Flora And Phytogeography Of Mt. Houmiling Nature Reserve,Hainan, China

The intact tropical rainforests are preserved on Houmiling Mountain,Hainan Island.The plant species are rich.Based on field work,the floristic characteristics of wild vascular plants species were analyzed.The main results are as follows:(1)1559 vascular plant speciesbelonging to208 families and 793 genera were recorded,including 180 species of pteridophytes(belonging to 43 families and 93 genera),9 species of gymnosperms(6 families and 9 genera),1370 species of angiosperms(159 families and 693 genera).(2)The typical families of pteridophytes are Pteridaceae,Athyriaceae,Thelypteridaceae,Aspidiaceae,Polypodiaceae.At the species level,tropical elements were the dominant components,in which pantropical species and tropical species contributed 67.22% of the total.There were 21 species endemic to C hina,including 9 species endemic to Hainan.The gymnosperms flora takes up 0.65% of the seed plants,which mainly contains Cycas hainanensis,Dacrydium pectinatum,Cephalotaxus mannii,etc.At the generic level,tropical elements were the dominant components of angiosperms,in which tropical and pantropical genera contributed 89.64% of the total(excluding cosmopolitan genera).There were five genera endemic to China,including one genera(Metapetrocosmea)endemic to Hainan Province.At the species level,tropical and pantropical elements contributed 76.79% of the total(excluding cosmopolitan species).Among them,293 species(21.59%)were endemic to China,including 91 species were endemic to Hainan province.(3)Compared with the flora of five neighbouring areas,the flora of Houmiling Mountain showed high similarity with that of Yinggeling Mountain,with the similarity coefficients of genera and species being 94.90% and 71.96%,respectively.A close affinity of flora between Houmiling Mountain and Jianfengling Mountain,Diaoluoshan Mountain also exists.The results showed that the similarity of flora in these area positively related to their latitude,altitude,climate,soil matrix.Houmiling Mountain contained more tropical elements than Dinghushan Mountain and Xishuangbanna of Yunnna,this is related to it‘s lacation which in the northern margin of the tropics and lower latitudes.(4)There are 50 rare and endangered species in Houmiling Mountain,of which 21 species belong to the List of Wild Plants Under State Key Protection(First Batch),and 19 belong to the List of Wild Plants Under State Key Protection(Second Batch),and 28 belong to The IUCN Red List of Threatened species.The destruction of the natural environment has posed a threat to the endangered plants.It is necessary to take effective measures to protect these plants.According to the field investigation and the actual distribution of these species,28 species are suggested to be listed in the list of wild plants under state protection.(5)There are 52 alien plants in the Houmiling Mountain,dominated by herbs.Some alien plants,such as Chromolaena odorata,Ageratum conyzoides,Lantana camara,Praxelis clematidea,have influenced the local biodiversity,ecological environment and agriculture etc.The diversity of Houmiling Mountain flora are facing the threat of illegal deforestation,according to the actual investigation,some recommendations are necessary,Public education plays an important role in improving the awareness of vegetation protection in local communities,and modifying the traditional agricultural structure to raise living standard of the communities.Comprehensive studies on biodiversity and endangered causes in this area are urgently needed to be carried out as soon as possible.