Abstract: The spatial patterns of plant populations are the results of coordinated adaptation of plants to environment, reflecting the life history strategy of plant populations. The heterogeneity of finescale spatial patterns in Oxytropis kansuensis population was studied by using the methods of community survey and point pattern analysis. Four kinds of alpine grassland were chosen, including undegraded grassland (Ⅰ), lightly degraded grassland (Ⅱ), moderately degraded grassland (Ⅲ) and severely degraded grassland (Ⅳ) in the northern slope of Qilian Mountains. The results showed that, with the increasing degree of natural grassland degradation, the population height, coverage and aboveground biomass and branch density increased, and the proportion of small bunch decreased, while the proportion of big bunch increased. The spatial distribution pattern of O. kansuensis showed a scaleassociated change trend. In the undegraded and lightly degraded grasslands, the distribution pattern of O. kansuensis showed a clumped distribution on a smaller scale, while showed a random distribution on a larger scale. Meanwhile, in the moderate and heavy degradation grasslands, the spatial distribution pattern of the population showed distinct pattern characteristics. With the increasing degree of natural grassland degradation, the clumped distribution patterns of plant populations shifted from a smaller scale to a larger scale, which reflected the dispersion and regeneration strategy of O. kansuensis population.

Key words: potential distribution area, DEM, spruce forest., site index model