A Study of the Growth Characteristics of Natural Liriodendron chinense Forest

The research was conducted on the growth characteristics of the natural Liriodendron chinense forest growing at Haiyingsi Forest Farm in Tongjiang county in Sichuan province by using stem analysis method.The results showed that the DBH,tree height and tree volume growth of the 25-year-old Liriodendron chinense were 25.38 cm,18.35 m and 0.397049 m³.Their mean annual increments were 0.73 cm,1.02 m and 0.015882 m³.The current annual increment of DBH reached maximum at the age of 12 while the mean annual increment was at the age of 16.They intersected at about 18 years old,which meant that the DBH growth process had reached its quantitative at the age of 18.The current annual increment and mean annual increment of tree height reached maximum at 8 years old.The quantitative mature age of tree height was 9.The current annual increment of timber volume reached maximum at 24 years old.The tree growth process did not reach its quantitative mature age at 26 years old.The volume increment percent began to becorne stable at 18 years old.The tree form was basically steady at about 10 years old.The growth dynamic models of DBH,height and volume of Liriodendron chinense were established with the Logistic Equation.Three regression equations were:y=18.63526/(1+7.2421*e^-0.18015x),y=26.81266/(1+18.24284*e^-0.20781x),and y=0.63661/(1+162.2645*e^-0.22093x).