Abstract: Desertification grasslands with different degree were taken as the research object. The characteristic factors of vegetation community, biomass, soil water content, volume weight, porosity were analyzed through scientific investigation, sampling and formulas to reveal the change of vegetation and soil characteristics with different desertification grasslands in Northwest Sichuan. Results showed that community succession presented the pattern of "hygrophyte-mesophyte-xerophyte" with the aggravation of desertification degree. The height and coverage of community decreased, species richness declined 88% and dominant species changed greatly. The diversity index of light-desertification grassland was the highest one among tested grasslands. Total biomass decreased 90.4%, and the underground biomass decreased far more than aboveground biomass. In desertification progress, both soil water content and capacity decreased, the volume weight showed uptrend and porosity showed downtrend, soil characteristics had large variation in the early stage of desertification. Aiming at this phenomenon, the recovery and treatment of desertification grassland should be carried out in the early stage.

Key words: Grassland, Desertification, Vegetation, Biomass, Soil

摘要： 以川西北不同程度沙化草地为研究对象,通过科学调查、采样和公式计算,对植被群落、生物量、土壤含水量、容重和孔隙度等特征因子进行分析,以揭示川西北地区由湿地到严重沙化草地演替的不同阶段植被和土壤特征的变化情况。结果表明:随着草地沙化程度加剧,群落呈现出"湿生-中生-旱生"的演替过渡格局,群落高度和盖度降低,物种丰富度下降幅度达88%,优势物种构成也发生较大变化;生物多样性指数在轻度沙化草地群落中最高,总生物量下降幅度达90.4%,群落地下生物量远大于地上生物量;沙化过程中,土壤中含水量和持水量下降、容重增大、孔隙度减小。沙化初期土壤特征变化明显,应针对这一现象在沙化初期开展恢复治理工作。

关键词: 草地, 沙化, 植被, 生物量, 土壤