Effects of ecological factors on plant communities of Ziwuling Mountain, Shaanxi Province
陕西子午岭生态因素对植物群落的影响

This paper explores the relationships between environmental factors and vegetation patterns. In 60 plots in the Malan Forest Region of Loess Plateau, 17 variables were used as indicators of spatial position, soil characteristics and topography. Plant community types in different successional stages in this region were analyzed by TWINSPAN. Environmental factors which have significant influence on the composition of plant communities in different successional stages were selected by forward selection and Monte Carlo tests. The relationship between the distribution pattern of plant communities in different succession stages and environmental factors was identified by DCCA. The influence of environmental and spatial variables and their interaction on the variation of community distribution patterns was quantitatively separated by Partial CCA. The results showed that: (1) The plant communities in this region can be divided into 13 types, and include four different successional stages. (2)Salt content and alkali-hydrolyzable nitrogen are the significant factors related to plant community distribution at early stages of succession. Elevation and humus are the significant factors in the transitional stage; elevation, slope aspect, forest floor, humus and pH are the significant factors for the sub-climax stage, while elevation, slope aspect, pH and available phosphorus are the significant factors for the climax stage. (3)The ecological characters and the distribution patterns of plant communities in different successional stages are consistent with environmental gradients. (4)As succession proceeds, the impact of environmental conditions on plant communities increases, while the total influence of spatial location, and the interaction between spatial and environmental factors decreases.