中文摘要：

采用野外调查与室内实验相结合的方法,研究了甘南地区青藏高原高寒草甸不同坡向上的植物群落物种多样性变化特点及与环境因子的关系.结果表明：阳坡—阴坡生境梯度上,光照、土温和含水量总的变化趋势为阳坡〈半阳坡〈阴坡.土壤养分除了全磷质量分数自阳坡到阴坡出现递增的趋势外,其他土壤养分质量分数均呈现阴坡〉阳坡,阳坡和阴坡稍高,半阳坡最低的趋势.阳坡—阴坡生境梯度上植物群落物种的α多样性的变化趋势为：阳坡〈半阳坡〈阴坡;β多样性从阳坡,半阳坡到阴坡为一单峰曲线,即呈现先升高后降低的变化趋势,这表明在土壤湿度和日照时间适中时,物种替代速率比较快.不同坡向上的植物群落α多样性和β多样性与光照和土温均呈负相关,与0～15,15～30 cm土层的土壤含水量和土壤全磷质量分数均呈显著正相关关系.通过主成分分析可以得出：引起α多样性和β多样性沿生境梯度变化的最重要因子是土壤水分和全磷质量分数.

英文摘要：

The traits of plant community diversity of different slopes and their relation with different environmental factors in Tibet alpine meadow were studied through fieldwork and laboratory work.The results showed that the total variation of the illumination,soil temperature and soil moisture in the habitat gradient from south-facing slope to north-facing slope is south-facing slopewest-facing slopenorth-facing slope. The variation of the soil nutrients that the north-facing slope is higher than the south-facing slope and the west-facing slope is the slowest（except the content of the total P,the total P increased from the south-facing slop to the north-facing slope）.The traits ofαdiversity of the habitat gradient from south-facing slope to north-facing slope is south-facing slopewest-facing slopenorth-facing slope.The variation ofβdiversity indexes increased firstly and then decreased form the south-facing slop to the north-facing slop,which indicated that species replacement rate is rapid in the condition of moderate soil moisture and sunlight time.Theαdiversity indexes andβdiversity indexes were negatively affected by light illumination and the soil temperature, which were positively affected by moisture and soil total P of different depths of 0～15,15～30 cm. Methods of principal component analysis proved that changes ofαdiversity indexes andβdiversity indexes of the habitat gradient from south-facing slope to north-facing slope were mainly affected by moisture and soil total P.