Abstract:

The research results showed that the mean height, DBH, the individual volume and the growing stock of 4.5-year-old Eucalyptus plantation decreased with the Continuous Planting Rotation(CPR)increasing. The mean tree height of the second, the third and the fourth rotation decreased by 7.4%, 7.9% and 20.0% respectively compared with the first rotation; the mean DBH decreased by 8.4%, 15.9% and 25.8% respectively; the individual volume decreased by 20.4%,32.8% and 50.4% respectively; and the growing stock decreased by 20.9%,38.7% and 50.5%; The changes of height, DBH, the individual volume and the growing stock with CPR increasing may be simulated by linear, parabola and exponential model: (1) y=a+bx; (2)y=a+bx+cx²; (3)y=ax^b. The corwn length and volume decreased with the CPR increasing, which indicated that the more CPR increased, the worse the growth poentials became, and in which the leaf biomass of the second, the third and the fourth rotation decreased by 10.2%, 44.7% and 71.0% respectively compared with the first planting rotation. Their changes with rotations accorded with the linear model. There was a significat multiple linear regression relationship between the parameter of crown structure and the standing growth index.

Key words: Continuous planting, Eucalyptus plantation, Growth characteristics, Crown structure