Abstract:

According to the data,the height and width of Ammopiptanthus mongolicus were classified. The results indicated that the population structures of A. mongolicus were different in different environmental conditions. The age structures of three A. mongolicus populations showed the decline trend. The spatial distribution patterns and pattern dynamics of A. mongolicus populations were studied by applying seven aggregate indices(C,K,m^*,I,1/K,m^*/m and I_δ ) in different environmental conditions. And the spatial distribution pattern with different quadrat scale was examined. The results indicated that the spatial distribution pattern and aggregation intensity were different in different environmental conditions,while the tendency of pattern aggregation was generally parallel. The figure of pattern scale and pattern intensity showed that plot 2 clumped in 25 and 100 m²,and plot 3 clumped in 150 m²,while plot 1 performed the pattern of random distribution in all quadrat scale. With the population age increased,the distribution pattern had a trend from random to clustering and finally to random. The young and old individuals performed the pattern of random distribution,while the individuals of middle age stage clumped. The environmental factors principally influenced the formation and development of the spatial distribution pattern of A. mongolicus populations.

Key words: Ammopiptanthus mongolicus, population structure, spatial distribution pattern, aggregation intensity