Dynamic change of characteristic factors of Salix cheilophila based on generalized additive mixed models(GAMM)
[Objective]The dynamic change of the Salix cheilophila characteristic factors was studied,and the dynamic change process of ground diameter and branch height was analyzed under the influence of environmental factors.[Method]Based on sample survey,sample collection and meteorological data collection,we explored the dynamic variation of shrub diameter,branch height,soil moisture(SM),mean annual temperature(MAT),mean annual precipitation(MAP)and age.[Result]1)For the generalized additive model(GAM)without random effects,diameter had a strong non-linear relationship with the influence factor(effective degrees of freedom E was greater than 8.20,and P＜0.001,it was significant),branch height was only non-linear with age,and linear with the other influence factors(E=1);2)Compared with GAM,GAMM under the influence of random effect,the nonlinearity between ground diameter and each influence factor decreased significantly(E became smaller),but in the model with shrub as the random effect,diameter and MAT tended to be linear relationship(E=1),while the branch height and age were more nonlinear relationship,and its residual factor was still linear relationship;3)GAMM considering random effects gave a better fit than GAM,and the nested mode.[Conclusion]The different characteristic factors of S.cheilophila had different effect response to the environmental factors,while the ground diameter was more variable than the branch height.This study was helpful to grasp the response mechanism of the dynamic changes of the characteristic factors to environmental factors,and to provide a scientific basis for further exploring the change of plant population,vegetation succession and vegetation management in the process of habitat change in sandy land.
characteristic factors of Salix cheilophilaenvironmental factorsgeneralized additive modelsgeneralized additive mixed modelsdynamic change law
万方数据
维普
