Based On Four Models, The Potential Geographic Distribution Prediction And Spatial Pattern Change Analysis Of Cistanche Deserticola

Species distribution model plays a vital role in the prediction and protection of species distribution,and most studies only focus on one model to predict species distribution.But the prediction of species distribution is also selective for the model,so the application of multi-model prediction and comparison can select the most effective model for the target species.The relationship between species and climate is the core of biology and environment.In recent years,the trend of climate warming has been strengthened,it is more meaningful to study the distribution of species coupled with climate change.In this study,the endangered plant of Cistanche deserticola was used to predict the potential geographical distribution in current and the representative concentration pathways(Rcp2.6,Rcp4.5 and Rcp8.5)of future,which based on 22 current environmental variables and the climatic data in future time periods of 2041-2060(2050s)and 2061-2080(2070s).In order to construct the potential distribution area of C.deserticola,the modeling framework was based on four models implemented in the Biomod2 package in R:MAXENT,RF,GAM and GBM were combined with ArcGIS.And in order to obtain the core potential geographical distribution of C.deserticola,which based on its main host plants(Haloxylon ammodendron)to further stack the calculation.Model performance was evaluated by AUC,TSS and KAPPA to gain the optimal model.By the same method to predict the core potential geographical distribution of C.deserticola in the representative concentration pathways(Rcp2.6,Rcp4.5 and Rcp8.5)of two futures time periods.Using the module of Measuring Geographic Distribution in ArcGIS to make the spatial pattern of distribution area of C.deserticola,and analyze its changing trend.The main conclusions of this paper:1.The predicted results of current environmental variables and future climate variables show that the core potential geographical distribution of C.deserticola is mainly distributed in arid desert areas of the study area,which are scarcity in precipitation and abundant in sunshine.While the potential distribution area of H.ammodendron is larger than C.deserticola,the habitat of them is same basically.The core geographical potentials of C.deserticola in the current environmental variables are larger than those in the next two time periods under three representative concentration pathways,indicating that the future climate warming will reduce the potential geographical distribution of C.deserticola.2.In the current environmental variables and the two future time periods under three representative concentration pathways,using four models MAXENT,RF,GAM and GBM to the predict of the potential geographical distribution of C.deserticola,which show that all of them were evaluated successfully.MAXENT presents the highest evaluation,and followed by RF,GAM,GBM,which models have little difference.3.In the next two time periods,the core potential geographical distribution area of C.deserticola and concentration pathways are not show regular changes,and the core potential geographical distribution area of C.deserticola in two time periods was not much different.4.The environmental factors of the four models show that the environmental factors are Biol(annual mean air temperature),Bio6(min temperature of coldest month),Bio 12(annual precipitation)and Bio 16(precipitation of the wettest quarter).The weight value of environmental factors in each model shows a difference,but the weight of the temperature index is greater than the precipitation index.5.The study shows that the geographical distribution of C.deserticola in different habitats is suitable for the range of major environmental factors were:Biol 8.5 ?-13.5 ?,Bio6-14.5 ?--12.5 ?,Biol2 140 mm-150 mm?Biol6 70 mm-90 mm.6.The spatial distribution of the core geographical habitat of C.deserticola from the current to 2050s and 2050s to 2070s showed "East-West" pattern under three concentration pathways.In the context of the future climate,the pattern of I(Xinjiang Uygur Autonomous Region)and II(the junction of Shaanxi-Gansu-Ningxia and Inner Mongolia Autonomous Region)varies to varying degrees,and the center of gravity migrates slightly toward the north,indicating that the climate is in the process of warming,which makes the habitat of C.deserticola is moving towards high latitudes.The distribution of C.deserticola in I is mostly scattered in the main trend,and is relatively decentralized,while the area II is more polarized phenomenon and is relatively centralized.This study not only provides data support for the conservation and cultivation of C.deserticola,also provides certain reference for suitable zoning of H.ammodendron,and establishing of the "ecological industry of C.deserticola and H.ammodendron",which promotes the benign development of C.deserticola industry,and is of great significance to the protection of ecosystems in Northwest China.