Effect of slope on plant diversity of a Stellera chamaejasme communityin subalpine meadow

Stellera chamaejasme is an important indicator species for degradation of natural grassland ecosystems. Exploring the response characteristics of S. chamaejasme community diversity to different slopes is of great significance for the control of S. chamaejasme. In this study, the community characteristics and grassland habitat conditions of an S. chamaejasme community in Hezuo, Gannan were studied by means of Quadrat survey. The S. chamaejasme community in a subalpine meadow was taken as the research object, and the slope of sample plot in the study area was divided into five gradient grades: Ⅰ (0° ~ 5°, Ⅱ (5° ~ 15°, Ⅲ (15° ~ 25°, Ⅳ (25° ~ 35° and Ⅴ (> 35°). Our results showed that: (1) S. chamaejasme is mainly distributed in the dry and sunny slope with good soil nutrient and moderate water condition at 2900 ~ 3050 m altitude and 15° ~ 35° slope in the subalpine meadow. (2) Most of the plant communities in the study area are adapted to the cold and windy environment. Plants were categorized into 10 families, 18 genera and 30 species in gradient Ⅰ, 7 families, 13 genera and 27 species in gradient Ⅱ, 6 families, 9 genera and 20 species in gradient Ⅲ, 14 families, 30 genera and 35 species in gradient Ⅳ, and 5 families, 10 genera and 15 species in gradient Ⅴ. (3) The distribution of the important values of Cyperaceae on different gradients was Ⅱ > Ⅳ > Ⅰ > Ⅴ > Ⅲ, and the distribution of important values of perennial rhizome grasses was Ⅴ on different gradients. The important values of perennial clump grasses on different gradients were Ⅴ > Ⅳ > Ⅰ > Ⅲ > Ⅱ, the important values of shrubs and subshrubs were Ⅳ > Ⅴ > Ⅲ > Ⅱ > Ⅰ, and the important values of perennials on different gradients were Ⅲ > Ⅱ > Ⅳ > Ⅴ > Ⅰ, while the important values of 1 and 2 years on different gradients were Ⅴ > Ⅳ > Ⅲ > Ⅱ > Ⅰ, the important values of shrubs and subshrubs on different gradients were Ⅴ > Ⅳ > Ⅲ > Ⅱ > Ⅰ, the distribution of important values of perennials on different gradients was Ⅴ > Ⅳ > Ⅰ > Ⅲ > Ⅰ, and the distribution of important values of perennials on different gradients was Ⅴ > Ⅳ > Ⅲ > Ⅱ > Ⅰ. Most of the plant functional groups had the most important values at gradient Ⅳ and Ⅴ, and the lowest values at gradient Ⅰ and gradient Ⅱ. (4) The richness index of plant community in the study area varied greatly on different slopes, and the diversity index of the community with complex habitat structure was high, the species diversity was relatively rich, and the slope was shown to influence the plant diversity distribution of the S. chamaejasme community.