青藏高寒草地植被生产力与生物多样性的经度格局

沿昌都到噶尔县的经度梯度,对西藏典型高寒草地植被生产力与植物多样性开展了1 700 km的野外样带调查。实验结果表明：高寒草地的群落结构特征（地上生物量、地下生物量、盖度和密度）与生物多样性（物种丰富度、物种多样性和物种均匀度）均具有明显的经度分布格局。整体而言,这些特征参数均表现出自西向东沿荒漠草原—典型草原—草甸草原呈逐渐递增的趋势;其经度格局主要受降雨量和平均气温所趋动,但降雨量和平均温度的影响在不同指标间存在较大差异;地上生物量由二者共同决定,而物种丰富度受降雨量的影响更大。西藏高寒草地的物种丰富度与地上生物量间存在显著的幂指数关系（y=0.219 7 x 0.754 9, R²= 0.61, P< 0.01）。上述规律的发现,不仅有利于我们更好地理解高寒草地对未来气候变化的响应机制与适应途径,也将帮助我们合理制定放牧策略以实现该地区高寒草地的可持续发展。

Longitudinal Patterns of Productivity and Plant Diversity in Tibetan Alpine Grasslands

In this study, we conducted an integrative field investigation for the grassland community, productivity, and plant diversity in the Tibetan Plateau grasslands along a 1 700-km west-east transect. The properties of plant communities (e.g., aboveground biomass, belowground biomass, coverage, and density) and indices of plant diversity (e.g., richness index, Shannon-Wiener diversity index, and Pielou evenness index) showed longitudinal patterns along the west-east transect. All these indices increased significantly from the alpine desert, alpine meadow steppe, to alpine meadow in the Tibetan Plateau. Climatic factors (mean annual temperature (MAT) and mean annual precipitation (MAP) were the main factors controlling these longitudinal patterns, but their relative contributions to different parameters differed. MAT and MAP both controlled aboveground biomass, but the influence of MAP on plant richness was much higher than that of MAT. There was significant power-function relation between aboveground biomass and plant richness in the Tibetan Plateau grasslands ( y=0.219 7x0.754 9, R²=0.61, P<0.01). These findings provide insights into the response and feedback of Tibetan Plateau grasslands to the climate change in the future, and may help us to effectively protect the Tibetan Plateau grasslands and promote its sustainable development.