Studies On The Stand Structure Of Taxus Chinensis Var. Mairei Forest In Yangmingshan National Nature Reserve Of Hunan Province In China

Taxus chinensis var. mairei, belonging to Taxaceae, is one of the state-protected one-grade rare and endangered plant.Its timber is fine and the sharp is graceful, in addition, it contains highly effective natural anti-cancer plant-paclitaxel.It is mainly distributed in the most part of southern yellow river:northern and southern Yunnan, middle and east Guizhou,western Sichuan,northen Guangxi,hunan,southern shan xi, western henan,Zhejiang,northern Guangdong,Jiangxi and Fujian etc. Due to the over-cut of Taxus chinensis var. mairei,it is damaged seriousely and on verge of being extinct.Taxus chinensis var. maire in Yangmingshan National Nature Reserve is study material for this article. Forest structures were studied by using forest management and forest ecology.The research contests including as follows:through field studies, understanding the geographical distribution of Taxus chinensis var. mairei;Analyzing the forest structure and space structure features; Given endangered reason and complied with the Socio-economic status and management of yangmingshan national nature reserve, some suggestions and strategies were discussed for protecting the rare species based on the situation of Taxus chinensis var. mairei in the field,.The mainly conclusions are following:(1) Taxus chinensis var. mairei mainly distributed in a protected area of Yiluocao,Erluocao,Sanluocao,as well as along the Beijiang chong (see Appendix A),elevation is 700-1100 m. The vegetation location is away from the neighbourhood and it is preserved fairly good.Along Yiluocao,Erluocao,Sanluocao, Most Taxus chinensis var. mairei mixed with bamboo.along the BeijiangChong, Taxus chinensis var. mairei. scattered needles and broad-leaved forest.In the region, its distribution scope was broad and the fruit was good, the largest diameter was more than 60 cm2.There were several communities which area reach to 590 hm2, other Taxus chinensis var. mairei sporadic distribution were 3500 hm2.(2) According to tree species composition of Taxus chinensis var. mairei forest in Yangmingshan, two forest land types are divided into, that is, Taxus chinensis var.mairei-Phyllostachys pubescens community and Taxus chinensis var. mairei-needles broad-leaved mixed community; After Taxus chinensis var. mairei diameter distribution analysis and mathematical model fitting,the research showed that the dia-meter distribution curve of two types are irregular single-mountain-shaped curve. weibull distribution reflected the type of diameter distributionf andχ2 checked it, the results were quite satisfactory, Some sample plots didn't obey Weibull distribution, which might be due to the existence of some tall reservative wood that caused the dis-ruption of forest structure; Judging from age structure, the chinensis var. mairei species were stable in Taxus chinensis var. mairei-Phyllost-achys pubescens commun-ity but increase in the latter. The chinensis var. mairei species of two forest land types were steadily increase, the storage of young seedlings were rich but relatively small comparing the quantity of young plant.(3) Various tree species of Taxus chinensis var. mairei-Phyllostachys pubescens community all belong to gathered Distribution except Cunninghamia lanceolata and Phyllostachys pubescens. it was rather similar to the latter mixed forest, but Taxus chinensis var. mairei in the laiter was closer to random distribution, Cunninghamia lanceolata was uniform distributed and the rest belong to gathered distribution. Those were accordance with the phenomenon of the local Phyllostachys pubescens and artificial Cunninghamia lanceolata forest;Using competitive high-crown,two mixed forest were divided into three layers according to the growth of the local Taxus chinensis var. mairei.The statistics showed that, Taxus chinensis var. mairei occupy the middle and lower classes, there was also a certain amount of reservative wood.(4) The endangered causes of T.chinensis var. mairei were analyzed, the results showed that there were some reasons which threatened this species, such as the less seeds, the lower sprouting rate and viability rate, the weaker competition,and the special adaptive to environment. Those causes the limitation of natural Taxus.chinensis var. mairei resourses, in addition,the human disturbance was one of the important factors, which threatened this species.Based on the situation of Taxus chinensis var. mairei and the problem of the management,some suggestions were discussed as follows:strength the forest management and strategies, improve forestry management measures, provocat the medical value and relative science knowledge of Taxus.chinensis var. mairei,determine its distribution and set personal care; adjust its forest structure, sparse the branches of large diameter trees and bad wood moderately in Taxus chinensis var. mairei-Phyllostachys pubescens community, improve light conditions and the nutrient area, increase updated preservation rate, control the growth and expansion of bamboo and expanse the Species diversities. Within Taxus chinensis var. mairei-needles broad-leaved mixed community, through reasonable human intervention to promote the natural regeneration of Taxus chinensis var. mairei,at the same time, strengthen protection measures to prohibit any business activities and continuously improve the quality of forest;do a good job in situ conservation, built on Taxus chinensis var. mairei protected areas in concentrative area, establish protected points for scattered mature tree and encourage the local implement organizations to establish the local units of seed-breeding base which create artificial Taxus chinensis var. mairei forest.