Study On The Flora Of Seed Plants In Dong'an Shunhuang Mountain National Nature Reserve Of Hunan

Dong'an Shunhuang Mountain National Nature Reserve of Hunan,located in the middle section of Yuechengling Moutains belonging to the northwest part of Nanling Moutains,is situated in the region of boundaries among Yunnan-Guizhou Plateau,Nanling Moutains and Chiang-nan Hilly Region.Its flora is characterized by the close relationship of floristic transition and vicariance to the adjacent regions.Unfortunately,as severe fragmentation of forests and plant resources,the study of the flora in Yuechengling Moutains appears insufficient.By the way of analysis in the level of floristic endemism and transition,this study can partly reflect the influence of this important mountain range on the plant diffusion and distribution,and will enrich the knowledges of Yuechengling Mountains flora.Moreover,rare plants always are the focal point in the conservation of plants diversity,the relative works in this paper will also provide critical basic data and fair suggestion.From October 2018 to October 2019,eight field investigations were carried out in Dong' an Shunhuang Mountain National Nature Reserve of Hunan,2606 specimens with 1276 records and more than 6030 color pictures were taken in all.As the supplements in previous specimens checked and related literatures reffered,the checklist of seed plants in study areas was compiled.For the sake of better understanding of the floristic characteristics of seed plants in this region,the floristic composition,endemism phenomenon and geographical connection have been analyzed,and the position of Dong'an Shunhuang Moutains on the floristic regionalization also have been discussed.In addition,we concern the status of rare plants in this region,the resource actuality,protective value and protection strategies were listed.The main results are as follows:1.The floristic composition of seed plant flora in Dong'an Shunhuang Moutains is abundant.There are 1692 wild seed plants species(including infraspecific taxa)in Dong'an Shunhuang Moutains,which belong to 716 genera of 162 families.Specifically,there are 11 species of gymnosperms in 8 genera of 5 families and 1681 species of angiosperms in 708 genera of 157 families.The families,genera,and species of Dong'an Shunhuang Moutains seed plants consist 78.11%,35.58%,and 34.52%of seed plants families,genera,and species of Hunan Province respectively.2.There shows complex geographical elements of floristic in Dong'an Shunhuang Moutains.At the familial level,tropical distribution type is the major part of geographical elements,occupying 45.30%of total families,and the R/T ratio(ratio between tropical and temperate distribution type)is 1.9.However,at the genera level,with the R/T ratio of 0.8,tropical and temperate type are basically equal.Laking typical tropical families and genera and existing abundant genera with single or few species,and species of distribution types of East Asia and Endemic to China which occupying 18.30%of total genera are distinct features in this region,which shows typical subtropical floristic characteristic.3.The flora of Dong'an Shunhuang Moutains is charactered by strongly relationship of floristic transition,in which the central China flora play a deeply influence.In the analysis of narrowly distributed species from adjacent regions,the species from Xuefeng Moutains-Yuechengling Moutains is the major proportion especially in the middle or high altitude,including many species from central China flora.Moreover,the flora of Dong'an Shunhuang Moutains are associated with Nanling Moutains,but lacking typical species from the south China flora.In addition,there are also several species spread here from Qiangui area.4.Dong'an Shunhuang Moutains,located in the middle section of Yuechengling Moutains,borders on Bashilidanan mountains which is the southern part of Xuefeng mountains.Such continuous landform sharps the flora deeply and make the flora closely relate and vegetation types and plant species to be an integration.The existence of some endemic species which only distribute in this region means that the flora of Yuechengling-Bashilidanan mountains range has mutual formation history.In floristic regionalization,the flora of Yuechengling-Bashilidanan mountains range should be divided into Nanling Sub-province,West Nanling District5.The rare plants in Dong'an Shunhuang Moutains sum to 110 species,and its protective value,ecological habits,population characteristics and threatened situation were statistically listed.Furthermore,we focused to analyse the resource actuality of plants with special protective value,and put forward countermeasures for conservation.6.In the process of plant diversity survey,six new species record of Hunan province was found,including Hemsleya pengxianensis,Rubus formosensis,Lysionotus heterophyllus var.lasianthus,Carex mitrata,Corydalis parviflora and Pellionia incisoserrata.