| The planting experiment (111 trees/667m~2, 124 trees/667m~2, 138 trees/667m~2, 152 trees/667m~2, 166 trees/667m~2) of 6- year-old Eucalyptus grandis pulp forest in two sites has proceeded in southwest Sichuan. The general content includes average DBH, average height, average individual volume, growing stock, stock shape, density effect model, main chemical components of wood and economic benefits. The results showed that:(1) The planting density had no obvious effect on height growth of trees, mean DBH, and average individual volume. When integrating two sites, the average individual volume will decrease with the density increasing. Density had obvious effect on growing stock Within 111~152trees/667m~2 of density, the growing stock increased with the density increasing, when the density being 166trees/667m~2, the growing stock decreased, and every factor was the best in the stand of 152 trees/667m~2. The planting density had no obvious effect on the stock shape in five densities stands, but which demonstrated certain difference. The stock shape was better in the stand of 138 trees/667m~2 in inferior site and the stand of 152 trees/667m~2 in superior site.(2) The production function of Conb-Douglas was compared with the other models of density effect. The productive elasticity and the marginal yield for the best model were analyzed, and the values of the productive elasticity and the marginal yield of Eucalyptus grandis plantation were calculated. The result showed that: presently, Eucalyptus grandis plantation in southwest Sichuan was negative effect staging; we should reduce stands density, in order to improve the stand productivity. Paying attention to its density control and management in the future, paying attention to the choice of forest land in planting Eucalyptus grandis, can't ignore stand density management.(3) The chemical components were different in two sites. The ash, water-extraction, 1 %NaOH-extraction, and lignin in the inferior site were more than which in the superior site. Benzene-alcohol extraction and cellulose in superior were more than which in inferior site.(4) The difference was significant in different site, and it was no significant in different density. The interaction didn't existed. The content of general cellulose was the most in stands of 138 trees/667m~2 in the inferior site and 124 trees/667m~2 in the superior site, and it was the least in stands of 166 trees/667m~2 in two sites.(5) The content of cellulose in the stock part was the most, and the content of Benzene-alcohol extraction was the most in the top part, and it was the least in the stock part The content of chemical components was different in the different densities.(6) The content of ash, water-extraction, l%NaOH-extraction and lignin in the heartwood and sapwood in the inferior site was more than which in the superior site. The content of cellulose and general cellulose in the superior site was more than which in the inferior site. In the superior site, the content of 1 %NaOH-extraction, Benzene-alcohol extraction and lignin in the heartwood were more than which in sapwood, and other components in the heartwood were less than which in the sapwood. In the inferior site, the content of cellulose and general cellulose in the sapwood were more than which in the heartwood, and other components were reverse.(7) The result of economic benefits indicated that: the economic benefits in the superior site were better than that in the inferior site. In southwest Sichuan, choosing density 152 trees/ 667m2 or 166 trees/667m2 to build the pulp forest of Eucalyptus grandis should be suitable, especially under terms not economic of area, the repayment of choosing these two kinds of density to afforest to the operator is considerable, and interests to the operator are secure too.(8) The compositor result of total score within five kinds densities in two sites show: from the high to low, it is 152 trees/667m2, 124 trees/667m2, 138 trees/667m2, 166 trees/667m2, 111 trees/667m2in the inferior site, 152 trees/667m2, 138 trees/667m2, 111 trees/667m2 , 166 trees/667m2,124 trees/667m2 in the superior site. Integrating two sites, the three kinds good densities were 152 trees/667m2(in the superior site), 152 trees/667m2(in the inferior site), 138 trees/667m2(in the superior site), and three kinds bad densities were 111 trees/667m2(in the inferior site), 166trees/667m2(in the inferior site). 124 trees/667m2 (in the superior site).
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