不同退化梯度草地植物和土壤的差异

The Difference Between the Grass and Soil in Different Stage of Grassland Deterioration.

对锡林郭勒大针茅草原不同退化阶段植物和土壤化学性状的研究表明，随着草地退化程度的加剧，植物群落特征、植物碳水化合物含量和土壤化学性状存在明显的差异，表现在：（１）植物群落组成发生明显的变化，优势种和亚优势种植物出现替代；（２）地上和地下总生物量递减，禾本科牧草地上生物量在群落中所占比例下降，而菊科牧草所占比例上升，０～１０ｃｍ地下生物量占总地下生物量的比例增加，根系有向土壤表层集聚的趋势；（３）植物体内碳水化合物的含量逐渐递减，未退化样地大针茅茎叶中碳水化合物含量是重度退化样地的５．５倍；（４）土壤有机质、氮和磷的含量下降，土壤有机质含量与土壤全氮、全磷和速效氮的含量呈明显的正相关，与植物根系也呈较强的正相关。

A research was conducted on Xilinguole grassland dominated by Stipa grandis for studying grass community and chemical character of soil in different stage of grassland deterioration, and the results showed that there occurred significant difference in grass community character, carbohydrate content and soil chemistry character with the degree of grassland deterioration increasing. The difference was exhibited in these aspects as the degree of grassland deterioration increased: (1) The community composition is changed obviously. (2) Above-and-under-ground biomass decreased. The ratio of grass family biomass to total aboveground biomass decreased in community, while the ratio of composite family biomass to total aboveground biomass increased. The ratio of under-ground biomass in depth of 0～10cm to that in 0～40cm increased. This indicated that there was a tendency of roots moving to soil surface. (3) The content of grass carbohydrate decreased, and Stipa grandis's carbohydrate content in underiorated grassland was 5.5 times as much as that in heavy deteriorated grassland. (4) The contents of soil organic matter, N and P decreased, and the content of soil organic matter was significantly positive to that of total soil N, P and quick N, as well as positive to root biomass.