Abstract: The dynamic changes of the species component and their community roles, and synthetic characteristics were discussed. Results showed:1. that in a mixed pasture of perennial ryegrass/white clover, there is a continuous shift in community composition toward the original vegetation, but they are pioneer stage of the recovery succession. Overgrazing accelerates this tendency. 2. Aboveground biomass,density, and coverage of cultivated herbages tend to decrease after degradation succession begins. The changes in the dominant plant popu1ation are obvious. 3. The variety and quantity of invasive weeds depend primarily on grazing intensity and are greatest in the extreme degradation stage. 4-Species diversity and homogeneity increase as the degradation succession proceeds, but community dominance decreases.

Key words: Mixed pasture, Degraded succession, Structural characteristics of community, Diversity of species

摘要： 对人工草地退化过程的植被组成、作用和群落综合特征的动态变化规律的研究,结果表明,1.多年生黑麦草与白三叶混播火工草地具有一定的脆弱性和不稳定性,过牧后逐渐向天然植被演替,但目前仍处于演替的先锋阶段。2.在演替过程中,多年生黑麦草和白三叶的地上生物量、密度和盖度明显下降,而入侵杂草则呈上升趋势。群落主要种的优势地位发生明显的替代变化。3.杂草入侵的种类和数量取决于放牧强度,在极度退化阶段的杂草入侵种类和数量最多。4.物种多样性和均匀性随着演替进程的延长而增大,而生态优势度则随着演替的发展而减小。

关键词: 人工草地, 退化演替, 群落结构, 物种多样性