川西北高寒沙地草本植物群落物种组成及多样性研究

A Study of Species Composition and Diversity of Herbaceous Plant Communities in Alpine Sandy Land in Northwest Sichuan

高寒草地沙化严重影响了植被物种组成和物种多样性,植被对人类和动物的生存环境起着不可替代的重要作用。本文选取了川西北高寒沙区典型沙化县若尔盖、红原、阿坝、色达、稻城、理塘等6个县的典型沙化区域为研究地,对不同沙化程度的植被特征及物种多样性进行了研究。结果表明:沙化进程中,物种种类呈先升高后降低趋势,植物群落优势种不断发生演替,禾本科、莎草科种类数量逐渐减少,被菊科、蔷薇科植物等替代;物种多样性呈显著先上升后降低趋势,露沙地和流动沙地物种多样性较低,固定沙地和半固定沙地较高;βT与CN呈基本相反的变化趋势,物种组成随沙化程度的加剧差异更加明显。植物群落组成及物种多样性受沙化程度影响最大,但最终分布是环境及生物因子共同作用的结果。

The alpine grassland desertification has seriously affected the species composition of vegetation and species diversity, and vegetation plays an irreplaceable role in human and animals living environ- ment. In this paper, the typical alpine desertification grassland areas were selected in northwest Sichuan as the research area, such as Ruoergai, Hongyuan, Aba,Seda, Daocheng and Litang counties, and stud- ies were made of their vegetation characteristics and species diversity with different desertification degree. The results showed that with the development of the desertification, the plant species also presented a trend to increase firstly and then decrease, and the dominant species displayed a continuous succession. Gramineae and Cyperaeeae plants decreased gradually, and were replaced by Asteraceae and Rosaceae plants; Species diversities were lower in exposed sandy and shifting sandy land than those in half-fixed sandy land and fixed sandy land. βT and CN diversity index presented an opposite trend, the difference of plant communities was in different desertification stress at the beginning, but they were ultimately deter- mined by various environmental and biological factors together.