THE EFFECT OF ELEVATION ON FOREST STRUCTURE AND TREE COMMUNITY COMPOSITION IN TROJAN FIR FORESTS IN KAZDAĞLARI (NW ANATOLIA, TÜRKİYE)

. Elevational contrasts offer natural experiments to investigate climatic and edaphic effects on forest structure. In the Mediterranean – Euxine transition, such contrasts can reorganize species assemblages and canopy architecture, yet plot-based evaluations integrating composition, density, and stratification are rare in the region. We examined Trojan fir ( Abies nordmanniana subsp. equi-trojani ) forests in Kazdağları (NW Türkiye) across two elevation zones — three low (600 – 800 m) and three high (1200 – 1400 m) sites — using 36 plots (25 × 25 m) were surveyed in October 2023. All woody individuals ≥ 30 cm were censused, crown overlaps mapped, and used to calculate cover, density, and vertical stratification. Community composition was assessed via NMDS, and structural variables were modeled with GLMMs and zero-inflated beta models. Across 13 taxa, ordinations clearly separated high from low situated plots, with tighter clustering at higher elevations. High sites were needle-leaved-dominated, while low sites supported mixed broad-leaved associates. Species-level patterns showed stable Trojan fir cover and density, denser Fagus orientalis at low elevations, and more Pinus nigra at high elevations. Canopies were generally limited to one – two layers, with ≥ 3 layers uncommon — especially at high elevations — indicating reduced vertical complexity. Elevation thus emerges as a driver of assembly and structure in Trojan fir forests; conserving heterogeneity across zones may strengthen resilience to warming climate.