滇西北高山微水体与溪流生境底栖动物多样性和环境特征

高山微水体由于面积微小且通过地表径流形成串联结构常常被认为与高山溪流具有类似的生境, 然而由于这两类生境中环境因子与底栖动物多样性存在差异, 它们在生态系统中的作用可能完全不同。滇西北地区是全球生物多样性热点区域之一, 境内高山微水体和高山溪流分布密集, 在区域底栖生物多样性维持方面具有重要的功能, 然而目前对这两类高山淡水生态系统的研究较少。为了比较这两类生境环境因子的异同及其对底栖动物多样性的维持作用, 2015年6月, 作者在云南省怒江州贡山县的高山峡谷内, 对27个高山微水体和同区域分布的1条高山溪流(海拔高差500 m范围)的底栖动物多样性和水环境因子进行了实地调查。结果表明: (1)高山微水体和高山溪流底栖动物群落中优势分类单元种群数量均比较庞大, 而稀有分类单元数量较多且种群较小; (2)两种生境在环境因子、物种多样性、功能多样性和群落结构方面的差异明显, 高山溪流有较高的物种丰富度、物种多样性和功能多样性; (3)高山微水体底栖动物多样性的分布与水环境因子无关, 而高山溪流底栖动物多样性与群落结构的形成受到与流速关联的水环境因子和海拔的影响。因此, 高山微水体与高山溪流不能简单地视为类似的生境类型, 它们对区域底栖动物多样性和生态功能维持可能具有不同的作用。

Diversity in benthic and environmental characteristics on alpine micro-waterbodies and stream ecosystems in northwest Yunnan

Due to the small area and the cascaded structure formed by surface water, alpine micro-waterbodies are often considered to have similar habitats to alpine streams. However, due to the differences between the environmental factors and the benthic diversity, the functions of these two habitats in the ecosystem may be completely different. Northwest Yunnan hosts one of the richest global biodiversity hotspots where alpine micro-waterbodies and streams are densely concentrated. These two fresh water ecosystems have important functions in regional benthic biodiversity maintenance, however, these peculiar freshwater ecosystems have barely received research attention. In order to compare the similarities and differences of environmental factors and biodiversity between these two habitats and their maintenance effects on benthic diversity, in this study, benthic biodiversity and the environmental factors of 27 alpine micro-waterbodies and a stream in the same region (9 sample sites within an altitude gradient of 500 m) were investigated in an alpine valley of Gongshan County, Nujiang, Yunnan Province in June of 2015. Results showed that: (1) The common characteristics of benthic communities in alpine micro-waterbodies and the stream were that the dominant taxa have large population size, while, the rare taxa had higher richness but small population size. (2) However, the environmental factors, species diversity, functional diversity and community structures were quite different between the alpine micro-waterbodies and the stream, the alpine stream had higher species richness, species diversity and functional diversity than alpine micro-waterbodies. (3) the benthic biodiversity and formation of community structure in alpine stream were related to the elevation and aquatic environmental factors relating to flow rate regulation, while, the aquatic environmental factors of alpine micro-waterbodies did not act as the drivers for the distribution of benthic biodiversity. Therefore, these findings suggest that alpine micro-waterbodies and streams are distinct ecosystems that each feature has very different characteristics, they cannot be regarded as similar ecosystem types. Both of them play an important role in the maintenance of regional benthic biodiversity and ecosystem functions.