Response Of Haloxylon Anmodendron's Potential Suitable Distribution Area To Climate Change In Arid Areas Of Northwest China

Climate change will lead to changes in species distribution and even species extinction.Haloxylon anmodendron(C.A.Mey.)Bunge is national 3 grade protection plant and growing only in desert.It plays a key role in the balance of wind and sand fixation in desert areas and maintains the balance of the balance of ecosystem.In order to explore the impact of climate change on the suitable distribution area of Haloxylon anmodendron(C.A.Mey.)Bunge.We evaluated the performance of GARP(Genetic Algorithm for Rule-set Production),ENFA(Ecological Niche Factor analysis)and Maxent(maximum entropy model),and selected the optimal model and 10 major environmental factors.We used the optimal model and 10 environmental factors to simulate the suitable habitats under the current climate conditions(1960-1999)in the Arid Area of Northwest China.The future habitats for the Haloxylon anmodendron(C.A.Mey.)Bunge were also predicted in two periods,2041-2060 and 2061-2080,under two climate change scenarios,RCP4.5(Representative Concentration Pathways 4.5)and RCP8.5(Representative Concentration Pathways 8.5).And the simulation results are divided into 4 grades(unsuitable area,low-suitable area,middle-suitable area and high-suitable area).In order to find out the difference of simulation results caused by different GCMs selection,we divided the simulation results into 2 grades(absence and presence).Two indicators of range change index(RCI)and kappa were used to compare the difference of the potential distribution of Haloxylon anmodendron(C.A.Mey.)Bunge caused by different GCMs.The results of the study are as follows:(1)The AUC average values of GARP,ENFA and MAXENT are 0.914,0.913 and 0.973.MAXENT is the best model and can simulate the potential distribution of Haloxylon anmodendron(C.A.Mey.)Bunge currently,and its internal level is obvious.(2)The jackknife method of MAXENT assess the importance of environmental variables.The results indicate that the total contribution rate of environmental factors related to precipitation was 60.5%,the contribution rate of environmental factors related to temperature was 14.8%,and the contribution rate of soil type and altitude factor accounted for 22.7% and 2%.The top ten environmental variables are precipitation of wettest quarter(39%),soil type(22.7%),standard deviation of temperature seasonality(9.1%),precipitation seasonal variation coefficient(8.3%),isothermal(6.4%),temperature annual range(3.5%),warmest month precipitation(2.2%),annual precipitation(2.1%),altitude(2%)and dry season precipitation(1.9%),the total contribution rate is up to 97.2%.(3)Under the current climate conditions,the potential suitable distribution area of Haloxylon anmodendron(C.A.Mey.)Bunge accounted for 65.2% of the study area,of which the low,middle and high suitable distribution areas accounted for 37.77%,18.43% and 8.98%.Under the RCP4.5 scenarios,in the 2050 period,the entire suitable distribution areas will increase 7.7%,of which the low suitable distribution areas will reduce by 9.36%,middle suitable distribution areas will increase 6.05% and 11.01%;under RCP8.5 scenarios,the entire suitable distribution areas will increase 8.0%,of which the low suitable distribution areas will reduce by 13.99%,middle suitable distribution areas will increase 3.5% and 18.49%;while in the 2070 period,under the RCP4.5 scenarios,the entire suitable distribution areas will increase 7.47%,of which the low suitable distribution areas will reduce by 13.48%,middle suitable distribution areas will increase 4.15% and 16.8%;under RCP8.5 scenarios,the entire suitable distribution areas will increase 9.07%,of which the low suitable distribution areas will reduce by 20.44%,middle suitable distribution areas will increase 4.29% and 33.8%.As time goes on,the total suitable area increased.The increase of suitable area is mainly due to the increase of the high-suitable area;(4)The results of the spatial statistical analysis of the main four Haloxylon anmodendron(C.A.Mey.)Bunge distribution areas included of Junggar basin,Tarim Basin,Alashan desert and Qaidam Basin,indicates that the high suitable distribution area of the Haloxylon anmodendron(C.A.Mey.)Bunge in the 2050 and 2070 period in the Junggar Basin will increase to 1.9 times and 2.03 times compared with the current climate conditions under RCP4.5 scenarios,while under the RCP8.5 situation,the high suitable distribution areas will increased to 2.19 times and 2.52 times compared with the current climate conditions.The high suitable distribution area of Haloxylon anmodendron(C.A.Mey.)Bunge in the 2050 and 2070 period in the Tarim Basin will increase to 2.26 times and 3.63 times compared with the current climate conditions under RCP4.5 scenarios,while under the RCP8.5 situation,the high suitable distribution areas will increase to 3.87 times and 7.69 times compared with the current climate conditions.The high suitable distribution area of Haloxylon anmodendron(C.A.Mey.)Bunge in the 2050 and 2070 period in the Alashan desert will increase to 2.2 times and 3.35 times compared with the current climate conditions under RCP4.5 scenarios,while under the RCP8.5 situation,the high suitable distribution areas will increase to 3.63 times and 7.53 times compared with the current climate conditions.The high suitable distribution area of Haloxylon anmodendron(C.A.Mey.)Bunge in the 2050 and 2070 period in the Qaidam Basin will decreased by 4% and 7% respectively in the two periods,and it decrease by 6% and 9%under the RCP8.5 scenario.(5)We used two indices of RCI and Kappa to measure the difference caused by GCMs.The result shows that GFDL-CM3 and INMCM4 are the GCM in the prediction of the maximum and minimum variation in the potential distribution of the Haloxylon anmodendron(C.A.Mey.)Bunge.In addition,the RCP8.5 is greater than the RCP4.5 scenario,and the difference is significant.