A Study On Floristc Phytogeography Of Seed Plants In North Of Chaotung Nature Reserve, Yunnan, China

North of Chaotung Nature Reserve (NZNR) is located in northeast of Yunnan Province and connects with Guizhou and Sichuan province. Its topography is lower in north and higher in south and gradually lifts from Sichuan Pan to Wumeng Mountain. This Nature Reserve includes four parts that are Sanjiangkou, Luohanba, Xiaocaoba and Haiziping Nature Reserve which are distributed in Daguan, Yongshan, Yiliang, Yanjin and Weixin five counties in city of Chaotung, extending from 27°3.5′～28°31′N and 103°15′～105°53′E, with an area 45,000 hectare. The main types of forest in north of Chaotung are Eastern moist evergreen broad-leaved forest area of middle subtropical zone belonging to inferior area of evergreen broad-leaved forest in east China(ⅡB). This area are not big in Yunnan province, but its natural environment and vegetation character are special and its flora is obviously different from Yunnan Plateau.On the basis of large investigation, collection and identification of specimen, reference of literatures, this paper discusses the floristic structure, character and adscription of flora, and analyses the flora in different level of family, genus and species. Based on the statistics, the analysis results as follows. 1.159 families, 640 genera and 1864 species of wild seed plants are recorded in the NZNR, and of these families, genera and species, there are 4 families, 5 genera and 5 species in Gymnospermae, 155 families,635 genera and 1859 species in Angiospermae. So the floristic is abundant. 2. The geographical ingredient of flora is multiplex and its connection is comprehensive. Of the total 15 distributing types of statistics, there are 11,15 and 15 types in family, genus and species level. We can know, through the statistics of species locating only in China, that the amount of species in common between NZNR and Sichuan and Guizhou province are the largest. These species are almost endemic to Central-China and indicates that this area is an important distribution and split (分化) place for endemic of China, especially for Central-China. At the same time, the amount in common between NZNR and Southwest-China, South-China, East-China is also larger. 3. The flora has evident transitional character from subtropics to temperate zone, and shows an obvious temperate zone character. Contrast between tropical and temperate ingredients of family, genus and species are 1.25﹕1,1﹕1.42,1﹕7 and these statistics show that when tropical ingredients are gradually disappeared and lots of temperate ingredients are developed and became the main body of flora. 4. North Temperate, East Asia and Tropical Asia ingredients are the three origins of the flora. The amount and percentage of each type are as follows: 127 genera(19.84 % ) ; 93 genera(14.53%);54 genera(8.44%)。5. The flora of NZNR belongs to Central-China of East Asia. The statistics of comparison of the generic areal-types between NZNR and its adjacent regions shows that the flora is similar to Fanjingshan's which is situated in Central-China. In addition, data of East Asia in genus level between NZNZ and China, Central-China, Yunnan province show that the flora of NZNR which is inclined to Sina-Japan is different from Yunnan plateau which belongs to Sina-Himalaya. So the flora of NZNR is vested in Central-China. 6. There are abundant endemic in NZNR. Davidiaceae is endemic of China and its appearance and development prove that the plant and vegetation in this area is ancient and special. There are 10 families of East Asia in the NZNR, which are Tetracentraceae, Dipentodotaceae, Torricelliaceae, Eupteleaceae, Actinidiaceae, Stachyuraceae, Helwingiaceae, Cephalotaxaceae, Aucubaceae, Cercidiphyllaceae. This statistics indicates that the NZNR is part of East Asia'and has consistency in geological history with East Asia and also makes know that this area has close correlation with East Asia. There are 27 endemics of the NZNR and this indicates the important position of the NZNR in Yunnan and even in China. 7. There are 73 new distributions in Yunnan at this investigation, belonging to 32 families and 58 genera. More than half of these species are herb which has stronger spread and adaptation abilities. Plenty of new distributions indicated the flora is abundance in this area. In addition, it also shows the investigations of plant and vegetation is few in this area. So the NZNR has very important value on plant diversity investigation and conservation in Yunnan, even in China.