Study On Flora Of Danxia Landform In Jiangxi

Danxia landform is a special habitat type.Lots of questions arise from it: its floristic elements and how these elements evolved,the formation history of this flora,and its affection to human society.To answer these,a thorough study of the plants from Danxia landform need to be carried out.Therefore,the study on flora of Danxia landform in Jiangxi have both theoretical and practical significance.It can provide scientific basis to biodiversity protection,ecosystem maintenance,and the development of special ecotourism.Through the expedition of Danxia landform from Lung Fu Shan and Guifeng of north Jiangxi,Lohan rocks of central Jiangxi,Xiaowudang Mount and Hanxianyan for south Jiangxi,the results are as follows:(1)rich in plant diversity and floristic elementsWild seed plants of Danxia landform in Jiangxi have 151 families,652 genera,and 1480 species in total,including 5 families,7 genera,8 species of gymnosperms,146 families,645 genera,1472 species of angiosperms.Comparing with other provinces,seed Plants of Danxia landform in Jiangxi have the highest diversity and the most endemic genera,including 6 rare and endangered species in China,and 70 rare and endangered species in Jiangxi(of which 16 are first-level).(2)typical subtropical floraAt family level,72 families(48% of total)are tropical distributed;35 families(23% of total)are temperate distributed.This data results in a tropical character of this flora.However,genera distribution can be more informative.At genus level,293 genera(46% of total)are tropical distributed;282 genera(44% of total)are temperate distributed.The equal between tropical and temperate elements shows a typical subtropical flora character.(3)obviously transitional characterAccording to Wu Zhengyi's floristic division,flora of Danxia landform in Jiangxi belong to east China region.It has obvious subtropical to temperate transitional character.The tropical and temperate elements interact and mixed with each other.(4)ancient originFlora of Danxia landform in Jiangxi contains many ancient and primitive families and genera,including gymnosperm such as Pinus(Pinaceae),Cunninghamia(Taxodiaceae),Juniperus(Cupressaceae),Taxus(Taxaceae);relic angiosperm from Cretaceous such as Magnoliaceae,Lauraceae,Ranunculaceae,Lardizabalaceae,Chloranthaceae,Saururaceae,Calycanthaceae,Sargentodoxa;catkin plants such as Fagaceae,Hamamelidaceae,Juglandaceae,Salicaceae,Ulmaceae,Betulaceae,Moraceae;also many monotypic and olygotypic genera,which reveal the ancient origin of this flora.(5)clear distinction between north and south regionComparing the south,central and north regions of Danxia landform in Jiangxi,the richest species diversity occurs in the north.A number of key tropical plants such as Baeckea frutescens,Calamus thysanolepis only distributed in the south and the central.Also some temperate species can only be found in the north region,such as Macleaya cordata,Rhaphiolepis major and Platycrater arguta.(6)clear content difference of elementsAccording to Wu Zhengyi's floristic division of seed plants in China,the distribution of six dominant trees can be divided into two types: temperate(Myrica rubra,Castanea mollissima,Castanopsis fargesii,Liquidambar formosana)and tropical(Cyclobalanopsis glauca,Schima superba).The content of chemical elements Mn,K,Ca,Mg,P,Fe,Cu,Zn,Na and B in trees of temperate distribution are higher than those in trees of tropical distribution.