Study On The Flora Of Seed Plants Of Tianqiaoshan Natural Reserve In Luxi County, Hunan Province

The Tianqiaoshan Provincial Natural Reserve is located at the northeastern Luxi county, Xiangxi Tujia and Miao autonomous prefecture of western Hunan province. The reserve is the stretch of the eastern Yunnan-Guizhou plateau and southern Wuling mountain, belonging to the subtropical monsoon humid climate. The parent rock is mainly consisted of purple sand shale. It still retains many native broad-leaved forest vegetation and is the best vegetation area in the purple soil region of the whole Hunan province. We have made a study on the main vegetation types, flora and the unusual communities in the purple soil habitat in this paper. The study results show that:1 The complex terrain conditions are conductive to form the small ecological environment and various types of vegetation. According to the results of the field investigation, there are 4 vegetation type groups,10 vegetation types and 38 formations in the reserve.2 There are 1208 species of seed plants belonging to 671 genera and 162 families, among them,7 families,12 genera,17 species are gymnosperms, and 155 families, 659 genera,1191 species are angiosperms. If removing the cultivated plants, there are 150 families,578 genera,1040 species of seed plants, and 4 families,4 genera,4 species are gymnosperms, and 146 families,574 genera,1036 species are angiosperms. According to the distribution types analysis of genera, the temperate composition is slightly more than the tropical components. The temperate composition is dominant with north temperate type and the tropical components is dominant with pantropic type. The reserve is located at the junction of Wuling mountain and Xuefeng mountain, belonging to the typical central China flora.3 The purple sand shale is easy to weathering erosion and lack of water and nutrients. Only the plants which are resistant to the drought and barren can grow well. Such as the Quercus acrodonta forests and Acer coriaceifolia forests are widespread in this poor habitat. These xerophytic community types are very rare in broad-leaved forest of subtropical regions in Hunan Province etc.4 The highest elevation is Tianqiaoshan which is 761.6 m, and the lowest is Maowujie,109 m. The relative height is 652.6 m. And the vertical distribution of vegetation is not obvious, but the horizontal distribution patterns are diverse.5 The species composition is characteristic with most of species belonging to the low mountains and hills, and lack of some typical species that depend on the habitat of high altitude mountains.