Taking alpine wet meadow in Lalu Wetland National Nature Reserve as research object, five water level belts(water levels of -15.0, -5.0, 0.0, 2.5, and 6.5 cm, respectively)were selected based on micro?geomorphology difference, and response rules of species diversity and biomass characteristics of above?ground part of wet meadow plant community in Lalu wetland in early growth period and vigorous growth period to water level gradient were analyzed by using typical plot community investigation. The results show that there are significant differences(P<0.05)in species diversity and biomass of above?ground part characteristics of wet meadow plant community in Lalu wetland under different water levels in early growth period and vigorous growth period. In general, species richness index, Simpson diversity index, Shannon?Wiener diversity index, and Pielou evenness index of the community are the highest under the water level of-15.0 cm,and are the lowest under the water level of 6.5 cm. With the increase of water level,species richness index,Simpson diversity index,and Shannon?Wiener diversity index generally show a tendency to decrease in two growth periods; Pielou evenness index shows a tendency to first decrease and then increase in early growth period,while shows a tendency of"decreasing-increasing-decreasing"in vigorous growth period. With the increase of water level, species richness index, Simpson diversity index, Shannon?Wiener diversity index, and Pielou evenness index generally show a tendency to increase under water level range of -5.0-2.5 cm. With the increase of water level,biomass of above?ground part(fresh weight and dry weight of above?ground part)of the community shows a tendency of"increasing-decreasing-increasing", while the ratio of dry weight to fresh weight of above?ground part shows a tendency to decrease. In early growth period,both fresh weight and dry weight of above?ground part are the highest under the water level of 6.5 cm,and are lower under the water levels of -15.0 and 0.0 cm; in vigorous growth period, both fresh weight and dry weight of above?ground part are the highest under the water level of -5.0 cm,and are lower under the water levels of 0.0 and 2.5 cm. It is suggested that species richness index and Shannon?Wiener diversity index can be used for monitoring and evaluation of vegetation in alpine wet meadow.%以位于拉鲁湿地国家级自然保护区的高寒湿草甸为研究对象,基于微地貌差异选取了5个水位带(水位分别为-15.0、-5.0、0.0、2.5和6.5 cm),通过典型样地群落调查,分析了生长初期和生长旺盛期拉鲁湿地湿草甸植物群落的物种多样性及地上部分生物量特征对水位梯度的响应规律.结果表明:生长初期和生长旺盛期不同水位下拉鲁湿地湿草甸植物群落的物种多样性及地上部分生物量特征均存在显著差异(P<0.05).群落的物种丰富度指数、Simpson多样性指数、Shannon-Wiener多样性指数和Pielou均匀度指数总体上在-15.0 cm水位下最大,在6.5 cm水位下最小.随着水位的升高,2个生长期群落的物种丰富度指数、Simpson多样性指数和Shannon-Wiener多样性指数总体上呈降低的趋势;生长初期Pielou均匀度指数呈先降低后升高的趋势,而生长旺盛期则呈"降低—升高—降低"的趋势;而在-5.0~2.5 cm水位范围内,随着水位的升高,2个生长期群落的物种丰富度指数、Simpson多样性指数、Shannon-Wiener多样性指数和Pielou均匀度指数总体上呈升高的趋势.随着水位的升高,群落的地上部分生物量(地上部分鲜质量和干质量)呈"升高—降低—升高"的趋势,而地上部分干鲜比呈降低的趋势.在生长初期,地上部分鲜质量和干质量均在6.5 cm水位下最大,在-15.0和0.0 cm水位下较小;在生长旺盛期,地上部分鲜质量和干质量均在-5.0 cm水位下最大,在0.0和2.5 cm水位下较小.研究结果显示:物种丰富度指数和Shannon-Wiener多样性指数可以用于高寒湿草甸植被的监测和评价.
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