Analysis on the Niche of the Main Plant Species of Oasis-deseart Ecotone in Fukang of Xinjiang

The niche differentiation of 7 main species in oasis-desert ecotone in Fukang of Xinjiang was analyzed quantitatively with respect to community gradients and single ecological factor gradients, i. e. soil moisture, soil salinity and soil acidity, by Levins formula and the method by Wang gang. The results were as follows: (1) according to community gradients, the order of niche breadth was Reaumuria soongorica (0.7010), Haloxylon ammodendron (0.6434), Ceratocarpus arenarius (0.4774), Bassia dasyphylla (0.3745), Kalidium foliatum (0.3541), Petrosimonia sibirica (0.3354) and Suaeda acuminata (0.2769); (2) the niche breadths of R. soongorica were 0.5274, 0.6039, 0.3620, 0.7325 respectively on dimensions of soil moisture, soil salinity, soil acidity, and soil organic, and that of H. ammodendron were 0.3320, 0.3083, 0.5103 and 0.5353 on the 3 dimentsions. The two plants were dominant species, and the others were dependent species based on their niche breadth; (3) Niche breadths of desert plants on community gradients were larger than the average on the 3 dimensions; (4) Niche overlaps between R. soongorica and H. ammodendron were the biggest on soil salinity dimension, it showed the two species had similar characteristics in absorbing soil salt. Level of niche were affected by biological factors such as soil moisture, soil salt, soil acidity and non-biological factors such as interspecies competition, exploitation and mankind destroy. In the area of the ecotone, species competed each other lightly view from their niche overlaps.