The Study Of Economic Benefits In Rodent Pest Control Under Different Grazing Patterns In Typical Steppe

There are great differences betweenrodent pest species,grassland vegetation types and grassland use patterns in different regions of typical steppe.Thus,It is necessary to formulate differentreasonable rodent pest control measures and different economic thresholds on the base of the damage degrees and control measures of rodent pests in different regions.A experiment with four grazing patterns,including monthly grazing(MG),seasonal grazing(QG),continous grazing(CG)and over grazing(OG)and grazing prohibition(CK)was conducted in typical steppe in Inner Mogonlia from 2012 to 2017.Species composition of rodents,catch ratio,annual variation of population density and the changes of plant composition and plant biomass in four different grazing patterns and grazing prohibition were investigated.Rodents were captured with live method.The rodent damage was estimated using daily intake of rodent to determine the loss of forge yield.The relationship between rodent density and forage yield loss was fitted to a model.The damage threshold and economic threshold of rodent control in four grazing patterns and grazingprohibition were determinedby fitting the relationship between rodent density and forage yield loss.The results are as follows:1.During the period of 2012 to 2017,7 species of rodents were captured under four types of grazing patterns and grazing prohibition areas,of which Lasiopodomys brandtii occupied the largest capturedamount,and Phodopus sungorus occupied the second.A total of 39 species of plantsdistributed in16 familywere recorded under the five treatments,which were divided into fourplants types:gramineous,legumes,compositae,and forbs.The biomass ofgramineousplants was higher in the grazing prohibition area and the seasonal grazing area.The biomass of legume was the highest in the grazing prohibition area.The biomass of the compositae was higher in the grazing prohibition areas and in the monthly grazing areas.The biomass of forbs were the highest in overgrazing areas.2.By fitting the relationship between rodent density(standard rat unit/hm~2)and forage yield loss ratios for the five treatments,a sigmoidal curve was obtained.As the density of rodents increases,the loss of forage yield also increases.But when rodent density reaches a certain degree,the forage yield loss will not continue to increase and reach a stable state.The damage thresholds(standard rat units/hm~2)under five treatments were obtained.The monthly rotation grazing was the highest,the seasonal grazing was the second,and continuous grazing and overgrazing were the lowest.3.The average economic threshold(standard rat unit/hm~2)of five treatments under rodent pest control,seasonal rotational grazing,grazing prohibition,and monthly rotation grazing were significantly higher than those under continuous grazing and overgrazing.4.This study concluded that the quality and yield of forage grass can be guaranteed in a great statue with high economic benefit underseasonal grazing.The damage threshold and economic threshold in seasonal grazing were higher than other grazing patterns.Therefore,in the typical steppe region,seasonal grazing pattern can ensure the economic benefits and achieve the purpose of sustainable use of the grassland.