基于广义加性混合模型(GAMM)的沙柳特征因子动态变化  

Dynamic change of characteristic factors of Salix cheilophila based on generalized additive mixed models(GAMM)

作　　者：王晓华 许昊[2] 锁岚 马俊杰 WANG Xiaohua;XU Hao;SUO Lan;MA Junjie(School of Forestry and Heraling,Ningxia University,Yinchuan 750021,Ningxia,China;School of Economics and Management,Ningxia University,Yinchuan 750021,Ningxia,China)

机构地区：[1]宁夏大学林业与草业学院,宁夏银川750021 [2]宁夏大学经济管理学院,宁夏银川750021

出　　处：《中南林业科技大学学报》2024年第9期60-70,104,共12页Journal of Central South University of Forestry & Technology

基　　金：宁夏自然科学基金项目(2022AAC03033);宁夏哲学社会科学规划项目(23NXBGL06)。

摘　　要：【目的】对沙柳特征因子的动态变化进行研究,分析环境因子影响下的地径、枝高动态变化过程。【方法】采用样地调查、样本采集、气象数据收集等手段,基于广义加性混合模型(GAMM),以灌丛、枝条以及二者的嵌套作为随机效应,探究灌木地径、枝高与土壤水分(SM)、年平均降水量(MAP)、年平均气温(MAT)及年龄等影响因子的动态变化规律。【结果】1)对于不考虑随机效应的广义加性模型(GAM),灌木地径与影响因子呈较强的非线性关系(有效自由度E均大于8.20,且P<0.001),枝高仅与时间呈非线性关系,与其他影响因子均为线性关系。2)相较于GAM,GAMM在随机效应的影响下,地径与各影响因子之间非线性显著降低(E变小),但在以灌丛为随机效应的模型中,地径与年平均气温趋于线性关系(E为1),而枝高与时间的非线性关系更强,与其余影响因子仍呈线性关系。3)考虑随机效应的GAMM比GAM的拟合结果更优,且嵌套模式下的GAMM拟合效果最好。【结论】沙柳不同特征因子对环境因子的响应有差异,而相比枝高,地径的变化程度更大。研究结果有助于掌握沙柳特征因子的动态变化对环境因素的响应机制,为进一步探究沙地生境变化过程中植物种群变化、植被演替及植被管理提供科学依据。【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.

关 键 词：沙柳特征因子 环境因子 广义加性模型 广义加性混合模型 动态变化规律 

分 类 号：S718.45[农业科学—林学]