青藏高原羽柱针茅草原的分布、群落特征和分类

Distribution, community characteristics and classification of Stipa basiplumosa steppe on Tibetan Plateau

羽柱针茅(Stipa basiplumosa)草原是青藏高原特有的群落类型,在羌塘高原中、北部有较为广泛的分布。利用2012-2015年的植被调查数据及已有的文献资料,对羽柱针茅草原的生态地理分布、群落特征和分类做了全面分析。结果表明:羽柱针茅草原分布在阿里地区、那曲地区和日喀则地区,占据海拔4350~5200 m的湖盆外缘和洪积扇中部,分布区干旱、寒冷。群落低矮、物种贫乏、植物稀疏、生物量低。物种组成简单,以菊科、禾本科、豆科、莎草科等为主;生活型以地面芽植物和一年生植物居多;水分生态类型以旱生成分占绝对优势;区系地理成分以青藏高原成分和中亚—亚洲中部成分为多。羽柱针茅草原群系可划分为7个群丛组、20个群丛。

Stipa basiplumosa steppe is an endemic vegetation formation that occurs restrictedly on Tibetan Plateau. Based on primary plots data obtained from fieldworks during 2012-2015 as well as some earlier documents, we studied the eco-geographic distribution, community characteristics and classification of the Stipa basiplumosa steppe. The results showed that： Stipa basiplumosa formation was distributeds mainly on the outskirts of lake basin and the central section of proluvial fan of Ngari, Nakchu and Shigatse prefectures. It is cold and arid in the distribution area. Quantitative values such as average height, coverage, aboveground biomass and species richness of the formation are lower than those of most of the other steppes. Species composition is simple, and families like Compositae, Poaceae, Leguminosae, Cyperaceae play important roles. In addition, hemicryptophytes and therophytes are in the ascendant among the species life forms. The ecological type of water is simply divided into xerophytes and mesophytes, accounting for 71% and 29%, respectively. Eight floristic geographic elements are involved; Qinghai-Tibet Plateau and central Asia-middle Asia elements are the two major floristic ones. Based on classification and nomenclature system of Chinese vegetation, Stipa basiplumosa formation is classified into 7 association groups, consisting of 20 associations.