四川若尔盖县不同退化程度高寒草地群落比较研究

Comparative study of the alpine grassland communities in varying degradation in Zoige County， Sichuan Province

关键词:  高寒草地  退化梯度  群落结构  物种多样性指数  生物量  干扰

Key words:  alpine grassland  degradation gradient  community structure  index of species diversity  biomass  disturbance

摘要:

于2008年、2009年在若尔盖县沿高寒草地退化梯度进行物种多样性和生物量等方面的群落监测，以期探讨不同退化程度高寒草地群落结构特征，并提出引起退化的原因。结果表明：（1）随着退化加剧，草地群落盖度、群落物种丰富度、Shannon Wiener指数和Pielou指数均递减。未退化群落以鹅绒委陵菜、无脉苔草为优势种，群落物种丰富，记录25种植物；中度退化群落以无脉苔草为优势种，记录植物20种；重度退化群落以二裂委陵菜、密花香薷、白苞筋骨草群落，记录16种植物；（2）未退化群落、中度退化群落、重度退化群落生物量鲜重多次监测的平均值分别为836.78、726.37 g/m2和542.78 g/m2，可见随着群落退化程度加剧，其生物量鲜重递减；未退化群落、中度退化群落生物量干重值在各个监测时段十分接近，而重度退化群落的值明显降低；（3）1965～1973年间挖沟排水可能是该区高寒草地退化的主要原因，放牧、干线公路、旅游开发等人为干扰是研究区草地群落退化的驱动因子。

Abstract:

The monitoring of species diversity and evenness of alpine grassland along the degradation gradient was conducted to characterize changes of the community structure in varying degradation and suggest possible causes in Zoige County in both 2008 and 2009. The results showed 〖JP3〗that:(1)the coverage，species richness，Shannon Wiener and Pielou indexes of species diversity of communities were decreasing from the non degradation to the highest degradation；(2)The aboveground biomass was decreasing from the non degradation to the highest degradation，with 836.78 g/m2，726.37 g/m2，and 542.78 g/m2 in fresh weight for non degraded，moderate degraded and heavy degraded communities. The weight of dry biomass of moderate degraded communities was quite close to non degraded communities and obviously higher than heavy degraded communities；(3)Excavating discharge ditches in 1965-1973 might be the main driving factor of community degradation. Other driving factors included overgrazing，highway construction and tourism.