Vulnerability Of Six Typical Deciduous Broad-leaved Tree Species To Future Climate Change In China

Climate change significantly threatens global biodiversity.Developing a more comprehensive and effective method for species vulnerability assessment is an important challenge for biodiversity conservation.Deciduous broad-leaved forest plays an irreplaceable role in conservation of soil and water,wind prevention and sand fixation in China.However,the survival and development of deciduous broad-leaved forest may face severe challenges under climate change in the future.In this study,we assessed the vulnerability of deciduous broad-leaved tree species under four future climate change scenarios,which can provide reference for the protection of deciduous broad-leaved forest and also provide a theoretical basis for the selection of tree species for afforestation and vegetation restoration in north China.A total of 6 trees species(Populus davidiana Dode,Betula platyphylla Suk.,B.albosinensis Burk.,Carpinus turczaninowii Hance,Q.dentata Thunb.and Quercus wutaishansea Mary)were selected in this study.The vulnerability of each species was described from three aspects: the sensitivity of species(including the marginality and specialization of climatic niche),the exposure(including the change of suitable habitat,the fragmentation of suitable habitat)and the adaptive capacity(including the degree of protection of suitable habitat and human disturbance).At the same time,these components affecting the vulnerability of species were uniformly transformed in order to make the vulnerability of different species comparable.This method is based on the Max Ent model to predict the changes in the suitable habitat of species to measure the impact of climatic change on the species,as well as fully considers the non-climate factors(including the intrinsic sensitivity of the species and the impact of human activities on the adaptability of the species)on the vulnerability of species.Therefore,the vulnerability of species under climate change can be evaluated more comprehensively and objectively,which could overcome the shortcomings of a single component method to assess species vulnerability.The results are as follow:(1)Among the climatic factors selected in this study,annual precipitation(AP)is the most dominant climatic factor for the 6 species.Comparing the specificity of the six tree species,it can be found that B.albosinensis occupies a wider niche,while Q.wutaishansea occupies a narrower niche.Comparing the marginality of the 6 tree species,it can be found that B.platyphylla occupies a more marginal climatic niche,while Q.dentata occupies a more central climatic niche compared with other tree species.(2)The effects of climate change on the suitable habitats of different tree species are different,but the range of suitable habitats of the six tree species will show an increasing trend in the future climate conditions,and the increasing trend of the suitable habitat are as gradually increases with the increase of emission scenarios on the whole.The degree of fragmentation in the suitable habitat of species has little effect on the vulnerability of species.The exposure value of each species is positive,indicating that future climate change will benefit species survival in the future.(3)The reduction of the human footprint in the suitable habitat of species has very little impact on the vulnerability and it even can be ignored in some climate scenarios.However,the increase of the protected area in the suitable habitat caused by the expansion of the range has a significant impact on the vulnerability.It shows that the adaptive capacity of species with the assistance of human activities has improved.(4)The vulnerability assessment method adopted in this study can effectively assess the vulnerability of 6 typical deciduous species to future climate change in China.Among the six typical deciduous species,P.davidiana,B.platyphylla,B.albosinensis and Q.wutaishansea are not at risk of extinction in the future climate scenarios.C.turczaninowii and Q.dentata may be at risk of extinction in the scenarios of RCP2.6,RCP4.5 and RCP6.0.The positive effects of exposure and adaptive capacity on species vulnerability can,to some extent,offset the negative effects of sensitivity on species.