Spatial Pattern Analyses On Typical Secondary Forest Communities In The Mountainous Region Of Southern Jiangsu Province

The spatial pattern of the dominant species is an important feature of the community. Spatial pattern of plant is determined by the biological characteristics of species and environmental factors. It has been the focus in community ecology.To explore spatial structure of secondary forest communities at different succession series in the hilly area of northern subtropical China, we set up 36 sampling plots in the Lishui Foresty Farm, Jiangsu Province, and conducted detailed field investigations on the woody plants in these plots. We distinguished four typical community types using canonical correlation analysis (CCA) across our study plots, and then used point pattern analysis (Ripley’s L function) and 2*2 contingency test to characterize the spatial distribution patterns and interspecific association of the main tree species for these community types. The results show that:1. In the study area, typical forest communities are represented as Pinus massoniana-Quercus acutissima community, Ilex chinensis-Pinus massoniana community, Quercus acutissima-Quercus variabilis community and Cunninghamia lanceolata-Vernicia fordii community. Gradient and slope direction appear to be the primary factor resulting in the difference of community composition. Soil condition might be the secondary factors.2. Most constructive species in the study communities show uniform patterns on the scale of >3 m, suggesting that the division of space and resources duing to intraspecific competition underlies such pattern formation. The pattern of subprime species shows a random distribution, which might because of the low number of superiority individual3. Interspecific spatial association often manifests neutral patterns, except for those species such as Q. acutissima and Q. variabilis, which present significant negative correlations. Interspecific competition due to similar functional traits of these species is a likely driving mechanism of such association.Through the research of typical secondary forest communities in the mountainous region of Lishui Foresty Farm, we found four tipical forest communities, which might represent the crucial stages of succession from Cunninghamia lanceolata plantation and Pinus massoniana to the zonal warm temperate deciduous broad-leaved forest. The results suggest the environmental and biological factors which determine the composition of communities and spatial patterns of species. Our study can provide a useful reference to effective management of secondary forests in northern subtropical China.