Reseach on the Growth Characters of Toona sinensis Plantation in Pengxi County

The research was conducted on the growth characteristics of the Toona sinensis plantation in Pengxi county in Sichuan province by using the stem analysis method. The results showed that the DBH, tree height and tree volume growth of the 27-year-old Toona sinensis plantation were 38.2 cm, 22.3 m and 0.9874 m³,respectively. Their mean annual increment were 1.41 cm, 0.83 m and 0.03624 m³. The current annual increment and mean annual increment of timber volume reached maximumat at the age of 15 and 24, and they intersected at the age of about 26, which meant that the Toona sinensis growth process had reached its quantitative maturity at the age of 26. The tree form was basically steady at the age of about 15. The growth dynamic models of DBH,height and volume of Toona sinensiswere established with the Logistic Equation. Three regression equations were:y=40.1890/(1 + 5.4884×e^-0.1719x), y=22.2083/(1 + 7.3383×e^-0.2352x) and y=1.0785/(1 + 27.0171×e^-0.2010x), and the correlation coefficients of fitting curve(R²) were 0.9782, 0.9722 and 0.9975.