Abstract:

The effects of thinning density on growth and economic benefit of masson pine plantation were analyzed by 10 years data of 20-year-old thinning density experiment stand（including treatments of A,B,C,D,their density remained is 1 200,2 000,2 800,3 400 trees·hm^-2 respectively）,the results showed that it had significant effects on stand growth,stand structure ,log type and mill run.With the increase of stand density,diameter at breast height（DBH）,single tree volume,crown diameter,ratio of crown length to tree height decreased,but tree height/DBH,self-thinning intensity increased.The thinning density had no significant effect on tree height.With stand age increasing,the difference of stand volume and total mill run of different density stand decreased.Trees percentage of small logs and mill run of small timber increased with the increase of stand density,but which of large timber decreased.So it is difficult to raise stand final productivity by thinning,but it can improve the wood quality.By a synthetic analysis of mill run,economic evaluation and growth law of masson pine plantation,stand density of cultivating short rotation industry timber could be determined as 2 000～3 400 trees·hm^-2 when the stand age entered the middle-aged stage ,to cultivate large or middle diameter timber,which could be determined as 1 200～2 000 trees·hm^-2.

Key words: massom pine, thinning density, density effects, economic analysis, mill run