Abstract: By using Ripley’s K(r) function and fractal dimension, this paper studied the spatial pattern and fractal characteristics of four ecotypes Haloxylon ammodendron population at different development stages in Gurbantonggut desert. Of the four ecotypes, soil ecotype clumped in 1-18 m scale, while sand, saline soil and gravel ecotypes clumped in all scales, suggesting that desert plant could adapt a habitat via clumping. The spatial pattern of H. ammodendron population differed with its development stage. Seedlings and saplings clumped, while adult trees showed random distribution. Compared with Ripley’s K(r) function, correlation dimension could reflect the ability of spatial occupation, but couldn’t directly reflect the clump or not clump in arid area. Moreover, the dimension was susceptible to the number and size of H. ammodendron.

Key words: Haloxylon ammodendron population, ecotype, distribution pattern, development stage, fractal characteristic, Taihu Area, return of green manure to soil,  topdressing of , inorganic nitrogen fertilizer, no basal dressing.