中文摘要：

以甘南高寒草甸为对象，研究了坡向梯度上环境冈子的变化特点及其与地上生物量和物种丰富度的关系．结果表明：0-20cm与20-40cm的土壤含水量均是自阳坡到阴坡呈递增的变化趋势，且20-40cm土壤的含水量高于0—20cm的；两层土壤的全磷质量分数和w（C）：w（N）与含水量的变化相同，土壤全氮、有机质、速效磷及速效氮质量分数的变化均呈先减小后增大的趋势，偏阳坡最小．土壤养分质量分数均是0—20cm的大于20-40cm的，表现出表层土壤养分富集的现象，土壤pH值沿阳坡到阴坡呈递减趋势．地上生物量和物种丰富度的变化特点均为阴坡〉偏阴坡〉偏阳坡〉阳坡，且地上生物量与物种丰富度显著正相关．同归分析表明：土壤含水量与土壤全磷、有机质质量分数是影响地上生物量和物种丰富度的主要因子，其中土壤含水量是关键限制性因子．

英文摘要：

The characteristics of environmental factors with slope gradient variations and the relationship between environmental factors and above-ground biomass and species richness were studied in grasslands of Gannan alpine meadows. The results showed that the soil water content increased from sunny slopes to shady slopes in 0-20 cm and 20-40 cm soil layer, and the soil water content in 20-40 cm soil layer was higher than that of 0-20 cm. The variation trends of w（P） and soil w（C） ： w（N） were the same as soil water content in the two soil layers. The variation trend of the content of the total N, the organic matter, available N and available P were at first decreased and later increased, the nutrients of the partial sunny slopes being the lowest. The content of soil nutrients were all higher in 0-20 cm than that in 20-40 cm, indicating a nutrient enrichment in the surface layer. Soil pH decreased from sunny to shady slopes. The variation characteristics of above- ground biomass and species richness were shady slope〉partial shady slope〉partial sunny slope〉sunny slope and above-ground biomass were positively correlated with species richness. The regression analysis showed that the soil water content and the content of the total P, the organic matter were the main factors that influenced above-ground biomass and species richness in grassland, the soil water content was the key limiting factor.