乌兰布和沙漠东北边缘植物群落物种多样性及其生态环境

应用群落多样性指数（Ｄ）、均匀度（Ｊ）、生态优势度（Ｃ）等指标，对乌兰布和沙漠东北边缘不同生境（荒漠区、绿洲外围、绿洲内）的天然植物群落进行了研究，结果表明这三种指标值能有效地表征群落的组成结构特征及生境的优劣；荒漠植物群落多样性指数（Ｄ＝０．６０３～２．９８４）和均匀度（Ｊ＝０．３３７～０．６９１）都较低，而生态优势度（Ｃ＝０．７２４～０．１９５）较高，说明荒漠植被生态环境的脆弱性，群落结构越复杂，多样性指数越高；多样性与生态环境关系密切，Ｄ和Ｊ随生境渐好而递增，Ｃ随生境渐好而递减，可作为环境评价指标；多样性在一定程度上体现了群落的发展阶段和稳定程度，越接近顶级阶段，多样性越高，且环境的改善有助于群落演替进程的加速；干旱区弃耕撩荒地次生演替植被，在弃耕初期多样性随弃耕年限增大而减小，后期处于一个较稳定的水平，且各演替阶段植物组成变化较大。

STUDIES ON THE SPECIES DIVERSITY OF PLANT COMMUNITIES AND THEIR ECOTOPES IN THE NORTHEASTERN ULAN BUH DESERT

plant communities at different habitats(desert area,peripheral area of the artificial oasis and the interior of artificialoasis) in the northeastern Ulan Buh Desert were studied by means of Shannon wiener diversity index(D),community evenness formula(J)and Simpson ecological dominance(C).The results show that three indexes have an efficient effect on indicating community structure and succession and their habitat conditions.The species diversity (D is from 0 603 to 2.984)of the desert is rather low,and the ecological dominance(C is from 0 724 to 0 195)is rather high,which show s the ecotope vulnerability of the desert.The species diversity and the community evenness increase and the ecological dominance decreases with the more complicated structrue,higher succession process and favourable ecological habitat condition.There is close correlation among three indexes and the ecological factors of desert comunnities,of which the soilmoisture has a significant effect.Also the succession of plant communities of the abandoned arable lands in the artificial oasis was analysed with three indexes.