There is an emerging interest in the relationships between forest structure and topographic aspects. Still, such patterns have been scarcely studied in undisturbed mixed beech forests in northern Iran. We investigated the influence of topographical factors including aspect, slope degree, and landform index (LI) on the distribution of dominant tree species and coarse woody debris (CWD). Tree density and basal area were not significantly correlated with any of the measured parameters, except a moderate relation between basal area and LI (r = - 0.376; P = 0.029). Redundancy analysis (RDA) of the tree layer revealed a significant relationship between the measured environmental variables and species distributions. CWD volume showed significant negative correlation with percent canopy coverage and was highly correlated with slope. Density of CWD in decay class IV was significantly correlated with aspect and percent of canopy cover. Analyses of CWD distributions in relation to both living vegetation and topographic gradients showed a highly complex interplay of factors driving the distribution of CWD across the forest stands.

Virgin oriental beech ( Fagus orientalis L.) forests of the Hyrcanian region in northern Iran are among the last remnants of temperate old-growth ecosystems worldwide, yet their ecological benchmarks remain poorly defined. We conducted an integrated, multiscale assessment of three virgin 1-ha pure oriental beech stands located in the Hyrcanian forests of Guilan Province, with 60 randomly distributed plots capturing a suite of 62 structural and functional indicators. These encompassed forest structure, herbaceous diversity, humus chemistry, and soil physical, chemical, and biological properties, together with fine root traits. Results revealed exceptionally high basal area, abundant large-diameter trees, and broad crowns that collectively typify structurally mature, late-successional stands. The understory was dominated by shade-tolerant, Euro-Siberian taxa, highlighting long-term ecological continuity with minimal disturbance. Humus layers stored substantial carbon and nitrogen, while soils showed moderate fertility and evidence of constrained phosphorus availability, indicated by low microbial P and enzymatic activity. Fine root traits suggested conservative strategies optimized for stable nutrient acquisition under mature closed-canopy conditions. Multivariate analyses identified two dominant nutrient pathways: (i) a tightly coupled humus–microbial–soil C–N continuum that stabilizes long-term fertility, and (ii) a partially decoupled P cycle driven by enzymatic and fine root processes. This study provides the first quantitative, multiscale ecological indicator ranges for virgin oriental beech forests, establishing a comprehensive benchmark for these globally rare ecosystems. The integration of structural, biological, and chemical indicators provides a functional reference framework for detecting nutrient imbalance, soil degradation, or canopy disturbance in managed beech forests. These reference values support forest managers in identifying early signs of structural or functional degradation, designing long-term monitoring programs, and evaluating restoration success. For policy makers and silviculturists, these benchmarks provide measurable targets for adaptive management, biodiversity conservation, and ecosystem-based planning under changing climatic and anthropogenic pressures. More broadly, these results emphasize the importance of preserving intact forest systems to better understand how ecosystem structure and nutrient dynamics co-evolve under minimal human disturbance, with direct relevance for temperate beech forest management worldwide.

Arasbaran represents one of Iran’s most valuable forest ecosystems, recognized as a sensitive and strategic biome due to its high biodiversity, genetic significance, and its critical role in regional environmental sustainability. Despite its protected status, the region faces persistent pressures arising from land-use change, livelihood dependence, and institutional constraints, underscoring the need for evidence-based management strategies. In this study, key ecological, social, and institutional factors influencing the Arasbaran Biosphere Reserve were systematically identified and classified using a Strengths–Weaknesses–Opportunities–Threats (SWOT) framework. These factors were subsequently structured into criteria and sub-criteria and evaluated through a network-based Analytic Network Process (ANP) to account for interdependencies and to quantify their relative importance. The integrated SWOT–ANP analysis identified strength–opportunity (SO) strategies as the highest-priority management pathway, indicating that sustainable outcomes are most effectively achieved by mobilizing existing ecological assets, strengthening social participation, enhancing education and awareness, and integrating scientific knowledge with management practice. Weakness–opportunity (WO) strategies ranked second, emphasizing the role of institutional reform, capacity building, and community empowerment as enabling conditions for proactive management. In contrast, strength–threat (ST) and weakness–threat (WT) strategies received lower priority, reflecting the limited long-term effectiveness of approaches centered primarily on restriction and deterrence. Overall, the findings demonstrate that sustainability in Arasbaran is best advanced through capacity-oriented, participatory, and knowledge-based governance rather than control-focused interventions. While the specific strategy rankings are context-dependent, the SWOT–ANP framework provides a transferable decision-support approach for managing complex forest ecosystems facing multi-layered ecological and socio-institutional challenges.