A continental biomass stock and stock exchange estimation approach for Australia.

To implement Australia's National Carbon Accounting System it is necessary to estimate biomass stock, continentally, and change in stock, at a sub-hectare spatial resolution. The approach developed to meet this requirement is a hybrid between GIS-based process modelling and empiricism. Multi-temporal mapping of productivity was carried out using a variant of the 3PG (physiological principles predicting growth) model. Relationships were found between mapped productivity indices and measurements of biomass at maturity (i.e. long-term-undisturbed stands). This information was then used to interpolate maps of biomass potential. Simple growth formulae were used to plot biomass accumulation, with the 'rate of approach to mature biomass' set by the age at which maximum current annual increment occurs and the predicted site plant productivity over time. The age of the forest stand was determined from disturbance events detected by twelve national coverages of Landsat MSS, TM and ETM+ remotely-sensed data collected between 1972 and 2002. Responses to thinning of existing forests are calculated using an adjustment of stand age concurrent with the intensity of the thinning event