Predicting crown width and length using nonlinear mixed-effects models: a test of competition measures using Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.)

Table 6 Comparison of different competition indices added to the CW—DBH basic model [CW4]

CW, crown width; CI, competition index; DBH, diameter at breast height; \({\phi }_{1}\), \({\phi }_{2}\) and \({\phi }_{3}\): formal parameters; Adjust R², adjusted coefficient of determination; MSE, mean square error; MSER (%), mean square error reduction (%) relative to the regression model with no competition index
^bP values for ϕ₁, ϕ₂, and ϕ₃ are lower than 0.05 in a T-test
^cP value for one or more than one coefficient are higher than 0.05 in a T-test
^dSuperior competition index selected from the two categories of CIs

ISSN: 1297-966X