EFFECT OF PLANTING DENSITIES ON GROWTH AND BIOMASS OF Eucalyptus urophylla PLANTATION IN VIETNAM

Eucalyptus plantation has been contributing to livelihood of million people living in rural areas of Vietnam. Different planting densities lead to different growth of planted trees, biomass, and consequently value of plantation. In this study, three planting densities were tested for Eucalyptus urophylla grown in Southern and North Central, Vietnam. The growth parameters (diameter at breath height/DBH, stem height, and crown diameter/Dc) were measured and dry biomass was estimated for 3-year-old plantations. The results indicated that planting densities had significant effects on growths of DBH, height, and Dc in the North Central. While, it had significant effects on growths of DBH and height in the Southern. In both sites, planting densities had significant effects on dry biomass of a 3-year-old plantation. The highest dry biomass was 66.3 Mg ha-1 at planting density of 1,110 trees ha-1 in the Southern and it was 20.9 Mg ha-1 also at planting density of 1,110 trees ha-1 in the North Central. Comparing between two sites for all three planting densities indicated that dry biomass at the Southern was significantly higher than that in the North Central. The difference was 45.4 Mg ha-1 at planting density of 1,110 trees ha-1, 33.7 Mg ha-1 at planting density of 1,330 trees ha-1, and 20.9 Mg ha-1 at planting density of 1,660 trees ha-1. It was concluded that growing E. urophylla with planting density of 1,110 trees ha-1 should be applied for both Southern and North Central, Vietnam.