Get reliable rangeland science

Australia's rangelands are under varying types of land-use and management, including cattle grazing, Indigenous fire management, and activities encouraging regeneration of native vegetation to restore biomass and earn carbon credits. Despite the typically sparse vegetation, the vast area of the rangelands (almost 6 million km2) is a substantial stock of land sector carbon. Changes in these stocks, whether due to management or wet-dry climate fluctuation, are thus a major contributor to Australia's overall carbon fluxes. Improving estimates of greenhouse emissions and sinks in the rangelands is thus essential to fulfil Australia's climate change treaty obligations, and also to account for land management effects in carbon credit schemes. Here we present a new approach to account for land-sector carbon, targeted principally at the rangelands. Recent work has quantified the relationship between canopy cover and above-ground biomass (AGB) across Australia's rangelands. We extend the widely-used Full Carbon Accounting Model (FullCAM), using a time-series of remotely-sensed woody cover to estimate changes in AGB through time. This time series is integrated with the FullCAM model, to combine observed changes in woody cover with the effects of fire, litterfall, decay and soil respiration, to account for greenhouse emissions and sinks through time. We introduce and demonstrate this approach for rangeland areas. Once this approach, informed by satellite monitoring of woody cover, is scaled up, it is anticipated that FullCAM will reduce model uncertainty by integrating empirical biomass estimates with a process-based modelling framework.