| The plateau pika(Ochotona curzoniae)is a multi-functional small mammal that acts as the primary consumer in the alpine rangeland ecosystem and play the vital role in the flow of energy and cycling of matter.However,the plateau pika has been regarded as the pest when its population exceeds the carrying capacity of the alpine ecosystem.For plateau pika conservation and pest management,there are fundamental works that delineate the suitable distribution area and its changes under the global climate change,quantify the ecological threshold of plateau pika damage,and develop the investigation techniques for the rangeland areas damaged by the plateau pika.To achieve the goals of the works above,the technical support of intelligent monitoring systems is the key.Based on the consideration above,this study investigated the main distribution areas of plateau pikas on the Qinghai-Tibetan Plateau(QTP)and used the combination of species distribution model and geostatistical method,the distribution and main influencing factors of the suitable area of plateau pika and the influence of future climate change on its suitable area distribution were clarified.Secondly,the investigation time threshold of plateau pika damage was determined through three years in the field.At the same time,two different alpine rangeland types in which plateau pikas live were selected to construct a plateau pika damage evaluation model,and a plateau pika damage monitoring and evaluation system based on unmanned air vehicle(UAV)images were developed.Finally,based on the suitable area and control threshold of plateau pika,a new technique for investigating the area of plateau pika damage by combining UAV low-altitude remote sensing and grid stratified sampling was proposed.The main results are as follows:1.The suitable area of plateau pika was 6.9×10~5km~2on the QTP,accounting for44.5%of the total rangeland area.Among them,the high suitable area was 1.09×10~5km~2,accounting for 15.6%of the total suitable area,mainly distributed in the northwest of Sichuan,southern Gansu and eastern Qinghai.The middle suitable area was 1.83×10~5 km~2 accounting for 26.2%of the total suitable area,mainly located at the edge of high suitable area.The low suitable area was 4.06×10~5 km~2,accounting for 58.1%of the total suitable area,mainly distributed in the central and eastern and central south of the QTP.2.Normalized Difference Vegetation Index(NDVI)was found to be the most important contributor to the distribution of suitable habitats for plateau pika.The suitable range of NDVI was 0.73～0.83,with an optimal NDVI of 0.81.And the high probability of occurrence in the regions with elevations ranging from 3438 m to 3831m,with an optimal elevation of 3837 m.Moreover,the plateau pika showed a high probability of regional occurrence when Human Footprint Index(HFI)was greater than13.The seasonal variation of precipitation ranged from 84 to 93,with an optimal value of 91 mm.3.Under the four shared socio-economic pathways of ssp-160,ssp-245,ssp-370and ssp-585,the suitable area of plateau pika will shift to high altitude areas with global climate change,and its distribution area has not been greatly reduced.Southern Qinghai Province,northwestern Sichuan Province,and south of Gansu Province are the central areas for the spread of plateau pikas.As climate warming intensifies,the risk of spreading to the southeast and southwest of the Tibetan Plateau will continue to increase.4.The prediction model of the plateau pika damage in alpine meadow was constructed by multiple stepwise regression,and three key predictors were screened,which involved effective hole number,bare patch ratio and aboveground biomass.The control standards for plateau pika on alpine meadow should involve the effective hole number of 600 per hectare,bare patch ratio>15%,and aboveground biomass<160 g/m~2.The prediction model of plateau pika damage on alpine steppe was constructed and three key predictors were screened,which involved effective hole number,community height and species richness.The control standards for plateau pika on alpine steppe should involve the number of effective holes is 200 per hectare,the community height<3cm,and the species richness<7.5.Using UAV remote sensing technology combined with a hierarchical sampling method to investigate the damaged rangeland area by plateau pika.Taken Maqu County as testing region,the total area of rangeland in Maqu was 4.6×10~5 ha,the suitable distribution area of plateau pika was 2.5×10~5 ha,and the damaged rangeland area by plateau pika was 1.05×10~4 ha.Compared with the traditional survey method in the field and mapping method,the new method can provide higher efficient,profits and accuracy approach for investigating the damaged rangeland area by plateau pika on QTP.6.The monitoring and evaluation software system of plateau pikas’damage on alpine rangeland was developed.The system included image batch uploading,damage feature recognition,damage evaluation and area calculation,and the recognition accuracy of plateau pika holes in alpine meadow can reach 90%,and the recognition accuracy of plateau pika holes in alpine steppe can reach 80%.The recognition accuracy of bare patches in two rangeland types can reach more than 90%.The recognition accuracy of alpine meadow aboveground biomass was 80.7%.The estimation accuracy of alpine steppe above-ground biomass was 70.6%.This software system combined with UAV investigation in the field can achieve efficient and intelligent monitoring of the plateau pikas’damage on the QTP.In conclusion,this study constructed a complete set of plateau pika prevention and control evaluation system from three aspects:distribution,damage intelligent monitoring and evaluation.The results have important theoretical guidance and practical application value for plateau pika damage prevention and control. |
