Study On The Spatial Pattern Of Plant Community In Alpine Meadow On Northeast Qinghai-Tibetan Plateau

Under two habitats(shady and terrace)and four grades(0.2-0.6m2,grade 1;0.6-2 m2,grade 2;2-3.6 m2,grade 3 and 3.6-8.6 m2,grade 4,respectively)of eight vegetation patches(Kobresia patches,Carex humilis+Kobresia capillifolia patches,Leontopodium leontopodioides patches,Artemisia smithii patches,Polygonum viviparum patches,Medicago ruthenica + Potentilla bifurca patches,Plantago lesnngi +Leymus secalinus patches)in northeastern Qinghai-Tibetan Plateau meadow,we used the power laws and photograph orientation method:(1)to quantitatively analyze the species composition and spatial heterogeneity of populations and communities;(2)to clarify the effects on the spatial distribution pattern of communities by the dominant species,sub-dominant species,accompanying species and rare species.This research results will provide some theoretical basis and practical experiences for the applications of power laws and photograph orientation method in vegetation spatial pattern.The main results are following:From two kinds of habitats communities,the plant species with a higher P value whose ? value was larger too;The ? value of the dominant and sub-dominant species was shady>terraces,the ?value of the accompanying species was shady<terraces;There were little differences between the 8 values in two habitats.However,the plant species with a higher P value whose ? value was smaller.The ? value of the dominant species or sub-dominant species was larger with increasing spatial heterogeneity index of community ?C value.The ? value of the accompanying species was close to zero,which maintains the community spatial distribution,while the ? value of the rare species changed largely.In eight vegetation patches,the relationship between the P value of plant species and their spatial heterogeneity index(?)and community heterogeneity index(?C)was,with the increase of the P value of plant species,if the ? was "?" type,its dominant species increased the ?C value of communities,while the accompanying species reduced ?C values of communities;if the ? value was a monotonically increasing type,its dominant species increased the ?C value of communities,while the rare species reduced the ?C value of communities.The spatial distribution patterns of two habitats and eight patches were aggregation distribution,and the spatial distribution pattern of plant community in terrace was more aggregation than that in shady.The combination of power laws with photograph orientation method could objectively analyze the spatial patterns of the vegetation patches communities in Qinghai-Tibetan Plateau meadow.It's a suitable way to analyze spatial pattern of grassland.