Abstract: A study was conducted on a plot of Leymus chinensis grassland on the Songnen Plains to reveal how soil expansion and contraction disturb the soil and the vegetation thereon.Sampling the soil on a crevice edge and the plants on it,the result shows that while a crevice accelerates the evaporation of soil homidity and tears apart the roots of the plants,vitiating the total density and biomass of the community,the crevices,at the same time,helps organic matter drip into the soil,improves its physico-chemical character,and decresses the soil pH value,conductance rate,and salt content,As a result,the total density and biomass of the vegetation community will increase in the coming year.Soil expansion and contraction effect a short-time disturbance on the grassland.

Key words: Soil expansion and contraction, Natural disturbance, Crevvice on grassland, Disturbance effect

摘要： 以松嫩羊草草原为对象,选取草原土壤裂缝边的土壤及植被,测试其理化性质。研究土壤胀缩运动对草原土壤及植被的干扰作用。结果表明,土壤开裂,加剧了水分蒸发,对植被根系产生撕裂作用,引起种群波动,使植被总密度和总生物量降低;而裂缝对物质的贮存作用及淋溶作用又改善了土壤理化性质,提高了缝内有机质含量,降低了pH值、电导率及含盐量,增大了翌年植被的总密度和总生物理。因此,土壤胀缩运动对草原能产生短期的干扰作用。

关键词: 土壤胀缩运动, 自然干扰因子, 草原土地裂缝, 干扰作用