不同施肥梯度对甘南退化高寒草甸生产力和物种多样性的影响

研究了不同磷酸氢二氨施肥梯度对甘南退化高寒草甸生产力和物种多样性的短期影响．实验结果表明：生产力随施肥梯度迅速提高，但施肥对生产力的作用不是简单的线性正相关，存在一个阈值(30g／m^2)，超过这个值，施肥的作用就不显著了；物种丰富度随着施肥先略微增加，然后降低，Shannon多样性指数、均匀度指数均随施肥增加而下降，但在施肥梯度30g／m^2和60g／m^2之间基本不变；施肥形成的生产力梯度和物种丰富度的关系近似线性降低．为了恢复退化草甸的生产力，同时维持较高的多样性，施入磷酸氢二氨30g／m^2是经济而合理的．

Effects of fertilizer gradients on productivity and species diversity in a degraded alpine meadow

A study was conducted for two years at the Pasture Land Station of Maqu, in southern Gansu, to determine the short-term effects of (NH4)2HPO4 fertilizer gradient on productivity and species diversity. The results showed that: (1) the aboveground net primary productivity increased significantly along the fertilizer gradient, but did not undergo similar increase after (NH4)2HPO4 fertilizer reached 30g/m2. (2) species richness increased at first and decreased subsequently; Shannon diversity index and evenness index decreased along the fertilizer gradient, but did not vary significantly from 30 g/m2 to 60 g/m2. (3) species richness decreased approximately linearly along productivity gradients. 30 g/m2 (NH4)2HPO4 was economical and reasonable for improving the productivity of the degraded meadow and for maintaining high species diversity.