Abstract: The world’s rangelands are often seen as offering considerable potential as a carbon (C) sink, which could contribute to the management of atmospheric C levels, but there are often few data available to assess this potential or to inform the type of management regimes that would be necessary. This paper reports on a review of the literature, a field study and modelling of C stocks under a selection of experimental fire regimes in two plant communities in Australia’s northern rangelands. The field study on an open eucalypt savanna woodland and a savanna grassland-open shrubland suggested that fire regime had no effect or an inconsistent effect on aboveground C stocks. However, modelling using the Century model for the open woodland site showed that increasing fire frequency was associated with reduced aboveground and soil C stocks. Thus, while infrequent fires allowed C stocks to increase (10-yearly fire) or remain stable (6-yearly fire) over a modelled 58-year period, a regime of more frequent fires (4- and 2-yearly fires) reduced C stocks over time. Simulation of C dynamics over 93 years of pastoral settlement suggested that total C stocks had increased by 9.5 t ha–1, largely due to an increase in C in woody vegetation following a reduction in fire frequency associated with pastoral settlement. Frequent burning, as recommended to maintain low woody density and promote pasture production for grazing, will, therefore, reduce aboveground and to a lesser extent soil C stocks where there has been a history of infrequent fire. The opportunities for pastoralists to increase C stocks will depend on the frequency of fire and vegetation type, especially its woodiness or potential woodiness. Reducing fire frequency in woody rangelands will increase C stocks but may have adverse effects on pasture and livestock production. Reducing grazing pressure or destocking might also increase C stocks but may be relevant only when a property is overstocked or where relatively unproductive land could be taken out of livestock production. Any C gains from altering fire and grazing management are likely to be modest.
Hunt, L. P., 2014, Aboveground and belowground carbon dynamics in response to fire regimes in the grazed rangelands of northern Australia: initial results from field studies and modelling, Volume:36, Journal Article, viewed 04 December 2023, https://www.nintione.com.au/?p=2679.