Effects of elevation and disturbance gradients on forest diversity in the Wulingshan Nature Reserve, North China

Forest diversity and conservation in the Wulingshan National Nature Reserve are ecologically important in North China. Forty-one forest plots of 20 m x 20 m were established along an altitudinal gradient. Data on species composition, environmental variables and disturbance intensity were measured in each plot. The TWINSPAN and CCA methods were used to analyze forest community diversity and the forest-environment relationship, and species diversity indices were used to analyze species diversity in this reserve. The results showed that eight forest formations were identified by TWINSPAN using species importance value data, and most of them were typical secondary natural forests. Each forest formation had its own characteristics of composition, structure, function and environment. Forest diversity was most significantly correlated with elevation and disturbance, and was also related to litter thickness, soil depth and slope. The species diversity showed a humped distribution pattern along the altitudinal gradient and a quadratic decreasing pattern along the disturbance gradient. Elevation and disturbance were the most important factors influencing species diversity. The effectiveness of conservation is apparent since the reserve was established.