| Above-ground biomass is an important index to measure the productivity characteristics of grassland community,and plays an important role in the study of grassland ecosystem.Grassland biomass measurement has always been an effective method to explore the law of grassland ecosystem change.However,in order to meet the measurement accuracy requirements,direct acquisition of biomass will destroy grassland vegetation.Therefore,in order to protect grassland vegetation and estimate the aboveground biomass accurately and conveniently,based on previous studies,a self-made macromolecule measuring board with a diameter of 35 cm was used in this study.The altitude of three grassland communities in Yangling abandoned grassland,Guanshan grassland and the meadow grassland near Weinan Wetland Ecological Park were measured to estimate the aboveground biomass,which provided an effective method for forecasting the aboveground biomass of grassland community.In the field survey,the measuring board was placed gently above the plant community,the distance between the measuring board and the ground was measured and recorded,and the height data of the community was obtained by measuring the average value of four times.Then the plants in the corresponding area under the measuring board were mowed on the ground,dried in the constant temperature dryer(65 C)to the constant weight,and the aboveground biomass of the plants in the corresponding area under the measuring board was weighed.Finally,the above-ground biomass of the plants in the corresponding area under the measuring board was obtained by weighing.The regression equation between plant average height and aboveground biomass was established by mathematical model and correlation analysis.The equation was tested by F-test.The optimal model was obtained by comprehensive comparison and analysis of total average relative error absolute value(RMA)and relative error(RS).Finally,the model was validated by field data,and the accuracy of estimating aboveground biomass by community height was determined.The results are as follows,(1)Setting the average community height from the measuring board to the ground as an independent variable and the aboveground biomass of the community as a dependent variable,a mathematical model for estimating aboveground biomass from the height of the community is established.The model is not only simple but also has high precision;(2)It is proved that the macromolecule measuring board with a diameter of 35 cm can be used for estimating aboveground biomass of three types of grasslands.(3)The best model for estimating biomass of abandoned grassland in Yangling is the linear model with simple form and convenient application.The best model for estimating biomass of abandoned grassland in Yangling is equation y=0.8645x+6.526,R~2=0.8058,and the accuracy of estimating biomass by this model is 88.78%.The best model for Estimating Grassland in Weinan is equation y=0.9282x+2.8525,R~2=0.9298,and the three-time verification accuracy is 93.24%,respectively.The best prediction models of Guanshan grassland are equation y=1.4889x+0.9994,R~2=0.9012,and the accuracy of estimating biomass with this model is 94.11%.(4)Using the optimal models of three types of grassland to cross-estimate,the accuracy of the optimal model of Guanshan grassland for estimating three aboveground biomass of Weinan meadow grassland was 86.19%,86.01%and 87.57%,respectively,and that of Yangling abandoned grassland was 85.53%,while that of Weinan meadow grassland was 84.75%and 84.75%respectively.71.85%of the total aboveground biomass of Weinan meadow grassland was estimated by the optimal model of Yangling abandoned grassland,with the accuracy of 91.80%,92.66%and 94.21%respectively,and that of Guanshan grassland was 89.93%.This method can be used to estimate the aboveground biomass of the three types of grasslands under different precision requirements. |
PDF Full Text Request