中文摘要：

在青藏高原东部的一个高山雪床，沿着融雪梯度分别设置早融、中间和晚融3个融雪部位，然后测定川西小黄菊（Pyrethrum tatsienense）、长叶火绒草（Leomopodium longifolium）和圆穗蓼（polygonum maerophyllum）在3个融雪部位上的物候差异以及种群分布格局的变化。结果表明：从早融到晚融的梯度上，3个物种的物候期都不同程度地有所推迟。其中，开始生长的时间推迟12～14d，始花期推迟6—8d，盛花期推迟6d左右，但同一种植物在不同的融雪部位上的衰老枯黄期趋于一致，这标志着在晚融部位同一植物的生长期要缩短。在种群层次上，长叶火绒草和圆穗蓼的分布格局随着融雪的推迟都发生了一定的变化，基本上表现为从早融部位的集群分布到中间或晚融部位的随机分布。川西小黄菊在各个融雪部位上都表现为集群分布，但集群的强度随融雪的推迟逐渐减弱。

英文摘要：

In an alpine snowbed on the eastern Tibetan Plateau, three portions were established along snowmelt gradient. At each portion, the phenology and population distribution pattern of three alpine species （Pyrethrum tatsienense, Leontopodium longifolium and Polygonum ma~rophyllum） were tested.. The results showed that from early-to late-melting portion, phenological phases of three species delayed to different extents. Plant emergence delayed 12 - 14 d, first flowering delayed 6 -8 d and peak flowering delayed nearly 6 d. For each species, how- ever, consenescence at three portions did not differed significantly, indicating that growing season length of a species at late-melting portion shortened. At population level, the distribution pattern of Leontopodium longifoli- um and Polygonum macrophyllum varied as the snowmeh delayed, changing from cluster pattern at early-melting portion to random pattern at late-melting or medium portion. Pyrethrum tatsienense showed cluster pattern at three portions. However, its intensity of cluster weakened as the snowmeh delayed.