破碎生境中种群大小对缙云卫矛生殖成功的影响

Effects of population size on reproductive success of endangered plant Euonymus chloranthoides Yang in fragmented habitat

生境破碎导致种群大小的降低,了解种群大小对生殖成功的影响对物种保护具有重要的指导意义。缙云卫矛(Euonymus chloranthoides Yang)为重庆特有濒危植物,目前缙云卫矛种群已遭受了严重的生境破碎,种群小且多处于隔离状态。本文对位于重庆北碚的该物种6个种群的生殖成功进行了研究。结果表明:小种群的自然坐果率低,种群间坐果率差异极显著(P=0.002);种群大小与坐果率之间呈显著相关(r=0.837,P=0.038);种群大小与种群幼苗比例呈显著相关(P=0.045),较小的种群中一龄级幼苗的比例也较小。这表明生境破碎后小种群不利于该物种的生殖成功,导致小种群的坐果率与幼苗比例降低。对该物种的保护要提高小种群的座果率,改善小种群的更新。

Habitat fragmentation can cause the decline of population size. To understand the effects of population size on reproductive success is of significance in species conservation. Euon- ymus chloranthoides Yang is an endemic and endangered plant in Chongqing of Southwest China. At present, the E. chloranthoides population has suffered from severe habitat fragmentation, with small population size and mostly in isolate status. In this paper, six E. chloranthoides populations at Beibei in Chongqing were selected to study the effects of population size on their reproductive success. Smaller populations had a lower natural fruiting rate, and the differences in the fruiting rate among the six populations were extremely significant （P = 0.002 ）. There was a significant correlation between the population size and fruiting rate （r=0.837, P=0.038 ）. The population size had a significant correlation with population＇ s seedling ratio （ P = 0.045 ）, and the first age- class seedling ratio of the smaller populations was also smaller. The present study indicated that habitat fragmentation induced the decrease of the fruiting rate and seedling ratio of smaller popu- lations of E. chloranthoides, which was not beneficial to the reproductive success of the plant species. Therefore, to conserve the E. chloranthoides, it would be necessary to enhance the fruit- ing rate of the small populations and improve their regeneration.