Abstract: Phellodendron amurense is listed as a secondgrade national key protected wild plant in China. In Beijing, it often scatters in broad-leaved forest. In order to understand the structure and spatial distribution of P. amurense population in Beijing, a total of twelve 20 m × 20 m plots in Baihua Mountain, Songshan and Wuling nature reserves were established, and the population characteristics including diameter classes and static life table, and spatial distribution of P. amurense were analyzed. The results showed that: 1) The individual amount of juvenile P. amurense was the highest, and that of adult P. amurense was in the middle rank, and old P. amurense had few individuals. Inverted “J” diameter class structure indicated a growing population of P. amurense. But in some local small populations, there were differences in the diameter class structures of the whole population. 2) There were three mortality peaks in the whole growth stage of P. amurense, with the first one from sapling stage to small tree stage, the second one from small tree to big tree stage, holding the highest mortality, and the third at the end of big tree stage. 3) The spatial distribution of P. amurense followed an aggregated pattern, while its distribution pattern would be different at different growth stages, due to its biological and ecological characteristics and the influence of intraspecific and interspecific relationship of P. amurense populations. Thus, it is critical for increasing P. amurense population to adjust diameter class composition in local population and facilitate aggregate distribution of young P. amurense.

Key words: Alhagi sparsifolia, saline and alkaline land, ion, adaptability