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.