Abstract: Grazing is the most important way for human beings to use grassland and significantly affects the physical and chemical properties of grassland soil. Caragana microphylla,as a leguminous shrub,its adjacent soil nutrient changes will have important effects on the structure and function of the graasland ecosystem. In order to study the effect of stocking rate on the nutrients content of the soil adjacent to Caragana microphylla in desert steppe,grazing experiments were carried out in Stipa breviflora desert steppe in Inner Mongolia. A total of four stocking rate treatments were conducted,namely the control-check (CK,0 sheep·hm^-2·a^-1),light-grazing (LG,0.93 sheep·hm^-2·a^-1),moderate-grazing (MG,1.82 sheep·hm^-2·a^-1) and heavy-grazing (HG,2.71 sheep·hm^-2·a^-1). In each treatment of the stocking rate,Caragana microphylla plants with the same size were selected and the four points were setup adjacent to the plants in the directions of East,South,West and North for soil sampling. The contents of alkaline hydrolysis nitrogen,rapidly available phosphorus and rapidly available potassium of the soil were tested. The effect of stocking rate on the contents of soil nutrients in desert steppe was analyzed. The results showed that with the increase of stocking rate,the content of soil alkaline hydrolysis nitrogen first increased then decreased;the content of soil available phosphorus first decreased then increased;and the content of soil available potassium content had been in a downward state. In LG treatment,the rapidly available phosphorus content of soil around the equilibrium point between the alkaline hydrolysis nitrogen and the rapidly available potassium showed the lowest value. In MG treatment,the content of alkaline hydrolysis nitrogen corresponding to the equilibrium point between the rapidly available phosphorus and the rapidly available potassium of soil adjacent to Caragana microphylla plants showed the highest value. The soil nutrients near Caragana microphylla plants vary with the change of stocking rate,which helps to improve the soil environment and optimize the resources management.

Key words: Desert steppe, Soil available nutrients, Stocking rate, Caragana microphylla

摘要： 放牧是人类利用草原最主要的方式，可影响土壤的理化性质。小叶锦鸡儿(Caragana microphylla)作为豆科灌木，其邻近土壤养分的变化对会对草地生态系统的结构和功能产生重要的影响。为研究载畜率对荒漠草原小叶锦鸡儿邻近土壤速效养分含量的影响，在内蒙古短花针茅荒漠草原进行放牧实验，共4个载畜率处理(对照CK (0羊单位·hm^-2·a^-1、轻度放牧LG (0.93羊单位·hm^-2·a^-1)、中度放牧MG (1.82羊单位·hm^-2·a^-1)和重度放牧HG (2.71羊单位·hm^-2·a^-1)，在每个小区中选定大小相近的小叶锦鸡儿植株，分为东南西北4个方向，测定植株邻近土壤碱解氮、速效磷和速效钾含量，分析这些参数之间的变化。结果表明：随载畜率增大，土壤碱解氮含量先升高后降低，速效磷先下降后上升，速效钾含量呈下降趋势。小叶锦鸡儿邻近土壤碱解氮和速效钾含量的平衡点对应的速效磷在LG区呈最小值，土壤速效磷和速效钾含量的平衡点对应的碱解氮在MG区呈最大值。

关键词: 荒漠草原, 土壤速效养分, 载畜率, 小叶锦鸡儿