Abstract: Ulmus pumila-dominated savanna, playing a great role in maintaining the region's ecological stability, is an important savanna type where U. pumila is a dominant species. In this paper, the structure and dynamics of U. pumila population were analyzed by the spatial series substituting for time series method. The static life tables and the curves of survival, mortality and loss rate for the population were calculated, respectively. In addition, the survival analysis were performed, including the survival, cumulative mortality, death density and risk rate. The results show that population density, diameter at breast height, height and crown diameter of U. pumila had a certain difference in four regions:There were the biggest population density and least values of the diameter at breast height, height and crown in the eastern region among the different regions. The ages of population were shown two peaks with a characteristics of sharp-dropping in the seedling, stability in juveniles, and slow-declining in the adults, suggesting an obvious declining of population. The sharp-dropping in seedling might be a result of comprehensive factors, such as natural disaster, land desertification, grazing, as well as man-made destruction. The declining in adults may be caused by the strong competition for moisture, light and nutrient among the trees. There was a number of seedlings in the study area, which suggests the U. pumila population will be regenerated under the reasonable managements. However, at least 30 years will be required to restore the U. pumila-dominated savanna ecosystem.

Key words: Ulmus pumila, age structure, life table, survival curve, population regeneration