Abstract: Abies georgei forests represent one of the major community types of subalpine cold-temperate coniferous forests in the Hengduan Mountains, which forms alpine treeline in southwest China. This study is based on survey data from the  a 20 hm² plot in subalpine coldtemperate coniferous forest of the Shangri-La National Park in Yunnan Province. We investigated species composition, diameter class structure, and habitat preference of woody species with diameter at breast height (DBH) ≥1 cm. The results showed that: (1) A total of 39106 independent individuals and 9888 branches belonging to 10 families, 15 genera and 28 species were tagged. Among them, there were 27463 individuals of A. georgei, accounting for 70% of total individuals. (2) The areal type of the family and genera predominantly represented the north temperate and its two varieties, accounting for 50% and 87%, respectively. (3) The diameter class distribution of dominant species A. georgei, Rosa omeiensis and Sorbus rehderiana exhibited an inverse J-shaped pattern, indicating a good natural regeneration. Lonicera tangutica, Dipelta yunnanensis, and Rhododendron rubiginosum exhibited a skew-normal distribution, indicating stable population structure. (4) Among the 22 targeted species with individuals ≥20, 10 species were significantly positively or negatively associated with at least one specific habitat (i.e., gully, low slope, high slope, and high valley). Among them, four species, including R. rubiginosum and D. yunnanensis, showed a positive association with high-slope habitat. Two species, Picea likiangensis and Cotoneaster acutifolius, showed a positive association with low-slope habitat. A. georgei was positively associated with high-valley habitat, while three species, including R. rubiginosum, S. rehderiana, and D. yunnanensis, exhibited a negative association with high-valley habitat. These findings suggest that the niche differentiation of habitats plays an important role in maintaining species diversity in the A. georgei forest at local scale. Our results provide a basis for future research on the mechanisms of community assembly and species coexistence in subalpine cold-temperate coniferous forests.

Key words: Abies georgei, community composition, diameter class structure, floristic composition, habitat association