Effects Of Enclosure On The Dynamics Of Grassland Communities

Enclosure is an important technical means for ecological restoration in arid and semiarid area, and Yanchi County is located in China's desertified edge, which is extremely sensitive and vulnerable areas. In order to evaluate the effect of grassland communities restoration in this area, and to provide a reference for the similar area of vegetation restoration in the future, this paper researched 3 types of grassland communities (year-round enclosure, seasonal enclosure, no enclosuer) in Liuyangpu enclosure, investigating in July and August of each year, including name, number, coverage, community height, biomass, crust coverage. Through the analysis of the diversity, complexity, stability and fluctuation of grassland communities in 2006—2015 years, the results showed that1) Shanno—Wiener and L(S) showed an upward trend in enclosure area, showing that enclosure could effectively contribute to the restoration of grassland communities;in sample area E2 was single dominant position, resulting in a higher Simpson and lower E index.2) Through M.Godron stability analysis, the ratio of the grassland communities in the three types of plots was not close to 20/80, and it showed that the grassland community structure in Liuyangpu enclosure was in an unstable state; and the relative stability of three types'size relation was E2>E1>E, which signified that long-term enclosure was not conductive to the stability of grassland vegetation.3) The vegetation fluctuation curves of the three types of plots was in the fluctuation, the fluctuation curve was consistent with the precipitation in the early period(June-April).4) According to the investigation by E-new grassland, long term enclosure could produce biological crusts; on E-new grassland vegetation diversity index of regression analysis, with the factors of ecological and economic benefit, it was appropriate of 5 years to 7years in Yanchi County of Ningxia.