西藏地衣物种多样性的海拔梯度分析(英文)

Altitudinal Gradients of Lichen Species Richness in Tibet,China

根据西藏地衣分类和区系的文献资料,对西藏地衣物种多样性的海拔梯度进行了分析。267个分类群按照生长型或者基物被分为六组。每一组地衣的物种丰度随海拔增加呈现单峰曲线形式的变化。多数组物种丰度的峰值出现在海拔3400～3900m之间,对应于山地寒温带针叶林带的上半部分,比尼泊尔对应类群出现极值的海拔要高。此植物带谱内复杂的生态系统可能是物种多样性高的主要原因。壳状地衣物种丰度的峰值出现在5100～5400m区间则可能是因为该区内高大的树木的消失以及具有充裕的阳光。西藏的地衣物种多样性远低于尼泊尔,两地共有的物种数量很少。对西藏地衣物种多样性的调查不充分应当是其主要原因,因此今后中国地衣学工作者应当加强西藏地衣多样性的研究。

Altitudinal gradients of lichen species richness in Tibet, China were investigated based on taxonomic and floral literatures. Two hundred and sixtyseven lichen taxa were classified into six groups based on their growthforms or substrates. The species richness of all groups varied according to altitudinal gradient in a unimodal way. The ma ximum species richness of most lichen groups were detected between 3400-3900m, corresponding to the upper part of montane boreal coniferous forest, and the extreme height of the occurrence of theses lichen groups in Tibet is hig her than that in Nepal. This was probably due to the complex ecosystems in this vegetation zone. The species richness of crustose lichens reached its peak at 5100-5400m, which may be attributed to the disappearance of trees and ample sunlight. However, comparisons showed that the species diversity in Tibet was much lower than that in Nepal. This suggests poor understandings of lichen diversity in the area, and further investigations are need.