A Preliminarily Study On Bryophytes Of Limestone Regions In Sino-vietnam Border Area Southwest Guangxi

Limestone regions in sino-vietnam border area southwest Guangxi, lying on the edge of north tropical of China, is the junction of north tropical zone and south subtropical zone. The climate is warm with plenty of rain, and the landform is complex. So many plants here grow well. However, the bryophytes in this region have not been investigated and studied. The present studies on bryophytes of limestone regions in sino-vietnam border area southwest Guangxi not only can fill the vacancy, but also can provide basic theory for study on vegetation diversity. At the same time, the present studies can also offer some credible basic theory for conservation of frorest ecosystems by discussing the relationship between bryophytes and habitats and the change of habitas. The results are as follows:1,There are 188 species (including subspecies and varieties) in 102 genera of 35 families in the limestone regions of sino-vietnam border area southwest Guangxi, including 129 mosses species (in 79 genera and 24 families) and 59 liverworts species(in 23 genera and 11 families). The characteristics of composition structure of families, genera and species is that dominant families and dominant genera are significant, and diversity of non-dominant families and non-dominant genera is notable. Typicality of dominant families and dominant genera and diversity of non-dominant families and non-dominant genera show that the relation between identity of the climatic zone Guangxi and diversity of geographical environment in in the limestone regions of sino-vietnam border area southwest is an organic unity.2,According to"The areal-types of Chinese genera of seed plant"by Wu Zheng-yi, the bryoflora of the limestone regions in sino-vietnam border area southwest Guangxi have been divided into 14 areal types. The results show that the most important elements are the tropical elements(51.14%), the second ones is the East Asian(24.43%) , and the third ones is the temprate elements(13.7). All of those indicate that the tropical element of the limestone regions is outstanding, and the result accords with its character of geographic location.3,The floristic geographical elements of the limestone regions and other 11 areas'were compared in this paper through the Statistic Analysis of Floristic Spectrum and Cluster Analysis. The conclusion based on the above research are as follow: the bryoflora of the limestone regions in sino-vietnam border area southwest Guangxi was close to those areas of Jiuwan Mountain, Yinzhulaoshan Mountain, Dawei Mountain, while was far from the other areas, like Taibai Mountain, Helan Mountain, Qitulaoshan Mountain. The result indicates that the bryofloras of these regions are in accordance with their geographic location. But the bryoflora of the limestone regions is far from Hainan. This result does not equate with their location. And the reason may related to their special environment.4,Ecological distribution of bryophytes of the limestone regions in sino-vietnam border area southwest Guangxi was divided into 8 types, including Petrophytia, Hydrophytia, Non-hydrophtia, Tree base, Tree trunk, Rattan cane, Rotten wood and Leaf-Epiphyllous. The result shows that the non-hydrophtia type is the richest. The second one is Geophytia types and the Hydrophytia type, the least one is the Petrophytia type. the result shows that the ecological distribution of bryophytes accords with the feature of geographical environment in the limestone regions.5,Based on ecological distribution of bryophytes, the ecological amplitude of the bryofloristisc habitat was divided into 8 classes. The analysis shows that the more types species can distribute, the higher class it can occupy and the stronger adaptability it can have. The species with lower ecological amplitude are divided into 3 types: restricted by soil, restricted by forest environment, restricted by special habitat.6,The research shows that there are 3 families, 8 genera and 11 species of epiphyllous liverworts in the limestone regions in sino-vietnam border area southwest Guangxi.