青藏高原高寒草甸群落特征对氮沉降和增水的响应

试验选择高寒草甸为研究对象,通过连续两年定位观测,采用模拟氮沉降与增水及其交互作用对高寒草地群落特征的影响,为高寒草地生产力功能提升提供科学依据。结果表明:模拟氮沉降和增水及其交互处理,当年均能够显著增加高寒草甸地上总生物量、禾本科植物、豆科植物生物量,但显著降低莎草科植物生物量;而在第2年,增水处理并未明显增加地上生物量,氮沉降与增水交互作用可以稳定地提高高寒草地生产力,各处理均能够明显提高禾本科和莎草科生物量、降低杂类草生物量。增水当年能够显著提高高寒草甸物种丰富度和生物多样性指数,但氮沉降和增水交互降低物种多样性指数;而在第2年,各处理物种数目和多样性指数均降低,且氮沉降与增水的交互作用影响效应达到极显著性检验水平。综合分析,氮沉降和增水及其交互作用在提升草地生产力、优良牧草生物量的同时,也可能造成高寒草甸物种丰富度和多样性指数降低,在草地的适应性管理方面需要引起足够的关注。

Response of plant community on nitrogen deposition and adding precipitation in alpine meadow on Qinghai-Tibetan Plateau

The effects of nitrogen deposition and adding precipitation,and its interaction on characteristics of plant community were studied for two years in alpine meadow at Haibei station of Chinese Academy of Sciences on Qinghai-Tibetan Plateau.The result indicated that the total aboveground biomass,biomass of gramineae and leguminosae were significantly increased in the first year.However,the biomass of sedge family was significantly decreased.Furthermore,the nitrogen deposition and its interaction with adding precipitation steadily raised the grassland production in the second year,but not for adding precipitation.All treatments could enhance the bio-mass of gramineae and sedge family but not for forbs.In addition,the precipitation increasing enhanced conspic-uously species richness and biodiversity of alpine meadow in first year,but nitrogen deposition and its interaction decreased the biodiversity.The species richness and biodiversity index under all treatments decreased in second year.It could be concluded that nitrogen deposition and adding precipitation and its interaction increase the grassland production,and decrease the species richness and biodiversity.