Studies On The Population Dynamics Of Plateau Zokor In The Eastern Qinghai-Tibet Plateau

Plateau zokor?Myospalax baileyi?is a native subterranean rodent in the Qinghai-Tibet Plateau and it plays key roles in rangeland biodiversity maintenance,energy flow and material circulation of alpine rangeland ecosystem.However,when their population density is over-abundant,their digging tunnels and pushing soil to build mounds leads to the decrease of rangeland productivity and soil erosion,which aggravates the grassland degradation.Over the past decades,the zokor has been eliminated by poison rodenticides or traps.These control activities neglect the functions and services of plateau zokor in the alpine rangeland ecosystem and result in biodiversity loss in QTP.Rodents damage is closely related to their population dynamics.Population dynamics include changes in population distribution and density on the temporal and spatial scale.Therefore,it is crucial that to understand population dynamics of pest rodents to regulate their population density instead of simply eliminating them.However,little is known about population dynamics of plateau zokor on the larger temporal and spatial scale.So,our aims are to study plateau zokor population spatial distribution and population size dynamics.On population distribution,we surveyed distribution region of plateau zokor in the eastern QTP based on the geographic scale,including Qinghai,Gansu and Sichuan Province,and used species distribution models to analysis the actual and potential distribution range of plateau zokor and evaluate effect of climate change on their distribution range.We also selected plateau zokor's habitat on the micro-habitat scale and used geographical statistical method to analysis influence environmental factors on distribution of plateau zokor.On population size,we used capture-mark-recapture method to monitor population fluctuation in the spring and fall from 2014 to 2016 year and surveyed climate and food resource to explore relationship between population fluctuation and environmental factors,and speculate the life-span of plateau zokor.Our results as follows:1.Plateau zokor was mainly distributed in the alpine meadow ranging from 100°¹03°E,33°³6°N,altitude was 3 500⁴ 000 m,annual temperature was-1?²?,precipitation was 500⁶00 mm and soil bulk density was 0.8¹.0 g/cm³.The major actual distribution region of plateau zokor was in the eastern Haibei and Guoluo,south-eastern Hainan Tibetan autonomous prefecture of Qinghai Province,south-western Gannan Tibetan autonomous prefecture of Gansu Province,northern Aba and southern Garzen Tibetan Autonomous Prefecture of Sichuan Province.Based on RF model,the potential distribution area of plateau zokor was 27.32×10⁴ km² and accounted for 19.15%of rangeland area in QTP,and potential distribution area in Qinghai,Gansu and Sichuan Province was 13.04×10⁴ km²,6.02×10⁴ km² and 8.27×10⁴ km²,respectively.2.Geographic distribution of plateau zokor was mainly influenced by precipitation and soil bulk density.We considered number of mounds as distribution preference for plateau zokor and found that distribution of zokor was significantly positive related to precipitation?r=0.402,P=0.003?and soil moisture?r=0.496,P=0.008?at a depth10-20 cm,and was significantly negative related to soil bulk density at a depth 0-10 cm.No significantly correlation was observed between altitude,average temperature,species richness,soil moisture at a depth 0-10 cm,soil bulk density at a depth 10-20 cm and distribution of zokor.We selected precipitation and soil bulk density to conduct multiple stepwise regression analysis,the optimal regression equation was Y=0.19X₁-150.22 X₂+115.25?X₁:precipiation,X₂:soil bulk density?.3.On the microhabitat scale,mounds of plateau zokor presented clumped distribution and their distribution was influenced by the richness of forb and grass.The results of across-variogram showed that the distribution of mounds had complicate spatial correlation with all environmental factors in multiscale,however,mantel test indicated that the distribution of mounds had significant negative spatial correlation with richness of sedge,and significant positive spatial correlation with richness of forage.4.The potential distribution area of plateau zokor was closely related to climate change.Under the RCP 2.6 scenario,the temperature in QTP will increase 2.1?and2.0?,respectively.The potential distribution area of plateau zokor will increase by2.33%in the 2050s,while the potential distribution area will decrease by 3.60%in the2070s.Under the RCP4.5 scenario,the temperature in QTP will increase 2.7?and3.0?,respectively.The potential distribution area of plateau zokor in the 2050s and2070s will increase by 11.86%and 9.32%,respectively.Under the RCP 8.5 scenario,the temperature in QTP will increase 3.4?and 4.6?,respectively.The potential distribution area of plateau zokor in the 2050s and 2070s will increase 11.74%and11.60%,respectively.5.Population size of plateau zokor presented annual fluctuation and showed declined trend.Population size of plateau zokor was increase from spring to fall in the same year.However,from fall to next spring,population size of plateau zokor presented decline trend.Population size was mainly influenced by temperature.Grey Correlation analysis showed that the relational degree between population size in spring between environmental factors was as follow:temperature?0.43?,maximum temperature?0.35?,minimum temperature?0.31?,belowground biomass of forb?0.27?,precipitation?0.24?,belowground biomass of grass?0.21?and belowground biomass of sedge?0.13?.The relational degree between population size in fall between environmental factors was as follow:temperature?0.50?,belowground biomass of forb?0.46?,belowground biomass of sedge?0.40?,maximum temperature?0.37?,minimum temperature?0.34?,belowground biomass of grass?0.30?,precipitation?0.28?.6.Average life-span in female zokors?28.17±9.02 month?was higher than that in male zokors?23.20±8.87 month?,but no significant difference?t₉=-0.916,P=0.384?.The longest and shortest life-span in male zokors was 34 months and 12 months,respectively,most male's life-span was about 24 months.The longest and shortest life-span in female zokors was 44 month and 17 months,respectively,most female's life-span was about 22 months.Above all,alpine meadow in the eastern QTP was the main distribution region for plateau zokor.Combined geographic and microhabitat scale,we found abiotic and biotic factors could influence habitat selection of plateau zokor,especially annual precipitation,soil bulk density and the richness of forb.Potential distribution area of plateau zokor will increase under the warm and wet climate in the future.Population size of plateau zokor was mainly influenced by annual temperature and their life-span was about 22²4 months.