Studies On Flora And Geographic Distribution Of Bryophytes In Liuheng Island And Its Surrounding Islands,Zhoushan,Zhejiang

Liuheng island and its surrounding islands are located in the southwest of Zhoushan Islands,bordering Zhoushan Island in the north,the East China Sea in the East and the mainland in the west.The studied region includes 378 islands,among them 26 are inhabited,with a land area of 202.3 km²,and a coastline length of 474.7km.Botanical studies on these region mainly focused on seed plants.So far no bryological documents on these islands have been available.Field ecological investigation and specimen collection on bryophytes of Liuheng island were conducted during August and October 2017.Seven islands,including Liuheng Island,Dengwei Island,Taohua Island,Ant Island,Shrimp Stand Island,Suspended Mountain Island and Fodu Island,were included in our study.Based on our field work and specimen identification,we quantitatively analyzed bryophyte composition,floristic composition,environmental impact factors and plant phylogenetic diversity in the study area.The results are as follows:1.There are 205 species of bryophytes belonging to 88 genera and 46 families in Liuheng and surrounding islands,including 10 families,12 genera and 24 species of liverworts and 181 species of mosses belonging to 36 families,76 genera.2.Potttiaceae,Brachytheciaceae,Bryaceae,Fissidentaceae,Hypnaceae,Maniaceae,Leucobryaceae,Entodontaceae,Locolphoeae,Funceae and Thdiaceae are the dominant families in this region,accounting for 23.91%of the total families,including 46 genera and 130 species.Bryum,Pohlia,Physcomitrium,Hypnum,Fissidens,Weissia,Eurhynchium and Dicranella are the dominant genera in this region according to their species number,accounting for 9.09%of the total genera and40.98%of the total species.3.A total of 204 specimens were collected from six substrate types,which were soil-borne?1373 specimens,60.33%?,saxicolous?373 specimens,16.93%?,hydrophilous?55 specimens,2.48%?,epiphytic?153 specimens,6.92%?,cement substrate-borne?159 specimens,7.23%?,and sandy soil-borne?85 specimens,3.87%?.4.Bryophygte flora of Liuheng and its surrounding islands are diverse in composition,including eight different types:East Asia?24.5%?,North Temperate Zone?24.0%?,World Wide Distribution?11.8%?,Pantropic Distribution?11.3%?,Old World Tropics?10.7%?,East Asia-North America?6.9%?,Old World Temperate Zone?6.4%?and China?4.9%?.East Asia and temperate zone are dominant,accounting for24.5%and 24%respectively,followed by the world wide distribution and East Asia-North America distribution,accounting for 11.8%and 11.3%respectively.These four elements account for 71.6%of the total,and are the most important geographical floristic elements in the region.5.Bryophyte species richness?y?in Liuheng and surrounding islands is mainly affected by island area?x1?,the nearest distance from the mainland?x2?,and the highest altitude?x3?Their relationships could be expressed by the following functions:y=16.8874*x1 ^0.502?r=0.937,n=18,P<0.001?,y=799.463x2^-1.346?S=23.596,r=0.823?,y=22.338*e^0.0.0036*x3?S=39.480,r=0.684?.