Allometric relationships to predict aboveground biomass of 8–10-year-old Eucalyptus grandis × E. nitens in south-eastern Mpumalanga, South Africa

Abstract

South Africa is new to the implementation of climate change policies, and the forestry sector in this country is taking ownership of estimating its  greenhouse gas inventories. Improving the level of accuracy of carbon stock estimations calls for the population of a national biomass database on commercially planted species. The development of models to predict the biomass of Eucalyptus grandis × nitens aids in the goal of estimating  aboveground carbon at Tier 2 and 3 levels as recommended by the Intergovernmental Panel on Climate Change (IPCC) guidelines for national greenhouse gas inventories. The recommended model set presented in this paper uses diameter at breast height (DBH) and total height as variables to model biomass and, ultimately, carbon. Model fitting followed a maximum likelihood approach, and model selection was based on overall fit, parsimony, ease of use and additivity. Pulpwood stands around clear-felling age (8–10 years) were used, which presented an average basic wood densities value of 498 kg m–3. The estimated average aboveground biomass per hectare of this hybrid was 137 ± 34 T·ha–1 with a biomass expansion factor (scaling from stem wood volume to total above ground biomass) value of 0.6108.

Keywords: biomass modeling, carbon quantification, forest mensuration, plantation forestry