Forest Community Species Diversity and the Influencing Factors in the Rock Stream Periglacial Landforms of Mt. Laotudingzi

Based on field survey data from 24 plots, we studied the forest community species diversity using the species richness, Shannon-Wiener and Jaccard similarity indices and the influencing factors in the rock stream periglacial landforms of Mt. Laotudingzi. The results showed that: (1) The average species richness index values for the deciduous broad-leaf, mixed broadleaf-conifer, and dark coniferous forests were 41 ± 10, 34 ± 5 and 31 ± 7, respectively. The variation coefficients of the species richness index of the forest community exhibited moderate variability. (2) The average Shannon-Wiener index values for the deciduous broad-leaved, mixed broadleaf-conifer, and dark coniferous forests were 1.67 ± 0.32, 1.50 ± 0.18 and 1.29 ± 0.25, respectively. (3) Similarity index values among plant populations of the rock stream periglacial landforms varied between 0.037 and 0.530, and were concentrated in two intervals of 0.25-0.5 and 0-0.25. (4) Correlation analysis showed that rock stream periglacial landforms altitude had a significant negative correlation with the species richness and Shannon-Wiener index of the forest community tree layer (P < 0.01), and an obvious negative correlation with the species richness of the shrub layer (P < 0.05). Both soil electrical conductivity and salt content had obvious positive correlations with species diversity of forest community in the rock stream periglacial landforms (P < 0.05). The pH value of the soil had a significant positive correlation with the species richness and Shannon-Wiener index of the shrub layer (P < 0.01). The CaO content in the soil had an obvious positive correlation with the Shannon-Wiener index and species richness of the tree and shrub layers (P < 0.05). Therefore, changes in plant diversity of the rock stream periglacial landforms were primarily influenced by altitude and the electrical conductivity, salt content, pH value and CaO content of the soil.