关键词: 毛乌素沙地, 空间变异, 植物群落, 土壤养分, 有机质, 速效磷

Abstract: 【Objective】The Erdos sand land is a typical desertification area in the northern China. The paper is presented on the effects of different desert plant community on the spatial variance of soil nutrients. 【Method】One grass community (Stipa byngeana) and its theoretic succession community (Artemisia sphaerocephala) were selected to compare the effects of plant succession on the distribution of soil nutrients. And the soil organic matter content and the available phosphorus content within a small net under each plant community were analyzed. 【Result】 It revealed that the soil organic matter content and available phosphorus content under the grassland dominated by Stipa byngeana community were higher than those values under the shrub land dominated by Artemisia sphaerocephala community with remarkable difference. The semi-variance of the soil organic matter content under the Stipa byngeana community could be simulated by spherical model (Range a=0.89m), and the semi-variance of the available phosphorus content could be simulated by exponential model (Range a=0.24). It showed that the distribution of soil nutrients under the grass community controlled by the mini plant structure and random factors. The semi-variance of soil organic matter content and available phosphorus content under the shrub community all could be simulated by spherical models, the ranges for organic matter, available phosphorus were 1.5m and 1.40m, which were very near the diameter of the shrub. The geostatic analysis showed the soil organic matter and available P were strongly heterogeneity. 【Conclusion】The distributions of soil nutrients under two kinds of plant communities were obviously different. In the sub-meter scale, the isograms of soil organic matter and available P under the grass community had no regular distributions, but the Isograms of soil nutrients under the shrub community did show as a island of fertility, which higher nutrients content were distributed near the center of the shrub clump.

Key words: sand land, spatial variance, plant community, plant communitysoil nutrients, island of fertility, Available phosphorus