【摘要】 【目的】研究长时期自然放牧条件下草地植物群落特征的变化。【方法】采用定位连续测定方法，分析测定1985～2001年分布于新疆天山北坡以镰芒针茅(Stipa caucsica)、博洛特绢蒿(Seriphidium borotalense)群落的种类组成、数量特征。【结果】在连续测定的17 a间，草地植物群落的种类组成与结构没有发生变化，而草地植物群落的数量特征始终处于动态变化过程；1985～1995年时段内，草地群落的高度、盖度和地上生物产量波动幅度不大，与自然降水量波动规律保持基本一致，影响草地基本数量特征的变化，降水量是主因，放牧干扰是次因；1996年～2001年时段内，草地基本数量特征波动较大。【结论】在1985～2001年期间，研究区草地群落植物种类组成与结构没有发生变化，群落优势种和主要伴生种在群落中的序位稳定，始终保持着群落原有的结构与功能。更多还原

【Abstract】 【Objective】 To analyze the changes of plant community characteristics under long-term grazing conditions. 【Methods】 The species composition and quantitative characteristics of desert steppe with Stipa caucsica and Seriphidium borotalense on the northern slope of Tianshan Mountains were analyzed, so did the data from 1985 to 2001 by using the method of positioning continuous measurement. 【Results】 The results showed that the species composition and communities structure did not change, but the communities quantitative characteristics changed in a dynamic process during the 17 years. The height, coverage, and above-ground biomass of the plant community did not change more, and they changed the same way with natural precipitation from 1985 to 1995, so we could know that natural precipitation was the major factor affecting the changes of the community’s quantitative characteristics, followed by the grazing factor. But the changes of the communities quantitative characteristics had a fluctuation greatly during the period from 1996 to 2001, whether it was the influence on climate or the role of grazing pressure that would be studied in the future.【Conclusion】 In the period from 1985 to 1995, the fluctuation range of the height, coverage and above-ground biomass of grassland community was small, which was basically consistent with the fluctuation law of precipitation. The main factor affecting the change of grassland community quantitative characteristics was precipitation. Grazing disturbance is a secondary cause; During the period from 1996 to 2001, the quantitative characteristics of grassland communities fluctuated more than before, and whether it is the effect of climate or grazing pressure needs to be further studied.The results can provide data basis for the rational grassland utilization strategy.更多还原