Impacts Of Climate Change On The Suitable Distribution Of Dendroctonus Armandi,Trypophloeus Klimeschi And Their Host In China

Biogeographical distribution is an important content of eco-geography research,species distribution models are widely used in the spatio-temporal distribution pattern of species,early invasion warning of alien species,the modes and pathways of disease transmission,and the impact of global changes on species distribution or diversity patterns,etc.numerous research fields.This study selected major forest pests in Qinling Mountains and Daba Mountains,China—Dendroctonus armandi Tsai and Li,an alien invasive species—Trypophloeus klimeschi Eggers,and a single host of D.armandi—Pinus armandii Franch.,a single host of T.klimeschi—P.alba var.pyramidalis as the research objects,aiming to study the important environmental variables that affect the geographical distribution of D.armandi,T.klimeschi and the host,and the impact of climate change on the suitable areas of D.armandi,T.klimeschi and the host in China via SDMs.The results of the study are as follows:1.D.armandi is distributed in patches in the Qinling Mountains and Daba Mountains,with a unique climatic niche.The precipitation of wettest quarter and the minimum temperature of coldest month are the key factors that restrict the north and south boundary of the geographical distribution of D.armandii,respectively;the distribution of host P.armandii doesn't constitute an important factor limiting the geographic distribution of D.armandi;terrain variables create habitat selection preferences for D.armandi,and D.armandi predominately intrusion hazard P.armandii on the southern slopes of valleys with elevations between 1300 m and 2400 m.D.armandi has a relatively narrow ecological niche,and D.armandi has a strong preference for invasion and selection of the host P.armandi.2.Under current climatic conditions,D.armandi is concentrated in southern Shaanxi,western Henan,northwestern Hubei,northern Chongqing,northeastern Sichuan,and southeastern Gansu,with a total suitable area of 15.83×10~4 km~2.Under future climate scenarios,the suitable area of D.armandi is projected to increase within the Qinling Mountains and Daba Mountains.D.armandi responds most strongly to the high greenhouse gas emission scenario RCP8.5.As time goes by,the highly suitable areas will continue to increase over time,and southern Shaanxi,northwestern Hubei,and northeastern Sichuan will be the highly areas where diffusion occurs.By 2050s,the highly suitable area of D.armandi is projected to increase by 0.82×10~4km~2.3.Currently,P.armandii is mainly distributed in the Qinling Mountains,Daba Mountains,Yunnan-Kweichow Plateau and Hengduan Mountains,with a total suitable area of 54.83×10~4 km~2.Precipitation and temperature are the main environmental factors restricting the current geographical distribution of P.armandii.Under future climate change,the suitable area of P.armandii will be greatly reduced.Under the high greenhouse gas emission scenario RCP8.5,P.armandii will lose the suitable area of 23.05×10~4 km~2,accounting for up to 42%.The suitable area of P.armandii in the Wushan Mountain connecting Daba and the Yunnan-Kweichow Plateau will gradually disappear,leading to interruption of the current ecological corridor,and the suitable area in the Hengduan Mountains will gradually lose.Ultimately,future distribution of P.armandii will be separated into two core regions,one in the Qinling Mountains and Daba Mountains and another in the Yunnan-Kweichow Plateau.However,the excellent suitable area of P.armandii in the Qinling Mountains and Daba Mountains will continue to expand.4.Currently,T.klimeschi is mainly distributed in the vast area between the southern edge of the Tianshan Mountains in Xinjiang and the northern edge of the Tarim Basin,and Dunhuang City in northern Gansu Province.The entire habitat distribution forms a transmission channel from west to east in China,with a total suitable area of 25.58×10~4km~2.The mean temperature of the coldest quarter and precipitation of wettest month are important environmental factors constraining the current distribution of T.klimeschi.Alar City and Korla City in Xinjiang are suitable areas for the survival of T.klimeschi.Under the future climate change,the total suitable area of T.klimeschi is projected to increase significantly over time.Under the high greenhouse gas emission scenario RCP 8.5,the distribution will extend to a larger area in northern Gansu,and Jiuquan City in Gansu is expected to become the next spread center,and enter western Inner Mongolia along the Hexi Corridor.By 2050s,the total suitable area will increase by 36.7×10~4 km~2.In the southeastern part of Xinjiang(including the northern part of Ruoqiang County and most of Korla City),the suitable area will be reduced and the transmission channel in this area will be interrupted.5.P.alba var.pyramidalis is widely distributed in China,and high suitable area is located in the northern China.The suitability of P.alba var.pyramidalis gradually declines as the latitude decreases.Precipitation and temperature are important environmental factors affecting the migration of P.alba var.pyramidalis to the southern China.Under the future climate change,the total suitable area and high suitable area of P.alba var.pyramidalis will decrease with the increase of greenhouse gas emission concentration,but the high suitable area in high latitude will increase,and the medium suitable area will mainly increase in the southeastern China.In the face of climate change,P.alba var.pyramidalis does not show a drastic response,does not show an overall southward or northward movement,and shows more small-scale changes in local areas.The suitable areas in the western and northern China are more vulnerable to climate change than those in the eastern and southern.6.In the future climate change,the suitable areas of D.armandi and T.klimeschi will increase.In addition,the adaptive evolution of the biology and ecology of D.armandi and T.klimeschi,and Corresponding changes will also occur in the occurrence area and host trees of D.armandi and T.klimeschi.Based on this,it is recommended to build a monitoring and early warning system for D.armandi and T.klimeschi,to investigate and monitor the population,population spread,and adaptive genetic variation of D.armandi and T.klimeschi in real time,so as to formulate the comprehensive management strategy of D.armandi and T.klimeschi,to achieve accurate monitoring,early warning,and prevention and control of D.armandi and T.klimeschi.