Species diversity of natural Phoebe sheareri communities with different disturbance intensities

Abstract

Due to the enhancement of disturbance, the natural communities of Phoebe sheareri, a precious species peculiar to China and one of the original species for the commercial timber production of Nanmu with golden tint, being scattered in some provinces and regions to the south of the Yangtze River, were studied. All 20 typical natural communities of P. sheareri in sample plots within 10 400 m2 of its distribution area were analyzed for responses of species diversity to different disturbance intensities and climatic conditions. Analyses of species composition, flora, and species diversity were based on the Patrick index for abundance, Shannon-Wiener index for diversity, Simpson index, and Pielou index for evenness. Results showed a total of 363 vascular species belonging to 236 genera of 103 families. Both genera and families of seed plants were abundant, but were mainly from north temperate and pan-tropical areas. Differences in the Patrick, Shannon-Wiener, Simpson, and Pielou indexes showed that both disturbance intensity and climatic conditions co-acted on the species diversity of P. sheareri-containing communities. With a disturbance of Grade Ⅴ, P. sheareri was absolutely dominant in the tree layer of the Luhetang Community, but was in a sub-dominant position in the shrub layer with a low diversity on the whole, which meant it was unfavorable for sustainable development. Disturbance intensity was found to be significantly correlated with the Patrick index (P=0.006, r=-0.643) and Shannon-Wiener index (P=0.037, r=-0.045)with a stronger disturbance having a lower species abundance and diversity in the tree layer. Also, the highest values of the Shannon-Wiener index, Simpson index, and Pielou index in the shrub layer occurred when there was a disturbance of Grade Ⅱ, meaning that an intermediate disturbance promoted species diversity in the shrub layer. Overall, P. sheareri was suitable for coexistence with many other plant species to form a community, and the disturbance intensity had more influence on species diversity in the P. sheareri community than climatic conditions.