Ecological Niches and Interspecific Associations of Dominant Species in Pseudotsuga sinensis Communities in Central Yunnan

To characterize the ecological niches and interspecific associations of dominant species in Pseudotsuga sinensis communities in central Yunnan, twelve 30 m × 30 m plots were established in Anning, Huize, and Zhanyi. The ten tree-layer species with the highest importance values in each area were selected for analysis using Levins’ and Shannon’s niche breadth indices, Pianka’s niche overlap index, the variance ratio method, the χ² test, and the association coefficient. The results showed that: P. sinensis ranked first in both importance value and niche breadth in all three areas, with importance values ranging from 31.20% to 53.66%. Among companion species, rankings by importance value and niche breadth were not entirely consistent. Species pairs with low niche overlap predominated in each area, with 64.44%–75.56% of pairs exhibiting overlap values below 0.2. The highest niche overlap between P. sinensis and its companion species was 0.530, recorded with Keteleeria evelyniana in Zhanyi. Most species pairs showed no significant interspecific association, accounting for 88.89%–93.33% of the pairs. Overall associations among dominant species were significantly positive in Anning, nonsignificantly positive in Huize, and nonsignificantly negative in Zhanyi. Some species pairs with relatively high niche overlap showed no significant association, whereas pairs with relatively low overlap could exhibit significant positive associations. The P. sinensis communities surveyed in central Yunnan shared the characteristics of pronounced dominance by P. sinensis, differentiation in niche breadth among dominant species, and nonsignificant associations for most species pairs. Niche overlap did not correspond directly to the statistical significance of interspecific associations. Conservation and management should account for local habitat conditions and companion species composition, conduct regeneration monitoring, and implement differentiated conservation measures.