Species Diversity Patterns And Potential Distribution Prediction Of Lauraceae And Fagaceae In Northern Tropics And Subtropical Regions Of China

This study characterized the species diversity and biogeographical distribution patterns of the major genera of two dominant families,Lauraceae and Fagaceae,in northern tropical and subtropical forests of mainland China.The study also examined the relationship between the species diversity of these two families and those of forest communities and explored possible historical factors that affect the distributions of their species diversity.The maximum entropy model(Maxent)and geographic information system(ArcGIS 10.3)software are used to quantitatively model the suitable distribution of several Litsea and Lithocarpus species in China,and predict their future distribution under two different climate scenarios.These species are economically valuable resource plants.The results show:(1)The dominant families in these forests are Lauraceae,Fagaceae,Theaceae,and Ericaceae.The species richness of both Lauraceae and Fagaceae are positively correlated with that of the forest communities where they occur,and compared to Fagaceae,Lauraceae contributes more to the species diversity of the forest communities.(2)The highest species richness of both Lauraceae and Fagaceae are found in the south-central parts southern China.The diversity centers of Cryptocarya and Beilschmiedia of Lauraceae and Castanopsis of Fagaceae are found in the northern tropical and southern subtropical regions,mainly in the southern Guangxi and southern Yunnan provinces.The diversity centers of the genera Cinnamomum,Neolitsea,Machilus,and Litsea of Lauraceae and Lithocarpus and Cyclobalanopsis of Fagaceae are found in the south-central part of the subtropical region,which corresponds to their family-level diversity distributions.However,the highest diversity of Lindera,Phoebe,and Actinodaphne of Lauraceae and Quercus of Fagaceae are found in the central and western parts of the study region.(3)Litsea cubeba is mainly distributed in the south of the Yangtze River in China.Under the future climate 2061-2080 year two(RCP2.6,RCP8.5)carbon dioxide concentration scenarios,the suitable area for its distribution would be shrinked by 4.9%and 0.5%,respectively.L.coreana is mainly distributed in central and northern subtropical regions of China.Under the two scenarios of carbon dioxide concentration,in 2061-2080 the total area of the suitable area would be increased by 5.6%and 4.5%,respectively.L.greenmaniana is mainly distributed in the south subtropical regions of Guangdong,Guangxi and Fujian provinces.Suitable areas for L.mollis are mainly concentrated in Guizhou province and Chongqing metropolitan region.Under the future climate RCP2.6 scenarios,the suitable area of the two species would be shrinked by 1.0%and 3.3%,respectively,and under the climate RCP8.5,the suitable area of the two species would be shrinked by 5.6%and 8.3%,respectively.(4)Lithocarpus litseifolius is widely distributed in the south to the Qinling Mountains-Huaihe River in China,and L.brevicaudatus is mainly distributed in the central and eastern subtropical regions of China.Under the future climate 2061-2080 year two scenario,the total proportion change of suitable distribution areas for L.litseifolius would be shrinked by 5.1%and 3.0%respectively,but L.brevicaudatus increased by 0.5%and 1.5%,respectively.The suitable distribution area of L.dealbatus is mainly at Northern Yunnan,southern Sichuan,and L.corneus mainly distributes in the southern subtropical regions of Guangdong and Guangxi provinces.Under RCP 2.6 scenario,the suitable area of L.dealbatus and L.corneus decreased by 12.1%and 17.8%respectively,while under RCP 8.5 scenario,decreased by 3.5%and 15.9%,respectively.L.elizabethae mainly distributes in Guangxi.In the future,its suitable distribution area under the RCP 2.6 and RCP 8.5 would be increased by 7.3%and 6.3%respectively.Our results reveal the ecological adaptation of a species and the biogiographical history leading to the present biodiversity distribution pattern of Lauraceae and Fagaceae.The prediction of the potential suitable distribution areas of several resource tree species of the genera Lithocarpus and Litsea under the future climate change scenarios can provide strategic guidance for their protection and utilization in the future.