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川中丘陵区柏木人工中幼龄林树高-胸径模型构建

Height-DBH Modelling for Young- and Middle-aged Cupressus funebris Plantations in the Central Sichuan Hilly Region

  • 摘要: 以川中丘陵区典型县—金堂县、简阳市、剑阁县、盐亭县、富顺县的柏木人工幼龄林(12~26 a)、中龄林(45~55 a)作为研究对象,共设置92个20 m×20 m标准地,获取1527株样本数据(幼龄林366株(建模用257株,验证用109株)、中龄林1161株(建模用703株,验证用458株)),选取Power、Bates and Watts、Schumacher、Logistic、Chapman-Richards等8个常用的模型构建柏木人工林适宜树高-胸径曲线,通过赤池信息准则(AIC)、均方根误差(ERMS)、平均绝对误差(EMA)、相对平均绝对误差(ERMA)以及调整后的决定系数(R2adj)等指标筛选最优模型。结果表明:幼龄林的最优模型为Naslund,调整决定系数为0.9128,均方根误差为1.0504 m;中龄林的最优模型为Logistic曲线,调整决定系数为0.9068,均方根误差为2.1591 m;整体最优模型为Chapman-Richards曲线,调整决定系数为0.9524,均方根误差为1.9942 m。本研究的结果可为柏木人工林多功能经营、立地质量评价、森林碳储量估算等提供参考。

     

    Abstract: Taking young (12~26 a)- and middle-aged (45~55 a) Cupressus funebris plantations in typical counties of the hilly area of central Sichuan, namely Jintang County, Jianyang City, Jiange County, Yanting County and Fushun County, as research objects, a total of 92 standard plots of 20 m × 20 m were established, and sample data of 1527 trees were obtained (366 young-aged trees: 257 for model calibration and 109 for validation; 1161 middle-aged trees: 703 for model calibration and 458 for validation). Eight commonly-used models including Power, Bates and Watts, Schumacher, Logistic and Chapman-Richards were selected to develop suitable height-diameter at breast height (H-DBH) curves for Cupressus funebris plantations. The Akaike Information Criterion (AIC), root-mean-square error (RMSE), mean absolute error (MAE), relative mean absolute error (RMAE), and adjusted coefficient of determination (Radj2) were adopted to select the optimal model. The results showed that the Naslund model performed best for young-aged stands, with an adjusted coefficient of determination of 0.9128 and a root-mean-square error of 1.0504 m. The Logistic model was optimal for middle-aged stands, with an adjusted coefficient of determination of 0.9068 and a root-mean-square error of 2.1591 m. For the pooled dataset, the Chapman-Richards model yielded the best fit, with an adjusted coefficient of determination of 0.9524 and a root-mean-square error of 1.9942 m. The findings of this study can provide references for multi-functional management, site quality evaluation and forest carbon stock estimation of Cupressus funebris plantations.

     

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