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基于GAM模型的长白山红松人工林产区区划研究
Research on the Zoning of Pinus koraiensis Plantations in the Changbai Mountains Based on the GAM Model
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摘要: 以长白山7个地区的红松人工林,142块调查样地数据为基础,根据Spearman相关性分析和VIF值筛选主导气候因子,对比线性模型(LM)和广义可加模型(GAM)的精度确定最优预测模型,通过预测基准年龄下蓄积值对长白山地区红松人工林进行产区区划。结果表明:平均最热月温度(MWMT)和年降水量(MAP)是影响红松蓄积生长的主导气候因子。在GAM模型的拟合中,P样条(PS)为最优平滑函数,其模型拟合优度(AIC=618.37,-2LogL=604.82,R2=0.81)显著优于广义线性模型(LM)。十折交叉验证证实GAM模型的预测精度满足应用要求,且稳定性优于LM模型。依据GAM模型预测,可将长白山红松人工林划分为最适宜、适宜和一般生长区3个等级。Abstract: Based on the data of 142 sample plots of Korean pine plantations in 7 areas of Changbai Mountain, the dominant climatic factors were screened according to Spearman correlation analysis and VIF value, and the optimal prediction model was determined by comparing the accuracy of linear model (LM) and generalized additive model (GAM). The production areas of Korean pine plantations in Changbai Mountain were divided by predicting the accumulation value at the base age. The results show that the average hottest monthly temperature (MWMT) and annual precipitation (MAP) are the main climatic factors affecting the accumulation and growth of Korean pine. In the fitting of GAM model, P spline (PS) is the optimal smoothing function, and its goodness of fit (AIC=618.37, -2LogL=604.82, R2=0.81) is significantly better than that of generalized linear model (LM). Ten-fold cross-validation proves that the prediction accuracy of GAM model meets the application requirements, and its stability is better than LM model. According to the prediction of GAM model, the study area can be divided into three grades: the most suitable, suitable and general growth area.
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