Age structure and population dynamics of rare and endangered <i>Fraxinus sogdiana</i>, China

AimsTo understand the current state of the population of Fraxinus sogdiana, a second-grade endangered species in China, and predict its development trend, a large sample survey was conducted in the Xinjiang Ili Fraxinus sogdiana National Nature Reserve.Methods By replacing the age structure with the diameter at breast height structure, a population static life table was compiled and related population structure was analyzed.The survival curve, mortality curve and survival analysis function curve were drawn, and population dynamic index was calculated, and the population fluctuation cycle was explored via using spectral analysis.Important findings 1) The populations of F. sogdiana on the east and west of the Kax River and total population exhibited growing age structure, with the survival curves towards Deevey-II type.2) The mortality peaks for the population on the east of the Kax River and total population were in the age classes of IV, VII, and X, while those on the west of Kax River population class had a mortality peak in age class V. 3) The dynamic change index ignoring the external interference (V pi ) and dynamic change index under external interference ( ) pi V of the populations on the east and west of the Kax River and total population were greater than 0, indicating that they were growing-type populations.But the pi V of population on the east of the Kax River was close to 0, suggesting that it was more resistant to external random environmental interference.4) Survival analysis revealed that the survival rate and cumulative mortality rate of populations in different habitats reached equilibrium in age