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Carbon stock change due to forest management and disturbance must be accounted for in UNFCCC national inventory reports and for signatories to the Kyoto Protocol. Impacts of disturbance on greenhouse gas (GHG) inventories are important for many countries with large forest estates prone to wildfires. Our objective was to measure changes in carbon stocks due to short-term combustion and to simulate longer-term carbon stock dynamics resulting from redistribution among biomass components following wildfire. We studied the impacts of a wildfire in 2009 that burnt temperate forest of tall, wet eucalypts in south-eastern Australia. Biomass combusted ranged from 40 to 58 tC ha−1, which represented 6–7% and 9–14% in low- and high-severity fire, respectively, of the pre-fire total biomass carbon stock. Pre-fire total stock ranged from 400 to 1040 tC ha−1 depending on forest age and disturbance history. An estimated 3.9 TgC was emitted from the 2009 fire within the forest region, representing 8.5% of total biomass carbon stock across the landscape. Carbon losses from combustion were large over hours to days during the wildfire, but from an ecosystem dynamics perspective, the proportion of total carbon stock combusted was relatively small. Furthermore, more than half the stock losses from combustion were derived from biomass components with short lifetimes. Most biomass remained on-site, although redistributed from living to dead components. Decomposition of these components and new regeneration constituted the greatest changes in carbon stocks over ensuing decades. A critical issue for carbon accounting policy arises because the timeframes of ecological processes of carbon stock change are longer than the periods for reporting GHG inventories for national emissions reductions targets. Carbon accounts should be comprehensive of all stock changes, but reporting against targets should be based on human-induced changes in carbon stocks to incentivise mitigation activities. [ABSTRACT FROM AUTHOR]

The Northern Territory (NT) in Australia has been perceived by many as a frontier for future agricultural development that could serve as a future food bowl for Australia. However, such development is likely to require the conversion of large areas of relatively intact savanna forests, woodlands and grasslands into other land uses, resulting in the release of large amounts of greenhouse gases. With the evolution of international carbon markets, new livelihood opportunities are arising from the management of carbon in landscapes, to enhance sequestration as a means of combating climate change. In order for land owners and governments to realise these opportunities, it is necessary to gain a better understanding of the potential carbon stocks that can occur across different ecosystems throughout the NT. This article assesses the utility of the National Carbon Accounting Toolbox (NCAT) for estimating and mapping carbon stocks in the NT. The NCAT modelling estimates that the NT environments hold approximately 21.5 billion tonnes of carbon dioxide equivalents. The estimates of carbon vary from 5 to 235 tonnes of carbon per ha, decreasing from the north, where the highest estimates are for north-east Arnhem Land and the Tiwi Islands, to the arid lands of the south. They are thought to be the lowest in the Spinifex grasslands east of Alice Springs and west of Tennant Creek. Estimates of potential emissions from clearing and burning of native vegetation range from 27 to 439 tonnes of carbon dioxide per ha, depending on the initial vegetation type. The NCAT estimates are already being used for land-clearing assessments in the NT and demonstrate that Indigenous lands hold high levels of carbon. The performance of NCAT will depend strongly on the quality of the data on which predictions are based and the robustness of model parameterisation. We suggest that further work on soils, fire, grasslands, wetlands and woody debris is needed to improve the validity of the NCAT estimates for carbon in north Australian environments. [ABSTRACT FROM AUTHOR]

Spontaneous combustion and low-temperature oxidation of waste coal and other carbonaceous material at open-cut coal mines are potentially significant sources of greenhouse gas emissions. However, the magnitude of these emissions is largely unknown. In this study, emissions from spontaneous combustion and low-temperature oxidation were estimated for six Australian open-cut coal mines with annual coal production ranging from 1.7 to more than 16 Mt. Greenhouse emissions from all other sources at these mines were also estimated and compared to those from spontaneous combustion and low-temperature oxidation. In all cases, fugitive emission of methane was the largest source of greenhouse gas; however, in some mines, spontaneous combustion accounted for almost a third of all emissions. For one mine, it was estimated that emissions from spontaneous combustion were around 250,000 t CO2-e per annum. The contribution from low-temperature oxidation was generally less than about 1% of the total for all six mines. Estimating areas of spoil affected by spontaneous combustion by ground-based surveys was prone to under-report the area. Airborne infrared imaging appears to be a more reliable method. [ABSTRACT FROM AUTHOR]

• Here, we evaluated how increased shading and declining net photosynthetic capacity regulate the decline in net carbon balance with increasing leaf age for 10 Australian woodland species. We also asked whether leaves at the age of their mean life-span have carbon balances that are positive, zero or negative. • The net carbon balances of 2307 leaves on 53 branches of the 10 species were estimated. We assessed three-dimensional architecture, canopy openness, photosynthetic light response functions and dark respiration rate across leaf age sequences on all branches. We used YPLANT to estimate light interception and to model carbon balance along the leaf age sequences. • As leaf age increased to the mean life-span, increasing shading and declining photosynthetic capacity each separately reduced daytime carbon gain by approximately 39% on average across species. Together, they reduced daytime carbon gain by 64% on average across species. • At the age of their mean life-span, almost all leaves had positive daytime carbon balances. These per leaf carbon surpluses were of a similar magnitude to the estimated whole-plant respiratory costs per leaf. Thus, the results suggest that a whole-plant economic framework, including respiratory costs, may be useful in assessing controls on leaf longevity. [ABSTRACT FROM AUTHOR]