Relationship Between Distribution Pattern And Vegetation Characteristics Of Microtus Fortis And Apodemus Agrarius In Dongting Lake

Rodent infestation is one of the important factors affecting the healthy development of agricultural ecosystem.Understanding the relationship between rodent population dynamics and vegetation is the premise of implementing rodent infestation ecological control.Dongting Lake area is an important commodity grain base in our country.In history,rat hazards occurred frequently in this area,which seriously threatened agricultural production.In this study,the lake-beach and lake-front farmland in this area were regarded as a unified whole,and a buffer of 10 km was built along the lake dike after vectorization to obtain the study area of 8,363 km2.The population changes of two main rat species in Dongting Lake area during 2000-2020 were analyzed through historical survey data around the lake.The spatial-temporal variation of vegetation coverage was studied by Sen trend analysis method and Mann-Kendall test.This paper studied the land use transfer matrix and dynamic attitude from 2000 to 2020,quantitatively analyzed the spatio-temporal changes of land use,and analyzed the relationship between vegetation and rodent distribution pattern.The results showed that:(1)Significant changes have taken place in rodent pattern in Dongting Lake area in the past 20 years.The population density of Microtus fortis,the first dominant rat species in lake beach,has decreased,and Apodemus agrarias,which live in farmland,have gained a large number of breeding and predominance in lake beach.In some survey sites,the capture rate was much higher than that of Microtus fortis,and the population density increased with time.The population density of Microtus fortis fluctuated greatly in the east Dongting area than in the south Dongting and the west Dongting area,and in the upper lake beach than in the farmland.In terms of survey sites,the rodent damage was the most serious in the Beizhouzi area of Datong Lake and the Chunfeng Lake area of Yueyang County.Lake flat is the source of migration and the most suitable habitat for Microtus fortis.The fattenity of Microtus fortis migrating to farmland will decrease due to rising water level,while the fattenity of Apodemus agrarius living in farmland is not different from that of Apodemus agrarius living in lake flat,indicating that Apodemus agrarius has strong adaptability to the environment.There were significant differences in rat fatness in different seasons,and the highest rat fatness was found at the survey sites in winter,and the variation of rat fatness was different at different survey sites in different seasons.(2)During the study period,the vegetation coverage in Dongting Lake area was relatively high on the whole,and the area with high vegetation coverage was more than 50%.The vegetation coverage change characteristics were different in different time periods,and the vegetation coverage was distributed in a circular pattern from low to high from the center of the lake to the periphery.The change characteristics of vegetation coverage area were different at different levels.Low and middle vegetation coverage fluctuated little,while high and middle vegetation coverage fluctuated greatly.The annual maximum vegetation coverage had a decreasing trend,and the vegetation coverage of farmland decreased obviously,and the decreasing areas were distributed in the west bank of East Dongting and the surrounding farmland of West Dongting,while the vegetation coverage of lake beach had an increasing trend,and the extremely significant increasing areas were mainly located near the entrance of the four water and three mouth into the lake.The vegetation coverage varies greatly in seasons,and the vegetation coverage is different in different seasons.In spring,the lake beach was mostly covered by high vegetation,while the farmland was mainly covered by medium vegetation in the same period.The vegetation coverage of the north bank of South Dongting decreased significantly.In summer,both high and low cover areas reached the maximum of the whole year.Lake beach was dominated by low cover,while most farmland was dominated by high cover.The change trend was small,and most areas remained basically unchanged.In autumn,vegetation coverage reached the maximum of the whole year.Spatially,vegetation coverage of farmland decreased,and the farmland on the west bank of East Dongting decreased significantly,while the lake beach increased significantly.In winter,the vegetation coverage decreased further,but increased significantly in the north bank of South Dongting and some parts of West Dongting.The vegetation coverage change was different in different regions,and the relationship between the population density of Microtus fortis and the population density of Apodemus agrarius was consistent with the vegetation coverage change.(3)The overall situation of land use:cultivated land>water body>beach land>grassland>construction land>forest land.The changes of different land types were different:construction land continued to increase,cultivated land and forest land were stable on the whole,water area and beach area were negatively correlated,and grassland area increased to some extent.The situation of land use transfer in different stages is different:the cultivated land area continues to decrease,and the reduced part is mostly converted into construction land;Construction land continued to increase,mainly for the conversion of cultivated land and woodland;The grassland area increased in the first stage(2000-2010),but decreased in the second stage(2010-2020).The change trend of beach land was opposite to that of grassland,the area increased first and then decreased.The water area continued to decrease,and the dynamic attitude of land use in descending order was:construction land>grassland>water body>beach land>cultivated land>forest land.The dynamic attitude of land use was different in different stages.From 2000 to 2010,grassland and construction land increased rapidly,while the area of beach land decreased rapidly.The tidal land increased rapidly from 2010 to 2020.Woodland changes were minimal throughout the study period.The population density of Microtus fortis was positively correlated with cultivated land,Apodemus agrarius population density was positively correlated with construction land,and the relationship between the density of rat seed fertilizer and land use was different at different survey sites.This study,covering a long period of time,comprehensively analyzed the temporal and spatial changes of population pattern of two rat species in Dongting Lake area,discussed the changes of vegetation coverage and land use,and analyzed the effects of vegetation coverage and land use on population pattern change,providing a basis for rodent control and economic and social sustainable development in Dongting Lake area.