A Study of Growth Process of Pinus massoniana Plantation on the North Margin of the Sichuan Basin

In order to research the growth process of Pinus massoniana,analysis was made of the stem analyses of Pinus massoniana collected from Heishipo Forest Farm.The results showed that the fast-growing period of current annual increment of tree height was from 6th year to 15th year,and the maximum of current annual increment and average increment appeared in 10-year-old period,and they intersected in 14-year-old period.The fast-growing period of DBH appeared two times,namely,during 10~14 years and 30~45 years.The maximum growth of current annual increment of volume appeared in 40-year-old period,with 0.024 00 m³.The average increment of volume did not reach the peak until the 48-year-old,and the volume did not reach the quantitative maturity.The logistic equation was good to mode the growth of DBH,tree height and volume of Pinus massoniana plantation,the goodness of fit was more than 0.98,fitting effect was obvious.The equations were Y_H=19.169 36/(1+exp(-0.087 94×(x-24.549 44))、Y_D=34.831 04/(1+exp(-0.079 36×(x-33.776 92))、Y_V=0.636 36/(1+exp(-0.147 32×(x-40.061 83)) respectively.