Biology and Life Sciences

Abstract: The expansion of sustainable timber harvesting on peatland forests is important for forest owners, contractors, and the forest industry. This study investigated the effects of site-specific conditions on summer-time harvesting operations and modeled the influence of a light nine-ton forwarder on rut formation. Three logistic mixed-effects models predicted peat surface disturbance (ROC = 0.60, 0.63, and 0.67), while a linear mixed model predicted rut depth when rutting occurred (R² = 0.35). Rut formation was associated with the number of machine passes, cumulative load, groundwater table depth, peat layer thickness, and interactions between stand and harvesting variables. The results indicate that timber can be successfully forwarded from peatlands with limited bearing capacity when operations are adapted to local site conditions. The findings highlight the importance of road-network planning, load management, and operator decision-making in reducing rut formation. This modeling approach also supports operator training, thereby contributing to more sustainable timber harvesting on low-bearing-capacity sites.

Abstract: (1) Background: As a critical landscape node in urban roads, the pedestrian refuge island is a key challenge for plant configuration; (2) Methods: This study investigated plant applications on pedestrian refuge islands in spring and winter, using the NCS color system and diversity indices to analyze the spatiotemporal characteristics of their plant communities; (3) Results: A survey of 17 traffic islands identified 53 plant species, comprising 27 in the herb layer, 15 shrubs, 8 trees, and 3 vines. For color diversity, the respective layers had 41, 29, 14, and 6 standard colors. Leaf color values showed seasonal variation: warm-toned in spring and cool-toned in winter. Quantitative characteristics and α-diversity indices of the plant community decreased progressively from the herb layer through the shrub layer to the arbor layer. The community’s Whittaker index (6.527) was lower than the mean species richness (7.71), while the Jaccard similarity coefficient decreased as the distance between quadrats increased; (4) Conclusions: Urban pedestrian refuge islands formed a vegetation landscape characterized by vibrant coloration and distinct seasonal dynamics by enhancing horticultural plant diversity. These patterns of diversity were significantly shaped by human disturbance and urbanization.

Abstract: Severe windthrow events can create highly favorable conditions for bark beetle outbreaks by generating large quantities of weakened breeding material. This study investigated the population response of the Mediterranean pine engraver, Orthotomicus erosus Wollaston, following a microburst windstorm that struck Marjan Forest Park, an urban Mediterranean Aleppo pine (Pinus halepensis Mill.) forest in Split, Croatia, in July 2025. Approximately 2,000 m3 of damaged timber remained in the forest until February 2026, enabling assessment of colonization dynamics and outbreak development. Field inspections, laboratory analyses, and pheromone trap monitoring were conducted between July 2025 and April 2026. Colonization of windthrown material began within two weeks after the disturbance, and infestation rates reached 94% of examined logs by December 2025. Most infested logs (86%) already contained emergence holes, indicating successful completion of beetle development. Pheromone traps captured a total of 131,588 individuals, with more than 88% recorded during spring 2026 and a pronounced peak occurring on 8 April 2026. The appearance of newly attacked standing trees in spring 2026 confirmed rapid population expansion from fallen material to living hosts. Results demonstrate the exceptional outbreak potential of O. erosus following extreme climatic disturbances and emphasize the importance of rapid sanitation measures and continuous monitoring in Mediterranean pine forests under climate change conditions. Delayed salvage logging after severe windthrow can rapidly trigger outbreak development of O. erosus.

Abstract:

Abies koreana Wilson (Korean fir) and Abies nephrolepis (Trautv. Ex Maxim.) Maxim. (Khingan fir) are ecologically and economically significant coniferous species in East Asia. However, morphological similarities and hybridization complicate species identification, affecting conservation, forestry management, and commercial activities. Here, we developed a species-specific DNA marker using single nucleotide polymorphisms (SNPs) within the mitochondrial nad5 intron 1 region to discriminate between A. koreana and A. nephrolepis. In particular, PCR amplification and sequencing analyses of candidate drought and heat stress-responsive genes as well as mitochondrial nad5 intron 1 and nad5 intron 4 revealed a species-specific T-to-G substitution in nad5 intron 1. Allele-specific primers were designed, and competitive allele-specific labeled light emission technology was employed for SNP detection. The primers were validated using real-time PCR, achieving high specificity and reliability. Overall, the molecular diagnostic tool offers a practical solution for accurate species identification, aiding conservation efforts and sustainable resource management.

Abstract: Accurately quantifying aboveground biomass (AGB) in tropical forest enrichment plantations remains challenging, particularly in managed regenerating stands where tree crown architecture, size structure, and species composition differ from the datasets used to calibrate classical allometric equations. Here, we assess whether AGB in tropical forest enrichment plantations can be estimated more accurately by combining tree-specific woody volume reconstructed from mobile laser scanning (MLS) with an explicit foliar-biomass component. We combined destructive measurements from 83 trees with high-resolution MLS point clouds to quantify biomass components, calibrate leaf-mass models, and assess the contribution of foliage to total AGB. Stems accounted for most of the biomass (65%), whereas leaves contributed only 3% on average. Among the models tested, Model 3, which included DBH, projected crown area, and wood density, showed the best performance (R² = 54.4%; RMSE = 2.43 kg). The main gain relative to regional (-20.4%) and pantropical (-25.6%) allometric equations came from the use of MLS-derived woody volume combined with species wood density, whereas the inclusion of predicted leaf biomass provided a moderate additional correction to the remaining bias. These results highlight the importance of canopy structure for biomass estimation in enrichment plantations and managed regenerating stands and support the use of LiDAR data as a robust alternative for AGB assessment in this context.

Abstract: Because wood anatomical traits and tree-ring features vary with species and climatic regime, cellular-scale measurements complement ring-width chronologies and help with understanding how forests may respond to future environmental change. We developed anatomical chronologies spanning the 1900-2019 period from multi-century old yellow pines (Pinus jeffreyi Balf. and P. ponderosa P & C Laws.) at four sites surrounding the Tahoe Basin of the Sierra Nevada, at the border between Nevada and California, USA. Measurements of earlywood and latewood traits included lumen area, lumen length, lumen width, wall length, wall-to-lumen length ratio, and conductive area. Climate sensitivity was estimated by bootstrapped response functions with precipitation and temperature (monthly and seasonal) from the Global Historical Climate Network interpolated to the site locations. Moisture emerged as the primary control on anatomical trait expression, as significant coefficients involved precipitation rather than temperature. Earlywood lumen size and conductive capacity were associated with late-winter through spring moisture, while cellular wall characteristics were connected with conditions during the growing season. Overall, our study provided new insights into the potential impacts of climatic changes on woody species of remarkable size and longevity in an area that is prized for its natural beauty and scenic mountain landscapes.

Abstract: Sub-Andean forests of the Colombian Central Cordillera are among the most biodiverse and threatened Neotropical ecosystems, yet their floristic, structural, and carbon dynamics remain poorly documented. We characterized the floristic diversity, vegetation structure, and aboveground carbon storage of the El Mangón sub-Andean forest remnant (24 ha; 1,600–1,700 m a.s.l., Cauca, Colombia) using free collections across the total area and a structural inventory in five 50 × 4 m transects (498 individuals, 35 species). A total of 281 species, 209 genera, and 100 families were recorded; epiphytes represented 44.13% of species, exceeding typical values (25–35%) for this forest type. Diversity indices were intermediate (H′ = 2.55; DMg = 5.47; 1−D = 0.89). Palicourea crocea dominated structurally (IVI = 45.12) and concentrated 31.2% of total carbon storage (894.41 kg·ha⁻¹; total = 2,866.23 kg·ha⁻¹). Three novel carbon indices (CVI, CCEI, CSI) integrate storage magnitude with ecological efficiency and spatial stability. The CSI was highest in low-aggregation species (1,618.23), with no significant differences among spatial groups (Kruskal–Wallis, p = 0.088). El Mangón ranks among the most diverse sub-Andean remnants of southwestern Colombia, underscoring its conservation priority in an increasingly fragmented landscape.

Abstract: Forest structural diversity is a critical determinant of ecosystem function, yet the long-term influence of disturbance history on stand architecture remains complex. Here, we evaluate how historical disturbances shape structural and compositional diversity across 59 fully mapped plots in temperate mountain forests. Using field-based measurements, we quantified a suite of spatial, size-based, and compositional metrics, including Shannon entropy, diameter/height differentiation, species intermingling, and composite indices (SDI, Arten–Profill). Plots were categorized by time since disturbance (Recent, Intermediate, and Historical). Our results reveal a decoupling of structural recovery trajectories: biomass and tree size metrics (QMD, height, volume) follow a predictable, linear path of accumulation with disturbance age. In contrast, complex spatial indicators—such as SDI, species intermingling, and Clark–Evans aggregation—exhibit a threshold-based recovery pattern, increasing rapidly during early succession before plateauing as stands mature. Multivariate analyses (PCA and hierarchical clustering) indicate that forest maturity is not a monolithic structural endpoint; rather, late-successional stands diverge into multiple successional trajectories, each defined by unique spatial and size configurations. Compositional metrics showed lower sensitivity to disturbance history than structural indices, suggesting that structural heterogeneity is a more persistent "memory" of stand development than species composition alone. These findings suggest that structural complexity is a "built-in" feature of early stand development. Consequently, management strategies should shift from volume-centric goals toward trajectory-based approaches, employing early-successional interventions (e.g., variable-density thinning) to steer uniform stands toward complex, resilient structural configurations before developmental thresholds stabilize.

Abstract: Seed enhancement technologies play a crucial role in improving germination performance and early seedling establishment of forest tree species. This study evaluated the effects of seed priming, microbial inoculation, and polymer coating on the germination behavior and seedling quality of Falcataria falcata. Fifteen treatments, including hydropriming (HP), plant growth regulators (GA₃), beneficial microorganisms, and polymer-based coatings, were assessed under controlled conditions. Results revealed that all seed enhancement treatments significantly improved germination and seedling growth parameters compared to the untreated control (p < 0.01). Hydropriming alone increased germination from 49.5% to over 93%, while combined treatments (HP + microbial inoculants + GA₃ + coating) achieved up to 97.5% germination and significantly enhanced germination index, vigor indices, root development, and nodulation. The highest seedling vigor (Vigor Index I = 2055.57) and root–shoot ratio (0.60) were observed in integrated treatments, indicating improved biomass allocation and stress adaptation potential. Principal Component Analysis explained over 90% of the variability in germination traits and 75% in seedling growth, clearly distinguishing superior treatments. The findings demonstrate that integrated seed enhancement strategies synergistically improve physiological performance, nutrient acquisition, and early growth dynamics. These results highlight the potential of combining priming, bioinoculants, and coating technologies to optimize seedling production and establishment of tree plantations and agroforestry ecosystems.

Abstract: The risk of wildfires is increasing due to high temperatures and dry weather conditions caused by climate change. Outbreaks and spread of wildfires are usually conditioned by weather, topography, and forest stand characteristics. In the Republic of Korea (hereafter ROK), most wildfires are caused by anthropogenic factors rather than by natural factors. However, the current forest fire forecasting system being operated in ROK does not account for anthropogenic factors. To analyze the impact of human factors, along with physical factors, on wildfire occurrence, a binary logistic regression model was constructed with data for the Gangwon and Gyeongbuk provinces from January 2022 to August 2025. The dependent variable was defined as the occurrence of a wildfire, while the independent variables comprised meteorological, seasonal, stand, and anthropogenic factors. To address multicollinearity, variables with high correlation coefficients were excluded from the independent variables, which were selected by three estimating approaches including logistic regression and two machine learning techniques (namely, Random Forest and XGBoost). With machine learning, the variables with high feature importance were identified. The explanatory power of the logistic regression analysis with independent variables selected by the machine learning models was about 1.3 times higher than the model using variables adjusted solely for multicollinearity. The results of logistic regression analysis revealed that weather and coniferous forests are the most important factors fostering wildfires, while the mean stand age was the most significant factor in hindering wildfires. Among the anthropogenic factors, forest road density acted as a suppressor of wildfire spread rather than a promoter of occurrence. Conversely, trail density tends to increase the risk of wildfire occurrence. Among forest management activities, artificial forests could boost forest fires, although this remains uncertain. These findings suggest that preventing wildfires requires a paradigm shift in forest resource management policies, including extending the rotation age of forests and the conversion of coniferous forests to broadleaf forests. Meanwhile, it also indicates the need to restrict the expansion of hiking trails and improve regulations regarding hiker access to prevent wildfires.

Abstract: Mangrove forests in northern Mozambique were impacted by human and natural pressures that caused channel blockage, permanent flooding, and tree die back. To address the issue, hydrological restoration was carried out in August 2024, excavating 6.88 km of canals with impact in 38 ha of degraded mangrove. This study reports on the monitoring results carried out 4 and 10 months later. Site salinity approached optimal levels for mangrove growth by dropping 56% in high salinity areas, and increasing above 100% in freshwater invaded areas. The intervention also homogenized the previously distinct upper, middle and lower zones (Dunn Post-Hoc: p > 0.05). Moreover, seedling density increased from 57.1±44.1 to 4864±1778.6 seedlings/ha; and regenerating species went increase in number (1 to 3 in middle zone; and 0 to 3 in lower zone). More regenerating classes (63:1:1 in upper, 11:1:0 in middle and 6:1:0 in lower) and die back of competing species Juncus kraussii and Cyperus articulates was also recorded. These changes result from the improved tidal flow and general habitat conditions in the restored site. This restoration offers a model for scaling restoration efforts across the region, where ecological restoration remains underrepresented in many mangrove restoration initiatives.

Abstract: Sweet chestnut (Castanea sativa Mill.) is a key European forest species, widely managed in coppice systems for timber production. Despite its ecological and socio-economic relevance, regional-scale genetic structure in coppice stands and its potential application to timber traceability remain underexplored. This study aimed (i) to assess genetic diversity and population structure in four coppice chestnut stands of the Lazio region using 12 nuclear simple sequence repeat (SSR) loci, and (ii) to evaluate the feasibility of developing an SSR-based framework for timber origin verification at regional and Mediterranean scales. A total of 160 trees from four Lazio populations were genotyped and analyzed together with published SSR data from eight European populations (Spain, Piedmont, Sicily, Greece, and Turkey). Genetic diversity indices revealed high intra-population variability (mean Na = 9.17; mean He = 0.738; mean PIC = 0.737), with most genetic variation partitioned within populations (96% by AMOVA) and moderate differentiation among stands (Fst = 0.038). Bayesian clustering indicated substantial admixture, reflecting extensive gene flow and long-term connectivity typical of coppice systems. Comparative analysis using five shared SSR loci across 12 populations resolved three main phylogeographic gene pools corresponding to Iberian, Central Italian, and Eastern Mediterranean groups. To enable timber traceability, a modified CTAB–PEG DNA extraction protocol was optimized for dried wood material collected from four sawmills (Lazio, Calabria, and France). Reliable multilocus genotypes were obtained from 40 timber samples using seven highly polymorphic SSR loci. Timber assignment was conducted through an integrated analytical approach combining Discriminant Analysis of Principal Components (DAPC), Bayesian clustering (STRUCTURE), and likelihood-based exclusion testing (GDA_NT 2021). At the regional scale, timber from Lazio sawmills was consistently assigned to the corresponding reference populations with assignment scores of 1.000 and negligible exclusion probabilities. At the Mediterranean scale, timber samples were correctly affiliated with broader phylogeographic clusters, although fine-scale discrimination was limited by regional genetic homogeneity and reference coverage. These findings demonstrate that Lazio coppice stands maintain high genetic diversity and confirm the technical feasibility of SSR-based macro-regional timber traceability in C. sativa. While further marker expansion and broader geographic sampling are required for operational implementation, the integrated framework developed here provides a robust basis for genetic origin verification, supporting sustainable forest management and transparent timber supply chains.

Abstract: The research is an exploration of how livelihood capital endowments affect the growth of Non-Wood Forest Products (NWFPs) in rural communities at the Koyten Dag part of Turkmenistan. The study is based on the Sustainable Livelihoods Framework and grounded by 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. The study also utilizes annual periods of time series data between 2001 and 2024 and applies the ARDL bounds testing method to test the short and long-run associations among livelihood assets and NWFP production. The results verify the high degree of long-run cointegrating, showing that the five capitals have a great impact through which they affect the development of NWFP in a positive way. Emerging as the ultimate drivers both in the short and long-term, education, skills, health, and digital connectivity become especially important. Financial and social capitals reflect the long-run contribution foundations and natural capital shows the significance of the availability of ecological resources and governance systems. The correction error term is a sign of a quick rate of adjustment meaning that the system of livelihoods is robust and can be brought back to equilibrium within a short duration of time in case of temporary shocks. Stability in results is checked by robustness tests conducted by FMOLS and DOLS. The paper has significant theoretical and practical implications such as that the policies have to be 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 an efficiency approach to the NWFP sector in Turkmenistan.

Abstract: Forests are increasingly exposed to interacting biotic and abiotic stressors, including invasive insects, emerging pathogens, and climate-driven disturbances. Understanding how trees resist or tolerate these stressors is therefore essential for sustaining forest health and ecosystem services. This review synthesizes current knowledge on forest resistance to insects and pathogens, revisiting classical concepts of resistance, tolerance, and resilience and examining how they operate under contemporary environmental change. We integrate insights from plant–insect–pathogen interactions, phenological dynamics, and multitrophic ecological processes to develop a conceptual framework describing how host traits, environmental conditions, and biotic antagonists jointly determine resistance outcomes. European ash (Fraxinus excelsior) is used as a model system to illustrate these processes in the context of two major invasive threats: ash dieback caused by Hymenoscyphus fraxineus and the emerald ash borer (Agrilus planipennis). Evidence from genetic, physiological, and chemical studies indicates that resistance in ash is polygenic and often expressed as reduced susceptibility or tolerance rather than complete immunity. Recent findings further suggest the existence of cross-resistance mechanisms that may simultaneously influence responses to fungal pathogens and insect pests. Climate change, environmental stress, and host-associated microbiomes may further modify these interactions and shape long-term resistance dynamics. Finally, we discuss implications for resistance breeding and adaptive forest management, emphasizing the importance of maintaining genetic diversity and ecosystem heterogeneity to enhance forest resilience under accelerating global change.

Abstract: Nondestructive assessment of wood quality in standing trees is increasingly essential for valuebased harvesting, precision forestry, and largescale monitoring. Yet most existing approaches rely on destructive sampling or plotscale measurements that cannot be feasibly extended across extensive forest areas. A major barrier to scalable assessment is the spatial misalignment between external structural measurements and internal woodquality responses, which introduces systematic bias when conventional regression methods are applied. We propose a generalized statistical framework called Regression based on Misaligned Covariates (RMC), that reconciles covariates and responses measured at separate spatial locations. By combining the Law of Total Expectation with kernelbased estimation of marginal relationships, RMC recovers heightdependent conditional means without requiring onetoone spatial correspondence. The framework is demonstrated using two physiologically contrasting conifers, eastern white pine (Pinus strobus) and red pine (Pinus resinosa), using covariates that are directly measurable through nondestructive, remotesensingbased structural characterization. RMC produced smooth, biologically interpretable estimates of knot volume along the bole for both species, even when trained on small datasets and using only a single structural covariate in addition to height. The resulting cumulative knotvolume profiles captured speciesspecific differences in knot accumulation and aligned with known patterns of crown architecture and stem form. RMC provides a scalable, nondestructive pathway for predicting internal wood quality from external structural measurements, supporting preharvest planning, logsorting decisions, and longterm monitoring of stand development. Because the method is portable, parsimonious, and not speciesspecific, it offers a general solution for any ecological or remotesensing application involving misaligned covariates and responses, extending well beyond woodquality modelling.

Abstract: Plant species in secondary forests can significantly influence soil nutrients. We assessed how soil micronutrients (B, Fe, Cu, Zn, Mn) and Al were affected by plant species in secondary forests at Masako Forest Reserve. Soil samples were collected in June 2022 and 2023 at three depths: 0–10 cm, 10-20 and 20-30 cm along five plant species. A com-pletely randomized design was used with 3 soil depths (SD) x 5 plant species (PS) replicated 4 times. Soil samples were air-dried, sieved 2 mm and sent to Brookside Laboratories (OH, USA) for analyses. Results showed that in 2022, Mn (p=0.0014) and Al (p=0.0216) were significantly affected by SD. Mn (18.30 mg/kg) concentrations were higher in 0-10 cm while Al (443.80 mg/kg) was concentrated in 20-30 cm depth. Boron, Fe, Mn, Zn and Al were all significantly affected by PS (p< 0.01). The soil under Musanga cercopoides had the highest concentrations of Mn, Cu (in magnitude), Zn and lowest in Al. Boron (0.50 mg/kg) and Fe (215.67 mg/kg) were highest in soils under Tricula Africana. As in 2022, Mn (p=0.0166) was also significantly affected by SD in 2023 with its highest concentration (5.45 mg/kg) in 0-10 cm. As for 2022, the soil under Tricula Africana had significantly higher concentrations of Fe (192.67 mg/kg) and Zinc (27.76 mg/kg). The 0-10 cm layer seems to significantly hold more nutrients as compared to deeper soil layers. Triculia africana seems to play a significant role in micronutrients cycling at Masaka Forest Reserve.

Abstract: This study investigated the effects of different application rates of spent mushroom substrate (SMS) from Morchella sextelata on soil properties and microbial communities in a moso bamboo (Phyllostachys edulis) plantation. Three SMS rates (2.4, 4.7, and 9.4 kg·m⁻² ) were applied, and soil samples were collected at 6 and 12 months from two depths (0–20 cm and 20–40 cm). One year after application, topsoil total phosphorus (TP) increased 12–20 fold, while available phosphorus (AP) and potassium (AK) were significantly elevated. Soil pH initially decreased but partially recovered, whereas electrical conductivity (EC) continued to rise, indicating salt accumulation. Urease (UA) and sucrase (SA) activities increased 10–17 fold and 3–5 fold, respectively, while catalase (CAT) and acid phosphatase (ACP) were temporarily suppressed. SMS application significantly altered microbial community composition, with Acidobacteriota and Basidiomycota becoming more abundant. Correlation analysis identified pH, organic matter, AP, and UA as key factors linked to microbial changes. The medium application rate (4.7 kg·m⁻² ) provided the best balance between soil improvement and environmental risk. These findings demonstrate that M. sextelata SMS can effectively enhance soil fertility while modulating microbial communities, but salt accumulation and short-term acidification warrant attention.

Abstract: Forest, wild, and exotic fruits are integral yet often overlooked components of agricultural landscapes in East and Southern Africa. These “hidden harvests” contribute to food and nutrition security, livelihoods, biodiversity conservation, and climate resilience, but remain marginal in dominant food system narratives and policy frameworks. This study aims to systematically synthesise existing evidence on the roles of forest, wild, and exotic fruits within agricultural landscapes of Tanzania, Uganda, Zambia, and Rwanda, with a focus on their nutritional, economic, environmental, and social contributions. A systematic review was conducted in accordance with PRISMA guidelines, drawing on peer-reviewed and selected grey literature published since 2000. Relevant studies were identified through major academic databases and screened using predefined eligibility criteria. The results indicate that fruits significantly enhance dietary diversity and micronutrient intake, provide seasonal food buffers during lean periods, and support income diversification, particularly for women and marginalised groups. Environmentally, fruit trees contribute to ecosystem services, biodiversity conservation, and climate adaptation through agroforestry and landscape-based systems. However, their potential is constrained by governance challenges, tenure insecurity, weak value chains, and policy fragmentation. The study concludes that recognising forest, wild, and exotic fruits as integral components of multifunctional agricultural landscapes is essential for advancing resilient, nutrition-sensitive, and sustainable food systems in the region.

Abstract: Variation and comparison of annual cone and seed productions, and seed characteristics (number and percentage of filled seeds per cone) were examined for three consecutive years at three seed stand populations of Taurus cedar (Cedrus libani A. Rich.) with distinct structural characteristics. Fertility variation in cone and seed production was analyzed and discussed to inform for management practices of seed stands and for other silvicultural interventions. The analysis of variance showed the significant differences among populations and years, as well as among trees within a population and a year for both cone and seed production and seed characteristics. Population x year interactions were also significant (p<0.05), highlighting the importance of cone collecting stand and seed harvesting year. The parental balance curves showed that the cone production was much closer to equal contribution to the gamete gene pool than the production of filled seeds across years, suggesting that the number of cones is a better indicator of overall seed production. Fertility variation () in cones and filled seeds (1.10≤≤ 1.71 except 2.38 in a population and year) showed small deviation among seed stands and among years within a seed stand. Gene diversity of seed crops has increased through clustering populations and pooling years reaching values of 0.998 and 0.997, respectively.

Abstract: Due to climate change, seedling damage caused by drought stress is expected to increase in both afforestation sites and nurseries. Therefore, to ensure stable seedling production under high-temperature conditions and to cultivate seedlings with enhanced drought tolerance through hardening treatments, the development of an effective irrigation system is required. Conventional physiological methods for non-destructive drought detection, such as chlorophyll fluorescence and leaf temperature measurements, require expensive and manual operation, thereby limiting their real-time applicability in forest nurseries. This study evaluated the feasibility of using image-based leaf angle measurements for drought stress detection in Quercus acutissima seedlings. One-year-old seedlings were grown under two water regimes—well-watered (control; CT) and unwatered (drought; DT)—and physiological parameters, including chlorophyll fluorescence, vapor pressure deficit, and leaf angle, were measured. Statistical analyses (RMANOVA) revealed that changes in the leaf angle parameter (PMD–MD: difference between the previous measurement day and the current measurement day) exhibited temporal patterns similar to physiological responses to drought on day 6 (D6), but not earlier than physiological changes. Multiple regression models identified air temperature, soil moisture, Fm′, and VPD as the main factors influencing leaf angle variation. These findings demonstrate that leaf angle monitoring can serve as an effective surrogate indicator of physiological drought stress responses in forest nursery seedlings, with potential for integration into automated irrigation systems for drought hardening management, thus enabling enhanced real-time applicability over conventional methods constrained by costly equipment and manual handling.