Geographic Alternative Distribution Pattern and Its Climate Dominant Factors of Pinus Forests in Southern China

The 5 dominant species of Pinus yunnanensis, P. densata, P. armandii, P. kesiya and P. massoniana were collected to reveal the alternative distribution patterns of Pinus forests and climatic constraints in southern China. MaxEnt model was used to predicted geographic distribution of Pinus forests after collecting the species and bio-climatic factors data. The differences of ecological niches among 5 species were quantified by discriminant analysis, variance analysis, kernel density analysis and principal component analysis to explain the geographic alternative distribution patterns of vegetation and dominant climatic factors. The results showed that prediction accuracy of habitat zone was higher as AUC values of the 5 Pinus forests were all greater than 0.9, indicating that the prediction accuracy of the suitable area was high; the typical geographic substitution distribution existed in 5 Pinus forests; the mean diurnal range, isothermality, and temperature seasonality were the dominant temperature factors causing the niche differentiation of the 5 species. And the precipitation in the driest month and the precipitation of coldest quarter were the dominant precipitation factors of the difference of ecological niche in 5 species. The differences of ecological amplitude variation among 5 Pinus forests in different climatic factors indicate the variables of characterizing seasonal differences, such as temperature change and seasonal precipitation were the main reason of geographic substitution in the distribution of the 5 Pinus forests in southern China.