Influence of different defoliation intensities to spatial heterogeneity of aboveground biomass of weeds in Lolium perenne+ Trifolium repens pasture

Pasture stability is one of the core issues in pasture establishment and management research，and weed invasion resistance is an important problem. Spatial patterns of the aboveground biomass of weed were determined using a geostatistical analysis in different defoliation intensity in Lolium perenne+Trifolium repens pasture. The results showed that the heterogeneity in spatial distribution of the aboveground biomass and the distance of spatial dependence varied significantly. Under different defoliation intensity, weed biomass had the biggest value of sill (C0+C) (12.53), indicating that the distribution of the aboveground biomass was not spatially heterogenous under heavy defoliation. The sill for CK was 4.751, the light defoliation intensity was 4.557, and middle defoliation intensity was 3.149.Similarly, the distance of spatial dependence also varied under different defoliation intensity. Analysis of spatial variation revealed that the spatial heterogeneity under different defoliation intensities in L.perenne+T.repens pasture as largely caused by spatial autocorrelation (50.3%～93.5%).The Krigingmap further showed a great spatial heterogeneity of the aboveground biomass.