Modeling Of Grasshopper Population Density And Forage Loss With Different Gradients

In maintaining the balance of ecological environment and protecting biodiversity,the widespread grassland area in our country is of great significance.Grassland plays a major role in maintaining the ecological environment of the whole country as the ecological main body of Inner Mongolia.Grassland locust infestation has occurred in Inner Mongolia for many years,causing serious damage to grassland vegetation and great negative impact on grassland ecology and animal husbandry economy,and seriously threatening the sustainable development of animal husbandry and grassland ecological environment quality in the autonomous region.Varying degrees of grassland locust plagues have occurred in Ar Horqin Qi over the years.Hence,it is of practical value to study the impact of grassland locust plague on animal husbandry economy in this area,thus providing scientific basis and data support for the prevention and control of grassland locust plague in Inner Mongolia.For the current grassland locust plague control work,researchers usually take controlling measures on the basis of some regional investigations and the historical occurrence data of grassland locust plague,which will not ensure to effectively explore the damage level of different grassland locust population density to animal husbandry economy.On the basis of a large number of experimental data obtained from field shrouding experiments with different population densities of locusts,in order to avoid the influence of locust population density on the growth rate of Leymus chinensis,this thesis adopts the area data and quality data of undamaged leaves of Leymus chinensis under different locust population densities to construct the yield models of Leymus chinensis under different locust population densities respectively,optimizes the yield model by the linear model of Leymus chinensis leaf area data and actual area of Leymus chinensis leaf,substitute the area data of damaged leaves of Leymus chinensis into the Leymus chinensis yield model to calculate the loss of Leymus chinensis under different locust population densities and verify the accuracy and applicability of the above calculation results through supplementary experiments,as shown below:Firstly,from August to September 2018,the first field shrouding experiment with different locust population densities was conducted in Ar Horqin Qi,Inner Mongolia to explore the loss of Leymus chinensis under different locust population densities.After the experiment,we obtained the following data:undamaged Leymus chinensis leaf area data and quality data,damaged Leymus chinensis leaf area data and quality data under different locust population densities.Secondly,construct the yield prediction model of Leymus chinensis under different locust population densities based on the area data and quality data of undamaged Leymus chinensis leaves.Take a group of Leymus chinensis leaf area data and quality data of each density as test data and conduct the significance test on the model(P<0.05),with more than0.9 for the model R2.Substitute the test data into the model and get the relative error less than 10%between the calculated results and the measured data.Thirdly,during the period from August to September 2019,the shape of the whole leaf of Leymus chinensis was rubbed on the calculation thesis with an accuracy of 0.01cm~2,and the actual area of more than 900 Leymus chinensis leaves was generated.Construct a linear model between Leymus chinensis leaf area data and the actual area of Leymus chinensis leaves,use the above model to optimize the leaf area of Leymus chinensis and re-establish the yield prediction model of Leymus chinensis under different locust population densities and conduct significance test on the model(P<0.05),with the model R~2 more than 0.93,which showed the increase in the accuracy of the model.In the forth chapter,adopt the optimized forecasting model of Leymus chinensis yield and the quality data of damaged Leymus chinensis leaves measured in the experiment to get the loss of Leymus chinensis under different locust population densities in the first field experiment shown as follows respectively:23.6488g,28.3335g,73.6466g,94.0956g,106.261g and 129.3543g.From August to September 2019,the locust feeding cage experiment and the second locust shrouding experiment were carried out in Sonid Youqi,Inner Mongolia.A total of 12 groups of Leymus chinensis loss data under different locust population densities were collected and the experimental results were basically consistent with the conclusions of the first field shrouding experiment,with the relative error of Leymus chinensis loss less than 10%under the same density.Lastly,a total of 18 groups of data of different density of locusts and loss of Leymus chinensis were obtained in three experiments.Take the loss data of Leymus chinensis under the three densities of 20 individuals/m~2,60 individuals/m~2 and 100 individuals/m~2 obtained in the second field experiment as test data and construct a linear model of different locust population density and Leymus chinensis loss based on the other 15 groups of data,with the model in good accuracy.Substitute the test values into the model and get the relative errors of 7.72%,7.79%and 0.22%,respectively between the calculated values and the real values,with the model accuracy meeting the business requirements.