Objective The community characteristics and population structure of Burretiodendron kydiifolium, an endemic plant species in the dry valley area of Yuanjiang, China, were analyzed to lay a theoretical basis for biodiversity conservation and sustainable development of endemic plant species.

Method 5 sample plots and 4 sample lines were set in the distribution area of Burretiodendron kydiifolium. The amount of B. kydiifolium individuals and the associated species in the community including the scientific name, amount or coverage, diameter at breast height, habitat conditions and anthropogenic disturbance types were recorded. The importance value, life form of the community and the structure of size classes of B. kydiifolium were analyzed.

Result B. kydiifolium distributed mainly in Pupiao, Yuanwalu, Baigoushen, Luyechong and Shidichong. The species distribution was sporadic and fragmented. The vegetation type of B. kydiifolium community was deciduous monsoon forest belonging to monsoon forest. 83 vascular plant species belonging to 69 genera, 39 families in the sample plots were recorded, of which the deciduous tree species were dominant with a proportion as high as 90.9%. The proportion of phanerophyte plants was the highest (60.24%) and followed by the chamaephyte plants (19.28%). The result of the analysis of 412 individuals indicated that the population structure of B. kydiifolium was stable, the percent of class Ⅵ (20 cm ≤ DBH) tree was the lowest (9.47%) and class Ⅴ (15 ≤ DBH < 20 cm) tree was 10.92%. There was no significant difference between other size classes. Because of some influencing factors such as anthropogenic disturbance and habitat conditions, the population structures of growing, declining and stable existed in different sample plots or sample lines.

Conclusion The vegetation type is deciduous monsoon forest belonging to monsoon forest. The population structure of B. kydiifolium is stable overall, while the growing, declining and stable structures exist in different sites. The seedlings and sprouting are the main regeneration approaches. The amounts of seedling and the young tree of B. kydiifolium vary greatly among different sites. Droughty habitat and anthropogenic disturbance are the reasons leading to poor regeneration of B. kydiifolium population.