The Primary Study On Population Ecology And Embryology Of Rare And Endangered Davidia Involucrate Baill

Davidia involucrate Baill is one of the rare and endangered plants in China. To discuss the endangering mechanism of Davidia involucrate Baill is helpful to protect it. The paper studies the reason of endangering mechanism of Davidia involucrate from population ecology and embryology.Through the investigation on population structure of Davidia involucrate in Mt.Qizimei Nature Reserve of Hubei Province, it's discovered that the size structure belongs to the shape of the reverse pyramid, and according to the life table ,it's concluded that the death rate of young tree is high and the survival curve has the trend to be the type between Deevey II and III,the population was stable in large size class and variable in small size class. The population was lack of seedling and the regeneration of Davidia involucrate was the combination of sexual reproduction and asexual reproduction.The spatial distribution pattern of Davidia involucrate was studied in Houhe Nature Reserve, Hubei province, and the result shows that the population of Davidia involucrate has a pattern of clump. Damp and soil were the major factors determining the distribution pattern of Davidia involucrate population. In one hand, this kind of distribution enhanced the ability to withstand the adverse environment condition, in another hand, this kind of distribution had no benefit to extend the population and had some effect on the endangered state of Davidia involucrate.Most of the endangered plant has the difficulty in sexual reproduction. Through the study on the megasporogenesis, microsporogenesis and development of gametophytes in Davidia involucrate, we found that there is no abnormal phenomenon in the process. The meiosis of microspore mother cell belongs to simultaneous type and the mature pollen is two -celled, and ovule is crassinucellate. Mature egg apparatus has eight nucleuses.In the end, some suggestion on the protection of Davidia involucrate was proposed and in-situ conservation and proper disturbance is considered to be important, at the same time, ex-situ protection and the study on reproduction must be carried out and propagandizing the importance to protect Davidia involucrate is necessary.