Responses Of Rodents Community And Dominant Species To Grazing And Climate Change In Typical Steppe

Global climate change is one of the major challenges facing mankind.It has an important impact on global species distribution,population dynamics,changes in biodiversity,and ecosystem functions.Typical grasslands are an important grassland ecosystem in China,and rodents are the main part of this system.As an important component,rodent activities have a greater impact on the grassland environment.Changes in their populations have an important impact on grassland productivity and system function recovery.Feeding and excavation behaviors have a direct impact on the health and stability of vegetation,soil and ecosystems.Or indirectly,analyze the change trends of grassland plant communities and rodent communities under the combined effects of typical grassland grazing disturbance and climate change and the dynamic characteristics of dominant species,which can clarify the process of rodent communities and their dominant species in response to grazing and climate change And mechanism,continuous monitoring through control experiments,analysis of the nonlinear relationship between rodents,grazing and climate change,revealing the natural constraints and leading factors of rodent population growth,and assessing the trend of rodent species population changes and corresponding The regulation strategy makes judgments and decisions,and finally defines the grazing method under the condition of "rat-livestock-grass" balance,which plays an important role in scientifically guiding grassland resources and ecological protection and grass husbandry production.This study carried out a grazing control experiment in the typical grassland of Dongwuzhumuqin Banner,Inner Mongolia from 2012 to 2019.Using completely random blocks,four different grazing areas and no-grazing areas were designed for overgrazing,continuous grazing,seasonal rotation grazing,and monthly rotation grazing(Control area),apply the marker recapture method to analyze the annual changes of rodent species composition,catch ratio,and population density in each grazing area.At the same time,use the sample method to investigate and analyze the plant characteristics in each grazing area,and use the mixed effect model to analyze The impact of climate change on plant communities and rodent communities.Redundant analysis(RDA)is used to analyze the action pathways of rodent communities under different grazing methods,and structural equation modeling(SEM)is used to analyze the response mechanism of dominant rodent species to grazing and climate change.On the basis of the rodent community’s response to climate change,the contribution rate of meteorological factors to the number of rodents is analyzed through principal components,and the BP neural network model is fitted and predicted on the basis of the hysteresis effect.Get the following conclusions:1.There are significant differences in plant community characteristics and plant diversity indexes in different grazing methods and years.2.There are significant differences in the number and diversity index of rodent communities in different grazing methods and years.3.Redundancy analysis(RDA)shows that: in the monthly rotation grazing area,the average temperature from 2012 to 2019 has a very significant impact on the total rodent community capture rate and the rodent community diversity index(P=0.002),in the seasonal rotation grazing area,The highest temperature from 2012 to 2019 has a significant impact on the total rodent community capture rate and rodent community diversity index(P=0.016).In the continuous grazing area,the monthly rainfall from 2012 to 2019 has a significant impact on the rodent community capture rate,The rodent community diversity index has a significant impact(P=0.012).In overgrazing areas,plant height has extremely significant differences on the total rodent community capture rate and rodent community diversity index from 2012 to 2019(P=0.004).In the no-grazing area,the wind speed from 2012 to 2019 has a very significant impact on the total rodent capture rate and the rodent community diversity index (P=0.002).4.Structural equation model(SEM)analysis shows that: in the monthly rotation grazing area,the average temperature from 2012 to 2019 has the greatest effect on the population of Brandt’s vole;in the seasonal rotation grazing area,the monthly rainfall in 2012-2019 has the greatest impact on Brandt’s voles.The total effect of voles population has the greatest impact; in continuous grazing areas,the total effect of wind speed on Brandt’s voles populations in 2012-20019 is the largest;in overgrazing areas,the total effect of wind speeds on Brandt’s voles populations in 2012-2019 The impact is the greatest;in the no-grazing area,the total effect of plant biomass on the population of Brandt’s vole has the greatest impact.5.The dimensionality reduction analysis can fit a BP neural network model with high accuracy.The simulation shows that there is a lag time of 4-5 months for the composition of typical grassland rodent communities to climate change.