Studies On The Liverwort Flora Of Sino-Vietnam Border Area

Southwest China is adjacent to Vietnam.Sino-Vietnam border area lies in southwestern part of Guangxi and southern part of Yunnan provinces,which is the junction of north tropical zone and south subtropical zone.It is located between 21°50'51.23",N-24°07'10.56"N and 102°16'06.63"E-108°52'34.15",with a complex and superior natural condition.There are low-altitude monsoon rainforests and high moss coppices here.What's more,there is also a large area of karst landform.With high biodiversity value,these habitats bear abundant biological resources,and provide an excellent growing environment for bryophytes.Less affected by human disturbance,this area is one of the few intact tropical forest ecosystems so far.However,due to some historical reasons,the bryophyte diversity of this area has poorly been deeply investigation before.In order to fill the gaps of liverworts research in the region,several field collections were carried out in the nature reserves in that region from November in 2012 to Feburary in 2015.Based on the identifications of all the specimens collected there and all published papers,the liverwort flora of Sino-Vietnam border area contains 347 species belonging to 73 genera in 36 families,which contains three species new to China(Acanthocoleus gilvus(Gottsche)Kruijt,Lejeunea trinitensis Lindenb.and Leptolejeunea punctata Herzog).Eight species in three genera are new to Guagnxi and three species in three genera are new to Yunnan.The dominant families are Lejeuneaceae,Frullaniaceae,Plagiochilaceae,Lepidoziaceae,Porellaceae,Jungermanniaceae,Radulaceae and Lophocoleaceae.In order to have a better understanding of the characteristics of the liverwort flora in the border area,comparisons were made between Sino-Vietnam border area and six other countries or regions(Hainan,Taiwan,Japan,India,Malaysia and Thailand)on species richness,species similarity and phytogeographical distribution,and etc.1.There are eight dominant families in Sino-Vietnam border area which have more than 10 species with 36 genera and 276 species respectively,accounting for 49.32%of total genera and 79.54%of total species.Lejeuneaceae is the largest family of dominant families,containing 120 species,accounting for 34.58%of the whole hepatic flora,followed by Plagiochilaceae.The largest genus of the largest dominant family is Cololejeunea,with 38 species,accounting for 10.95%of the total number.There are 15 families and 37 genera with only single one species,accouting for 41.67%and 50.68%of the total number of families and genera separately,which evidently shows the complex and ancient features of the Sino-Vietnam border area.2.The ecological types of plants in this region are very rich,and can be divided into four types:geophytia,petrophytia,epixylophytia and epiphyllitia.Among them,epixylophytia is the most abundant type which can be divided into four different kinds:on tree bark,on tree branch,on the rotten tree and on tree base.However,the types of epiphyllous liverworts are the most distinctive character.3.The geographical elements of liverworts in Sino-Vietnam border area can be classified into 12 areal-types,of which the tropical Asiatic has 94 species and East Asiatic contains 129 species,accounting for 27.09%and 37.18%of the whole liverworts flora,respectively.4.In comparison with six other areas(countries)like Japan,India,Malaysia,Taiwan,Hainan and Thailand on the abundance and genus coefficients of similarity,the abundance of Sino-Vietnam border area is closest to Hainan,much lower than other areas(countries),and has a high similarity with Hainan and Taiwan.Combined with the latest relevant information,this article provides updated checklists of the liverworts of Sino-Vietnam border area.All specimens are kept in HSNU(the herbarium of East China Normal University).