Abstract: 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. Euonymus 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 populations 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 fruiting rate of the small populations and improve their regeneration.

Key words: growth strategy, morphological characteristics, nutrient absorption, Phyllostachys rivalis,  rhizome and root system, waterlogging.