The Floristic Phytogeography Of Spermatophyte Flora In Luoxiao Range

Luoxiao Range is a large mountain by direction to north and south,located in the junctions of Jiangxi,Hunan and Hubei Province.From north to south it can be divided into five medium-sized mountains,which are Mufu Mountain,Jiuling Mountain,Wugong Mountain,Wanyang Mountain and Zhuguang Mountain.Luoxiao Range is an important ecological corridor which connects east China,central China and soutn China.It is also an important watershed of Xiangjiang river basin and Ganjiang river basin.Therefore,the floristic phytogeography study of Luoxiao Range has special meaning.It has great significance to illuminate the floristic history of East Asiatic Kingdom,especially species relocation and diffusion in geological time.At the same time this study provided theoretical basis for biological resources exploitation,and biological diversity and ecological environment protection in Luoxiao Range.From July 2012 to December 2016,we went to Luoxiao Range for taking the field investigation 23 times,total more than 260 days,and collected 17434 specimens.In addition,we also checked more than 20000 specimens collected in Luoxiao Range by other people,and checked literature to compile the seed plant catalogue of Luoxiao Range.Then we analyzed the floristic characteristics,endemism,relict phenomenon,transition phenomenon,and formation history of flora in Luoxiao Range.Also we compared with other floras,further put forward the floristic regionalization about Luoxiao Range.The conclusions are as follows.(1)The floristic composition of seed plant flora in Luoxiao Range is abundant,and their forming process is very complex.In total 4739 species(included subspecies and variants)of wild seed plant flora belonging to 1174 genera and 227 families distributed in Luoxiao Range.Included 34 species of gymnosperm belonging to 21 genera and 10 families,4704 species of angiosperm belonging to 1153 genera and 217 families.The geographical elements of families could be divided into 12 areal-types and 11 sub-types.The geographical elements of genera could be divided into 14 areal-types and 33 sub-types.The geographic distribution model is complex and diversified,which fully reflects a complexity formation history of flora in Luoxiao Range.(2)The seed plant flora of Luoxiao Range shows a subtropical property,and floristic transition phenomena in Luoxiao Range are obvious.In Luoxiao Range,it distributed about 111 tropical families,occupying 59.68% of total of the non-world families,and 75 temperate families,occupying 40.32% of total of the non-world families.And typical families of flora are Pinaceae,Lauraceae,Theaceae,Fagaceae,Rosaceae,Caprifoliaceae,Vitaceae,Aquifoliaceae,Aceraceae,Symplocaceae,Hydrangeaceae,Actinidiaceae,Ulmaceae,Styracaceae,Hamamelidaceae,Magnoliaceae,Lardizabalaceae,Cornaceae,Ericaceae,Clethraceae,Primulaceae,Juglandaceae,et al.Total 525 tropical genera distributed in Luoxiao Range,occupying 47.99% of total of the non-cosmopolitan genera,569 temperate genera,occupying 52.01% of total of the non-cosmopolitan genera.The proportion of tropical genera and temperate genera is roughly equal.And typical genera of flora mainly are Pinus,Tsuga,Ilex,Acer,Viburnum,Rhododendron,Symplocos,Actinidia,Smilax,Eurya,Vitis,Lonicera,Camellia,Lithocarpus,Cerasus,Cyclobalanopsis,Neolitsea,Hydrangea,Castanopsis,Machilus,Lindera,Elaeagnus,Tilia,Cornus,Asarum,Styrax,Aucuba,Yulania,et al.Typical tropical families and genera are not rich in Luoxiao Range,and most of them are widespread species.Furthermore,distribution center of the tropical families and genera of Luoxiao Range are East Asia subtropical area.It reflected the subtropical property of seed flora in Luoxiao Range.Floristic transition phenomenon within Luoxiao Range is obvious.The R/T value increase from north to south,the lowest one is Hubei Jiugong Mountain about 0.66,the highest is Jaingxi Qiyun Mountain about 1.3.Zonality phenomenon of typical families in five medium-sized mountains is obvious.In the northern of Luoxiao Range(included Mufu Mountain and Jiuling Mountain)mainly distributed deciduous and widespread trees,such as Liriodendron chinense,Manglietia decidua,Lithocarpus glaber,Castanopsis sclerophylla,Rhododendron simsii.In the middle south of Luoxiao Range(included Wugong Mountain,Wanyang Mountain and Zhuguang Mountain)mainly distributed evergreen and middle subtropical coniferous trees,such as Exbucklandia tonkinensis,Tutcheria hirta,Semiliquidambar cathayensi,Amentotaxus argotaenia,Cathaya argyrophylla,Tsuga longibracteata.It indicates that north of Luoxiao Range impacted by central China flora,so the temperate composition proportion is higher,and south of Luoxiao Range impacted by south China flora,then which distributed more tropical elements.(3)The endemism of the flora is obvious.It included 5 familiesendemic to China,60 genera endemic to China,1792 species endemic to China,and 44 species local endemic to Luoxiao Range.The endemic genera are mostly ancient endemic genera which reflects the origin antiquity of flora in Luoxiao Range,such as Cathaya,Pseudolarix,Pseudotaxus,Cunninghamia,Cyclocarya,Bretschneidera,Fortunearia,Semiliquidambar.The main causes for endemism of Luoxiao Range is climate fluctuation since the Miocene,and the another important reason is habitat diversity within the Luoxiao Range.The floras of Luoxiao Range,east China,central China and south China are closely correlated.The common endemic elements in this 4 areas include 25 genera endemic to China,and 592 species endemic to China.About 1166 China endemic species are shared in Luoxiao Range and east China,included Yulania amoena,Camellia chekiangoleosa,Quercus stewardii,Briggsia chienii,Speirantha gardenia,etc.About 1055 species endemic to China are shared in Luoxiao Range and central China,such as Manglietia decidua,Saxifraga rufescens,Yua thomsoni var.glancescens?,Rhododendron auriculatum,Clematoclethra scandens.About 1165 species endemic to China are shared in Luoxiao Range and south China,included Abies beshanzuensis var.ziyuanensis,Manglietia kwangtungensis,Ilex syzygiophylla,Machilus breviflora,Oreocharis argyreia,et al.(4)The relict genera and species in Luoxiao Range are rich,which reflects the reflict character of flora.In total,260 relict species belong to 147 genera distributed in Luoxiao Range.Most of the relict species origin in late Cretaceous or Oligocene and became relict under the influence of climate fluctuations since Miocene.The relict species distributed in Luoxiao Range mainly derived from early Tertiary Arctic-Teriary Flora and Boreotropical Flora.Middle south of Luoxiao Range is a typical refuge regions of the relict flora,where distributed many relict plants community,representative edificatory included Cathaya argyrophylla,Fokienia hodginsii,Tsuga chinensis,Tsuga longibracteata,Keteleeria davidiana,Exbucklandia tonkinensis,Tapiscia sinensis,Halesia macgregorii,etc.(5)The main mountains located in Luoxiao Range are important representative of subtropical floras.And floristic composition of mountains located in north of Luoxiao Range are differ from south mountains.In this study compared the R/T value,FS(floristic spectrum),and genus similarity clustering of 57 floras(included 17 mountains located in Luoxiao Range).The results indicated that these 57 floras can be divided into 4 classes,i.e.1)North China area,included Taihang mountain and Northwest Hebei mountain,2)Tabit-Hengduan Range area,included Tabit,Gaoligong Mountain,and Hengduan Range,3)Southwest-South China area,included Xishuangbanna,Hainan,Nanling etc,4)Central-East China area,included all of the mountains located in Luoxiao Range,and Emeishan,Qinling mountains,Jiangxi Wuyi mountain,Sanqingshan,Tianmu mountain,Dabie mountain etc.The 17 main mountains located in Luoxiao Range shows south-north differentiation character.Mountains located in Mufu mountain and Jiuling Mountain are more obvious in temperate elements,so that they cluster with Tianmu mountain,Dabie mountain and Huangshan.Mountains located in Wugong mountain,Wanyang mountain and Zhuguang Mountain are more obvious in tropical elements,so that they cluster with Donggong mountain,Jiangxi Wuyi mountain,Fujian Minjiangyuan,Matoushan etc.(6)The modern seed plant flora of Luoxiao Range at least originated from early Eocene,and formed in Miocene.Before the Cretaceous,Luoxiao Range flora was composed by ferns,gymnosperms,and some extinct angiosperms.And those typical genera could be found in Paleocene-Eocene stratum at Luoxiao Range,such as Juniperus,Salix,Zelkova,Magnolia,Cinnamomum,Prunus.During the Miocene,East Asia monsoon climate formation and the Luoxiao Range formed modern flora.And the impact of Quaternary glaciation on flora of Luoxiao Range is weak.Many refuges exist in the Luoxiao Range because the ecological niches are diversity in this area.So that the modern flora of Luoxiao Range is continues from Miocene flora.(7)On the floristic regionalization,Luoxiao Range located in the boundary of Central China Province and South China Province.The family,genus,species similarity coefficient of Luoxiao Range and Nanling Range is 0.93,0.84,and 0.68 respectively.The family,genus,species similarity coefficient of Luoxiao Range and Wuyi Range is 0.98,0.89,and 0.72.The family,genus,species similarity coefficient of Luoxiao Range and Zhewan Mountains is 0.89,0.76,and 0.51.The similarity coefficient indicates that the history of flora in Luoxiao Range,Nanling Range and Wuyi Range could be similar.But the similar coefficient of Luoxiao Range and Zhewan Mountains is lower,which reflects that the history between two floras is different.The characteristics of floras in north Luoxiao Range and south Luoxiao Range(and East China area)were different in early Tertiary.The development history of flora in south Luoxiao Range(included Wugong Mountain,Wanyang Mountain,Zhuguang Mountain)is similar to Wuyi Range and Nanling Range.They are descendant of Tertiary Boreotropical Flora,so that many evergreen and gymnosperm relict species remained in this area included Tsuga,Keteleeria davidiana,Exbucklandia tonkinensis,Altingia chinensis.The development history of flora in north Luoxiao Range(included Mufu Mountain,Jiuling Mountain)is similar to central China and Zhewan mountains.Most of the relict species distributed in this area were migration from northern high latitude region under the influence of climate change since Miocene.Representative relict species included Ginkgo biloba,Pseudolarix amabilis,Dipteronia sinensis,Cercidiphyllum japonicum.So “east China area” should be divided into Central China Province and South China Province.And north of Luoxaio Range belongs to Central China Province,Yangtze River downstream mountainous sub-province,Mufu-Jiuling district.The representative species of the flora included Monimopetalum,Changium,Changnienia,Pseudolarix amabilis,Torreya grandis,Manglietia decidua,Decumaria sinensis,Anoectochilus zhejiangensis etc.South of Luoxaio Range belongs to South China Province,Wuyi-Luoxiao sub-province,Luoxiao district.The representative species of flora included Disanthus cercidifolius subsp.longipes,Tsuga,Abies beshanzuensis var.ziyuanensis,Fokienia hodginsii,Pseudotaxus chienii,Rhododendron,Parakmeria lotungensis,Barthea barthei,Petrosavia sakuraii,Elaeagnus jiangxiensis,Gelidocalamus stellatus,Hemiboea subacaulis var.jiangxiensis,Ilex venusta,Chamaegastrodia nanlingensis etc.(8)New species and new records found in Luoxiao Range.New species is Bredia changii W.Y.Zhao,X.H.Zhan & W.B.Liao,sp.nov.,Saxifraga shennongii W.B.Liao & L.Wang,sp.nov..One new record family to Jaingxi is Petrosaviaceae.Three new record genera to Jiangxi are Petrosavia,Sedirea,Chamaegastrodia.Eleven new record species to Jiangxi are Phyllagathis guidongensis,Rubus xanthoneurus,Lysimachia huitsunae,Sedirea subparishii,Chamaegastrodia nanlingensis,Ilex syzygiophylla,Anoectochilus zhejiangensis,Petrosavia sakuraii,Melampyrum laxum,Chrysosplenium delavayi,Oreocharis argyreia var.angustifolia.Eight new record species to Luoxiao Range are Mitchella undulata,Taeniophyllum glandulosum,Ilex wenchowensis,Burmannia nepalensis,Gastrochilus japonicas,Pleione hookeriana,Goodyera yangmeishanensis,Gastrodia peichatieniana,Ilex venusta.