Improving estimates of savanna burning emissions for greenhouse accounting in northern Australia: limitations, challenges, applications

Abstract

Although biomass burning of savannas is recognised as a major global source of greenhouse gas emissions, quantification remains problematic with resulting regional emissions estimates often differing markedly. Here we undertake a critical assessment of Australia’s National Greenhouse Gas Inventory (NGGI) savanna burning emissions methodology. We describe the methodology developed for, and results and associated uncertainties derived from, a landscape-scale emissions abatement project in fire-prone western Arnhem Land, northern Australia. The methodology incorporates (i) detailed fire history and vegetation structure and fuels type mapping derived from satellite imagery; (ii) field-based assessments of fuel load accumulation, burning efficiencies (patchiness, combustion efficiency, ash retention) and N : C composition; and (iii) application of standard, regionally derived emission factors. Importantly, this refined methodology differs from the NGGI by incorporation of fire seasonality and severity components, and substantial improvements in baseline data. We consider how the application of a fire management program aimed at shifting the seasonality of burning (from one currently dominated by extensive late dry season wildfires to one where strategic fire management is undertaken earlier in the year) can provide significant project-based emissions abatement. The approach has wider application to fire-prone savanna systems dominated by anthropogenic sources of ignition.

Can savanna burning projects deliver measurable greenhouse emissions reductions and sustainable livelihood opportunities in fire-prone settings?

“…An essential premise underlying Australia's recently developed savanna burning methodology (Russell-Smith et al 2009a;DCCEE 2012;Meyer et al 2012) is that reductions in fire frequency result in reduced GHG emissions because more of the fuel biomass (mostly grass and leaf litter) is decomposed biologically through pathways that, compared with savanna fires, produce lower relevant emissions per unit biomass consumed (Cook and Meyer 2009). In unburnt north Australian savannas, emissions of CH 4 and N 2 O arising from biological decomposition pathways are likely to be less than 10 % than that from fire (Cook and Meyer 2009;Jamali et al 2011).…”

Australia's landscapes in a changing climate—caution, hope, inspiration, and transformation

“…This program, modelled on and continuing indigenous patchwork burning patterns, was funded by carbon offset payments from large energy companies. Building on extensive trials, research consistently confirmed and quantified the value of early-season burns compared with late-season fires, with benefits including reduced CO 2 emissions, conservation of biodiversity and cultural practices, and connections to country and improvements in health and education in remote communities (Russell-Smith et al 2009). The cooperative program covered the great bulk of the savannas and involved indigenous communities, conservation NGOs, graziers, and government agencies.…”

“…These dynamics are currently being investigated (Douglass et al 2011). Payments for enhanced carbon sequestration and cultural and biodiversity conservation through changing burning practices are already under way (Russell-Smith et al 2009). Furthermore, these practices are likely to expand, as the Commonwealth's Carbon Farming Initiative lists savanna burning as eligible for government's carbon grants (DCCEE, www.climatechange.gov.au/government/initiatives/ carbon-farming-initiative/activities-eligible-excluded/additionalactivities-positive-list/positive-list-guidelines-proposal-form.aspx).…”

“…(10) Establishes property rights regimes that establish and support more equitable, efficient, and sustainable resource use or management (Young and McCoy 1995). (11) Enhances capacity to sequester carbon in the landscape, while delivering multiple social and economic benefits (Russell-Smith et al 2009). (12) Builds and tests general principles and guidelines for improved resource and ecosystems management including via optimisations tools Lewis et al 2010);…”

Unassisted invasions: understanding and responding to Australia’s high-impact environmental grass weeds

“…Paradoxically, imposing anthropogenic disturbance regimes, such as strategic grazing, within conservation reserves may help suppress high impact environmental alien grasses (Popay and Field 1996;Friedel et al 2011). Prescriptions for optimal fire regimes continue to be refined in different parts of Australia in response to competing land uses (Russell-Smith et al 2009;Friedel et al 2014) and major ongoing changes in water management and flow regimes are expected in Australia's largest catchment, the Murray-Darling Basin (Pittock and Connell 2010) and elsewhere. However, implications for grass invasions need to be better integrated into land management recommendations and prescriptions.…”