Selection of Superior Trees of Taiwania flousiana Based on the Multiple Entry Quantity Model

The site factors and growth traits of 236 candidate Taiwania flousiana trees of pure forest, mingled forest, scattered wood and isolated wood in 13 counties were measured. The correlation analysis of candidate trees showed that volume could be used as the main indexes for selection of superior trees of T. flousiana. The regression equation with individual volume was established by using 6 quantitative factors including longitude, latitude, altitude, slope, the depth of black soil layer, ages of trees and 7 qualitative factors including slope aspect, slope position, slope shape, bedrock, soil type, origin, tree type. Its multiple correlation coefficient was 0.799. There was a difference between theoretical and realistic volume, the frequency of difference was in normal distribution. The superior tree selection was based on the comparison of I_i and the mean value of difference I ± standard deviation δ. The superior tree selection standards with 70% selective ratio were as follows:Class Ⅰ superior tree, I_i ≥ I + 0.3δ, that is I_i ≥ 1.644 6. Class Ⅱ superior tree, I + 0.3δ > I_i > I - 0.3δ, that is 1.644 6 > I_i > -1.644 6. Class Ⅲ superior tree (normal tree), I_i ≤ I - 0.3δ, that is I_i ≤ -1.644 6. 54 strains of class Ⅰ superior trees and 114 strains of class Ⅱ superior trees were selected by the standards. They accounted for 22.88% and 48.31% in all candidate superior trees respectively. The genetic gain of the class Ⅰ and class Ⅱ superior trees reached 20.82%.