Flora Analysis And Phytocommunity Studies On The Deciduous Monsoon Forest At Lower Reaches Of Luozha River In Yunxian County, Yunnan

According to the classification scheme of tropical plant formations by Schimper, Monsoon Forest is discontinuously distributed in the tropical monsoon climate of Asia,Africa and America. The monsoon forest in Southeast Asia is the most flourishing. Monsoon Forest is mainly distributed in the valleys of south and southwest of Yunnan, below 1000m alt. Luozha River is a first branch of Lancang River in its middle section with a typical dry-hot valley habitat. Based on our investigation; banks of Luozha River is distributed by deciduous monsoon forest. With the building hydraulic power station, the forest will be submerged. 69 families, 180 genera and 251 species of seed plants were recorded in the deciduous monsoon forest of lower reaches of Luozha River in Yunxian County. The principal families of the flora are Papilionaceae,Compositae,Euphorbiaceae,Gramineae and so on. From analyze of the genera and species, we found that tropical distribution is the dominant element in the flora. The flora is influenced by several tropical distributions, but the Asian tropical distribution influenced more than others.Compared with the flora in dipterocarp forest of Xishuangbann,monsoon broad-leaved forest of Xishuangbanna and dry-hot valley of Lancang River, we concluded that the deciduous monsoon forest is close to dry-hot valley of Lancang River. The study area is near to the boundary of Malaysian flora and Chinese-Himalayan flora. From the research of the deciduous monsoon forest, we know that: The deciduous monsoon forest is 15-20m tall with Lannea coromandelica,Colona floribunda,Mallotus philippensis as the dominant tree species, and Microstegium ciliatum,Eupatorium odoratum,Ageratum conyzoides are the dominant species in the shrub-herb layer. The species richness is higher in the shrub-herb layer than in the tree layer, the liana and the epiphyte layer. Most of the trees have DBH(diameter breast height) between 5-10cm, and big trees with large DBH are fewer. Compared with the tropical montane rain forest and the evergreen broad-leaved forest in Southern Yunnan, the deciduous monsoon forest has lower species richness than the tropical montane rain fores, but close to the evergreen broad-leaved forest.