Relationship between species distribution of sandy alpine grasslands and microtopography in the source regions of Yangtze river

Dynamic of sandy alpine grasslands affect the progress and reversal desertification in source regions Yangtse Rivers. To understand geomorphic driving mechanism species distribution pattern, we examined compositions delineated most important landform factors influencing grassland using two-way indicator analysis (TWINSPAN), detrended correspondence (DCA), canonical (CCA). Field survey were conducted summer 2016 stratified random methods hilly sloped lands, floodplains, foothills, valley land study region. In total, 29 plant grouped into 27 genera 16 families identified. Leymus secalinus , Elymus dahuricus Corispermum declinatum are dominant communities different microtopography. The present vegetation reflected xerosere character, which indicated that is progress. Standard frequency varied with microtopography, proportion was generally lower than rare species, community a highly successional stage. Seven groups distinguished through TWINSPAN, DCA ordination graph showed similar ecotype clustered together. results CCA revealed slope aspect among microtopography determining grassland.