Volume Prediction in Eucalyptus grandis Crops

In Eucalyptus grandis the number of plants planted varies greatly. The rate of growth in various localities has been also greatly different. There is mortality in earlier stages but later the number tends to stabilise. The problem was to arrive at an equation which would be based on number and top height. It was found that an equation earlier used by Steill (1961) gave good relults. The regression equations calculated are: Vo = - 74.684814 + 17.614124x + 2.131032x²; (R² =0.9314) & Vu = - 62.453599 + 13.488326x + 1.972164x²; (R² =0.9228) where x = top ht (m). (No. of stems ha)¹/6/10 and Vo & Vu are volumes (m²) over bark and under bark, per hectare, respectively. This equation has shown to be independent of rate of growth (quality). Based on this equation and top ht/age curves the values of volume and MAI, both o.b. & u.b., have been tabulated for various numbers. The numbers are the stabalised number in 5th year (or bave been assumed to have stabilised). Rotations of 9, 10 & 11 years have been suggested for quality I, II & III crops in E. grandis.