Studies On Community Ecology And Genetic Diversity Of Fagopyrum Cymosum (Trev.) Meisn.

Fagopyrum cymosum (Trev.) Meisn., a perennial herb of the genus Fagopyrum Mill. in Polygonaceae, is recorded as the National Important Wild Conservative Plants in China. It has great ecological and genetic values. In Chongqing, it mainly distributes in Wanzhou, Fuling, Qianjiang, Nanchuan and Youyang. Scientific studies have proved that it is a valuable plant and has a good further for medicinal uses. The present study mainly focused on macroscopical community ecology and microscopical genetic diversity to discuss the current living situation of F. cymosum. In this paper, with the help of the numerical classification and ordination, study the ecology of communities and then discuss the relationships among F. cymosum and other species and the relationship between F. cymosum communities and their environments. By RAPD marker we studied the genetic diversity of F. cymosum both within population and among populations. On the ground of that some evidences have been given for its nutritional and official uses as well as its conservation. The results are as followings:1) In the studied communities, the results showed that the niche breadth of F. cymosum ( Trev. ) Meisn. changes to a larger extent, which indicates the species is widely distributed and strongly resource-obtainable. F. cymosum also has high niche overlapping with other dominant species in the studies communities, which showed that these dominant species have highly similar requirements to resources, but F. cymosum can coexist nicely with other dominant species in the studied communities. So it shows F. cymosum communities can maintain high species diversiy and relative stability.2) Using two-way indicator species analysis (TWINSPAN) and detrended correspondence analysis (DCA) to analyze F. cymosum communities, the results of classification and ordination are consilient, i.e., these groups took on obviously gradient change from slope in the shade to slope exposed to the sunlight. Species also took on obviously gradient trends followed the altitude grades from low to high. According to the results it is suggested that the major factor restricting distribution and composition are illumination and altitude.3) According to the results of RAPD, it showed that F. cymosum had abundant genetic diversity within population. Genetic diversity not only exists within populations but also among populations. By Shannon index, the ratio of genetic diversity among 7 populations is 17.13%, and by Nei's index, the genetic differentiation index is 19.24%. The results showed that F. cymosum possessed a higher level of genetic diversity within population than that among populations. In these populations, it didn't have special primer, but with special locus, and it was obvious among F. cymosum populations. Populations of this species show a clustered pattern strictly following their geographical distance, which indicates that certain ecological factors in a specific micro-habitat could affect genetic express of individuals of certain population.4) The main reason for the endangering of the wild populations of F. cymosum is not related to their genetic background but to some environmental factors, such as the human interference and destroys activities. So it was suggested the related deparment should pay attention to these regions that were interfered strongly by humanbeing to strengthen propagandizing against demolishing behavior, control excavating and establish conservation area for this species.