Study On The Flora Of Seed Plants In Jiangyong Yuankou Provincial Nature Reserve Of Hunan

Hunan Jiangyong Yuankou Provincial Nature Reserve located in the southwest of Hunan Province,the western part of Nanling Mountains,which is the southern part of Dupangling mountain system and the northern end of Huashan Mountain.It is one of Hunan flora enclaves that there are abundant seed plants,many south China tropical composition,native broad-leaved forest preservation very well.Yuankou Nature Reservehas only been studied in the 1980s for woody plants,but not for seed plants.The floristic studies of woody plants were only carried out in Yuankou Nature Reserve in the 1980s,but the complete floristic studies of seed plants were not carried out.In order to find out the floristic composition of Yuankou Nature Reserve and provide basic data for the management and construction of the reserve,this study through 10 field investigations,collection and identification of specimens and literature review from September 2019 to January 2022,shows that there are 171 families,712 genera and 1446 species of wild seed plants in Yuankou,accounting for 80.28%,50.78%and 26.33%of the families,genera and species of seed plants in Hunan.There are few species of gymnosperms,including 6 families,8 genera and 9 species.Angiosperms are the main floristic component in the study area,with 1437 species in 704 genera,165 families.According to the sorted list of seed plants in Yuankou,analyze its floristic composition,distribution type,endemic phenomenon and geographical connection,explore the position of Yuankou Nature Reserve in floristic division and its importance in Hunan flora,analyze the threatened factors according to the current situation of endangered protected plants,and put forward reasonable protection suggestions.The main results are as follows:(1)The dominant families and genera with rich species and high degree of differentiation are obvious.At the family level,dominant families with more than 20 species accounted for 12.28%of the total number of families and 52.01%of the total number of species,such as Poaceae,Asteraceae and Rosaceae,etc.At the genus level,dominant genera with more than 6 species accounted for 4.92%of the total number of genera and 23.58%of the total number of species,such as Rubus,Ilex and Carex,etc.(2)The seed plant families and genera in Yuankou Nature Reserve are mainly developed in primitive or isolated or even undifferentiated few species families and genera.At the family level,96 families were monotypic family and depauperate family(including 2-4 species),accounting for 56.14%and 13.00%of the total number of families and species.At the genus level,there are 677 genera of monotypic genus and depauperate genre(including 2-5 species),accounting for 95.08%and 76.42%of the total species in the whole reserve.(3)Yuankou Nature Reserve located in the evergreen broad-leaved forest area in the transition from the middle subtropical zone to the south subtropical zone.In terms of flora,it is located below the"⊥",shaped area where the flora of South China meets that of Central and East China.It belongs to the northern edge of the tropical flora of South China.The floristic composition of seed plants is complex and varied,and they are divided into 11 areal types at the family level.There are 81 tropical families and 38 temperate families,and the ratio(R/T value)of tropical families to temperate families is 2.13:1.At the genus level,there are 14 distribution types and 6 variations,except for the central Asian distribution type,the rest of the distribution types,including 365 tropical genera,270 temperate genera,and 20 endemic genera in China.The ratio of tropical genera to temperate genera is 1.35:1.At both family and genus levels,tropical and subtropical components dominated,followed by temperate components,showing obvious tropical and subtropical nature.(4)Yuankou Nature Reserve is closely related to the flora of similar areas adjacent to Nanling Mountains,which is also the transition from the middle subtropical to the south subtropical.At the genus level,the highest similarity is the Hunan Dupanging National Nature Reserve,which belongs to the Dupang mountains of Nanling Mountains.The two places penetrate each other in the floristic composition,with a similarity of 86.6%,Yuankou Nature Reserve has a high similarity with Hunan Mangshan National Nature Reserve and Hunan Jiulongjiang National Forest Park which belong to the pearl River system of Nanling Mountains,with 83.6%and 83.1%respectively.(5)There are many new data on rare and endangered protected plants and flora.At present,49 species of protected plants have been found in Yuankou,including 1 species of national grade I,22 species of national grade II,26 species of key protected wild plants in Hunan Province.A new species is found,which is Paraphlomis jiangyongensis.Besides,there are 15 newly recorded species in Hunan Province,including 3 newly recorded genus.This study accurately and completely analyzed the floristic composition,floristic characteristics,distribution types and unique phenomena of seed plants in Yuankou Nature Reserve for the first time,determined the position of Yuankou Nature Reserve in Hunan flora,explained the current situation and threatened factors of endangered protected plants,and put forward protection suggestions,so as to provide background data and reference basis for accelerating the optimization and integration of the reserve and implementing effective and reasonable protection measures.New species and records not only enrich the flora of Hunan,but also reflect the particularity and richness of Yuankou Nature Reserve flora and its importance in Hunan flora,and fill the weakness of Yuankou Nature Reserve seed plant flora.