| This study is based on the MaxEnt model,combined with Arc GIS geographic information system,remote sensing images,global allele system,etc.to collect and organize ground survey data.By obtaining the effective distribution points of Tibetan locust species and various habitat factors that affect the survival and development of Tibetan locusts,the risk areas of occurrence of Tibetan locusts are repeatedly simulated.With the assistance of geostatistics and various analysis and processing software,we aim to achieve the fusion,analysis,and processing of multiple data sources,and clarify the various risk areas of Tibetan locusts in the entire Tibet Autonomous Region and the dominant habitat factors that affect their occurrence of risk disasters.This provides important reference and theoretical basis for the subsequent field survey and cross regional joint prevention and control of Tibetan locusts in the Tibet Autonomous Region,as well as early warning,monitoring,and the development of reasonable protective measures for Tibetan locusts.This study constructed MaxEnt models for the disaster risk of Tibetan locusts under six different habitat factors,and then conducted knife cut tests and Pearson correlation analysis to screen the dominant environmental variables during the construction process of each model.The output results of each model were validated,analyzed,and interpreted.Then,a MaxEnt model for the disaster risk of Tibetan locusts in Tibet was constructed by mixing the dominant environmental variables of various habitat factors,and the predicted results were compared with the actual presence of locusts in Tibet.The main research results are as follows:(1)MaxEnt model of Tibetan migratory locust disaster risk under the bioclimate variable,the AUC value output by the model is 0.966,and the dominant environmental variables screened are:annual average temperature of bio-1,seasonal temperature of bio-4,lowest temperature of the coldest month of bio-6,temperature range of bio-7,average temperature of the hottest season of bio-10,average temperature of the coldest season of bio-11,precipitation of bio-12,alt altitude.Tibet locust high-risk areas:Zhada County,Ga’er County,and Geji County in the Ali region;Dingjie County,Sakya County,and Lazi County in Shigatse City;The central and southern counties and districts of Changdu City.(2)The MaxEnt model for the risk of locust disasters in Tibet under soil factor variables,with an AUC value of 0.872 as the output of the model.The dominant environmental variables screened are:Carbonate content and t in the top layer of t＿caco3 soil、The p H value of the top layer of t＿ph＿h2o soil、Basic saturation of the top layer of t＿bs soil、Volume percentage of crushed stone at the top layer of t＿gravel soil、Organic carbon content in the top layer of t＿oc soil.High disaster risk areas for locusts in Tibet:some areas of Zada County,Ga’er County,and Ritu County in the Ali region;A strip passes through Shigatse City,Lhasa City,and Shannan City from west to east;Shannan Cuona County,the entire territory of Linzhi City,and the central and southern counties and districts of Changdu City.(3)The MaxEnt model for the risk of locust disasters in Tibet under the January December precipitation variable(pre-represents the precipitation of locust habitats from January to December).The model outputs an AUC value of0.955,and the dominant environmental variables selected are:pre c-3,pre c-5,pre c-10,and pre c-12.High disaster risk area for locusts in Tibet:Xiangquan River Basin,Zhada County,Ali Prefecture;Langjia County in Shannan,Milin County and Bayi District in Linzhi City;The central and southern part of Changdu City.(4)The MaxEnt model for the risk of locust disasters in Tibet under the lowest temperature variable from January to December(tmin-represents the lowest temperature of locust habitats from January to December),with an AUC value of 0.930.The main environmental variables selected are:tmin-1,tmin-3,tmin-4,tmin-5,tmin-7,tmin-9,tmin-10,tmin-11,and tmin-12.Tibet locust high-risk areas:Zhada County and Ritu County in the Ali region;From west to east,it forms a strip that passes through parts of Shigatse,Lhasa,Shannan,and Linzhi;All over Changdu.(5)The MaxEnt model for the risk of locust disasters in Tibet under the highest temperature variable from January to December(tmax represents the highest temperature in locust habitats from January to December),with an AUC value of 0.947.The dominant environmental variables selected are:tmax-3locust habitats with the highest temperatures in March,tmax-4,tmax-5,tmax-6,tmax-9,and tmax-11.Tibet Locust High Disaster Risk Area:Zhada County in Ali Prefecture;Bomi County in southeastern Tibet and the central and southern counties of Changdu;Saga County and Sangzhuzi District in Shigatse City,Gongga County,Zhabao County,and Qiongjie County in Shannan City.(6)The MaxEnt model for the risk of locust disasters in Tibet under the average temperature variable from January to December(tavg-represents the average temperature of locust habitats from January to December),with an AUC value of 0.938.The main environmental variables selected are tavg-1,tavg-2,tavg-3,tavg-4,tavg-6,tavg-10,tavg-11,and tavg-12.Tibet Locust High Disaster Risk Area:Zhada County in Ali Prefecture;Changdu City and some areas of Linzhi City;The central southern region of Tibet passes through Shigatse,Lhasa,and Shannan in strips.(7)By selecting 40 dominant variables from the first 6 models,a MaxEnt model was constructed for the disaster risk of Tibetan locusts under mixed habitat factors.The AUC value output of the model was 0.961,and the 7 models in the IPCC report reached excellent standards.Through spatial extraction analysis and reclassification using Arc GIS,a disaster risk level zoning prediction map for Western Tibetan locusts in the Tibet Autonomous Region was obtained.The results indicate that the high-risk areas for locusts in Tibet are mainly located in most of the counties and districts in the three major regions of Changdu in eastern Tibet,Ali in western Tibet,Linzhi in southern Tibet,and Shannan,with an area of approximately 2.4568*10~4km~2,accounting for approximately 2%of the land area of the Tibet Autonomous Region.The medium to high risk area is mainly located around the contour of the three high-risk areas,which belong to the valley area in terms of terrain.The area is about 4.9136*10~4km~2,accounting for about 4%of the land area of the Tibet Autonomous Region.The medium to low risk area is mainly located in the central Tibet region of the Tibet Autonomous Region,with an area of approximately 15.9692*10~4km~2,accounting for approximately 13%of the land area of the Tibet Autonomous Region.The low-risk area is mainly located in the vast northern part of the Tibet Autonomous Region,with an area of approximately 99.50043*10~4km~2,accounting for approximately 81%of the land area of the Tibet Autonomous Region.By reviewing relevant literature and comparing data with the grassland pest survey team in the Tibet Autonomous Region,the predicted results are in line with the actual distribution of Tibetan locusts in the Tibet Autonomous Region in the past. |
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