriana (Chinese zelkova). However, the comparative effects of different exogenous phytohormones on seed germination of this species and the associated molecular responses remain insufficiently understood. To evaluate the effects of exogenous phytohormones on seed germination and to explore the underlying molecular basis, a germination experiment was conducted from January to March 2024 at Central South University of Forestry and Technology, Changsha, Hunan, China, in which seeds were treated with different concentrations of 6-benzylaminopurine (6-BA; 20, 40, and 80 mg/L), gibberellic acid (GA3; 125, 250, and 500 mg/L), indole-3-acetic acid (IAA; 100, 200, and 300 mg/L), brassinolide (BR; 10, 20, and 30 mg/L), and abscisic acid (ABA; 50, 100, and 150 mg/L). Germination traits were assessed, and transcriptome sequencing was performed for the BR treatment showing the strongest promotive effect. The results demonstrate that exogenous hormones exerted distinct regulatory effects on seed germination, among which BR at 10 mg/L showed the strongest promotive effect, increasing the final germination rate at 40 d from 50% in the control to 68%, whereas higher concentrations caused inhibitory effects. Transcriptome analysis identified 169 differentially expressed genes between BR-treated seeds and the control, mainly associated with reactive oxygen species (ROS) metabolism, redox regulation, energy and carbohydrate metabolism, and plant hormone- and MAPK-related signaling pathways. Antioxidant enzyme assays showed that BR10 increased POD activity but decreased SOD, CAT, APX, and GR activities. Endogenous hormone-related analysis further revealed marked BL accumulation and significant decreases in ACC, GA3, GA4, IAA, JA, and SA. Overall, exogenous BR promotes seed germination of Z. schneideriana through coordinated physiological and molecular regulation, providing a useful basis for seed pretreatment and seedling propagation.

Forests doi: 10.3390/f17050614

Authors: Tiam Mahmoudian Rosilei Garcia Aziz Laghdir Alain Cloutier

Wood-based panels are increasingly used in exterior applications; however, comprehensive evaluations of their durability under standardized aging conditions remain limited. This study evaluates the dimensional stability and mechanical performance of three industrial panels designed for exterior use: a three-layer particleboard (PB1) and a single-layer particleboard (PB2), both bonded with phenol–formaldehyde adhesive, and a medium-density fibreboard (MDF), bonded with polymeric methylene diphenyl diisocyanate through accelerated aging. The panels were subjected to six accelerated aging cycles according to the ASTM D1037-12 (2020) standard. Equilibrium moisture content, residual thickness swelling (Residual-TS), bending modulus of rupture (MOR), modulus of elasticity (MOE) in both parallel and perpendicular directions, and internal bond (IB) strength were measured under aged and non-aged conditions. PB2 demonstrated superior dimensional stability (Residual-TS: 0.49%) and strong mechanical retention (MOR: 67%, MOE: 56%–64%, IB: 75%). PB1 showed intermediate dimensional stability and mechanical retention (Residual-TS: 1.58%; MOR: 66%–74%, MOE: 56%–58%, IB: 71%), while MDF exhibited higher sensitivity to aging, with excessive Residual-TS (5.43%) and lower IB strength retention (30%). Specimen orientation did not affect dimensional stability but did influence the bending properties of the particleboard after aging, specifically MOR in PB2 and MOE in PB1. The results demonstrate that PB2 offers superior performance for demanding exterior applications, while PB1 and MDF are suitable for semi-protected uses. All panels were tested in an unfinished state, although surface coatings in actual applications may further enhance the resistance to aging.

Forests doi: 10.3390/f17050615

Authors: Yuqing Zeng Jiawei Lin Quanzhi Zhang

Forest soils serve as critical terrestrial carbon sinks. While broad hydrothermal controls on soil respiration (Rs) are established, uncertainties persist regarding high-frequency temporal dynamics and moisture-dependent variations in temperature sensitivity (Q10). Specifically, conventional reliance on discrete, clear-day sampling obscures how precipitation disrupts diurnal patterns. To address this, we continuously monitored Rs and environmental factors in two Northeast Chinese mixed forests (Korean pine, Pinus koraiensis (KP), and Dahurian larch, Larix gmelinii (DL)) to quantify weather-driven daily dynamics and carbon fluxes. Precipitation primarily drove daily variability, but more importantly, it reshaped day–night asymmetry. Under clear-day conditions, Rs exhibited a consistent daytime-dominant pattern, with daytime fluxes being significantly higher than nighttime fluxes (p < 0.05). However, precipitation events fundamentally neutralized this asymmetry, resulting in no significant day–night differences across most phenological stages. Annual Rs effluxes (759 and 965 g C m−2 yr−1 for KP and DL, respectively) lacked significant inter-stand or temporal variations. Seasonal emissions peaked unimodally in July, with the non-growing season contributing merely 5%–8%. Notably, spring freeze–thaw Rs in the KP stand surged interannually by 143%. While Rs correlated positively with temperature (p < 0.001), Q10 was co-regulated by forest stand and moisture. Under moderate moisture, the KP stand’s Q10 (2.72) was significantly lower than the DL stand’s (3.81); however, this divergence neutralized under low moisture. Consequently, soil moisture acts as both a direct Rs driver and a fundamental regulator of its temperature sensitivity. These empirical findings provide critical data to calibrate forest carbon models, improving predictions of soil carbon feedbacks under future climate scenarios.

Forests doi: 10.3390/f17050613

Authors: Álvaro Luís Pasquetti Berghetti Matheus Severo de Souza Kulmann Juliana Hoepers Marchioro Tedesco Maristela Machado Araujo Lincon Oliveira Stefanello Jair Augusto Zanon Marcos Vinícius Miranda Aguilar Lucas Soares Miguez Marcos Gervasio Pereira Moreno Toselli Elena Baldi Renato Marques Gustavo Brunetto

Understanding how P availability affects root turnover and P redistribution within plants is essential for optimizing fertilization strategies and sustaining forest growth under low-P soils. This study evaluated the effects of P fertilization on root system dynamics, plant growth, and P nutrition of Handroanthus heptaphyllus, a flowering landscape tree, cultivated in a subtropical climate. Plants were grown under two soil P levels (low and high). Plant height, stem diameter, leaf P concentration, soil P availability, total numbers of living and dead fine roots, total fine root surface area, and fine root production rate were measured at 18, 24, 30, and 36 months after planting. Phosphate fertilization increased soil P availability during the first 24 months and resulted in significant gains in plant height, stem diameter, fine root production, total surface area, and the ratio between living and dead fine roots, indicating a higher proportion of living roots relative to dead ones. Under high P availability, the greatest fine root production and surface area of living fine roots occurred in the 0–20 cm soil layer, reflecting localized P application near the plants. High P availability enhanced root system development, promoted greater soil exploration, and improved P uptake. These results indicate that under P supplementation, plants strategically invest in root growth, improving nutrient acquisition efficiency and reducing dependence on external inputs. Increased phosphorus availability enhances root growth and increases fine root production and turnover. Minirhizotron monitoring effectively captured shifts in root system dynamics driven by P availability, including enhanced root growth, increased fine root production and turnover, and improved nutrient uptake under high P, as well as limited root activity under low P conditions, indicating a more conservative strategy with reduced investment in root production.

Forests doi: 10.3390/f17050612

Authors: Chuyun Wu Jingwen Bi Yawen Shen

To investigate the carbon footprint of bamboo-based activated carbon from different manufacturing pathways, this research evaluated cradle-to-gate manufacturing emissions under a unified system boundary and allocation baseline based on primary data from a 10,000 t/year continuous industrial production line. An LCA model was constructed and verified using an allocation ratio interval scanning method. Results showed that carbon footprints of granular, powdered, and extruded activated carbons were 184.76 kg CO2 e/t kg CO2 e/t, 236.75 kg CO2 e/t, and 293.36 kg CO2 e/t. Although these products shared identical carbonization and steam activation units, the carbon footprints from milling, molding, and binder inputs accounted for 25.01%, 41.48%, and 52.77% of the total emissions. Internal thermal energy recovery via by-product gas recycling decreased emissions by 81.7%, 77.7%, and 73.8%, respectively. Compared with traditional coal-based alternatives, bamboo-based products achieved a reduction in emissions of about 95%. This study provides scientific guidance for the low-carbon production process of bamboo-based activated carbon and demonstrates the potential of biomass substitution for climate change mitigation.

Forests doi: 10.3390/f17050610

Authors: Shaofei Jin Haifeng Huang Junjie Liao Yan Huang Xiaoli Liao Gaolong Zhu Xiangzhe Shangguan Dexiang Zheng

Silicon (Si) plays a crucial role in forest ecosystem functioning by influencing plant nutrient cycling, stress resistance, and biogeochemical processes; however, how Si and phytolith characteristics respond to environmental gradients in subtropical forests remains poorly understood. This study investigated the variations in silicon and phytolith characteristics in the leaves of Castanopsis fargesii across different elevations in the Guoyan Mountain Nature Reserve (Nanping City, China). It aimed to identify the dominant phytolith morphologies and their proportions, and to examine the effects of elevation, leaf nutrient elements, and soil physicochemical properties on these parameters. Plots were established at 100 m elevation intervals within the natural distribution range of Castanopsis fargesii forests in the Guoyan Mountain Nature Reserve, covering elevations from 600 to 900 m. Fresh leaves, leaf litter, and soil samples (0–20 cm depth) were collected to analyze fresh leaf silicon content and phytolith contents, leaf nutrient elements, and soil physicochemical properties. From 600 to 900 m elevation, silicon content in fresh leaves, leaf litter, SCDI, and phytolith content all exhibited consistent patterns, with significantly higher values at 900 m than at 600 m. The dominant phytolith morphologies in leaves were elongate, flabellate, acute, trapeziform psilate, and blocky. At higher elevations (900 m), the proportions of elongate, acute, and trapeziform psilate phytoliths were relatively higher, while flabellate and blocky forms were more abundant at lower elevations (600 m). However, elevation had minimal influence on the overall proportions of dominant phytolith morphologies. Leaf calcium (Ca) and soil properties—including available calcium, organic matter, and available silicon—were identified as major factors affecting fresh leaf silicon content and phytoliths. Elevation, leaf nutrient elements, and soil physicochemical properties significantly influenced silicon and phytoliths in Castanopsis fargesii leaves. Certain phytolith morphologies in the leaves may be indicative of environmental changes.

Forests doi: 10.3390/f17050611

Authors: Xuan Zhang Yingxin Teng Wenjing Fu Junfeng Lou Abdul Basir Shengbin Chen

Administrative fragmentation, whereby political boundaries are used as analytical extents, can disrupt ecological flows and weaken ecological network planning by creating a mismatch between governance units and ecological processes. However, the pathways through which such fragmentation alters network structure and function remain insufficiently quantified. This study quantifies these effects and identifies the landscape conditions that shape the effectiveness of cross-boundary integration. Using a multi-scale buffer experiment (1–32 km) across 30 representative counties in China, we constructed ecological networks based on Morphological Spatial Pattern Analysis and on the minimum cumulative resistance model. Results show that relaxing administrative boundaries reduced structural distortions and lowered total ecological flow cost, indicating that fragmentation increases connectivity costs. Mechanistically, reducing redundant internal links and forced detours improved network efficiency mainly by shortening corridors and lowering flow costs, whereas mean corridor resistance changed little. This suggests that functional degradation is driven primarily by topological disruption rather than by declines in corridor quality. The benefits of cross-boundary integration were greater in counties with regular shapes, high grassland cover, humid climates, and rugged terrain, but weaker under strong human pressure and warmer temperatures. Improvements leveled off beyond 32 km, suggesting a 32 km buffer (study-specific) for integration and supporting context-specific strategies for ecological network planning.

Forests doi: 10.3390/f17050609

Authors: Boling Liu Qianying Wei Lin Zhang Xuejie Guo Ping Zhou Tao Tao Ruoke Ma

Background: As a transcription factor superfamily unique to plants, WRKY plays broad roles in both secondary development and secondary metabolic processes. Robinia pseudoacacia is renowned for its durable and naturally durable heartwood, which holds significant commercial value. However, their potential association with heartwood formation remains largely unexplored. Results: Leveraging published genomic data from Robinia pseudoacacia, we conducted a comprehensive bioinformatics analysis that identified 85 WRKY transcription factors. An uneven distribution across 11 chromosomes was observed for the RpWRKY genes, which were systematically named RpWRKY1 to RpWRKY85 according to their genomic locations, as determined by chromosomal localization. By conducting a phylogenetic comparison between RpWRKY and AtWRKY (from Arabidopsis thaliana), the RpWRKY family was categorized into three primary clades (I, II, and III), wherein group II was additionally partitioned into subgroups designated IIa through IIe. Conserved structural features and motif patterns were observed among members of each subgroup. Purifying selection was suggested by collinearity analysis as the primary evolutionary driver of RpWRKY, leading to structural and functional diversification. Finally, four candidate genes (RpWRKY78, RpWRKY45, RpWRKY50, RpWRKY80) potentially involved in heartwood formation regulation were identified through analysis of xylem tissue-specific expression patterns. Conclusions: For this economically important tree species, the present study not only provides the first systematic characterization of RpWRKY but also identifies potential regulators of heartwood development. Thus, the present study lays the groundwork for subsequent research aimed at uncovering the molecular processes that regulate heartwood development.

Forests doi: 10.3390/f17050608

Authors: Yujie Liu Jinde Ji Kaihong Xie Zhongyi Zhan Lihua Tao Tingwu Li Qi Jiang

Rapid detection of wilt-affected pine crowns in mountainous forests is hindered by occlusion, self-shadowing, and heterogeneous backgrounds in conventional nadir products. We evaluated whether oblique UAV RGB imagery improves crown-level detection relative to nadir imagery under matched site, season, sensor, and workflow conditions. The workflow was designed for rapid post-flight screening of geotagged UAV photographs. Paired nadir orthophotos and 45–70° oblique photographs were acquired over pine stands in Wenshan Prefecture, Yunnan, China, and organized into D1 (nadir), D2 (oblique), and D3 (simple mixed-view concatenation). Three YOLO11 detectors were trained for crown shoot damage ratio (SDR)-derived operational classes: early-stage (SDR < 50%), severely damaged (SDR ≥ 50%), and withered (needle-free dead crowns). A paired crown-level RGB subset (n = 20 crowns observed in both views) was analyzed as supporting evidence for view-dependent appearance differences. The oblique-image model (D2) achieved the highest validation performance, with precision of 0.994, recall of 0.991, F1-score of 0.989, mAP@0.5 of 0.995, and mAP@0.5:0.95 of 0.880. The paired subset showed a significant multivariate RGB profile difference between views (Hotelling’s T2 = 58.91, F = 3.10, p = 0.044), driven mainly by reduced Excess Green and greater dispersion of blue-related traits under oblique viewing. These results indicate that oblique UAV photographs retain additional crown-edge, lateral-structure, and chromatic context for detecting wilt-affected pine crowns. Oblique RGB imagery therefore provides a practical, low-cost input for rapid forest health surveillance and targeted field verification in rugged pine landscapes.

Forests doi: 10.3390/f17050607

Authors: Artemis Papafoti Dimitrios Tsioutsiourigas Marialena Argyraki Christos Astaras Nikolaos Markos Dionisios Youlatos

The forest dormouse (Dryomys nitedula) is a small, nocturnal, arboreal rodent widely distributed across Central and Eastern Europe. Yet, it remains one of the least studied European glirid species, with information on its ecology in southern populations being scarce. This study presents the first systematic investigation of the diel (24 h) activity patterns of D. nitedula in Greece. From March to December 2024, camera traps were deployed on trees facing branches or artificial nest boxes at 26 locations within a 30 ha forest–meadow mosaic in Northern Greece. Based on 958 independent detections at 22 sites, activity was highest at nest boxes and exhibited two nocturnal peaks that were consistent across seasons: a major one around midnight and a secondary one before sunrise. Temporal activity overlap between nest-box cameras and branch-facing cameras was high across all seasons. Activity, measured as the number of independent detections per night, was highest during short, humid nights with low levels of moonlight. Temperature and precipitation were not good predictors of activity levels. These findings confirm that the behavior of D. nitedula is predominantly nocturnal and reveal key environmental drivers shaping its activity in the Mediterranean region. Moreover, this study highlights the value of camera trapping as a non-invasive method for monitoring small arboreal mammals and provides essential baseline data for future ecological and conservation research on this understudied species.

Forests doi: 10.3390/f17050606

Authors: Jumi Cha Sunjeoung Lee Eunho Choi

Peatlands cover approximately 3% of the global land area but store about 44% of the world’s soil carbon, making them a major carbon sink. Indonesia alone accounts for about 37% of global tropical peat carbon stocks. However, large-scale carbon emissions caused by fires and drainage during past economic development have transformed peatlands from carbon sinks into carbon sources. In response, restoration efforts have been implemented at both international and national levels. Tropical peatland restoration typically includes rewetting, revegetation, and community-based approaches, highlighting the need for quantitative assessments of carbon storage under different restoration strategies. This study focuses on the Perigi peatland in South Sumatra, Indonesia. We conducted field surveys of vegetation and soils to estimate carbon stocks per unit area and developed time-series land cover maps using satellite imagery. Based on these data, we assessed potential carbon storage under different restoration intensity scenarios. The results show that carbon stocks in the Perigi peatland are lower than the Indonesian average. However, under a full restoration scenario, up to 950,259 tC of additional carbon storage is possible, indicating high restoration potential. In contrast, without restoration, further carbon emissions are likely, underscoring the necessity of restoration efforts. Effective restoration requires a phased strategy from vegetation recovery to peat layer recovery, combined with socioeconomic approaches that consider local livelihoods, enabling degraded tropical peatlands to function as effective carbon mitigation systems.

Forests doi: 10.3390/f17050605

Authors: Nsalambi V. Nkongolo Darceline A. Mokea Maria Luisa Fernandez-Marcos

Plant species can significantly influence soil micronutrients. We assessed how soil micronutrients (B, Fe, Cu, Zn, Mn) and aluminum (Al) were affected by soil depth (SD) and plant species (PS) in a secondary forest at Masako Forest Reserve. Soil samples were collected in June 2022 and June 2023 along five PS (Entandrophragma utile, Hevea brasiliensis, Milettia laurentii, Musanga cecropoides, and Triculia africana). Four trees (replications) were selected per plant species. A completely randomized design was used with five PS and three SD (0–10 cm, 10–20, and 20–30 cm) and was replicated four times. To collect soil samples, a pit was dug at each sampling location (near a tree), and three soil samples were taken horizontally in the middle of each layer on one of the four faces of the pit, with a 5 cm height and 5 cm diameter cylinder. Soil samples were air-dried, mixed, and sieved to 2 mm, and a 20 g subsample was sent to Brookside Laboratories (OH, USA) for analyses of soil micronutrients. The results showed that most micronutrients were concentrated in the topsoil (0–10 cm). Plant species such as Treculia africana, Millettia laurentii, and Musanga cecropoides enhanced micronutrients in the soil in which they grew, especially iron (Fe) and zinc (Zn). The effect of the year of sampling on micronutrients was prevalent for many micronutrients, which remained significantly higher in 2022 than in 2023. These findings provide a foundational framework for developing nature-based biofortification strategies. By prioritizing key native plant species, local stakeholders can optimize soil health in the Congo Basin.

Forests doi: 10.3390/f17050604

Authors: Bingcai Liu Brent Sohngen Justin S. Baker

To protect the endangered Northern Spotted Owl, the U.S. Fish and Wildlife Service established extensive conservation areas across the Pacific Northwest (PNW). While this policy effectively contributed to the preservation of an endangered species, it also generated significant short- and long-term impacts on the U.S. forestry market. This study investigates the impact of federal timber harvesting restrictions in the Pacific Northwest in the early 1990s on the U.S. softwood market, particularly on softwood planting in the South. By constructing and analyzing a panel dataset covering 537 counties in seven southern U.S. states from 1977 to 2007, the research finds that timber-harvesting restrictions triggered by the listing of the Northern Spotted Owl as threatened led to a significant increase in softwood planting rates in the Southern U.S. Previous studies have shown that set-asides can shift timber harvesting from one region to another and raise prices in the short term. This study illustrates a different outcome of set-asides: tree planting. We argue that accounting for long-term investment responses, such as tree planting, is critical when evaluating the impacts of forest policies, as these can significantly alter estimates of net carbon balance and overall market outcomes.

Forests doi: 10.3390/f17050603

Authors: Andrea Rosario Proto Stanimir Stoilov Stelian Alexandru Borz

Logging causes damage on residual trees, with differing characteristics and severities. The causal agent, as well as the size and type of injury, is influenced by the type of machines, the harvesting technology adopted, and the machine operator. This study descriptively documents residual tree damage observed in two sledge-yarding operations conducted under contrasting stand and operational conditions: a beech stand managed with a full-tree system and a Scots pine stand managed with a cut-to-length system. Two stands were selected: the harvesting intensity was 50% in the coniferous stand (salvage logging) and 20% in the deciduous stand (thinning). In each stand, six 20 × 20 m plots (0.04 ha) were delineated to assess residual tree damage. In the two observed cases, the beech operation showed a higher proportion of damaged residual trees, 32.2%, than the Scots pine operation, 5.3%. In the deciduous stand, bark injuries were mainly slight wood exposure (75%), whereas in the coniferous stand, crushed bark (42.9%) was most frequent, followed by slight wood exposure (35.7%). No concerning damage to seedlings was detected. In general, the number of damaged trees and the severity of injuries were considerably lower than those typically observed when extracting with a cable skidder, and especially with an adapted farm tractor. To reduce mechanical damage to residual trees, protective devices can be deployed around trees at risk of root and stem injury. Another effective measure is to financially motivate workers to implement environmentally sound forest operations.

Forests doi: 10.3390/f17050602

Authors: Aida López-Sánchez Juan Carlos López-Almansa Cristina Lucini María López Javier Velázquez

Agroforestry and perennial tree crop production systems, particularly in Mediterranean regions, exhibit a high degree of integration among trees, herbaceous, and soil components. They provide essential services including provisioning, regulation, support, and cultural services, which enhance human health, well-being, and economic stability. However, guaranteeing their long-term resilience in the face of environmental challenges, including drought and soil degradation, is essential for the sustainable management of these systems. We examine the impact of microsite conditions (soil and herbaceous layer) and their management on olive trees (Olea europaea L.) under varying levels of drought stress. A fully factorial design was implemented in a Spanish agroforestry system, combining two irrigation regimes (rainfed vs. summer irrigation) and two soil management practices (customary plowing vs. herbaceous layer conservation) across four independent and replicated zones. Twelve olive trees per zone were individually monitored, treating each tree as the experimental unit, with one 50 × 50 cm sampling plot per tree in which microsite conditions were characterized for each tree. Plowed areas (shallow tillage) showed lower industrial extraction yield (%), fat yield based on dry matter (%), olive maturity and phytosanitary status compared to areas conserving their herbaceous layer cover (0.81, 0.96, 0.92, and 0.65-fold lower, respectively). Rainfed areas (i.e., those without supplemental water supply) showed a reduction in both industrial extraction yield (%), olive yield (kg tree−1) and oil yield (kg ha−1) (0.77, 0.86 and 0.67-fold lower, respectively). Under combined tillage and water-deficit conditions, oil yield (kg ha−1), industrial extraction yield (%), and total phenolic content (ppm) were considerably lower (0.50, 0.60, and 0.67-fold lower, respectively). Furthermore, low quality of the herbaceous layer dominated by nitrophilous invasive species were associated with decreased leaf nutrient content, lower industrial extraction yield, reduced olive maturity and poorer phytosanitary status of olives. These findings suggest that maintaining a spontaneous herbaceous layer with a high-quality species (legume incorporation) and well-managed herbaceous cover, i.e., repeated mowing of the herbaceous layer instead of customary plowing, can enhance sustainable olive production by improving soil resilience, reducing water stress, and optimizing nutrient use, thereby supporting long-term ecosystem stability and agricultural productivity.

Forests doi: 10.3390/f17050601

Authors: Jinglin Liu Yuning Jia Chengliang Wu Yang Zhang

This paper uses a young fruiting body harvesting experiment to examine how uncertainty affects improper behavior and how two nudges, prior selection and consequence viewing, can mitigate or shape this behavior. Uncertainty promotes improper harvesting, with harvesting rates higher under ambiguity than under risk. It also induces belief bias, yet this bias drives behavior only when consequences are observable. Prior selection reduces harvesting through an anchoring mechanism, whereas consequence viewing alone has little effect. Notably, combining the two nudges produces a boomerang effect: harvesting rates rise above those observed under prior selection alone. These findings inform behavioral interventions for natural resource management.

Forests doi: 10.3390/f17050600

Authors: Christopher Hawkins Christopher Maundrell Jeffrey Beale

In northeast British Columbia (BC), Canada, industrial forestry is gradually converting 10+ M ha of broadleaf–conifer (mixedwood) boreal forest to conifer plantations. This is due in part to governmental free-to-grow (FTG) regulations, which specify a minimum competition-free radius around conifer crop trees. FTG implementation is a poor investment; it reduces stand biodiversity and productivity and infringes on Indigenous Treaty Rights. Trials were established on three geographically separated boreal sites with no stand management (brushing) since planting. The goal was to determine the effect of FTG criteria on conifer growth in mixedwoods compared to growth of pure conifer stands using the BC Government growth model TIPSY (Table Interpolation Program of Stand Yield) projections. At trial establishment, less than a third of trees were FTG. The number of FTG trees increased at the last measurement but only reached 50 percent on one site. After a decade, conifer DBH (diameter at breast height) growth and stand productivity met or exceeded the model projection regardless of the initial FTG status. The DBH relative growth rate (RGR) indicated that spruce DBH growth was not impacted by competitors. These observations suggest that brushing on similar sites to meet timber objectives is likely unnecessary. Maintaining mixedwood stands supports greater biodiversity and carbon storage, and this approach better aligns with an Indigenous world view and Treaty Rights. There is an opportunity in northeast BC to shift forest management from conifer-based performance metrics to prioritizing ecological resilience and long-term forest health and productivity.

Forests doi: 10.3390/f17050599

Authors: Yijing Lv Junyan Fan Deshuai Sun Suqing Li Shuyue Fang Cuiling Ye Xiaolan Li

As a typical mountain ecosystem in the western Tianshan Mountains, the Ili River Valley possesses abundant vegetation resources. Soil nematodes are effective biological indicators for evaluating soil micro-food webs. Nevertheless, the response mechanisms of nematode community structure to distinct vegetation types, especially native trees and forest-edge shrubs, remain poorly understood in this region. In this study, two dominant tree species (Picea schrenkiana and Malus sieversii) and two forest-edge shrub species (Berberis heteropoda and Berberis sibirica) were investigated. We analyzed the composition, diversity, and energy structure of rhizosphere soil nematodes and further compared their differences among plant species. The results indicated that tree rhizospheres had significantly higher amounts of nitrate nitrogen (NO3−-N and microbial biomass carbon (MBC), along with a lower amount of extractable organic carbon/extractable total nitrogen (EOC:ETN) than shrub rhizospheres (p < 0.05). Picea schrenkiana (PS) exhibited greater root carbon storage, higher root biomass, and a higher root carbon-to-nitrogen ratio (RC:RN) than Berberis heteropoda (BH) and Berberis sibirica (BS) (p < 0.05). The genus Chiloplacus dominated the nematode community across all four woody plants. The relative abundance of omnivore-predatory nematodes was markedly higher in shrubs (BH and BS) than in trees (PS and MS). The soil food webs of PS and MS were degraded, whereas shrub food webs were in a transitional state between structured and degraded habitats. Shrubs presented a higher maturity index, structural metabolic footprint, and energy flux of omnivore-predatory nematodes, but a lower energy flux of bacterivorous nematodes. Additionally, PS had the highest nematode carbon use efficiency (NCUE) and the lowest energy flux uniformity (U). NO3−-N extractable total nitrogen (ETN), soil organic carbon (SOC), and root traits were the primary factors driving variations in nematode communities and carbon indicators. Therefore, nematode carbon indicators closely associated with soil carbon and nitrogen cycling have the potential to serve as sensitive auxiliary biological metrics for evaluating material cycling and energy flow in pure forests and shrub ecosystems. This study provides empirical support for the assessment of regional ecosystem stability.

Forests doi: 10.3390/f17050598

Authors: Huayong Zhang Jianjun Guo Yihe Zhang Zhongyu Wang Zhao Liu

Quercus baronii Skan (Q. baronii) is an ecologically important tree species in arid and soil erosion-prone areas of northern China, and also holds significant potential as a bioenergy tree species, providing substantial ecological benefits. Global climate change has profoundly influenced the suitable habitats and habitat fragmentation of Quercus baronii forests. This study employed the Maximum Entropy (MaxEnt) model to project the current and future suitable habitats of Q. baronii forests, along with their trends of contraction and expansion. Concurrently, composite landscape indices were used to assess the fragmentation of these suitable habitats. The results indicate that the suitable habitats for Q. baronii forests are primarily located in the eastern part of Northwest China, the northern part of Central China, and the southern part of North China. Minimum temperature of the coldest month (bio6), annual precipitation (bio12), and temperature seasonality (bio4) emerged as the primary determinants of habitat suitability. Under three future climate scenarios, the centroid of suitable habitats for Q. baronii forests is projected to shift towards higher latitudes in the northwest, with the elevation of suitable habitats also gradually rising in tandem with increased carbon emissions. Under low carbon emission scenarios, the extent of suitable habitat for Q. baronii forests is expected to expand; under medium and high carbon emission scenarios, it is expected to first increase and then decline. Although over two-thirds of the suitable habitat for Q. baronii forests is projected to remain relatively intact, future suitable habitats are expected to be more fragmented compared to the present. This fragmentation is projected to intensify with increasing carbon emissions, primarily occurring at the edges of the suitable areas. The results of this study lay the groundwork for both the preservation of forest biodiversity and the ecological conservation and sustainable management of temperate broad-leaved forest ecosystems.

Forests doi: 10.3390/f17050597

Authors: Agata Kobyłka Natalia Korcz

Forests in Poland play a key recreational role, and the growing interest in sylvaturism requires optimized management. Despite the growing body of research on forest recreation, existing studies rarely address the role of small-scale infrastructure in shaping user preferences and its integration into spatial planning frameworks, which constitutes a research gap in this study. This study aimed to identify user preferences for small infrastructure and to develop an application-oriented, socially sensitive model for forest trail design that supports sustainable management. The research was conducted in 2021–2024 using the CAWI method on a group of 402 adult Poles. Data analysis included descriptive statistics, Pearson’s chi-square tests to assess demographic differences, and correspondence analysis to identify user preference profiles. The results not only confirmed a clear hierarchy of needs but also demonstrated that differences between user groups relate primarily to the intensity rather than the structure of preferences. A clear hierarchy of needs was confirmed, with route map boards (86.32%), educational boards (72.64%), and benches (71.14%) dominating. Based on the results, a modular design model was developed (modules: basic, comfort, accessibility, and activity), which constitutes a conceptual advancement over existing planning approaches by introducing a flexible, user-oriented framework that links social preferences with spatial decision-making. By integrating empirical social data into the planning process, the proposed framework extends current knowledge on recreation planning and provides a structured basis for adaptive forest trail design. This tool could help managers efficiently channel tourist traffic, protect ecosystems, and promote public health.

Forests doi: 10.3390/f17050596

Authors: Arijit Sinha Donald Devisser Aanisa Gani Jeff Hume Yuichi Sato Hideo Kato

This study evaluates the mechanical properties of Hinoki (Chamaecyparis obtusa) from Japan to determine reliable design values for its application as structural dimension lumber species in the United States. A comprehensive experimental program was conducted on 1464 (approximately 240 per grade/size) dimension lumber in-grade specimens sourced from prominent Hinoki-growing regions of Japan. These specimens were tested in bending, compression perpendicular to the grain, and horizontal shear. Tests were conducted, and the results were subjected to statistical analysis and adjustment factors to determine base reference values in accordance with ASTM International standards. The four-point bending tests showed moderate numerical variation across growing regions; however, one-way ANOVA confirmed no statistically significant regional effect on MOR or MOE. Compression parallel to grain and tensile strength were estimated from the MOR values using empirical relationships per ASTM D1990. The base design values after adjustments for 15% moisture content, specimen size, and volume effects fall within the expected range for high-quality structural species and support the acceptability of Hinoki as a load-carrying wood species. The results constitute the first complete, statistically verified dataset for Hinoki, and provide a basis for its use in wood design specifications such as the National Design Specification (NDS) for Wood Construction (NDS). Wider recognition of Hinoki as a viable structural species could expand its commercial use and support sustainable forest management practices in Japan.

Forests doi: 10.3390/f17050595

Authors: Angela Balzano Maks Merela

Urban trees are increasingly exposed to persistent anthropogenic drivers that extend beyond climatic forcing and fundamentally alter the conditions of secondary growth. While climatic controls of cambial phenology and xylogenesis are well established, the mechanisms by which non-climatic drivers regulate cambial activity and wood formation remain fragmented and are often inferred only indirectly. Here, we develop a cambium-centred framework to synthesise current evidence on how anthropogenic drivers shape wood formation in urban and peri-urban trees. To our knowledge, this is among the first syntheses explicitly linking anthropogenic drivers to distinct stages of xylogenesis. Anthropogenic drivers are typically chronic, spatially heterogeneous, and temporally decoupled from seasonal climatic rhythms, and may alter cambial kinetics and generate anatomical signatures not captured by ring width alone. We evaluate major driver domains, including root-zone constraints, altered hydrology, urban microclimate, pollution, salinity, and mechanical disturbance, while also considering emerging drivers such as artificial light at night and microplastics. Evidence is stratified into three levels: direct observations, indirect physiological evidence, and mechanistic plausibility. Across driver classes, three recurrent anatomical patterns emerge: reduced conduit size under hydraulic or osmotic stress; anomalies in wall deposition under carbon limitation or oxidative stress; and pronounced circumferential heterogeneity under spatially localised forcing. Integrative approaches combining xylogenesis monitoring, quantitative wood anatomy, dendrometer observations and spatially explicit sampling are essential to disentangle anthropogenic from climatic effects and improve assessment of tree resilience.

Forests doi: 10.3390/f17050594

Authors: Xiangyi Li Kexin Jin Yuxin Bai Guanhua Dai Xiaochun Wang

The response of tree growth to environmental (climatic) changes has largely been analyzed through ring width–climate relationships, yet such analyses often lack the dynamic process of radial growth in response to environmental changes. Therefore, this study focuses on Korean pine (Pinus koraiensis Siebold & Zucc.) and white birch (Betula platyphylla Sukaczev) at three elevations (750 m, 950 m, and 1150 m) in the broadleaved Korean pine forest on the northern slope of Changbai Mountains, China. We systematically monitored cambial activity and the dynamics of xylem formation stages to analyze the different adaptation strategies of the two species in terms of phenology, cellular characteristics, growth rates, and climatic responses during cambial and xylem formation stages. The results showed that the phenological stages of xylem formation in Korean pine were more sensitive to elevation, while the phenological changes in birch were smaller, indicating greater growth stability. The seasonal dynamics of the number of xylem cell layers in both species followed a unimodal or sigmoid curve, but high elevations significantly inhibited the number of mature cell layers. Gompertz model fitting revealed that the maximum growth rate of Korean pine decreased significantly with increasing elevation, whereas no significant change was observed in birch. With increasing elevation, temperature emerged as the primary factor influencing cambial phenology and growth duration in both species, while precipitation dominated changes in growth rates. Xylem growth in Korean pine was co-regulated by growth rate (R2 = 0.62) and growth duration (R2 = 0.35), with tracheid diameter closely related to the duration of expansion (R2 = 0.36). The regulatory pattern of xylem growth in birch was similar to that in Korean pine but with weaker correlations. In summary, Korean pine, as a coniferous dominant species, is more sensitive to temperature changes induced by elevation and adapts to elevational variations by adjusting phenology and cell development. In contrast, birch, as a broadleaved pioneer species, exhibits a high buffering capacity in xylem formation in response to elevational changes, thereby maintaining growth stability. The divergent growth strategies of the two species reveal the potential response pathways of temperate forest tree species to environmental changes and provide important insights for predicting the dynamics of broadleaved Korean pine forests.

Forests doi: 10.3390/f17050593

Authors: Eunjai Lee Sanghoon Chung Yongkyu Lee Sang-Tae Lee

Natural forest regeneration offers economic, ecological, and environmental advantages over artificial regeneration; however, its application is often constrained by uncertainties in stand development and management outcomes. Pre-commercial thinning (PCT), a key assisted natural regeneration practice, is widely used to regulate stand density and improve early stand development. Nevertheless, empirical evidence remains limited regarding how post-thinning residual density influences both tree growth and operational performance in high-density naturally regenerated Pinus densiflora stands. This study evaluated three residual density treatments (RD2000, RD3000, and RD5000) following PCT in naturally regenerated pine stands with an initial density of approximately 30,000 stems ha−1. Diameter at breast height, tree height, and crown area were monitored annually over three years, while thinning productivity and operational costs were quantified during treatment implementation. Residual density significantly affected both biological and operational outcomes. The intermediate residual density (RD3000) showed the most consistent growth responses, whereas the lowest residual density (RD2000) resulted in suppressed growth. The highest residual density (RD5000) achieved the highest productivity and lowest operational costs despite moderate growth performance. These results indicate a trade-off between growth performance and operational efficiency and suggest that an intermediate residual density may provide a balanced strategy for managing naturally regenerated pine stands.

Forests doi: 10.3390/f17050592

Authors: Fan Yang Yuwei Liu Xin Zeng Kaijun Yang Yu Tan Jiaping Yang

Wildfires severely disrupt soil nitrogen (N) cycling, yet the mechanisms driving this disruption in fragile karst forest ecosystems remain poorly understood. We investigated how wildfires affect soil N transformation dynamics and the microclimatic drivers of these dynamics in a karst forest. Using an in situ paired burned versus unburned plot design, we evaluated post-fire soil physicochemical properties, N fractions, and N-acquiring enzyme activities in the 0–10 cm soil layer. Wildfires significantly deteriorated the soil microenvironment, increasing mean soil temperature by 9.93% and bulk density by 36.66%, while sharply reducing soil water content, porosity, and saturated hydraulic conductivity. Consequently, the fires severely depleted total and organic soil N pools. Furthermore, N-acquiring enzymes (urease, protease, nitrate reductase, and nitrite reductase) initially declined in activity before gradually recovering. Notably, partial least squares structural equation modeling (PLS-SEM) revealed a fundamental shift in the drivers of nitrogen transformation. In unburned soil, abiotic climatic factors regulated N dynamics. After wildfire, enzyme-mediated biological processes controlled N dynamics, and these processes were constrained by altered soil physics. Restoring soil physical structure and stimulating enzymatic mineralization are therefore critical, rate-limiting steps for the recovery of soil N reservoirs in fire-prone karst landscapes.

Forests doi: 10.3390/f17050591

Authors: Jinjin He Yucheng Ding Zuxin Wang Wenxu Yue

The hot-pressing process for reconstituted bamboo suffers from issues such as insufficient process monitoring, scattered quality data, difficulties in quality traceability, and a lack of intuitive on-site management. This paper designs and implements a digital twin quality monitoring system tailored for the hot-pressing process of reconstituted bamboo. The system adopts an overall architecture combining a data acquisition layer, a business logic layer, and a display and interaction layer. It collects key data—such as on-site hot-pressing temperature, pressure, displacement, and equipment operating status—via PLCs and industrial communication interfaces. Based on Spring Boot and MySQL, the system handles data reception, storage, processing, and interface publishing. It integrates web pages and Unity 3D interfaces to enable basic information management, quality traceability, hot-pressing temperature monitoring, retrieval of prediction results, equipment status display, and operational data visualization. The system was deployed and validated at the enterprise’s hot-pressing production site. Test results indicate that the system continuously recorded hot-pressing process data for 2040s; the average synchronization delay between the physical end and the virtual model was 520 ms, with a maximum synchronization delay of 1360 ms and a 95th percentile synchronization delay of 910 ms, meeting the requirements for second-level monitoring and visual display of the hot-pressing process. Field application results demonstrate that the system can stably support data acquisition, quality information management, retrieval of predictive results, and digital visualization for the hot-pressing process of reconstituted bamboo, providing systematic support for quality monitoring, process traceability, and digital management of the hot-pressing process.

Forests doi: 10.3390/f17050590

Authors: József Garab Zsolt György Tóth Ahmed Altaher Omer Ahmed László Bejó

Screw withdrawal force is a key mechanical property related to the load-bearing capacity and reliability of mechanically fastened timber structures. This study investigates the screw withdrawal performance of cross-laminated timber (CLT) manufactured from spruce, beech, and poplar, including both homogeneous and hybrid layups. The selected species represent materials with different densities and regional availability in Hungary. A one-component polyurethane adhesive was used for panel manufacturing. Screw withdrawal force was determined using two methods: a universal testing machine (UTM) and a manual portable device (MPD). The highest withdrawal forces were observed in beech-based configurations, while the lowest values were measured for spruce. Poplar-based configurations demonstrated intermediate but competitive performance, exceeding the reference spruce values. Statistical evaluation confirmed a significant effect of layup configuration on withdrawal resistance. The MPD measurements were on average approximately 9% higher than UTM results, indicating a consistent and quantifiable inter-method difference. The results demonstrate that hybrid CLT configurations can be optimized by combining species of different densities and that portable testing methods provide reliable estimates of withdrawal performance. These findings contribute to the understanding of connection behavior in hybrid CLT and support the practical application of semi-destructive testing methods for in-situ assessment.

Forests doi: 10.3390/f17050589

Authors: Mariana Sedliačiková Marek Kostúr Mária Osvaldová

Family businesses represent an important part of the wood-processing and furniture industry and may play a significant role in sustainable forest-based development. This study aims to analyze how family businesses perceive selected external determinants of the microeconomic environment, assess the role of non-economic goals in their management, and propose a strategic framework for their sustainable development. The research was conducted in Slovakia through a questionnaire survey administered between August 2024 and May 2025. The final dataset included 507 valid responses, of which 432 businesses were identified as family businesses. The data were analyzed using non-parametric statistical methods, particularly the Kruskal–Wallis test and multiple comparison analysis. The results confirmed significant differences in the perceived importance of external determinants, with customers identified as the most important factor and intermediaries as the least important. The findings also showed that non-economic goals, such as sustainability and intergenerational continuity, are relevant, although not the most prominent characteristic. Relational factors, especially trust, reputation, and long-term relationships, play a more central role. Based on these findings, a conceptual strategic framework was developed using the Ishikawa diagram. The study highlights the role of family businesses in long-term competitiveness and sustainable forest-based development.

Forests doi: 10.3390/f17050588

Authors: Bobae Lee Hong-Duck Sou Seoncheol Park Chan-Ryul Park

Urban forests (UFs) are increasingly promoted as a nature-based solution for mitigating particulate matter (PM) pollution, yet their removal performance can vary depending on surrounding emission sources and environmental conditions. Here, we quantified the particulate matter reduction efficiency (PMRE) of UFs located near roads, industrial complexes, and urban areas, together with background forests in South Korea, based on field observations during the late autumn–spring period across two consecutive years (November–May in 2021–2022 and 2022–2023). We applied vector autoregression (VAR) to examine the dynamic relationships between PMRE and meteorological and air pollutant variables across eight representative sites. The results revealed that PM mitigation dynamics were strongly particle-size-dependent and context-specific. Across all sites, ΔPM10 RE was predominantly self-driven, explaining over 90% of its own variance, whereas fine-particle dynamics showed stronger interdependence. In particular, ΔPM2.5 RE consistently acted as a key mediator, accounting for up to 70%–80% of the variation in ΔPM1.0 RE depending on source context. Industrial-complex-adjacent UFs exhibited the strongest cross-variable interactions, while urban-core UFs were largely governed by intrinsic mitigation processes. Roadside UFs showed site-specific responses associated with CO and temperature variability. Notably, PMRE responses exhibited damped oscillation patterns across all source contexts, converging toward equilibrium over time, indicating stabilization of mitigation performance following disturbance events. These findings demonstrate that urban forest air-quality benefits are highly context dependent and governed by particle-size-specific dynamics. Our results provide evidence-based guidance for designing and managing urban forests, emphasizing the need for source-specific strategies and prioritization of PM2.5-oriented mitigation, particularly in industrial and roadside environments where fine-particle interactions are strongest.

Forests doi: 10.3390/f17050587

Authors: Elena Górriz-Mifsud Marc Rovellada Ballesteros Elisa Fernández Descalzo Adolfo Miravet Laura Ojalvo Ortega Ricardo Quiroga Aida Rodríguez-García Mariola Sánchez-González

Although Non-Wood Forest Products can offer interesting economic opportunities for rural communities, little is known about their commercial harvesters. Our work aims to shed light on the labour profiles, their accessibility to new entrants, and attractiveness for future green jobs. Through in-depth interviews, we explored the five-capitals profile of commercial resin, cork, mastic foliage, chestnut, pine nut, and wild mushroom harvesters in Spain. We found either freelance harvesters or entrepreneurs with a small gang. Our data show a typical male collector, who started the activity through his social networks (Social Capital), and whose origin depends on the product and Spanish region. Some commercial female harvesters were found in mushroom, chestnut and resin harvesting. Social constructs around the masculinization of these activities may explain their limited attractiveness for women. The ratio of non-Spanish commercial harvesters correlates with the weight of migrants in the analysed regions. Only a subgroup of resin harvesters devotes most of their year to this single activity. The rest complement NWFP income with a main forestry (cork and pinenut) or non-forestry occupation (mushroom, chestnut and mastic). For the latter products, access to Natural Capital was found to be crucial for job progress, as non-landowners require administrative and/or negotiation capacities to secure harvesting permits. Human Capital differs across NWFPs, from simpler skills such as recognising marketable produce and handling easy tools (mushroom, chestnuts, pine nut ground gathering and mastic), to complex abilities needed to balance efficiency with minimising tree damage (in resin tapping, pinenut shaking, and cork extraction). Such specialised tools and machinery (Built Capital) typically act as a barrier to entry and advancement. These profiles are expected to help decision-makers to design instruments promoting and regulating commercial harvesting, and tackle their risks: local landowners in allocating harvesting rights to external collectors; regional policymakers as competent authorities in forest legislation; and state-level administration concerning cultural, fiscal and labour-permit aspects.

Forests doi: 10.3390/f17050586

Authors: Jean A. Magalhães Margarida Tomé

Stand-level canopy base height (Cbh) is a key variable controlling crown fire initiation, yet it is commonly computed as the mean of tree height to the base of the crown (hbc), which does not reflect the lower portion of the hbc distribution governing the transition from surface to crown fire. This study investigates the relationship between physically based Cbh definitions and the hbc distribution. We develop a general multi-percentile modeling framework to estimate hbc percentiles at the stand level. Using a dataset of Pinus pinaster Aiton trials in Portugal, percentile-specific models (5th to 50th) were fitted and synthesized into a nonlinear multi-percentile formulation. Results show that the height at which canopy bulk density exceeds the critical threshold does not match mean hbc, but instead corresponds to lower percentiles, typically around the 10th percentile, varying with stand structure and age. Mean-based Cbh tends to overestimate the lower canopy boundary, reflecting its inability to capture structural variability. The final model predicts hbc at any percentile and incorporates effects of stand height, basal area, tree density, and age, ensuring positive predictions and high predictive accuracy (adjusted R2 = 0.9770; RSE = 0.4073 m; PRESS R2 = 0.9769). The framework provides a consistent representation of canopy base height for fire behavior modelling.

Forests doi: 10.3390/f17050585

Authors: Yiwen Ji Lei Zhang Chuntao Li Xinchen Gu

Non-built-up green areas are essential for preserving the ecological functions of cities and fostering sustainable growth. Focusing on Shanghai, we developed a comprehensive framework of driving forces that integrates socioeconomic, natural, policy, and financial indicators. To assess the spatial-temporal changes in regional green space configurations and their underlying mechanisms between 2000 and 2020, we utilized stepwise regression alongside Geographically Weighted Regression (GWR) techniques. The results show that regional green space exhibited a clear stage-dependent evolution, with the total area decreasing from 580.56 km2 in 2000 to 506.43 km2 in 2005 and then increasing continuously to 905.70 km2 in 2020. Forest land consistently expanded and became the dominant land type, while wetland showed a “decrease–increase” pattern and grassland experienced an early decline followed by partial recovery. The primary elements driving these changes underwent substantial transformations over the study period. During the initial phase, socioeconomic variables, particularly real estate investments (β = −0.296), demonstrated pronounced adverse impacts. Conversely, post-2005, financial allocations for landscaping and policy interventions emerged as the main favorable drivers (β = 0.598). Furthermore, environmental aspects like NDVI and waterway density provided a continuous positive influence on green space enlargement. Certain socioeconomic indicators, notably population density, transitioned from exerting adverse impacts to having beneficial effects during the latter periods. The primary drivers demonstrated considerable spatial variation; socioeconomic impacts were largely localized in regions undergoing urban growth, whereas environmental and policy variables exerted broader and more consistent influences. Overall, these outcomes highlight a shift from a socioeconomic-dominated evolutionary process to one governed by a synergy of multiple factors. This offers a theoretical foundation for refining urban ecological strategies and harmonizing city expansion with ecological conservation.

Forests doi: 10.3390/f17050584

Authors: Luis Alejandro Acosta-Martínez Solhanlle Bonilla-Duarte Ulises J. Jauregui-Haza

The accelerated growth of cities has intensified interest in the ecosystem services provided by urban forests, increasingly conceptualized as socio-ecological systems (SESs). This study presents a structured narrative review combined with bibliometric analysis of research published between 2010 and 2025 to examine how urban forests are addressed in relation to ecosystem service provision and climate change adaptation. The literature search and screening process followed procedures informed by the PRISMA framework to enhance transparency in the identification and selection of relevant studies. The results reveal a marked increase in scientific production during the last decade, with approximately 70% of publications concentrated in five countries: the United States, China, Italy, Canada, and Brazil. Although research methodologies are diverse, a strong bias toward quantitative ecological models—particularly tools such as i-Tree—persists, often prioritizing carbon sequestration while overlooking social dimensions of urban forest governance. A key finding is the disconnect between objectively modeled ecosystem services and the benefits perceived by citizens, which may influence the long-term sustainability and acceptance of urban green infrastructure. In addition, emerging research highlights the importance of considering ecosystem disservices, such as allergenic pollen, infrastructure conflicts, or maintenance costs, within urban forest planning. Finally, the review identifies a significant research gap in Latin America and the Caribbean, where rapid urbanization requires context-specific socio-ecological approaches. Advancing urban forest management therefore requires transdisciplinary frameworks that integrate ecological processes, social perception, governance, and climate adaptation to support more resilient and equitable cities.

Forests doi: 10.3390/f17050583

Authors: Qiuyi Wang Zhuchao Xu Han He Xinzhou Wang Yanjun Li

Bamboo flattening technology provides an efficient approach for improving bamboo utilization, but the heterogeneous stress response and the mechanism of bamboo nodes during the flattening process remain insufficiently understood. In this study, a universal mechanical testing machine equipped with a temperature-controlled chamber was used to simulate the stress state during the flattening process. The effects of different heat treatment temperatures on the transverse mechanical response and chemical properties of different layers of bamboo internodes and nodes were systematically investigated. The results showed that at room temperature, the transverse strength of bamboo exhibited a gradient characteristic of outer layer bamboo (OB) > middle layer bamboo (MB) > inner layer bamboo (IB). Nodes showed higher transverse strength than internodes. As the temperature increased, the transverse properties of all layers significantly declined, with transverse tensile strength showing higher sensitivity. The IB exhibited the poorest thermal stability. Chemical analysis revealed the continuous degradation of cellulose and hemicellulose, while the relative lignin content and relative crystallinity of cellulose increased. This study clarifies the mechanism of heat treatment temperature on the physicochemical characteristics of different parts of bamboo, providing a scientific theoretical basis for temperature control in the industrial production of crack-free flattened bamboo boards.

Forests doi: 10.3390/f17050582

Authors: András Csótó József Csajbók Tamás Ábri Károly Pál Andrea Zabiák Kata Mihály István Attila Kocsis Erzsébet Sándor

Black locust (Robinia pseudoacacia L.) has exceptional growth capacity in nutrient-poor environments and is therefore widely used for afforestation and land reclamation on degraded soils. However, drought stress can restrict sapling growth, which undermines the success of their establishment. The effect of a product containing two endophytic strains (Trichoderma afroharzianum P. Chaverri, F.B. Rocha, Degenkolb & Druzhinina TR04 and Trichoderma simmonsii P. Chaverri, F.B. Rocha, Degenkolb & Druzhinina TR05) was studied on a black locust sapling stand under severe drought in eastern Hungary. The two-year-old saplings were root-soaked before planting in sandy soil. The growth of Trichoderma-treated plants improved by late spring. Compared to the control trees, average height increased by 25.75%, and root collar diameter was 21.96% larger. Treated plants also showed 9.1% higher chlorophyll content and 11.1% Normalized Difference Vegetation Index (NDVI). The reduced intercellular CO2 concentration, together with slightly lower stomatal conductance and increased transpiration rate, suggests tighter stomatal regulation and altered water-use dynamics under drought conditions. These responses indicate improved short-term drought acclimation rather than enhanced carbon assimilation capacity. Pre-planting inoculation with endophytic Trichoderma strains provides a sustainable method to enhance the early establishment and drought resilience of black locust, thereby increasing the efficacy of forest restoration by improving the survival of black locust on challenging degraded sites.

Forests doi: 10.3390/f17050581

Authors: Hantao Wu Zhongke Qu Yan Qu Yongbiao Ji Shaohui Zhang Huiwen Li

Soil organic carbon (SOC) is pivotal to the terrestrial carbon cycle and climate regulation, yet its spatiotemporal dynamics and future climate responses across soil layers remain insufficiently understood in mountainous ecosystems. Taking the Qinling Mountains, a typical mountainous ecological barrier in central China with a total area of approximately 38.18 × 104 km2, as the study area, we analyzed historical SOC changes (1980s–2010s) and projected its future dynamics under different scenarios using a validated Random Forest model (R2 = 0.81 for 0–20 cm, SOC20; 0.73 for 0–100 cm, SOC100), and further disentangled dominant drivers. Results showed historical mean SOC density increased, with higher storage in western/central high-elevation zones and lower values in southern/eastern low-elevation areas. Climate was the primary driver of SOC20 dynamics, while SOC100 was jointly regulated by climate, vegetation, and environmental factors, indicating weakened climatic control with increasing soil depth. Precipitation increases partially offset warming-induced SOC loss, leading to small changes in regional mean SOC density, but strong spatial heterogeneity resulted in substantial total SOC stock losses (SOC20: −1.41 to −6.59 Tg C; SOC100: −6.86 to −28.76 Tg C), with net losses in high-elevation zones and gains in low-elevation areas. SOC within the whole 1 m soil profile exhibited larger climate-driven changes than topsoil. These findings advance understanding of SOC dynamics in complex mountainous ecosystems and provide key scientific insights for regional carbon cycle assessments under climate change.

Forests doi: 10.3390/f17050580

Authors: Zhimin Feng Huiqiang Wang Ruiping Li Xiangwei Meng Liying Zhou Xiaoming Ma

Conventional Interferometric Synthetic Aperture Radar (InSAR)-based sub-canopy topography retrieval models often suffer from insufficient characterization of scattering mechanisms, strong nonlinearity, and poor parameter convergence. To address these issues, this study proposes an improved Interferometric Water Cloud Model (IWCM) that integrates Fractional Vegetation Cover (FVC) to retrieve sub-canopy topography. The proposed method accounts for both volume and ground scattering and introduces FVC as a constraint to improve the model’s physical realism. In addition, this study utilizes InSAR observations derived from TanDEM-X dual-baseline data, which enhance the information content of the measurements by providing multiple independent interferometric observations. A two-step nonlinear least squares optimization strategy is further employed to enhance the convergence of model parameter estimation. The proposed method was validated in the forested region of Genhe City, Inner Mongolia. Airborne LiDAR-derived surface elevation data were used for assessment. The results indicate that, compared with the original InSAR-derived Digital Elevation Model (DEM), the accuracy of the retrieved sub-canopy topography improves by 39.04%. Furthermore, compared with the previously proposed Normalized Difference Vegetation Index (NDVI)-based method, under their respective optimal initial extinction coefficient conditions (μ0), an additional accuracy improvement of 11.69% is achieved. These results demonstrate that the proposed method effectively reduces the influence of the forest canopy on interferometric phase observations and improves the capability of sub-canopy topography reconstruction in complex forest environments. The method also provides a new approach for dual-baseline and multi-baseline InSAR-based sub-canopy topography retrieval.

Forests doi: 10.3390/f17050579

Authors: Yonghua Zhang Chanjuan Lai Xi Liu Yunpeng Zhao Zupei Lei

Broussonetia monoica (Moraceae) is an ecologically, medicinally and economically valuable species but lacks adequate molecular resources for genetic studies. Here, we developed the first set of expressed sequence tag-derived simple sequence repeat (EST-SSR) markers for B. monoica and applied them to characterize genetic diversity and Broussonetia species relationships. Transcriptome sequencing of B. monoica generated 185,167 unigenes, from which 8921 candidate polymorphic EST-SSRs were mined. Twenty-one primer pairs (21/27, 77.78%) were successfully validated across 100 B. monoica plants. Cross-species transferability was high (14/18, 77.78%), enabling comparative analysis revealing significant genetic differentiation among the Broussonetia species (FST = 0.284). Seventeen polymorphic loci revealed moderate to high genetic diversity in six B. monoica populations, with significant population structure (FST = 0.119) and sub-structuring into three clusters. Bayesian clustering, principal coordinate analysis, and neighbor-joining trees consistently resolved three Broussonetia species boundaries. These novel EST-SSRs provide robust tools for population genetics, germplasm conservation, and molecular breeding in Broussonetia species, addressing a critical resource gap for this genus.

Forests doi: 10.3390/f17050578

Authors: Shaopeng Zhang Hongge Zhu

For researchers in the forestry field, a holistic, multi-dimensional perspective undoubtedly represents the most compelling approach for analyzing modern forestry production and development [...]

Forests doi: 10.3390/f17050577

Authors: Shuna Dong Xinbo Zhou Yufen Yu Ying Guo Yongcun Fu Jiquan Zhang

Against the background of ecological civilization construction and the transformation of state-owned forest regions after the logging ban, balancing economic development with ecological protection has become an important issue in China’s forest areas. The development of the non-timber forest-based economy plays a critical role in advancing high-quality, green economic growth in China and contributes significantly to sustainable resource utilization. This study examines data from key state-owned forests and the natural environment in the Changbai Mountain region of Jilin Province from 2013 to 2023. A comprehensive evaluation model and a coupling coordination model, based on the human–land relationship framework, are employed to assess temporal changes in economic growth quality, ecological environment carrying capacity, and their coupling coordination. The quality of non-timber forest-based economic growth exhibited an overall upward trend. Fusong County, Wangqing County, and Dunhua City consistently maintained high levels, while Helong City experienced the largest decline. The spatial distribution followed a “high center, low periphery” pattern, with the 2015 logging ban serving as a key turning point in promoting ecological transformation. The per capita ecological environment carrying capacity improved across the region, with significant increases in Dunhua, Helong, and Antu Counties. A radial decline from the central to peripheral areas was observed, with the highest values in Wangqing and Antu Counties. The coupling coordination degree between economic growth and ecological environment fluctuated between 0.4 and 0.6. In 2023, Wangqing County reached a state of intermediate coordination (index > 0.7), whereas Linjiang remained in a dysfunctional state (index < 0.5). Spatial clustering of coordination weakened over time, as indicated by Moran’s I values of 0.32, 0.21, and 0.09 in 2013, 2018, and 2023, respectively. These findings provide a quantitative foundation for promoting the coordinated development of human–land systems and guiding high-quality regional growth in forest-based economic zones.

Forests doi: 10.3390/f17050575

Authors: Hadi Mahmoudi Meimand Jiaxin Chen Daniel Kneeshaw Changhui Peng

Monitoring boreal above-ground biomass (AGB) change requires approaches that are both measurement-based and spatially explicit. We integrated permanent sample plots from Quebec and Ontario with Landsat-7 spectral trajectories (1999–2023) to quantify non-fire-related AGB change after excluding wildfire-affected intervals and to evaluate whether annualized AGB change can be predicted from spectral change at the plot-interval scale. Tree height was estimated using a multilayer perceptron model (R2 = 0.83) and combined with species-specific allometry to derive plot-level AGB and interval ΔAGB. These estimates were aggregated to ecodistricts using effective sample sizes and confidence intervals. Across well-sampled ecodistricts, mean annualized ΔAGB ranged from −0.82 to +3.54 t ha−1 yr−1, with lower or negative changes mainly occurring in eastern regions. Spectral indices derived from NIR–SWIR bands showed relatively stronger associations with ΔAGB than greenness-based indices, consistent with the sensitivity of moisture- and disturbance-related metrics to canopy stress, including defoliation. An XGBoost ensemble correctly predicted the direction of change in 77% of intervals. These results provide a measurement-constrained and scalable framework for monitoring non-fire-related biomass change and supporting greenhouse-gas reporting across boreal forest landscapes.

Forests doi: 10.3390/f17050576

Authors: Xingyue Lan Zhongxuan Huang Jiaoling Wu Haotian Duan Lixin Chen Junhao Wu Jingwen Peng Kuangji Zhao Guirong Hou Xianwei Li

Accurate prediction and assessment of carbon storage are crucial in the context of global climate change. However, existing research has largely focused on large-scale regions, while studies on small-scale ecologically fragile alpine regions remain insufficient. This study focuses on Zoige County, integrating the PLUS model, InVEST model, and Random Forest model to form a composite analysis workflow. Through this workflow, we simulated the distribution of land use types in 2030 and quantified carbon storage from 1990 to 2030, subsequently analyzing their spatial distribution and driving factors. The key findings include: (1) Under the natural development scenario (NDS) and the ecological protection scenario (EPS) for 2030, the primary land use transition involved the conversion of grassland to forest and wetland. Conversely, wetland was converted into cropland under the economic development scenario (EDS). (2) Under the NDS, EDS, and EPS, carbon storage would be 8.396 × 107 t, 8.252 × 107 t, and 8.432 × 107 t, respectively. The EPS yielded the largest increase in carbon storage. (3) In all three scenarios, carbon storage showed a clustered distribution. Compared with 2020, the carbon storage hot spot areas under both NDS and EPS showed an expansion trend, whereas the cold spot areas also expanded in three scenarios. (4) The key drivers of carbon storage include slope, elevation, soil type, and mean annual temperature. This study concludes that the EPS represents the most favorable development pathway for carbon storage accumulation. This finding can provide a basis for future carbon storage dynamics and land use planning for Zoige County.

Forests doi: 10.3390/f17050574

Authors: Jiaxin Zhang Hao Li Hongwen Ma Aining Li

Poplar (Populus spp.) canker severely threatens poplar shelterbelt stability in Wuwei, Gansu. Field experiments were conducted from 2024 to 2025 to screen 16 single fungicides and 10 compound formulations via spray and smearing, using lesion inhibition and callus formation rates as core criteria, and establish a precise hierarchical control scheme. Results showed preventive agents (300-fold Bordeaux mixture, 45% lime sulfur mixture) achieved >75% control efficacy. 43% tebuconazole and 1.8% xinjunamine acetate had the strongest bacteriostatic effects, while compound systems combining fungicides, penetrants and immune inducers showed >88% efficacy. A four-grade precise control strategy was finally established, providing technical support for eco-friendly poplar canker control in arid Northwest China.

Forests doi: 10.3390/f17050573

Authors: Qinmin Lin Yingxin Wen Cunyi Tan Yifan Wu Zijie Lin Shujie Lin Zekai Ding Xinghao Tang Shijiang Cao Zhenzhen Zhang Yankong Zhu

Phoebe bournei is a rare and economically valuable tree species native to China that plays an important ecological role. In this study, we conducted a genome-wide identification of the SQUAMOSA promoter-binding protein (SBP) transcription factor family in Phoebe bournei and characterized 19 PbSBP genes distributed across 10 chromosomes. Phylogenetic analysis grouped these genes into five distinct subfamilies, each of which showed homology to SBP genes in Arabidopsis thaliana and Oryza sativa, indicating strong evolutionary conservation within the family. All identified PbSBP proteins contain the conserved SBP domain, and some members also harbor additional motifs such as the ANK domain, which may mediate protein–protein interactions. Tissue-specific expression profiling revealed that several PbSBP genes are predominantly expressed in root bark and leaves, suggesting their potential roles in defense responses and developmental regulation. Moreover, qPCR validation showed that PbSBP2, PbSBP9, and PbSBP16 were significantly upregulated under PEG-induced drought stress, implying their involvement in abiotic stress responses. This study provides a foundational understanding of the SBP gene family in P. bournei and highlights candidate genes for future genetic improvement and breeding for stress resistance.

Forests doi: 10.3390/f17050572

Authors: Aleh Marozau Sławomir Piętka Piotr Borowik Konrad Wilamowski Ewelina Bagińska

This study assessed phenotypic variation among open-pollinated half-sib families from a single relict population. Autochthonous silver fir (Abies alba Mill.) preserved in the Tisovik Reserve of Białowieża Forest represents the northeasternmost isolated relict population of the species in Europe. To secure its genetic resources and evaluate its breeding potential, a conservation plantation of open-pollinated half-sib families was established in the Hajnówka Forest District outside the natural species range. This study assessed the effects of half-sib family affiliation on the growth and phenotypic performance of almost two thousand 28–31-year-old trees representing 20 half-sib families and compared them with age-matched managed stands in the State Forests of Poland. Significant within- and among-family variation was observed for diameter at breast height (DBH) and height (H), while environmental factors had only marginal influence under the uniform site conditions of the plantation. Several half-sib families produced disproportionately high numbers of individuals with exceptional phenotypic performance, including DBH values exceeding 25 cm and height values surpassing those of managed stands. Based on a combined assessment of qualitative traits, selection differential, and 95th percentile values, 30 prototype plus trees were selected as sources of scions for establishing a future seed orchard. The outstanding growth parameters of these individuals correspond to stand ages of 40–65 years according to yield tables, despite their biological age of only 28–31 years. The results confirm the high breeding value and substantial genetic variability of the Tisovik population and demonstrate its potential for producing genetically diverse planting material adapted to lowland sites under changing climatic conditions.

Forests doi: 10.3390/f17050571

Authors: Raffaele Spinelli Natascia Magagnotti Pietro Gallo Marcello Biocca

Abandoned and semi-abandoned chestnut (Castanea sativa Mill.) orchards can be restored to production by removing invasive vegetation and pruning overgrown crowns. Both interventions stimulate a strong reaction from the old trees, which sprout abundant suckers at the root collar and along the stem. Suckers must be removed promptly to boost fruit-bearing branches. Sucker removal can be achieved with traditional manual tools (e.g., pruning saws or pole saws) or with more modern semi-mechanized methods relying on battery-powered saws. The latter are much more expensive than the former and questions arise regarding the minimum amount of work necessary to justify their purchase. This study compared the two methods, showing that the introduction of a battery-powered saw would boost work productivity by 67%, that is, from 18 to 31 trees per day. At current cost levels, that productivity margin would justify investment in a semi-mechanized system when treating at least 100 trees per year. In that case, the de-suckering cost would amount to 3.8 and 3.9 € tree−1 respectively for semi-mechanized and manual systems. Shifting from manual to semi-mechanized operation also resulted in a significant reduction in the physiological workload imposed on the workers, which would decrease by −4% to −71% depending on the circumstances. Productivity and workload variations followed the same trend, but their magnitude was highly dependent on the individual worker.

Forests doi: 10.3390/f17050570

Authors: Jifeng Deng Yueyao Li Yifan Wang Chang Sun Yanfeng Bao

In this study, natural Pinus koraiensis Siebold & Zucc. forest, Pinus sylvestris var. mongholica Litv. plantation, Quercus mongolica Fisch. ex Ledeb. plantation, Juglans mandshurica Maxim. plantation, and natural mixed coniferous–broad forests were selected in Qingyuan County. Treeless plots were set as the control check, and comparisons were then made across soil particle size composition, average particle size, standard deviation, skewness, kurtosis, single- and multifractal dimensions, and spatial distribution of soil physicochemical properties and their relationships with fractal dimensions under natural conditions. The results indicated the following: (1) The soil particle size compositions of both the topsoil and sub-topsoil in all forest stands were dominated by sand. (2) The soil particle size was characterized by excellent sorting, skewness, and a narrow peak. (3) The average particle size, single-fractal dimension, and soil physicochemical properties of the forest stands were all higher than those of the control check plots. (4) From coniferous forests to broadleaved forests and then to mixed forests, the aforementioned soil indices showed an overall increasing trend. (5) The single-fractal dimension and capacity dimension were significantly positively correlated with the volume fractions of clay and silt, as well as with soil physicochemical properties. This indicates that the contents of soil clay and silt gradually recovered under the protection of forest stands, with a better recovery effect in the topsoil. (6) Multifractal analysis showed non-uniform soil particle size distribution; thus, evaluating soil quality requires combining single- and multifractal dimensions to characterize physicochemical properties and particle size variation.

Forests doi: 10.3390/f17050569

Authors: Julia Zabala-García Guzmán Carro-Huerga Andrea Antolín-Rodríguez Víctor Marcelo Marcos Guerra Pedro A. Casquero Andrés Juan-Valdés Lucía Delgado-Salán Álvaro Rodríguez-González

The holm oak (Quercus ilex) is a keystone species in Mediterranean ecosystems due to its ecological relevance and economic value. However, its forests are experiencing increasing decline driven by poor regeneration, prolonged drought, diseases, and wood-boring insect infestations. This study evaluates the impact of Coraebus florentinus on the mechanical properties of holm oak wood. Laboratory bending tests on healthy and insect-damaged branches assessed resistance in relation to applied load, diameter, and length until maximum deflection and breakage. Results showed that C. florentinus damage (considered as a categorical variable, it was not quantified based on the presence or absence of visible symptoms and characteristic larval galleries, and we acknowledge this as a limitation of the study) altered the bending behavior of holm oak branches, mainly by reducing deformation capacity before failure. However, bending strength showed a site-dependent response, indicating that the mechanical effect of infestation may vary according to local branch characteristics and damage distribution. Infestations of C. florentinus in Q. ilex stands, whether used for timber production or pasture systems, may contribute to the loss of photosynthetically active branches and potentially affect tree productivity.

Forests doi: 10.3390/f17050568

Authors: Arzuv Allayarova Hongge Zhu

This research explores how livelihood capital endowments affect the growth of Non-Wood Forest Products (NWFPs) in rural communities in the Koyten Dag region of Turkmenistan. This study is grounded in the Sustainable Livelihoods Framework. It draws on the Capability Approach, Institutional Theory, and Human Capital Theory, which are considered to have a strong influence on NWFP development within the exclusive post-Soviet socio-ecological environment. This study also uses annual time-series data from 2001 to 2024. It applies the ARDL bounds testing method to examine the short- and long-run associations among livelihood assets and NWFP production. The results confirm strong long-run co-integration, indicating that the five capitals have a significant impact on NWFP development. Emerging as the ultimate drivers in both the short and long term, education, skills, health, and digital connectivity become especially important. Financial and social capital reflect long-term contributions, while natural capital highlights the significance of the availability of ecological resources and governance systems. The correction error term indicates a rapid rate of adjustment, suggesting that the livelihood system is robust and can return to equilibrium quickly in response to temporary shocks. This research uses the Autoregressive Distributed Lag (ARDL) method of co-integration, which is effective for small-sample analyses of long-run relationships. The empirical analysis is conducted in a systematic process, which is the unit root tests based on augmented Dickey–Fuller (ADF) and Phillips–Perron (PP) techniques, in order to establish the order of integration of variables. The Akaike Information Criterion (AIC) is used to determine the appropriate lag length for the ARDL model to achieve the best model specification. In the robustness analysis, we perform fully modified OLS (FMOLS) and dynamic OLS (DOLS) estimation. Sub-period analysis was performed to test structural breaks. The variance inflation factor (VIF) test was used to detect multicollinearity. This paper has significant theoretical and practical implications, including the need for policies that are integrative and, at the same time, enhance human capabilities, digital infrastructure, institutional quality, and resource governance. This knowledge can be used to promote the sustainable development of rural areas and as an efficient approach to the NWFP sector in Turkmenistan.

Forests doi: 10.3390/f17050567

Authors: Domena A. Agyeman Thomas O. Ochuodho Omkar Joshi

Closely related industries are often aggregated in US forest sector economic contribution analysis, yet the choice of aggregation scheme can influence results. The Impact Analysis for Planning (IMPLAN) system is the most widely applied input–output model for forest economic contribution analysis in the US. In IMPLAN, the level of industry aggregation determines which inter-industry transactions are restricted, thereby influencing the magnitude of estimated indirect and induced effects. Although IMPLAN practitioners can model individual industries to avoid aggregation bias, they must still decide whether to analyze forest industries as a single group, as traditional subsectors, or individually. This decision can alter estimated economic contributions and the conclusions drawn from them. This study evaluates how three aggregation approaches affect economic contribution estimates for the Kentucky forest sector: analyzing all forest industries as a single group, as six traditional subsectors, and individually. Direct contributions were identical across all approaches. However, indirect and induced effects differed significantly between the single-group approach and both the subsector and individual-industry approaches. These differences indicate that aggregation is not simply a reporting choice but has measurable, systematic effects on contribution estimates. Clear specification and justification of aggregation choices are therefore essential in forest economic contribution analysis.

Forests doi: 10.3390/f17050566

Authors: Ivan Milenković Ana Žugić Slobodan Milanović Jovan Dobrosavljević Milan Milenković Vanja Tadić

Phytophthora species are devastating oomycete pathogens affecting agriculture, horticulture, and natural ecosystems globally, primarily spread through the international trade of nursery stock. While synthetic fungicides remain a primary control method, there is an increasing demand for sustainable biocontrol agents. This study evaluated the inhibitory potential of essential oils from three Cupressaceae species, × Hesperotropsis leylandii (needles), Platycladus orientalis (needles), and Juniperus communis (ripe berries), against four common nursery and forest pathogens: P. cactorum, P. plurivora, P. pseudocitrophthora, and P. × cambivora. The essential oils were evaluated at concentrations of 0.1%, 0.25%, and 0.5% (v/v), while the commercial fungicide Infinito® (propamocarb + fluopicolide) served as a positive control. Results demonstrated significant dose-dependent inhibition across all treatments, with the 0.5% concentration yielding the highest efficacy. Notably, essential oil from J. communis achieved 90.2% inhibition against P. × cambivora, while Pl. orientalis essential oil reached 82.8% and 73.1% inhibition relative to the Infinito® effect against P. × cambivora and P. cactorum, respectively, underscoring the potential antimicrobial properties of these coniferous essential oils compared to the tested synthetic standard. Although the chemical analysis revealed that all investigated essential oils (× H. leylandii, Pl. orientalis, and J. communis) contained significant quantities of α-pinene (32.11, 16.01, and 32.29%, respectively), their chemical compositions differed. Namely, GC analysis revealed the presence of δ-3-carene in × H. leylandii and Pl. orientalis (18.51 and 37.98%, respectively), while cedran-8-ol was detected in significant quantity in Pl. orientalis (19.96%). Sabinene and myrcene (18.52 and 14.57%, respectively), besides α-pinene, were most abundant in J. communis essential oil. The observed differences in the evaluated activity might be due to the determined essential oils’ chemical composition.

Forests doi: 10.3390/f17050565

Authors: Didik Suprayogo Arif Firmansyah Muhammad Al-Faruqi Desca Wahyu Ramadhan Istika Nita Kurniatun Hairiah Meine van Noordwijk

Pine plantations on volcanic slopes in Indonesia are considered to be forests and are managed for wood production and slope protection. Logging practices followed by replanting may affect soil health. Existing agroforestry management contracts allow farmers to intercrop with vegetables in young plantations and grow fodder grasses in older ones. However, critical data on hydrological functions in such systems are scarce, while concerns over heavy rainfall and floods increase. We explored the relationships between soil cover, soil carbon, earthworms, soil porosity and infiltration rates in relation to slope class in second-rotation pine plantations around two years of age (intercropped) and at ten-year old pine-grass stages. Five slope classes (0%–8%, 8%–15%, 15%–25%, 25%–45%, and >45%) were compared with three measurement points each. Basic soil chemical and physical characteristics were measured for the 0–10, 10–20 and 20–30 cm layers. Remnant natural forest was available as a historical reference only on the steepest slope class. Organic soil carbon (COrg) divided by a texture-based reference level was 1.12, 0.32 and 0.49 for natural forest, young and old agroforestry on very steep slopes, respectively. Within pine-based agroforestry relative decline with slope class (1–5) was pronounced in earthworms (biomass −3.46, population −4.18) and infiltration rates (−2.35) while bulk density increased (0.49); for soil carbon (COrg), nitrogen, available phosphorus and exchangeable Mg effects in the −1.26 to −1.68 range indicated a loss of functional topsoil. Differences with age of the agroforestry systems were much smaller but included a decreasing earthworm population but an increase in mean earthworm weight and partial recovery of the COrg/CRef ratio. Pine-based agroforestry on very steep soils had only 10%–14% of the earthworm biomass and 35% of the infiltration rate of reference natural forest. Understory vegetation biomass and litter layer necromass were more than five-fold higher in the natural forest. Across all samples a higher COrg and higher earthworm biomass were associated with complementary positive changes in infiltration rates and soil porosity. Regression analysis suggests equal skill of tree cover, soil COrg, porosity, aggregate stability and earthworms to predict infiltration rates while explanatory variables were strongly correlated. Management of the pine plantations may have to achieve a closer approximation of the conditions in natural forests to effectively protect upper watersheds.

Forests doi: 10.3390/f17050564

Authors: Viacheslav I. Kharuk Il’ya A. Petrov Sergei T. Im Alexander S. Shushpanov Sergei O. Ondar Andrey M. Samdan

Changing hydrothermal regime leads to pronounced changes in growth and ranges of Siberian tree species that are mostly negative at the southern part of the trees’ habitat. Here we analyzed the response of Larix sibirica and Populus laurifolia to moisture changes in unique refugia that border the Mongolian desert in Southern Siberia. The great age of old-growth larch trees (>500 years) suggests that the refugia have existed throughout the Holocene. We aimed to (1) analyze larch and poplar growth and range response to the changing temperature and moisture regime, (2) explore the potential migration of trees into the desert, and (3) analyze Gross Primary Productivity (GPP) dynamics within the refugia and adjacent desert. We used on-ground surveys, remote sensing data, and dendroecological analysis. We found that since the warming onset (c. 1980), larch and poplar trees have increased their growth and population within and beyond the refugia (+300% for poplar and +45% for larch). Both species’ growth has been controlled by atmospheric and soil droughts (measured by the Standardized Precipitation Evapotranspiration Index (SPEI) and Self-Calibrating Palmer Drought Severity Index (scPDSI)) and by microtopography-dependent moistening. Summer winds impair trees’ growth via increased evapotranspiration. Both species were migrating to the southern sandy dunes. Although poplar is less drought-resistant than larch, it was shifting ahead of larch (5.6 m/year vs. 0.8 m/year). The mean and maximum treeline shifts were 260 and 450 m for poplar and 35 m and 70 m for larch. P. laurifolia occupied new climate-caused niches ahead of drought-resistant L. sibirica due to its higher prolificacy. We found a “desert greening” phenomenon, i.e., a significantly increasing GPP trend (R2 = 0.31) in both refugia and sandy dunes. The GPP increase correlated with tree growth increase (r2 = 0.36–0.39). The larch and poplar migration to the desert contradicts the predicted shrinkage of the tree ranges within their southern boundary. However, the projected increase in the moisture deficit by 2080–2100 may impair this phenomenon. Nevertheless, current changes in the hydrology regime are favorable for larch and poplar growth and expansion into the adjacent Mongolian desert.

Forests doi: 10.3390/f17050563

Authors: Ruiying Ren Kai Zhang Liang Qi Maocheng Zhao Weijun Xie Chi Zhou Mingguang Li

With increasing demand for fine-scale ecological management under carbon neutrality frameworks, multi-temporal assessment of carbon stock change (ΔC) at the individual-plant scale has become essential for understanding plant-level carbon dynamics and supporting management decisions. However, methodologies for repeated monitoring at this scale remain fragmented, showing limited cross-temporal comparability, weak cross-scale consistency, and insufficient integration across methods. Existing approaches can be grouped into three pathways: (i) process-based methods derived from CO2 exchange measurements, (ii) state-based approaches estimating biomass and ΔC, and (iii) sensing-based approaches using structural, spectral, thermal, and fluorescence signals. These approaches offer complementary strengths, yet none simultaneously achieve high accuracy, temporal continuity, and operational scalability for multi-temporal ΔC estimation. Among these, stock-based and structural approaches form the primary estimation pathways, while flux-based and functional sensing methods provide complementary constraints. This review synthesizes and compares these approaches in terms of their theoretical basis, spatial support, temporal characteristics, and uncertainty structures. To address the lack of methodological integration, we propose a structure–function–scale framework that links heterogeneous observations across spatial and temporal domains and emphasizes cross-scale consistency as a prerequisite for reliable ΔC estimation. Within this framework, we further examine how multi-source integration can connect structural and functional observations through segmentation, co-registration, scaling, temporal alignment, and uncertainty propagation. By integrating traditional measurement logic with emerging remote sensing technologies, this review provides a unified methodological framework for ΔC estimation and identifies key directions for advancing fine-scale carbon monitoring, spatiotemporally consistent data fusion, uncertainty-aware inference, and MRV-oriented verification systems.

Forests doi: 10.3390/f17050562

Authors: Yadi Liu Ruidong Lu Purui Guo Ying Wang Yidan Shi Chunze Xie Yuanhang Wu Yu Zeng Lu Zou Ke Zhu He Li Song Sheng

Bamboo is a rapidly renewable lignocellulosic resource widely used in construction, composites, and bio-based materials. However, its practical applications are often limited by high hygroscopicity, biological degradation, and dimensional instability under humid conditions. This review synthesizes current research on bamboo structure, microbial interactions, and material modification strategies to better understand how bamboo-associated microbiomes influence both deterioration and potential material enhancement. We summarize conventional chemical and thermal modification approaches that improve hydrophobicity, durability, and mechanical stability while also discussing their technical limitations. Emerging studies on bamboo-associated microbial communities reveal complex interactions between fungi, bacteria, and lignocellulosic substrates, including enzymatic degradation, nutrient cycling, and potential bioprotective functions. Advances in multi-omics technologies have further provided insights into the functional gene pools and metabolic pathways involved in bamboo–microbe interactions. Recent conceptual developments in microbiome engineering and engineered living materials (ELMs) suggest possible future directions for integrating microbial functionality into bamboo-based materials. However, direct experimental evidence for microbial enhancement of bamboo structural performance remains limited. Future interdisciplinary research integrating material science, microbial ecology, and synthetic biology will be essential to evaluate the feasibility and safety of such biohybrid systems.

Forests doi: 10.3390/f17050561

Authors: Ivan Klement Zuzana Vidholdová Tatiana Vilkovská

This study investigates strategies to reduce mould growth on steamed beech wood by evaluating drying-based and fungicide-based protection approaches. The drying-based approach focused on optimising the temperature of warm-air drying parameters to control moisture content and limit mould development. The fungicide-based approach involved testing selected agents, including 3-iodo-2-propynyl butyl carbamate, boric acid, quaternary ammonium compounds, and nano-ZnO, for their effectiveness in preventing mould formation. Mould growth was assessed by macroscopic observation and classified according to standardised intensity levels. The results indicate that adjusting drying parameters alone is insufficient to prevent mould growth, whereas specific fungicide treatments provide effective surface protection. These findings offer practical guidance for minimising mould development on beech wood during drying and storage.

Forests doi: 10.3390/f17050560

Authors: Gang Lu Andres Susaeta Marcus Kauffman Brandon Kaetzel John Tokarczyk

We estimate Oregon’s mass timber-related market value and economic contribution using two complementary valuation strategies and two IMPLAN implementations. Although mass timber includes CLT, glulam, nail-laminated timber, dowel-laminated timber, mass plywood panels, and structural composite lumber products, the empirical market-value estimates are centered primarily on CLT- and MPP-related evidence because these products have the most consistently available Oregon-specific data. Market value is inferred from production-based approaches, including facility capacity, Oregon’s share of U.S. output, and tracer-product scaling, and from demand-based approaches, including harvest routing, construction floor area, and U.S. demand allocation. These direct values are then entered into industry contribution analysis (ICA) for Oregon’s Engineered Wood Member and Truss Manufacturing sector and into analysis-by-parts (ABP) using a custom mass timber spending pattern. During 2018–2023, production-based estimates were larger and more variable than demand-based estimates, bracketing a plausible scenario range rather than providing a single point estimate. In 2022 price scenarios, all price-exposed cases scale proportionally with assumed panel prices. When identical direct values are used, ABP produces larger total employment and output effects than ICA because it routes more activity through upstream supplier industries. Output-per-worker sensitivity affects only direct employment in ABP. Forward scenarios for 2030 and 2035 indicate substantially larger total effects under ABP than ICA, but these estimates are conditional scenarios rather than forecasts. The framework provides a transparent basis for policy, investment, supplier-development, and workforce-planning discussions in an emerging industry with incomplete product-level data.

Forests doi: 10.3390/f17050559

Authors: Miao Liu Chunju Cai Guanglu Liu Xiaopeng Shi Shuguang Li Shaohui Fan

Bamboo plantations are increasingly recognized as significant terrestrial carbon sinks, yet accurate estimation of biomass and carbon stocks requires species-specific, regionally validated allometric models. Bambusa emeiensis L.C.Chia & H.L.Fung (ci bamboo) is among the most ecologically and economically important clump-forming bamboo species in southwestern China, but robust multi-regional allometric models are lacking. Using destructive sampling data from 127 culms across two major production areas—Sichuan Province (n = 82) and Guizhou Province (n = 45)—we developed additive biomass and carbon storage model systems enforcing mathematical additivity via nonlinear seemingly unrelated regression (NSUR). Allometric equations used diameter at breast height (D), culm height (H), and compound variables (DH, D2H) as predictors. Regional models achieved Ra2 of 0.0879–0.8320 total relative error (TRE): −0.99% to 0.04% for biomass and Ra2 of 0.0923–0.8282 (TRE: −1.01% to 0.03%) for carbon storage; culm and total aboveground models attained Ra2 ≥ 0.52. Organ-level carbon content (40.79%–44.46%) was significantly lower than the intergovernmental panel on climate change (IPCC) default of 50% (one-sample t-test, p < 0.01 for all organs), with Sichuan values exceeding Guizhou values (independent-samples t-test, p < 0.01), indicating that use of the default would overestimate carbon stocks by 12%–22%. Cross-regional validation revealed prediction biases of up to ±19.24% when applying single-region models outside their training area, whereas the combined model held errors within ±11.36% for biomass and ±8.49% for carbon storage. External validation using 32 independent culms from Hunan, Yunnan, and Chongqing confirmed the robustness of the combined model (TRE: −6.30% to 4.27%). A key limitation is that belowground biomass was not measured. The established models provide scientifically rigorous and practically applicable tools for regional carbon accounting of B. emeiensis plantations under China’s national greenhouse gas inventory framework and for informing sustainable bamboo management planning, and demonstrate that species- and region-specific carbon fractions are essential for accurate carbon stock assessments.

Forests doi: 10.3390/f17050558

Authors: Rong Xia Yuechu Shi Haiyan Xia Hao Yuan Haolin Zhao Paolo Vincenzo Genovese

Urban forest fragmentation can weaken ecological connectivity and reduce the spatial continuity of cooling benefits, highlighting the need for structure-function integrated planning. Using 2020 as the baseline year, this study combined the Markov Chain-Future Land Use Simulation model, Morphological Spatial Pattern Analysis, the Minimum Cumulative Resistance model, and Kernel Density Estimation to simulate the evolution of Hangzhou’s forest-dominated ecological network under Business-as-Usual, Economic Development, and Ecological Conservation scenarios for 2030. A Random Forest model with Shapley Additive Explanations was further used to quantify the nonlinear relationship between landscape spatial context and land surface temperature. The results show that the Economic Development and Business-as-Usual scenarios intensify forest fragmentation and weaken the structural integrity of potential ecological corridors, whereas the Ecological Conservation scenario improves network stability through patch amalgamation, core area expansion, and reduced breakpoint density. Land surface temperature was strongly associated with built-up land adjacency. Built-up areas near forest patches showed a maximum relative cooling benefit of 8.04 degrees Celsius, and corridor cooling effects were most pronounced within 300 m, remaining detectable up to about 900 m under the Ecological Conservation scenario. These findings support structure-oriented planning for urban forest conservation and heat mitigation.

Forests doi: 10.3390/f17050557

Authors: Min Wu Ziheng Huang Shuang Liu Zhilong Wu Tao Hong Xisheng Hu

Quantifying vegetation dynamics has become a critical scientific imperative in the context of global ecosystem restoration initiatives targeting degraded forests. Previous studies have explored vegetation-cover change trends at different spatial scales worldwide using the Theil–Sen (TS) estimator and Mann–Kendall (MK) test, yet few have accounted for the uncertainty in resulting trends across time-series datasets of varying lengths. Taking the coastal zone of Fujian Province in Southeast China as a case study, we investigated the uncertainty of vegetation-cover change trends using normalized difference vegetation index (NDVI) datasets of different lengths (e.g., 20-year, 15-year, and 10-year) via the TS estimator and MK test. Additionally, piece-wise regression was employed to detect turning points and shifts in vegetation trends between 2001 and 2020. The results indicate significant discrepancies in trend estimation across datasets of different lengths, with consistency ratios ranging from 46.1% to 64.7% among the 20-year, 15-year, and 10-year series. The MK test is more sensitive to time-series length than the TS estimator, with areas of significant change decreasing by over 50% when transitioning from a 20-year to a 10-year dataset. The spatial distribution of trend shifts exhibits a distinct “coastal–inland” polarization pattern, with 2010 as the turning point. Eight modes of vegetation trend shifts were identified based on pre- and post-turning point dynamics. Furthermore, piece-wise regression improved trend accuracy by approximately 15%. This research advances the mechanistic understanding of spatiotemporal vegetation dynamics and supports adaptive ecosystem management strategies.

Forests doi: 10.3390/f17050556

Authors: Katché Komlanvi Akoete Kossi Adjonou Atsu K. Dogbeda Hlovor Kossi Novinyo Segla Jana Balzer Sally Janzen Vincenzo Polizzi Yvonne Walz Kouami Kokou

The degradation of forest landscapes in West Africa, particularly in Togo, threatens ecological and socio-economic sustainability. This study analyzes the spatio-temporal dynamics of land use in the central plains of Togo between 1991 and 2022, and projects its evolution for 2030 and 2050 to guide restoration strategies. The methodology integrates the interpretation of Landsat images (1991, 2005, 2022) and the analysis of indicators, including conversion rates and the anthropization index. Prospective modeling (Markov chains and neural networks) follows a trend scenario. The results reveal a sharp decline in natural forest formations: dense semi-deciduous and dense dry forests (−50.55%) and woodlands (−62.06%), converted mainly to cropland, plantations, and built-up areas. Shrub/tree savannas, the dominant class, represent a transitional stage resulting from forest degradation. The average annual deforestation rate is 0.75%. The ecological disturbance index increased from 0.24 (1991) to 0.45 (2005), and then to 0.56 (2022), reflecting increased human impact and fragmentation. Projections indicate that these trends will continue, highlighting the growing vulnerability of ecosystems and the need to integrate this dynamic into sustainable management and restoration policies.

Forests doi: 10.3390/f17050555

Authors: Qiao Gao Gang Xu Yi Hu Meiyu Liu Xuyang Lu Baoli Duan

Primary succession following glacier retreat provides a natural system for testing whether soil development simply shifts fine roots along a single acquisitive–conservative axis orinstead changes the nutrient-acquisition pathway that dominates at the community level. We hypothesized a stage-dependent sequence, from substrate-limited exploration, to transient morphological capture, and finally to rhizosphere-mediated biochemical mobilization. To test this idea, we quantified fine-root morphology, absorptive-transport partitioning, anatomy, phosphatase activity, exudation, community-scale belowground structure, and soil and rhizosphere properties across woody communities representing approximately 20, 40, and 90 years since deglaciation in the Hailuogou Glacier foreland. Across succession stages, bulk density and pH declined, whereas field capacity, soil carbon, and soil nitrogen increased, indicating rapid development of the belowground resource environment. Fine-root strategies did not fall along a single acquisitive–conservative continuum. Instead, morphological nutrient capture peaked at intermediate succession: the 40-year stage had the highest specific root length, specific root area, absorptive-to-transport root length ratio, and root nitrogen concentration. In contrast, the 90-year stage showed lower specific root length but higher dry matter content, thicker cortex, greater standing fine-root biomass, larger rhizosphere volume, higher phosphatase activity, and greater area-based carbon exudation. This late-successional syndrome coincided with stronger extracellular enzyme activity, larger dissolved organic carbon and nitrogen pools, and higher microbial biomass, despite negative net nitrogen mineralization. Species-level analyses showed that biochemical-input traits were jointly shaped by successional stage, species identity, and their interaction. Together, these results show that primary succession did not simply increase or decrease root acquisitiveness. Instead, as soils developed, it changed the nutrient-acquisition pathway that dominated, with direct implications for nutrient cycling and vegetation dynamics in rapidly developing glacier-foreland ecosystems.

Forests doi: 10.3390/f17050554

Authors: Jesse E. Gray Mandy Slate Alyson S. Ennis Courtney L. Peterson John B. Bradford Adam R. Noel Michael C. Duniway Tara B. B. Bishop Ian P. Barrett Chris T. Domschke Joel T. Humphries Nichole N. Barger

Pinyon–juniper (PJ) woodlands, one of the most extensive mature and old-growth woodland types in the Western United States, provide critical ecological, cultural, and economic benefits but face increasing threats from climate change, altered disturbance regimes, invasive species, and pests. We developed the PJ Woodland Climate Adaptation Management Menu, a decision support tool designed to guide adaptive, climate-informed management of PJ ecosystems, particularly within the Colorado Plateau ecoregion. The menu was created through an iterative, collaborative process involving literature review, integration of strategies from existing adaptation frameworks, and extensive input from scientists, land managers, and community partners during workshops and focus groups. The menu links specific, evidence-based approaches to each of six broad strategies, including soliciting community input, mitigating disturbance, enhancing and maintaining biodiversity, conserving ecotones, timing actions for optimal outcomes, and accepting climate-driven changes when appropriate. It is intended for use with the Adaptation Workbook to help managers connect local goals and climate vulnerabilities to tailored management tactics. Hypothetical scenarios demonstrate the menu’s application to contrasting PJ woodland conditions, from die-off events to old-growth maintenance. Lessons learned during development underscore the value of early stakeholder engagement, cross-sector collaboration, and balancing diverse ecological objectives. This menu offers a flexible, transferable framework to strengthen climate resilience in PJ woodlands and serves as a model that could improve adaptation planning in other dryland forest ecosystems.

Forests doi: 10.3390/f17050553

Authors: Zhimin Liu Xiao Zhao Linhao Guo Ming Chang Xuemei Wang Bo Peng Weiwen Wang

Mangroves are important coastal wetland ecosystems with high ecological service values and strong carbon sequestration capacity, serving as a crucial barrier for coastal ecological security. However, current afforestation efforts often ignore environmental suitability differences among mangrove species, while the applicability value and ecological risks of exotic species (Laguncularia racemosa and Sonneratia apetala) for restoration remain poorly understood. Five native and two exotic mangrove species along China’s coasts were selected in this study. Using the MaxEnt model, we identified key environmental factors governing their distribution, predicted their current and future suitable habitats (under the SSP245 scenario in the 2070s), and quantified niche overlap between native and exotic mangroves. The results showed that temperature-related factors (air and sea temperature) are the core climatic drivers shaping the typical mangrove distribution, followed by sea surface salinity, with precipitation contributing little. Currently, niche overlap between native and the two exotic species is low (D.overlap: 0.129–0.340), indicating certain niche differentiation. Under the SSP245 scenario in the 2070s, except for Rhizophora stylosa, other studied species appear to experience expanded suitable habitat areas and a northward latitudinal distribution shift. Compared with Sonneratia apetala, Laguncularia racemosa exhibits a more pronounced expansion of suitable habitats in the future, with its overall suitable area second only to the native Kandelia obovata, indicating its stronger adaptive potential to climate change. Clarifying niche differentiation and constructing species-specific management frameworks may facilitate biological invasion control, mangrove restoration, and species diversity improvement.

Forests doi: 10.3390/f17050552

Authors: Noor Azland Jainudin Gaddafi Ismaili Faisal Amsyar Redzuan Ahmad Fadzil Jobli Iskanda Openg Jamil Matarul Mohamad Zain Hashim Meekiong Kalu Mohd Effendi Wasli Zurina Ismaili Ahmad Nurfaidhi Rizalman Nur Syahina Yahya Mohamad Asrul Mustapha

This bibliometric study examined 179 Scopus-indexed publications on the physical and mechanical properties of medium-density fiberboard (MDF) published between 2016 and 2025. BiblioMagika® was used for performance analysis, and Biblioshiny was used for keyword co-occurrence, thematic mapping, and thematic evolution. The papers identified as the cohort for analysis had received 2830 citations in total, with an average of 15.81 citations per paper, and an average h-index of 30. The European Journal of Wood and Wood Products and BioResources were the most productive sources. Three distinct categories were identified through keyword mapping among the studies reviewed: (1) advanced composites and reinforcement, (2) adhesive and emission-related studies, and (3) circular-material strategies. Thematic evolution showed a trend away from traditional resin-performance topics toward broader sustainability-related themes, particularly bio-based adhesives and recycling-related topics. Overall, this review provides a quantitative overview of publication patterns, influential sources, and thematic development in MDF research. It also provides direction for future MDF research, focusing on durability, large-scale feasibility, life-cycle assessments, and practical implementation.

Forests doi: 10.3390/f17050550

Authors: Lucian Dinca Danut Chira Gabriel Murariu

Freezing rain is a high-impact winter weather phenomenon that acts as a major disturbance agent in forest ecosystems, causing canopy damage, stem breakage, tree mortality, and long-term changes in forest structure and functioning. Although ice storms have been studied for decades, research on freezing rain impacts on forests remains fragmented across multiple disciplines, and few studies have attempted an integrated synthesis that simultaneously combines climatological, ecological, and methodological perspectives. In this study, we present a systematic and integrative review of the scientific literature on freezing rain and forests, combining a large-scale bibliometric analysis with an in-depth qualitative synthesis. A total of 241 publications retrieved from the Scopus and Web of Science databases were analyzed following PRISMA guidelines. The bibliometric assessment examined publication trends, geographic distribution, institutional contributions, research domains, and keyword networks. The qualitative review synthesized current knowledge on freezing rain climatology, forest damage mechanisms, species-specific vulnerability, major ice storm events, detection and modeling approaches, and ecological consequences. Results reveal a strong increase in scientific output over the last two decades, dominated by research from North America and northern Europe. Ice accretion intensity emerges as the primary driver of forest damage, while species traits, crown architecture, tree size, stand structure, topography, and exposure strongly modulate damage severity. Freezing rain affects a wide range of forest types worldwide and triggers both immediate structural damage and long-term ecological effects, including altered successional dynamics and reduced forest productivity. Recent methodological advances—including passive remote sensing (e.g., optical satellite data), active remote sensing (e.g., LiDAR), experimental ice storm simulations, reanalysis datasets, and machine learning approaches—have significantly improved detection, monitoring, and forecasting capabilities. Despite these advances, major research gaps remain, particularly regarding long-term ecosystem recovery, trait-based vulnerability, socio-economic impacts, and future freezing rain regimes under climate change. This review highlights freezing rain as an increasingly important but underappreciated forest disturbance and underscores the need for interdisciplinary research and adaptive management strategies in ice-prone regions.

Forests doi: 10.3390/f17050551

Authors: Li Yi Kehao Cao Dennis W. Hess Lianpeng Zhang Xijuan Chai Kaimeng Xu Linkun Xie

Wood is a sustainable material, but hygroscopicity can affect dimensional stability and mechanical durability. Recent research has increasingly focused on combining citric acid with various polyols as eco-friendly crosslinking systems to improve wood properties. Herein, a solvent-free and catalyst-free method was used to synthesize bio-based polyesters from citric acid and mannitol. In situ curing was carried out after vacuum-pressure impregnation of fast-growing poplar wood (Populus deltoides Marshall). Morphological characterization showed that the polyester filled the cell lumen and penetrated the cell wall structure. It was confirmed by Fourier Transform Infrared (FTIR) and cross-polarization/magic angle spinning (CP/MAS) 13C nuclear magnetic resonance (NMR) analysis that the polyester formed covalent ester bonds with wood hydroxyl groups, which indicated successful chemical grafting. The dimensional stability and mechanical properties of the modified wood were greatly improved. The parallel compressive strength of the grain reached 41.5 MPa, which was 41.7% higher than that of the untreated wood. This research adopted a citric acid–mannitol polyester, providing a sustainable, economical, and scalable approach for the development of high-performance, degradable wood composites for construction/furniture applications.

Forests doi: 10.3390/f17050549

Authors: Jae-hak Song Mi-na Jang Byung-doo Lee Woong-hee Lee Seong-kyun Im Hyunseok Lee Sung-yong Kim

Recent climate change-driven warming and prolonged drought have reduced fuel moisture in forests, increasing the frequency and severity of wildfires. In particular, crown fires have become more frequent, highlighting the importance of quantifying crown fuel characteristics. However, studies on the crown fuel biomass of Pinus densiflora in South Korea remain limited. This study aimed to quantify crown fuel biomass and develop a diameter at breast height (DBH)-based allometric model across major P. densiflora distribution areas. A total of 67 sample trees were destructively sampled across seven regions. Crown fuel components were classified into needles and branch diameter classes, and their dry biomass was measured. A log-transformed allometric model was developed, and its reliability was evaluated using correction factors, confidence intervals, and prediction intervals. Branches accounted for approximately 78% of total crown fuel, while needles accounted for approximately 22%. The model demonstrated high explanatory power, with Radj2 ranging from 0.783 to 0.945. Combustible fuels (≤1.0 cm) accounted for approximately 45% of total crown fuel. The developed model can be used as an input for wildfire spread prediction and provides a basis for crown fire risk assessment and fuel mapping.

Forests doi: 10.3390/f17050548

Authors: Mosab Khalil Algidail Arbain Peter Márton Roman Kadlečík Šimon Saloň Milan Koreň

Tree detection is a core task in forest inventory and mapping, yet reliable stem identification remains difficult in dense and structurally complex forests. This study systematically reviews the literature on terrestrial laser scanning (TLS)-based tree detection to summarize methodological development, identify persistent challenges, and highlight research gaps. Records were retrieved from Scopus and Web of Science (WoS). Following PRISMA 2020, 39 articles were included and analyzed using Bibliometrix v 5.2.1 package in R Studio 2026.01.1 and qualitative content coding. The reviewed studies were published between 2011 and 2025 in 20 peer-reviewed journals and involved 169 authors from 73 institutions across 24 countries. The literature was organized into three developmental phases: foundational development (2011–2015), rapid growth (2016–2020), and refinement and integration (2021–2025). Across these phases, methods evolved from geometric fitting and clustering to voxel-based and increasingly integrated workflows. Reported performance varied markedly with scan configuration, forest structure, and algorithm design, ranging from very low detection rates to near-complete detection under favorable conditions. Overall, TLS shows strong potential for forest inventory; however, dense stands, multilayered forests, and regeneration-rich environments remain major challenges.

Forests doi: 10.3390/f17050547

Authors: Vít Šrámek Kateřina Neudertová Hellebrandová Ondřej Špulák Věra Fadrhonsová

Soil organic carbon (SOC) storage in forests is governed by complex interactions between site conditions and vegetation. This study quantifies SOC stocks across a gradient of Target Management Sets (TMS) in the Czech Republic (Central Europe) to evaluate the baseline storage capacity of distinct ecological sites and the modifying effects of dominant tree species, specifically Norway spruce and European beech. Utilizing large-scale spatial data, linear mixed-effects models, and piecewise structural equation modeling (pSEM), we analyzed SOC stratification across middle (≈400–600 m a.s.l.) and higher (≈600–800 m a.s.l.) elevational zones. The results indicate that while overall SOC stocks inherently increase with elevation due to climatic constraints, tree species dictate the vertical carbon distribution within the soil profile. Specifically, conifers (i.e., Norway spruce and Scots pine) accumulate SOC primarily in the organic layer, whereas broadleaves (mainly European beech and oak) translocate and stabilize carbon in deeper mineral horizons. The pSEM analysis revealed that beech functions as a ‘calcium pump’, increasing topsoil pH and driving calcium-mediated SOC stabilization in mineral soils. This mechanism is highly effective at middle elevations but partially overridden by abiotic limits at higher elevations. We conclude that inherent site conditions (TMS) determine total SOC capacity, whereas tree species management controls SOC stability. Although no significant differences were observed in total SOC stocks between conifers and broadleaves at the same sites (medians of total SOC ranged from approx. 5 to 16 kg·m−2, depending on the site), converting purely coniferous stands into broadleaves represents an effective strategy for long-term mineral SOC stabilization, particularly in middle-elevation sites.

Forests doi: 10.3390/f17050544

Authors: Lei Yin Jianwan Ji Yuchao Hu Xiaoxiao Zhu Haixia Chen Lei Zhang Yinpeng Zhou

Under the context of global change, forest cover, as a critical component of terrestrial ecosystems, exerts a profound influence on regional ecological security and sustainable development through its spatiotemporal evolution. Current research on forest cover change primarily focuses on pattern description and single-factor driver analysis, with insufficient in-depth exploration of the interactions among multiple factors and their associated nonlinear mechanisms. To address this gap, this study focuses on the Wumeng Mountain area, a typical ecologically fragile karst region in Southwest China. By comprehensively employing methods such as Theil–Sen Median trend analysis, land use transfer matrix, standard deviation ellipse, and spatial autocorrelation analysis, this study systematically reveals the spatiotemporal evolution characteristics of forest cover from 1985 to 2024. On this basis, an integrated eXtreme Gradient Boosting–SHapley Additive exPlanations (XGBoost-SHAP) model is introduced to construct an indicator system comprising 16 driving variables, including elevation, slope, aspect, temperature, precipitation, soil type, soil pH, soil thickness, soil organic matter, soil moisture content, GDP, population, distance from water, distance from railway, distance from grade highway, and distance from government. This model quantifies the influence intensity of each driving factor on forest change. The main findings are as follows: (1) From 1985 to 2024, the forest cover rate in the Wumeng Mountain area significantly increased from 54.7% to 60.2%, exhibiting a “high-low-high” heterogeneous spatial distribution pattern along the northeast-southwest axis; (2) Forest increase primarily originated from the conversion of cropland and grassland, with contribution rates reaching 93.58% and 5.9%, respectively, indicating an overall trend of “increase in low-value areas and decrease in high-value areas”; (3) Forest cover change is driven by both natural and anthropogenic factors, with dominant driving factors exhibiting phased replacement over time. Overall, this is manifested as long-term stable constraints exerted by natural background factors, alongside strong disturbances from anthropogenic factors such as social-economic, and transportation-related activities. Natural factors remain the primary driving force behind changes in forest cover. The core findings of this study elucidate the complex driving factors of forest change in karst mountainous areas, thereby providing scientific support for the precise management of regional forest resources, the planning of ecological restoration projects, and the implementation of sustainable development strategies.

Forests doi: 10.3390/f17050546

Authors: Wojciech Szewczyk Katarzyna Szewczyk

This study provides an operational-scale assessment of internal decay caused by Porodaedalea pini in managed Scots pine stands based on data collected during harvesting operations. Unlike previous studies relying on indirect indicators such as fruiting bodies, this work quantifies the actual proportion of logs affected by decay under real-world production conditions. Although the mean decay share was relatively low (3.29%), substantial variability among stands was observed. A moderate relationship between stand age and decay occurrence was detected; however, statistical models showed limited explanatory power, highlighting the influence of additional stand-level factors. A potential threshold around 110 years may indicate an increased risk of decay in overmature stands. These findings underline the importance of incorporating decay risk into forest management decisions while acknowledging the uncertainty associated with predicting internal decay under operational conditions. These results may support forest management decisions regarding rotation age and timber quality risk assessment.

Forests doi: 10.3390/f17050545

Authors: Lepeng Lin Gongxun Bai Tianlong Han

As a critical component of urban ecological infrastructure, urban forests play a pivotal role in regulating regional climate and mitigating the urban heat island (UHI) effect. However, existing studies have predominantly focused on single temporal snapshots or aggregate spatial scales, with limited attention to the seasonal dynamics of urban forest landscape patterns and a lack of systematic quantification of their nonlinear regulatory mechanisms. Empirical evidence from subtropical cities remains particularly scarce. In this study, Hangzhou was selected as the study area. Land Surface Temperature (LST) was retrieved using the Google Earth Engine (GEE) platform, and the Thermal Field Variance Index was employed to classify UHI intensity. Six representative forest landscape indices were selected to construct an evaluation framework. Pearson correlation analysis and the XGBoost model were further applied to quantify the relationships between landscape patterns and seasonal LST variations. The results reveal that: (1) LST in Hangzhou exhibits pronounced seasonal variability, following the order of summer > spring > autumn > winter. Areas without UHI effects dominate in spring, summer, and autumn, whereas the extent of strong UHI zones increases markedly in winter. (2) All landscape indices are significantly correlated with seasonal LST; forest ratio and forest largest patch index show negative correlations, while forest patch density, forest landscape shape index, number of patches, and landscape division index (DIVISION) are positively correlated. (3) The XGBoost model indicates that DIVISION consistently exhibits high contribution across all seasons, identifying it as a key determinant of LST variation. These findings provide a scientific basis for optimizing urban forest landscape configuration and developing effective UHI mitigation strategies.

Forests doi: 10.3390/f17050543

Authors: Anastasiia Kovalova Marcin Chodak

Microbial nutrient cycling in afforested mine soils may be affected by the plant litter quality. This study investigated how different tree species—Scots pine (Pinus sylvestris), silver birch (Betula pendula), European larch (Larix decidua), and black alder (Alnus glutinosa)—influence microbial carbon (C), nitrogen (N), and phosphorus (P) limitations in reclaimed sandy mine soils. We combined substrate-induced respiration (SIR) and ecoenzymatic stoichiometry (EES) to diagnose these metabolic constraints. The SIR analysis revealed a universal primary limitation by labile C across all tree species, with glucose addition stimulating respiration by 271%–333%, regardless of the soil organic carbon content. However, EES revealed distinct secondary nutrient constraints driven by species-specific litter quality. Alder stands exhibited severe P limitation, likely due to high P demand for symbiotic N-fixation and intense competition for P between trees and microbes. In contrast, birch stands showed stoichiometric homeostasis and a slight N deficiency. Coniferous species exhibited P limitation and low enzymatic activity, indicating a strategy focused on intensive nutrient acquisition under low-energy conditions associated with recalcitrant needle litter. These findings demonstrate that while energy limitation is a universal constraint in mine soils, tree species determine the nature and intensity of secondary nutrient limitations due to differences in litter stoichiometry.

Forests doi: 10.3390/f17050541

Authors: Shulin Chen Weixi Zhang Hengming Zhang Lulan Miao Zhongyi Pang Yanhui Peng Wenxu Zhu Keye Zhu Changjun Ding Rusheng Peng

Monoculture plantations often face challenges of soil degradation and declining ecosystem services. Intercropping is beneficial to improving soil quality; however, the long-term effects of intercropping woody plants with medicinal herbs on soil ecosystems remain unclear. This study aimed to investigate the temporal effects of different durations of poplar intercropping with Aralia elata on soil physicochemical properties, enzyme activities, and soil microbial community structure. Soil samples were collected from the 0–20 cm soil layer, with composite samples obtained by mixing four soil cores per plot. We determined soil physicochemical properties, including pH, total carbon (TC), total nitrogen (TN), and total phosphorus (TP); soil enzyme activities, including invertase, urease, phosphatase, and β-N-acetylglucosaminidase (NAG); and soil microbial community structure using high-throughput sequencing of the bacterial 16S rRNA gene and fungal ITS region. Intercropping significantly affected soil chemical properties and enzyme activities in poplar plantations. Compared with the monoculture control (Y), TN (p < 0.01) and TC (p < 0.01) contents increased significantly in the 3- and 7-year intercropping treatments. The activity of β-N-acetylglucosaminidase (NAG) was enhanced following poplar–Aralia elata intercropping. In addition, intercropping significantly changed the composition and structure of soil microbial communities. In summary, introducing Aralia elata into poplar plantations can effectively improve soil fertility and reshape soil microbial community structure. This positive effect is time-dependent and becomes more significant with a 7-year intercropping duration. Poplar–Aralia elata intercropping represents a feasible management strategy to enhance ecological sustainability and soil health in plantation ecosystems of Northeast China.

Forests doi: 10.3390/f17050542

Authors: Shaopeng Zhang Thi Yen Nhung Nguyen Hongge Zhu

This study examines the impact of Sustainable Livelihood Capital (SLC) on women’s participation in production activities in Vietnam’s mangrove areas, using a gender-focused approach to advance gender-sensitive livelihood theory. Employing binary Logit regression and cross-tabulation analysis, model robustness was confirmed via the Bayesian Information Criterion (BIC). Findings identify financial and human capital as core factors influencing participation, with access to credit emerging as the factor exhibiting the strongest correlation. Livelihood stability and practical vocational training support women’s long-term productive engagement. The study highlights the livelihood paradox and resource lock-in effects: over-reliance on mangrove income reduces participation, limiting diversification, while over-exploitation correlates positively with participation as a survival strategy, exerting short-term environmental pressure. Conversely, owning traditional assets like fishing boats negatively affects participation, showing traditional factors hinder economic restructuring. The findings of heterogeneity analysis emphasize the necessity of policy intervention. For example, women under 56 are primarily financially driven; those over 56 exhibit lower participation and face severe human capital bottlenecks, especially education. Larger households face significant financial barriers despite having abundant human capital. Married women face dual constraints from financial and traditional physical capital, while single/divorced women hold advantages in education and opportunities. Furthermore, In areas far from fishing ports, financial and human capital are core drivers. This research provides quantitative evidence on the complex, heterogeneous effects of SLC on women’s productive engagement, offering a scientific foundation for multi-dimensional, targeted policy measures to foster sustainable livelihood diversification.

Forests doi: 10.3390/f17050539

Authors: Wenhui Zheng Xin Yu Menglei Wu Jingjing Zhao Xiufang Zheng Hong Su Kaijin Kuang Fuzhong Wu

Acid rain is a severe global environmental issue, and clarifying its impacts on litter decomposition and underlying mechanisms is critical for accurately forecasting future climate change. Litter consists of components (e.g., non-structural carbohydrates, lignin, cellulose, and hemicellulose) with distinct decomposition resistance, but how acid rain affects these components to modulate overall litter decomposition across different decomposition stages remains unclear. Therefore, a microcosm experiment was conducted to determine decomposition rates of Chinese fir (Cunninghamia lanceolata) litter and its components based on litter mass loss under different simulated acid rain intensities (pH 4.5, moderate acid rain, MA; pH 3.0, severe acid rain, SA; and pH ≈ 7.0, tap water, CK) over two decomposition stages (0–5 months: initial decomposition stage; 6–16 months: late decomposition stage). Meanwhile, to analyze the factors influencing the litter decomposition rate, soil samples were collected at 5 and 16 months of decomposition for soil property analysis. Results showed that MA had no significant effect on litter decomposition in either stage. Conversely, SA led to a significant 43.7% increase in the litter decomposition rate in the initial decomposition stage, driven by its acid dissolution effect that accelerated the decomposition of cellulose and hemicellulose. However, SA significantly decreased the decomposition rate by 42.0% in the late decomposition stage by inhibiting the decomposition of lignin, cellulose, and hemicellulose, which was due to the reduced activities of soil peroxidase and xylosidase under soil acidification. Notably, neither MA nor SA significantly affected the litter decomposition rate over the entire decomposition period (0–16 months). This study indicates that acid rain’s effect on litter decomposition depends on its intensity and decomposition stage, emphasizing the necessity of distinguishing litter components and decomposition stages to explore its underlying mechanisms and precisely predict global climate change.

Forests doi: 10.3390/f17050540

Authors: Yiwen Wang Xiyu Guo Hui Zhu Fengxia Wang

Mangroves play a vital role in climate change mitigation due to their exceptional carbon sequestration capacity, as a highly productive blue carbon ecosystem. Current research on mangroves in Bamen Bay has been limited to short-term observations, lacking systematic analysis of long-term spatiotemporal dynamics and carbon storage. This study developed a decision tree method integrating SWIR1, NDVI, and NDMI, achieving high-accuracy mangrove mapping. Spatiotemporal dynamics from 2000 to 2020 were analyzed using the dynamic degree model, standard deviation ellipse, centroid model, and landscape pattern indices. Carbon storage was quantified through the InVEST model, grey prediction model, and scenario analysis. The results reveal significant mangrove expansion, with substantial net growth. Spatial aggregation strengthened despite persistent fragmentation, characterized by a shrinking standard deviation ellipse and northeastward centroid migration. Carbon storage increased considerably over the two decades. Under the baseline scenario, carbon storage would continue to grow by mid-century. Among alternative scenarios, the Green Revival scenario achieves the highest carbon storage, outperforming the baseline, while the Hard Preservation scenario achieves slightly above the baseline. The Missed Opportunity and Ecological Collapse scenarios project declines. This study provides a valuable framework for mangrove monitoring, carbon assessment, and ecological restoration, supporting regional conservation and carbon neutrality goals.

Forests doi: 10.3390/f17050538

Authors: Junhui Zhang Guimei Cui Yue Gu Yangao Jiang

Climate change is intensifying drought stress in temperate forests, yet the mechanisms governing gradual versus threshold responses remain unclear, limiting adaptive management. This study tested whether tree morphological traits can help detect these response patterns and whether they vary with species identity, drought timescale, and stand structure. Using 2026 plot records (1022 larch, Larix principis-rupprechtii Mayr; 1004 Chinese pine, Pinus tabuliformis Carrière) from plantations across northern China, we combined random forest and generalized additive models to evaluate the height-to-diameter (H/D) ratio as a drought indicator. The H/D ratio outperforms height or diameter alone in detecting drought responses. Two distinct nonlinear strategies were identified: larch exhibited high sensitivity to spring drought with a threshold near SPEI ≈ −0.47, while Chinese pine showed resilience to short-term stress but nonlinear responses to cumulative drought (thresholds 0.07–0.12). These differences align with biomass allocation patterns, with Chinese pine maintaining lower H/D ratios. Stand structure significantly influenced responses, with strong Age × Density × Drought interactions (p < 0.001) highlighting vulnerability in young, dense stands. Overall, the H/D ratio provides a candidate early-warning indicator of drought vulnerability and may support species-specific monitoring and risk screening in young, high-density stands, although experimental validation is still needed.