Population structure and dynamic characteristics of extremely small populations of Changiostyrax dolichocarpa C. J. Qi

We investigated the communities of Changiostyrax dolichocarpa C. J. Qi, a wild plant with extremely small populations distributed in four extant regions of China (Sangzhi, Shimen, Wufeng, and Zigui). We first constructed a population structure map and established a static life table, then plotted survival curves for survival analysis and predicted future development trends of the populations using time series analysis. Results showed that the Sangzhi, Shimen, and Wufeng populations were all increasing, but the Zigui population was declining. However, all four populations were sensitive to external disturbance. The population survival curves tended to be Deevey-Ⅱ type, showing a decrease in the early stage, stabilization in the middle stage, and recession in the late stage. Survival analysis showed that the Sangzhi and Zigui populations entered the declining stage early, mainly due to environmental pressure, while the Shimen and Wufeng populations entered the declining stage relatively late, mainly due to physiological decline. Time series analysis indicated that the number of young individuals in the Sangzhi, Shimen, and Wufeng populations will decrease, while the number of middle-aged and old individuals will increase in the future 2-8 age classes. For the Zigui population, the number of young and middle-aged individuals will gradually decrease, while the number of old individuals will first increase and then decrease. Results suggest that strengthening the protection of the original habitat and research on artificial propagation technology may help promote population growth.