Studies On Flora And Geographic Distribution Of Bryophytes In Dongchong Peninsula And It's Adjacent Islands,Fujian Province,China

Dongchong peninsula is located in the southernmost tip of Dapeng Peninsula,Southeast of Xiapu County,Fujian Province,between Taiwan Strait and sandu'ao.Botanical studies on these region mainly focused on seed plants.So far,there has been no systematic studies on bryophyte flora,distribution and nestedness levels,small island effect,and relationships between their richness and island traits.During March,2018 and October,2018,we systematically investigated the island traits and collected 2741 bryophyte specimens on Dongchong peninsula and its fourteen adjacent islands?Xiyang island,Fuying island,Nigu island,Maci island,Kuishan island,Xiaoxiyang island,Huangwan island,Sandu island,Baipao island,Changyao island,Qingshan island,Doumao island,Jigongshan island and Langqi island?.After systematical identification of these specimens,we obtained a species list of bryophytes in the study region and their distribution in the fifteen islands.According to the distribution data of bryophytes in these islands,together with the island landscape traits including area,elevation,vegetation percentage,disturbance intensity by human activities,isolation degree,and coastal length,we further analyzed the floristics,geographic distribution types,nestedness level of distribution,relationships between bryophyte distribution and island traits,the existence of small island effect?SIE?.The main results are as follows:1.A total of 230 bryophyte species and 16 varieties were identified from the 2741 specimens from the study region,which belonged to 42 families and 81 genera.Among them,mosses were much richer than liverworts,the former contained 34 families,72 generas,220 species and 16 varieties,while the latter only included 8families,9 generas and 10 species.2.Pottiaceae,Bryaceae,Brachytheciaceae,Hypnaceae,Fissidentaceae,Leskeaceae and Thuidiaceae were the first seven dominant families in this region,including 33 generas and 140 species,the they accounted for the 16.67%,40.74%,and 56.91%of the total corresponding taxa,respectively;Bryum,Fissidens,Brachythecium,Hypnum,Entodon,Claopodium,Didymodon,Dicranella and Philonotis were the nine dominant genera in the region accounting to their species number,accounting for 11.11%of the total genera and 36.99%of the total species.3.All the species were collected from six substrate types,which were soil-borne?156 species,22.45%?,soil-borne on rocks?151,21.73%?,saxicolous?119,17.12%?,gully substrates?87species,12.52%?,cement substrate-borne?56 species,8.06%?,and epiphytic mosses?53 species,7.63%?.The various substrates of bryophytes indicated a well-protected vegetation condition in the study region to some extent.4.The geographical elements of the bryophytes in Dongchong peninsula and its adjacent islands could be divided into eight types:Northern temperate,East Asia-Northern America disjunctive element,Pantropic element,Old world temperate element,Old world tropical element,Eastern Asia element,Endemic to China and Cosmopolitan element.Among them,Eastern Asia element was the main type?26.69%?,Northern temperate?21.19%?was ranked as the second,followed by the Old world tropical element?11.86%?and Pantropic element?11.02%?.The species number of the above four elements accounted for 70.76%of the total.5.According to their bryophyte flora at island level,the Dongchong Peninsula was distinctly different from the other 14 islands,which is more similar to Sandu island and Qingshan island in their bryophyte composition compared with other islands.The area?A?,elevation E)and coastline length?C?of the islands play important roles in species richness of bryophytes?S?on these islands,following:S=25.094*A^0.389?S=21.561,r=0.893?,S=8.310*e^0.006*E?S=19.009,r=0.921?and S=10.012*C^0.602?S=17.886,r=0.928?.6.The piecewise regression function was used to fit the species area relationship of bryophytes in 15 islands in the study area.The comparison of the result with those from 20 non segmented regression functions showed that there existed a small island effect?small island effect,SIE?for mosses among the 15 islands of the study region.The area threshold of SIE for mosses,acrocarpous mosses and pleurocarpous mosses were 3.91,2.85,1.97 km²,respectively.7.To solve the SLOSS dispute,we investigated the distribution pattern of species number of bryophytes among the islands with different area sizes.We found that the species number in several small islands was higher than those in single?or a few?large islands.8.According to the matrix temperature and NODF index,the bryophytes in the study region were obviously nested distributed,with a high nestedness level.In summary,bryophytes were rich in Dongchong peninsula and its adjacent islands,with eight different geographical distribution types.There existed an area threshould of 4.0 km²,under which species number independently varied with the increase of island area.Though there existed a relatively high nestedness level for bryophyte distribution in the study region,the species number of bryophytes in several small islands were richer than one?or a few?larger island?with the same or similar area size?.Quantifying and understanding the effects of island traits on bryophyte species richness,bryophyte nestedness level,small island effect provide a potential strategy managing fragmented environments for conservation of bryophyte biodiversity in the coastal region of Fujian province,China.We suggested that we had better design several small landscapes or habitat patches than a single?or several? larger landscapes for the conservation of bryophytes in the coastal region of Fugjian if the area size of the landscape was limited.