Studies On Species Diversity Of Vascular Plants In Yachang Orchid National Nature Reserve Of Guangxi

On the basis of comprehensive literature collection,field-investigation and herbarium study,the floristic compositions,characteristics and endemism in Yachang Orchid National Nature Reserve were studied.Rare and endangered plants of this region were statistically analyzed and evaluated,followed by proposing the corresponding protection countermeasures.The main results of this study are as follows:1.There are 1915 vascular plant species(including infraspecific taxa),belonging to 858 genera in 195 families in Yachang Orchid National Nature Reserve,of which 159 species of pteridophytes belong to 73 genera in 34 families,16 species of gymnosperms belong to 8 genera in 6 families and 1740 species of angiosperms belong to 777 genera in 155 families(including 1385 species of dicotyledons belonging to 614 genera in 134 families,and 355 species of monocotyledons belonging to 163 genera in 21 families).2.There are 159 species of pteridophytes belonging to 73 genera in 34 families,accounting for 18.47%(861 species),45.91%(159 genera),and 59.65%(57 families)of the pteridophytes in Guangxi,accounting for ca.6.12%(ca.2600 species),31.60%(231 genera)and 53.97%(63 families)of those in China.The dominant families are Polypodiaceae,Dryopteridaceae,Pteridaceae,Athyriaceae and Aspleniaceae,adding up to 80 species and covering 50.31%of the total pteridophytes in this region;The dominant genera are Pteris,Selaginella,Adiantum,Allantodia,Asplenium,Cyrtomium,Dryopteris,Polystichum and Pyrrosia,adding up to 62 species and covering 38.99%of the total pteridophytes in this region.3.The gymnosperm plants are scarce in Yachang Orchid National Nature Reserve,with only 16 species belonging to 8 genera in 6 families,holding a low proportion of the total wild seed plants in this area of 0.91%(species),1.02%(genera)and 3.73%(families).4.There are 1740 species of angiosperms belonging to 777 genera in 155 families in Yachang Orchid National Nature Reserve.The dominant angiosperm families are Orchidaceae,Compositae,Fabaceae,Gramineae,Rosaceae,Lauraceae,Labiatae,Rubiaceae,Cyperaceae,Urticaceae,Euphorbiaceae,Moraceae,Liliaceae,Celastraceae,Gesneriaceae,Asclepiadaceae,Scrophulariaceae,Verbenaceae,Caprifoliaceae and Acanthaceae,which add up to 927 species belonging to 430 genera,occupying 53.28%in species and 55.34%in genera of the angiosperms in this area,respectively.The dominant angiosperm genera are Ficus,Carex,Rubus,Begonia,Cymbidium,Euonymus,Lysimachia,Pittosporum,Smilax,Liparis,Clematis,Viola,Dendrobium and Ilex,which are 210 species in total,covering 12.07%of the angiosperms species in this region.5.The flora in Yachang Orchid National Nature Reserve are dominantly tropical or subtropical elements.Pteridophytes,whose families and genera are obviously tropical or subtropical elements,comprise 43 genera in 23 families,covering 78.18%and 95.83%of the total pteridophyte genera and families(except the Cosmopolitan families and genera),respectively.At the families level of the seed plants flora in this area,the tropical or subtropical elements and the temperate elements cover 45.96%(74 families)and 19.25%(31 families)of the total wild seed plants families,respectively.Similarly,at the genera level,the tropical or subtropical elements and the temperate elements cover 57.84%(454 genera)and 18.60%(146 genera)of the total wild seed plants genera,respectively.In general,with respect to the families and genera levels,the seed plants flora in this region exhibit mainly tropical and subtropical elements,while the temperate elements also play a role in this area.6.The majority of the recorded families and genera in Yachang Orchid National Nature Reserve are either oligotypic(the families or genera only have 2-4 species)or monotypic(the families or genera only have 1 species).For pteridophytes,oligotypic or monotypic families amount to 25,which accounts for 73.53%of the total families of pteridophytes,while the corresponding figures for oligotypic or monotypic genera are 64 and 87.67%,respectively.As for the seed plants,there are 113 monotypic or oligotypic families,accounting for 70.19%of the total families of wild seed plants,while the corresponding figures for oligotypic or monotypic genera are 707 and 90.06%,respectively.7.Numerous taxonomic groups which are endemic in East Asia were found in Yachang Orchid National Nature Reserve,including 4 families(Actinidiaceae,Stachyuraceae,Cephalotaxaceae and Torricelliaceae)and 22 genera(e.g.the Cyrtogonellum of pteridophytes and Notoseris of seed plants).In addition,there are 13 species of pteridophytes endemic in China and 21 species of wild seed plants endemic in Guangxi,such as Huperzia nanlingensis and Daphne longituba.8.There are 172 rare and endangered species(including 1 pteridophyte species,4 gymnosperm species and 167 angiosperm species)belonging to 80 genera in 18 families in Yachang Orchid National Nature Reserve,in which 14 species(3 and 11 species are under first and second class state protection,respectively)are on the list of Wild Plants Under State Key Protection issued in 1999 and 158 species are on the list of protection of Guangxi wild plants list.In light of the author's field investigation and the IUCN's Evaluation Standards of endangered species,95 species in addition to the above-mentioned 172 species are suggested to be included in the list of wild plant protection.The causes leading to rare and endangered plants being threatened had been discussed in this study,and we will put forward some corresponding protection measures according to the actual situations.9.Two new species(Oreorchis yachangensis and Habenaria yachangensis),four newly recorded genera and eighteen newly recorded species in Guangxi were found in the field exploration of the diversity of vascular plants in Yachang Orchid National Nature Reserve.10.The vascular plants in Yachang Orchid National Nature Reserve were studied in taxonomic,and most of the families and genera were compiled the retrieval table,except the monotypic families and genera.