Evaluation of some stem taper models for Camellia japonica in Mount Halla, Korea

Abstract

This study was conducted to evaluate the performance of the four stem taper models on Camellia japonica in Jeju Island, Korea using fit statistics and lack-of-fit statistics. The five statistical criteria that were used in this study were standard error of estimate (SEE), mean bias (), absolute mean difference (AMD), coefficient of determination (R2), and root mean square error (RMSE). Results showed that the Kozak model 02 stem taper had the best performance in all fit statistics (SEE: 3.4708, : 0.0040 cm, AMD : 0.9060 cm,R2 : 0.9870, and RMSE : 1.2545). On the other hand, Max and Burkhart stem taper model had the poorest performance in each statistical criterion (SEE: 4.2121, : 0.2520 cm, AMD : 1.1300 cm,R2 : 0.9805, andRMSE: 1.5317). For the lack-of-fit statistics, the Kozak model 02 also provided the best performance having the best AMD in most of the relative height classes for diameter outside bark prediction and in most of the DBH classes for total volume prediction while Max and Burkhart had the poorest performance. These stem taper equations could help forest managers to better estimate the diameter outside bark at any given height, merchantable stem volumes and total stem volumes of the standing trees of Camellia japonica in the forests of Jeju Island, Korea.