沙地草场放牧试验植物群落的TWINSPAN数量分析

TWINSPAN ANALYSIS OF PLANT COMMUNITY COMPOSITION UNDER EXPERIMENTAL GRAZING IN A SANDY GRASSLAND

在长期严格沙地草场放牧试验的基础上，通过样方调查和TWINSPAN数量分析，揭示了植物群落的物种组成及种群在放牧压力下的变化趋势，主要结论是：1）不同的放牧压力使试验地的群落发生分化，形成差异明显的类群，而相同的放牧强度又使群落趋同，使群落的组成和物种的生态适应特性趋于一致。2）随着放牧强度的增加，群落中多年生成分减少，一年生杂类草增多，排列出了不同植物种组与放牧强度的对应关系。

We investigated changing patterns of plant community composition together with population dynamics under grazing pressure in a strict, long-term grazing test. This was achieved with a TWINSPAN (Two-way Indicator Species Analysis) analysis of quadrat data. The maln results are that: 1 ) community composition diverged under varying grazing pressure to form distinct different groups in test fields, while the application of replicate grazing intensity treatments resulted in composition convergence. 2) With increasing grazing pressure perennial species decreased and annual herbs increased in communities.