| The negative impact of climate change caused by carbon emissions on ecological environment and social economy is becoming more and more significant,and the related research on forest carbon sequestration is becoming more and more important.Traditional forest carbon sequestration calculation methods are time-consuming and difficult to implement,so it is of great practical significance to study an accurate and suitable carbon sequestration prediction model for tree species in certain area.In order to reduce the workload of carbon sink measurement in the field,it is necessary to establish a carbon sink model with high precision and suitable for tree species in the area.In this paper,the DBH,height growth equation and carbon sink prediction model of individual tree species were constructed based on the existing analytical wood data of sample plots in mountainous area in the middle of Shandong province.The carbon sink of each tree species in mountainous area in the middle of Shandong province is predicted dynamically by means of simultaneous equations.The main results are as follows:(1)Prediction model of DBH and height growth of single tree.Based on the data of 171analytic trees from 367 sample plots of Platycladus orientalis,Pinus koraiensis and Robinia pseudoacacia in Shandong Province,five commonly used theoretical equations(Logistic equation,Mitscherlich equation,Gompertz equation,Korf equation and Richards equation)were usedto make regression fitting,respectively.The regression least squares method was used to test the equation,and then the optimal single tree DBH and height growth prediction model was constructed.(2)Study on the factors affecting carbon sequestration.The change trend and interaction of five important factors,site,age,tree height,DBH and carbon sequestration,were compared and analyzed.The results showed that the change rule of each factor of the three tree species was basically the same;with the increase of age,the carbon sequestration of forest trees showed an overall growth trend,and the better the site conditions,the larger the carbon sequestration value of individual trees,which accorded with the law of forest growth;the effects of DBH and tree height factors on carbon sequestration of individual trees were the same,but the effects of site factors on carbon sequestration of individual trees were not significant through factors.The results showed that there was a strong correlation between carbon sequestration per tree and DBH,tree height and their combination variables,which laid a foundation for the selection of model variables.(3)Prediction model of carbon sequestration single wood.The analytical wood data under different site conditions were selected to establish the carbon sequestration model of individual trees,80%of which were used for fitting,and the remaining 20%were used to test the accuracy of the model.Firstly,12 commonly used individual tree carbon sink models were fitted by non-linear least squares method,and then two test indices,MSE and R-Square,were selected to test the optimal individual tree carbon sink model under different site conditions.The results showed that for Platycladus orientalis model 9 and model 10,R-Square was the highest,MSE was the lowest,and the test of parameters was significant.Therefore,model 9and model 10 were used as the optimal models to simulate the carbon sink of single tree under different site conditions of Platycladus orientalis.For Robinia pseudoacacia and Pinus koraiensis,the R-Square of model 5 and model 6 was the highest and MSE was the smallest.Therefore,model 5 and Model 6 were considered as the optimal models under different site conditions of Robinia pseudoacacia and Pinus koraiensis.(4)Study on dynamic prediction model of carbon sequestration single wood.The DBH,height and carbon sequestration models of individual trees under different site conditions were constructed by data fitting and selection.The dynamic prediction model of carbon sequestration of individual trees was constructed in the form of simultaneous equations.The parameters were estimated by the similar unrelated regression SUR and two-stage least squares ITOLS.The results show that the coefficients of model variables of the two methods pass t test and F test,P<0.01,and the determination coefficients R~2 are above 0.8.The fitting effect of the two-stage least squares method was ideal.(5)Carbon sink system design of different tree species in mountain area in the middle of Shandong province.In order to verify the accuracy and applicability of the proposed dynamic prediction model for carbon storage of individual trees,the system architecture and functional structure design,data flow design,database structure design of various parameters and system interface design were carried out.Based on the design,a program was written to realize the application of carbon sink dynamic prediction system.In this study,carbon sequestration was combined with tree age,and carbon sequest ration dynamic models of Platycladus orientalis,Robinia pseudoacacia and Pinus koraie nsis were successfully constructed,and carbon sequestration dynamic prediction system of different tree species in mountainous area in the middle of Shandong province wa s further compiled.It is of certain practical significance to provide important decision making basis for the future operation and management of in mountainous area in the middle of Shandong province and to improve the work efficiency of forestry workers. |
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