Studies On Flora And Geographic Distribution Of Bryophytes In Shengsi Archipelago, Zhoushan, Zhejiang

Shengsi archipelago is located in the north of Zhoushan Islands in Zhejiang Province.It is located in the east of Hangzhou Bay,and the southeast of the Yangtze River.It consists ofhundreds of groups of islands at the junction of the Yangtze River and Qiantang River.In May 2014 and July 2016,we had gone to 18 islands of Shengsi archipelago and collected altogether 944 specimens of bryophytes.After the identification of specimens,combined with the ecological data,quantitative classification,sorting and other statistical methods were applied to study the bryoflora,ecology and diversity pattern and impact factors of bryophyte vegetation in Shengsi archipelago.The main results are as follows:(1)A total of 132 bryophyte species belonging to 57 genera and 30 families in Shengsi archipelago.Of these,14 species,belonging to 9 genera and 7 families,are liverworts,118 species,belonging to 50 genera and 23 families,are mosses.(2)Pottiaceae,Bryaceae,Brachytheciaceae,Mniaceae,Funariaceae,Hypnaceae,Fissidentaceae and Lophocoleaceae is dominant families of bryophytes in Shengsi archipelago.They contain 91 species totally.Bryum,Pohlia,Physcomitrium,Hypnum,Fissidens,Weissia,Eurhynchium and Dicranella is dominant genera.They contain 55 species totally.The 8 dominant families and 8 dominant genera account for 68.94% and 41.67% of the total species of bryophytes respectively.(3)The ecological type of bryophytes in Shengsi archipelago is diverse.According to the habitat frequency from high to low,it is soil,stone,soil on stone,tree,cement,sandy soil.(4)The geographical elements of the bryophyte in Shengsi archipelago can be divided into eight types: cosmopolitan element,pantropic element,old world tropical element,north temperate element,East Asia-North America disjunctive element,old world temperate element,East Asia element and Endemic to China.Except the cosmopolitan element,the dominant geographic element is north temperate element(33.07%)and East Asia element(31.36%).(5)According to the analysis of ecological distribution and impact factors of the bryophytes in Shengsi archipelago,Dahuanglong Island,Jinjishan Island,Majishan Island,Beidingxing Island and Baijieshan Island are similar with Caiyuan Island in their bryophyte flora,relatively.By using the redundancy andalysis(RDA),we found that the environmental factors influencing the distribution of mosses in Shengsi archipelago are human population density,island area,traffic frequency,coastline length,building density,altitude and the ratio of exposed rock.(6)The number of bryophytes(Y)in Shengsi archipelago increased with the increase of island area(X1),traffic frequency(X2),altitude(X3)and coastline length(X4),respectively.Their relationships could be described by the following functions: Y=22.338*x10.502(P<0.001),Y=2.7011*e0.6771*x2(P<0.001),Y=0.00103*x32.095(P<0.001)and Y=0.03054*x40.749(P<0.001).The relationship between the number of bryophytes and area is consistent with the theory of island biogeography.