The Effects of Stand Density and Site Condition on the Growth and Resin Yield of Pinus elliottii × P.caribaea

The stand density of 14-year-old Pinus elliottii × P.caribaea was used to study effects interaction of stand density, site conditions and resin yield. The result indicated that effects of stand density and site conditions varied considerably on growth and resin-productivity. DBH and height under living branch were most sensitive to stand density, height was next. As the density increased, the average DBH of forest decreased. But there were increased in tree height and height under living branch with density increasing. The volume grew best under the stand density of 1 125 per ha. There were obvious different resin yields among 5 different densities of stands. The annual average individuals resin yield always increased with DBH increasing. The resin production with low density increased with density increasing, but it decreased with density increasing when it got to a certain high level. The resin-productivity grew best under the stand density of 900 per ha. The results indicated that the suitable stand density of high yield and volume was 900-1 125 plant per ha.