Structure and dynamic characteristics of Betula luminifera populations in different regions of Southwest Hubei Province, China

Abstract

We investigated Betula luminifera populations in three regions (Mulinzi, Qizimei Mountains, and Jinzi Mountains) in the southwest Hubei Province, China. Population structure was divided by age classes and height classes. Population structure figures were drawn. The static life tables of B. luminifera populations in different regions were analyzed using the method of substitution of space for time. The survival curve, mortality rate curve and disappearance rate curve were created. Four functions of survival analysis were used to analyze the dynamics of B. luminifera population in different regions. The results showed that the B. luminifera populations in three regions were the increasing type. The height class structures were relatively complete. Some age classes were absent from the age structures of B. luminifera populations in Qizimei Mountains and Jinzi Mountains. Although the dynamic index of trees number Vpi＞0, but it was sensitive to external disturbance. The survival of B. luminifera of different age classes varied greatly in static life table, which gradually decreased with increasing age class, with Deevey-type 2 survival curve. The trend of mortality rate changed similarly to the disappearance rate, but fluctuated differently. All B. luminifera populations in different regions appeared to decrease in the early stage and keep dynamically stable in the medium-late stage.