Abstract:

The composition of plant communities and the interspecific association reflect the spatial relationship between plant species, which is crucial for revealing the trends and stability of grassland succession. We analyzed the changes of community biomass composition based on three Kobresia communities in south pastoral area of southern Qinghai Province, and investigated plants interspecific association and community succession using Ochiai interspecific association index and Spearman rank correlation analysis on the basic of the 2×2 contingency table and plant species abundance. The results showed that the biomass of K. tibetica community exceeded significantly that of the K. pygmaea+Stipa aliena community and the K. pygmaea+Forbs community, and was mainly composed of cyperaceous plants, accounting for about 45% to 80% of the biomass, while the grasses, forbs and inedible plants only was 8.1%, 15.2% and 16.4%, respectively; the species pairs of three communities exhibited three kinds of relationship, namely, complete association, absolute association and complete independence, where the independent species pairs in the K. tibetica community and the K. pygmaea+Forbs community accounted for 38.1% and 40.0%, respectively, being more than other pairs and the associative species pairs in the K. pygmaea+Stipa aliena community accounted for 36.3%; more species pairs in three communities showed a significant association in which the significant positive association species pairs were more than the significant negative association ones, and the same species pairs in different communities had a distinctive interspecific association; and three Kobresia communities were in the stage of stable development.

Key words: Biomass, Important value, Kobresia meadow, Ochiai interspecific association index, Spearman rank correlation analysis

摘要：

植物群落构成和植物种间联结,反映植物物种空间上相互关系,对于草地演替动态及稳定性的揭示具有重要理论意义。以青南牧区南部3个嵩草群落为对象,分析了群落生物量构成变化;并基于2×2列联表及植物种多度,采用Ochiai种间关联度指数及Spearman秩相关分析,探讨了不同嵩草群落的植物种间关系及群落演替特征。结果表明:藏嵩草群落的生物量显著高于高山嵩草+异针茅/杂类草群落,群落生物量主要由莎草科植物构成,其占总生物量的45%~80%,而禾草、杂类草和不可食植物则分别约占总生物量的8.1%,15.2%和16.4%;3个嵩草群落内的植物种对一般存在完全关联、绝对关联和完全独立3种关系,藏嵩草群落和高山嵩草+杂类草群落中完全独立的种对较多,为38.1%和40.0%;而高山嵩草+异针茅群落中完全关联种对较多,为36.3%;3个群落中较多植物种对间存在显著联结性,且显著正联结种对数多于显著负联结种对数,同一种对在不同群落中的种间关系不同;各嵩草群落均处于稳定发展阶段。

关键词: 生物量, 重要值, 嵩草草甸, Ochiai关联度指数, Spearman秩相关