Effect of thinning on growth of Chinese-fir plantation

With the 12-year-old Chinese-fir plantation for 2 thinning,including 1st thinning at stand age of 12 years old and 2nd thinning at stand age of 17 years old,for felling at stand age of 23 years old,the effect of thinning on growth of Chinese-fir plantation was studied by using different thinning intensity and different thinning methods.The results showed that the B treatment with thinning intensity of 1st 35% 2nd 15% was more appropriate,by which the total stock volume per unit area(thinning+felling) was the maximum and the DBH growth and stand volume were also the maximum.The method of thinning from below had better effect on growth of Chinese-fir,by which the stock volume per unit area(felling) was the maximum.The different thinning intensity had a great influence on the quantity proportion of trees with large and medium DBH class(more than 14cm),and the B treatment was the most suitable for the highest quantity proportion.But there was no obvious difference in the quantity proportion of trees with large and medium DBH class between the two thinning methods.