Tree biomass equations for short rotation eucalypts grown in New Zealand

Five species of eucalypts, namely Eucalyptus ovata, E. Saligna, E. globulus, E. nitens and E. regnans were planted, sampled and harvested to develop regression equations to be used for non-destructive estimations of total tree dry weight when grown under a short rotation regime. A total of 458 trees were sampled between 2 and 5 years old. Their diameters ranged between 10 and 314 mm, heights 1.6–18.1 mm and weights 0.4–199 kg. A number of equations were developed from these parameters and tested statistically. The best-fit equation for a group of Eucalyptus species incorporated the product of the square of the diameter (D2) and height (H): tree dry weight (W) = 1.22D2* H × 10−4. This equation predicted the above ground tree dry weight to within 20% accuracy. The equation developed for eucalypts would be suitable if directly applied to other tree crops such as Pinus radiata or Acacia dealbata under SRF management regimes.