Effects of planting density on tree growth and wood quality and modeling the wood quality of Populus×xiaohei

To investigate the effects of planting density on tree growth and wood quality,the differences in tree growth characteristics and wood quality were analyzed for Populus×xiaohei from three planting densities.Meanwhile,models for evaluating wood quality based on tree characteristics were established.Results indicated that planting density had various degrees of impact on growth characteristics.As planting density decreased,diameter at breast height(DBH),stem taper and the ratio of diameter to height increased obviously,whereas live branch height decreased.Tree height was independent of planting density.Similarly,planting density imposed different influences on wood quality characteristics: as planting density decreased,modulus of elasticity in bending(MOE) and modulus of rupture in bending(MOR) tended to decrease,while wet heartwood area,sapwood area,juvenile and mature wood area,as well as the proportion of juvenile wood and wet heartwood increased obviously.Wood basic density was basically independent of planting density.Regression analysis showed that,wood quality characteristics,eg MOE,MOR,wet heartwood area and juvenile wood area,could be estimated fairly well using selected tree characteristics and planting density as predictors,while wood basic density was hardly estimated from tree characteristics.