Abstract: By the methods of point pattern analysis and spatial sequence instead of time series, this paper studied the fine-scale spatial pattern of Stellera chamaejasme population in the degraded alpine grassland in northern slope of Qilian Mountains. With the increasing coverage of S. chamaejasme, its individual number decreased after an initial increase, young plants transited from random distribution to clumped distribution, aggregation intensity weakened after an initial strengthening, and elder plants showed a random distribution. When the coverage was lower, the S. chamaejasme population had a random distribution at 0-100 cm scale; when the coverage was higher, the distribution pattern transited from clumped to random with the development of the population. The spatial pattern had close correlation with the dispersion stage of the population. The dispersion of S. chamaejasme population was realized through the combination and annexation of patches, and the inter-conversion of competition and synergy.

Key words: Erythroneura sudra, Erigonidium graminicola, Spatial distribution, Geostatistics