Abstract: Aims To 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 Kashi 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 Kashi River and total population were in the age classes of Ⅳ, Ⅶ, and Ⅹ, while those on the west of Kashi River population class had a mortality peak in age class V. 3) The dynamic change index ignoring the external interference (Vpi) and dynamic change index under external interference of the populations on the east and west of the Kashi River and total population were greater than 0, indicating that they were growing-type populations. But the of population on the east of the Kashi 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 classes II–III. The hazard rate curve of the population on the east of the Kashi River exhibited relatively smaller fluctuations, indicating that this area is more suitable for the growth of F. sogdiana. 5) Spectral analysis showed that the fluctuations of F. sogdiana populations are primarily controlled by their own biological characteristics. The population on the east of the Kashi River and total population exhibited small cycle fluctuation characteristics with multiple harmonics superimposed during the large cycle. It is recommended protecting and improving habitat of F. sogdiana, accurately nurturing individuals in age classes I and II, and promoting the natural regeneration and development of the population.

Key words: Fraxinus sogdiana, endangered species, population structure, static life table, survival analysis, spectral analysis