The Responses Of The Spatial Distribution Of Micro-pattern For Leymus Chinensis Population To Defoliation Disturbance

To explain the vegetable's response and adaptive mechanism when suffered disturbance such as environmental interruption (defoliation) and provide the theoretical base for making the valid programming and using of grassland, one experiment was conducted to investigate the population dynamics, spatial distribution pattern, community characteristics, microlandscape and soil environment for the grassland of Leymus chinensis with different cutting intensities by applying the theory and method of population ecology and landscape ecology. In the experiment, we choose the area where the topography is smooth and the distribution of L. chinensis is relatively even. The defoliation experiment design was three treatments (medium cutting-M, heavy cutting-H and over-cutting-HH) with three paddocks per treatment and there was also a contrast (CK). We use gridding to measure the population distribution pattern and intensity, in the same time, using Kriging Spatial interpolating to obtain the figure of spatial pattern of L. chinensis and make vector analysis of data to explain the influence on the micropattern of L. chinensis under different cutting intensities. The results showed that:(1) The population characteristics varied with the increasing of cutting intensities. Firstly, the population height fell with the increasing of cutting intensities and differed significantly among treatments of medium (M), heavily (H) and over defoliation (HH) in the scale of P<0.05. Secondly, the population density decreased with increasing of defoliation intensity, but the difference is not significantly. Lastly, cutting made the biomass of L. chinensis per tiller fewer than CK significantly (p<0.05) and the biomass reduced by 41.61, 54.14, 61.30% and 58.98, 67.36, 75.26% respectively compared to contrast in 2005 and 2006; Cutting also reduced the population biomss in aboveground.(2) The spatial distribution patterns of L. chinensis in the treatments were aggregation after the last cutting; the aggregation intensity of population for L. chinensis enhanced with increasing of cutting intensities and the effects of continuous disturbance were embodied; the largest population aggregation pattern haven't change distinctly with the aggregation area of 1.28m2, but small clumping patterns appeared with increasing of cutting intensities. Cutting also improved biodiversity of community.(3) Defoliation as a way of disturbance has an important influence on micro-patch of L. chinensis. In the same year, numbers of patch increased with cutting intensities enhanced, the area of patch reduced and the landscape appeared fragmentation. Degree of fragmentation had a little drop in the second year. The edge density in landscape and fragmentation index both have increased with the increasing of clipping intensities, that is to say, the landscape...