Abstract: Excentrodendron hsienmu is listed in the Chinese National Key Protected Wild Plants (Class II) as a rare species due to the anthropogenic disturbances and the lack of effective protection measures. To understand the relationships between E. hsienmu community and its environmental factors is helpful for the ecological restoration of this community. In this paper, the species composition and structural characteristics of E. hsienmu community and the related edaphic and topographical factors in the karst mountainous region in southwestern Guangxi, China were studied by twoway indicator species analysis (TWINSPAN), and their coupling relationships were analyzed by principal component analysis and canonical correlation analysis. A total of 135 woody plant species in the E. hsienmu community were recorded, belonging to 103 genera and 52 families. The E. hsienmu community was divided into six groups, and classified into four ecological types at the third level by TWINSPAN. In the E. hsienmu-Pistacia weinmanniifolia community, the species number was the largest, with the maximum Shannon diversity index in E. hsienmu secondary forest. The higher soil fertility level was found under the better developed plant communities. The PCA showed that the soil exchangeable calcium, total potassium, and available potassium contents were the most important environmental factors in the coordinated variations of environmental factors and plant community structure. The CCA showed that the Shannon index of the plant community was closely correlated with soil organic matter, total potassium, available potassium, and total nitrogen. Elevation had important effects on the species diversity. Soil total nitrogen and phosphorus had close coupling relationships with slope position and elevation.

Key words: Electrona carlsbergi, elliptical Fourier analysis, otolith, morphological diversity.