Abstract:

The reciprocal equation of the C-D effect, I.e. 1/ w = Aρ_I +B ( w and ρ_I respectively represent mean stem volume and density,A and B are coefficients) was used to describe the C-D effect in Populus × euramericana (Dode) Guinier cv. `San Martion' plantations. The data observed from different growth stages were well fitted with the C-D curve given by the reciprocal equation of the C-D effect on logarithmic coordinates, and the C-D curve shifted upward with the progress of time. The change trends of biological time τ, the coefficient A and B, the coefficient of growth λ(t) and the final yield Y(t) were given. The biological meanings of coefficient A and B were obtained. Biological time τ increased gradually with physical time t . With increasing τ, the coefficientA increased abruptly up to its maximum value, and then decreased gradually, whereas the coefficient B decreased exponentially and tended to close to zero. With stand growth the coefficient of growth λ(t) decreased gradually and final yield Y(t) increased gradually. Based on the C\|D effect, intermediate cutting for 7-year-old P. euramericana plantation with high-density was proposed.

Key words: The C-D effect;Reciprocal equation;Populus ×, euramericana cv.`San Martion'