Study on growth rhythm of Pinus massoniana plantation in the south of Guizhou Province

The stem analyses of Pinus massoniana forest of 35-year-old were conducted.The results show that the total increments of diameter,height and volume increased with forest age increasing before 35-year-old.The maxmium average growth of diameter and height appeared in 15-year-old,and the maxmiun of current annual increment appeared in 10-year-old.Volumn reached the fast growing period after 20-year-old,and current annual increment was over 0.020 m3.Current annual increment and average increment did not reach the maxmium before 35-year-old,and their's curves which were not intersection show that Pinus massoniana before 35-year-old did not reach the quantitative mature age.Pinus massoniana fitting model between forest measurement factors and forest age in this area were: Ydiameter=97.342 9×(1-EXP-0.014 6 x)1.253 3,Yheight=20.352 9×(1-EXP-0.089 4 x)1.827 0,Yvolumn=3.183 4×(1-EXP-0.035 0 x)4.115 1.Intense split apart period of diameter and height were in 15-year-old,and intermediate cuttings was done in this period.Through Pinus massoniana volumn growth model,with the trend of two curves current annual increment and average increment,it was found that the quantitative mature age was 65-year-old,and the principle felling could be done in this period.