甘肃尕海湿地不同海拔草地群落组分及物种多样性研究

以青藏高原东部甘肃尕海湖西侧坡地为研究对象,在尕海湖边到坡地顶部(海拔3 485~3 650 m)内,调查了不同海拔梯度上植物群落物种组成和群落特征数据,分析不同海拔草地群落特征、物种生活型变化及人类活动的影响,以期探讨高寒湿地附近草地群落组分与物种多样性对海拔梯度和人为干扰的响应。结果表明,尕海湖西侧坡地共调查到59种被子植物,分别属于20科46属,其区系特征以温带分布为主,且植物生活型和功能型以多年生和非固氮植物为主。在不同海拔梯度上草地群落可分为早熟禾-银莲花群落、羽毛委陵菜-平车前群落、紫花针茅群落、早熟禾-菭草群落、早熟禾-嵩草群落和嵩草-莎草群落。人类活动严重影响着草地群落特征,即在人类活动较弱的区域以禾本科和莎草科为主,而在人类活动较强的区域,由早熟禾为主的高寒草原群落类型演变为羽毛委陵菜-平车前群落和紫花针茅群落。此外,物种多样性指数与海拔间存在明显的负相关,即物种丰富度、物种密度、相邻群落间共有物种数目和相似性指数随海拔升高而逐渐降低。可见,海拔和人类活动强烈影响着高寒草地群落的组成和多样性,尤其人类活动影响更为剧烈。因而,为保证高寒草地生态系统可持续发展和物种多样性的维持,应采取合理有效的保护措施,尽量减少人类活动的影响。

Study on grassland community characteristics and species diversity along altitudinal gradients in the Gahai wetland, Gansu province

To explore the responses of grassland community characteristics and species diversity to the altitudinal gradient and human activities,the species composition and plant life form of grassland community along altitudinal gradients from 3 485 to 3 650 m in the west-wing area of Gahai Lake,Gansu province,located in the eastern region of Qihai-Tibet Plateau,were investigated.The data showed that 59 species were found in this region,which belongs to 20 families and 46 genera.Most distribution type of these genera is the temperate,and the majority of these species are the perennial and non-leguminous nitrogen-fixing plants.The six grassland community types were classified along the altitudinal gradients,namely Poa annua-Anemone obtusiloba community,Potentilla plumose-Plantago depressa community,Stipa purpurea community,Poa annua-Koeleria cristata community,Poa annua-Kobresia myosuroides community,and Kobresia myosuroides-Cyperus community.The dominant species in the natural grassland are mostly consist of Gramineae and Cyperaceae families,while the species were replaced by the Potentilla plumose-Plantago depressa and Stipa purpurea in the human strongly active area,and herein human activities strongly influence the grassland community characteristics.In addition,the negative relationships between altitude and indexes of species diversity(such as,species abundance,species density,similarity index,and the number of common species) were also found.Obviously,both altitude and human activities strongly affect the community characteristics and diversity of the alpine grassland,even the human activities are more pronounced.Therefore,in order to sustain the species diversity and ensure sustainable development of alpine grassland,we should take the reasonable and effective protection and minimize the impact of human activities.