Effects of anthropogenic disturbances on the species diversity and niche of the dominant populations in a Castanopsis fargesii secondary forest community in Bifengxia, Sichuan

To further understand the effects of anthropogenic disturbances on the ecological environments and on the ability of resources utilization and ecospace occupation of the dominant population in the ecotourism area of Bifengxia,we investigated the effects of anthropogenic disturbance on the species diversity and niche of the dominant population in aCastanopsis fargesii secondary forest in this area. The results showed that a total of 156 species belonging to 70 families and116 genera were found in a 7200 m2 quadrat. Specifically,there were 33 tree species from 16 families including 23 genera,95 shrub species from 39 families including 67 genera,and 47 herbaceous species from 38 families including 42 genera. The level of species diversity in arborous layer was lowest under intermediate disturbance,and no obvious difference was found between communities under slight and severe disturbance. However,species diversity level in shrub layer was highest under intermediate disturbance,and lowest under slight disturbances. An obvious decrease for the level of species diversity was found in the herbaceous layer. With increase in the strength of disturbance,the niche breadth value for the dominant species( C. fargesii) in arborous layer was consistently the highest,and the value overlapping with other species decreased at certain degree under intermediate disturbance. The niche breadth value for Quercus serrata decreased,but such value for Theaceae increase as well as the overlapping value. In the shrub layer,the niche breadth value for Smilax china decreased under severe disturbance,as well as C. fargesii seedings. The niche breadth values for the majority of other species were lowest under intermediate disturbance. In the herbaceous layer,the niche breadth values and overlap values for Pteridium aquilinum var. latiusculum and Setaria plicata both increased under severe disturbance,with wider adaptive range and intensifying interspecific competition. The results suggest that anthropogenic disturbances have significant impacts on the species diversity,species status in community,and interspecific relationship in the C. fargesii secondary forest,indicating urgent measures in ecological protection and appropriate management.