| Euonymus chloranthoides Yang is an endangered plant species which is endemic to Jinyun Mountain and Dongwenquan of Chongqing with the most favorable habitat in the forest of Sinocalamus affinis (Rendie) Mclure. We made field investigations on three natural populations available presently in the whole distribution areas of E. chloranthoides . Base on the data collected from the field investigations, we analyzed the static life table, age structure, spatial distribution patterns of the populations of E. chloranthoides. We further studied the intraspecific competitions within the species and the interspecific competitions between the species and other concomitant species in the communities. With the helps of the Logistic Equation, Leslie's Matrix and the Average Moving Law method we simulated and estimated the population dynamics of this endangered plant species. Base on all the analyses mentioned above, we further studied the endangering cause of E. chloranthoides and put forward some measures for the conservation of this species. The result shows as the followings:1. The age structure of the three populations is basically a bell-shaped one. The seedlings in each population are relatively rich. The populations studied seem to be the somewhat stable types.The static life table of three populations shows that the physiological life span of E. chloranthoides is not too long with only 8-13 years. The life span of individuals in Dongwenquan population is much lower than those of the two others, which is probably because the density of Sinoalamus affinis (Rendie) Mclure in the community is much bigger in Dongwenquan and too strong shdding in the community has restrained the growth of E. chloranthoides .The numbers of individuals after 10 years old in 2 populations studied and that ofindividuals after 6 years old in Dongwenquan population are sharply reduced, which explains that the population is going to be feeble after 10 years or 6 years if not recruited with enough new individuals in the populations.2, The survival curves of populations of E. chloranthoides in Jigong Mountain and Dongwenquan are diagonal, which indicates that the individuals of each age grade within the two populations possesses the roughly identical death rate and the populations belong to the stable ones, while the survival curve of population in Beiwenquan is concave, which shows that the population belongs to the increase one. The death rate of the population in Jigong Mountain is fairly lower initially and relatively stable afterwards. But after 9 years, the death rate of individuals in the population raised and achieved the biggest physiological life span at 12 years. The death rate of individuals in Beiwenquan population is fairly higher initially and stable afterwards, while after 10 years, the death rate has appeared several waves, and then achieved the biggest physiological life span at 13 years with the death rate sharply up. The death rate of individuals in Dongwenquan population shows another pattern with slowly raise along with the age.3 With the use of the dispersal index ( DI ) clump intensity ( CI's ) mean crowding ( m* ) patchiness index ( PAI ).. Green's index ( GI ) and intensity index as parameters, we further studied the spatial distribution patterns of the three populations. At the same time, we studied the distribution patterns of the young, middle-aged and old individuals respectively in the three populations as well as in other several concomitant species in the communities in which E. chloranthoides lives. The distribution pattern of the three populations is mainly the clumped type except that of the old individuals of Dongwenquan population. The species exhibits clonal growth ability with the ramets centered around the genet, and in addition the seeds are fairly heavy and spread and germinated also near the genet, which may explain the clumped distribution patter of the species. The distribution pattern also shows that the environment is heterogeneous and the competition is intense among the species.
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