Studies on Species Diversity and Spatial Distribution Pattern of Dominant Populations in the Transition Zone between Minqin Oasis and Desert

With the transition zone between Minqin oasis and desert as subjects,using the quadrat survey procedure,species diversity and spatial distribution pattern of dominant populations in the transition zone between Minqin oasis and desert have been studied through testing species important value,abundance index(R),Shannon-Winer species diversity index(H′),Simpson dominance index(D),evenness indices(Jsw),diffusion coefficient(C),negative binomial parameter(K),mean crowding(m*),clumping index(I),patchiness index(PI),Green index(GI),Cassie index(CA),dispersal index(Iδ) in various types region.The results showed that the dominant species populations are Calligonum mongolicum,Nitraria tangutorum,Haloxylon ammodendron,and the companion species are Salsola ikonnikovii,Bassia dasyphylla,Phragmites communis,griophyllum squarrosum.Suffering the influence of the sand dune type and the habitat,every population indicated the accumulation distribution pattern,but the accumulation degree had certain difference;The species diversity and the abundance changed regularly with gradient of Minqin oasis and desert,but overall performance showed tendency to ascend.The habitat and the type of sand dune in this region are a determining factor for species diversity and spatial distribution pattern of populations.