Study On Dominant Populations Distribution Of Plant Community In Desert Steppe Under Different Stocking Rates

Populations distribution pattern is a key point for grazing ecology research, the research was conducted with 15 plants populations under 4 stocking sates based on the long-term survey of Stipa breviflora in desert steppe in Siziwang Banner, Inner Mongolia, using T test of diffusion coefficient, mean crouwding intensity, clumping index, patchiness index, GREEN index, CASS index to study the pattern distribution types, pattern scale and clump intensity of Stipa breviflora under different stocking rates and the effect of the pattern distribution types, pattern scale on different stocking rates. The main results:1) Population spatial pattern: 15 desert plant populations presented the distribution of separating, except Astragalus scaberrimus in North-south direction in the control presenting a uniform distribution; in light stocking area, Caragana stenophylla presented a uniform distribution in West- East and North- South directions; in heavy stocking area, Astragalus scaberrimus presented a uniform distribution in West- East ;2) Population pattern intensity: 15 plant populations, population pattern intensity presented ranging differences under different stocking rates and directions, by increasing stocking rates, the Cleistogenes mutica, Convolvulus ammannii, Artemisia frigida and Salsola collina became the main dominant populations;3) Population pattern scale: It presented separation distrbution in West-East direction for Stipa breviflora in the control and heavy stocking area, Convolvulus ammannii in the heavy stocking area, Cleistogenes mutica in the light stocking area and Salsola collina in the heavy stocking area; Stipa breviflora in the light stocking, Artemisia frigida and Salsola collina in the heavy stocking in the North-South direction;4) Correlation analysis: There was a positive correlation between mean crowding and mean density.