Influence of Dummy Variables of Artificial Management Measures on Accuracy of DBH-Height Model of Styphnolobium japonicum Street Tree:A Case Study of the City Core of Beijing
In order to clarify the influence of the factors to artificial urban tree management on the DBH(diameter at breast height)-H(tree height)relationship of Styphnolobium japonicum street tree in mega-cities,a DBH-H relationship model for Styphnolobium japonicum street tree is proposed to be constructed with the artificial management factors as dummy variables.According to the sampling survey of street trees in the city core of Beijing in 2022,the measured data of 685 Styphnolobium japonicum street trees are obtained.Combined with 12 models drawn from in literature,the optimal basic model is selected based on four evaluation indexes including determination coefficient(R2),mean prediction error(MPE),Akaike information criterion(AIC),and root mean square error(RMSE).The effects of seven factors to artificial management in a typical urban environment on the DBH and the tree height of S.japonicum are analyzed.The results show that:1)Model M2(R2=0.647,MPE=-2.241%,AIC=600.720,RMSE=1.683)has the best comprehensive fitting degree;2)The installation of anti-trampling ground nets,the shading of buildings and the side length of tree grates significantly affect the DBH growth of Styphnolobium japonicum(P＜0.05).Whitewashing protection,the installation of anti-trampling ground nets,buildings'shading,vertical structure,and the side length of tree grates significantly affect the height of Styphnolobium japonicum(P＜0.05).The differences in plant spacing and adjacent tree species have no significant effect on DBH and tree height(P＞0.05);and 3)After introducing the dummy variables of anti-trampling ground protection,whitewashing,buildings'shading,and tree grates'side length into the model,its accuracy is significantly improved,while R2 increases by 15.8%,MPE decreases by 29.5%,AIC value decreases by 29.0%,and RMSE value decreases by 15.0%.Therefore,the introduction of artificial management factors as dummy variables into the DBH-H model of Styphnolobium japonicum can effectively improve the fitting accuracy and applicability of the model,which could provide a theoretical basis and science evidences for the planting,management,protection,and carbon storage evaluation of street trees in the future.
Styphnolobium japonicumstreet treegrowth modeldummy variablewhitewashing protection of tree trunkanti-trample ground protection
NETL
NSTL
万方数据
