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Session 1: Overview / Landscape ecology and health

Chair: David Garnett

Achieving a sustainable future for Australia’s savannas: lessons from a decade of cooperative research. John Ludwig et al

This paper is an overview of some key lessons learned over the last 12 or more years about how to effectively foster cooperation and integration to achieve practices leading towards the sustainable management of savanna landscapes in northern Australia. These lessons are based on the combined experiences of TS-CRC Chief Executive Officers (Duff, Garnett), a Communication Coordinator (Jacklyn) and Research Theme Leaders (Landsberg, Ludwig, Morrison, Novelly, Whitehead).

Savanna carbon dynamics:  Dick Williams et al

Savannas constitute approximately 30% of Australia’s carbon stocks, and make a substantial contribution to national Greenhouse gas (GHG) emissions. GHG emissions from Australian rangelands derive from three main sources: land-use change, livestock production and savanna burning. Understanding the stocks, flows, responses of savannas to elevated CO₂, savanna sequestration capacity and the markets for savanna carbon have been the foci of this project.

Closing the gate after the grass has bolted: research to improve future weed management and policy: Michael Douglas and Sam Setterfield

There are approximately 160 species of naturalised grasses in northern Australia. Several species have been identified as serious weeds and are emerging as a significant threat to tropical savannas for conservation, Aboriginal, pastoral, mining, and defence land users. Although concerns about the environmental impacts of exotic grasses have been raised since the early 1990’s, progress on this issue was hampered by an active campaign of denial and misinformation about their impacts and by a lack of published scientific information evaluating environmental effects. Research supported by the Savannas CRC addressed this knowledge gap and demonstrated that species such as Gamba grass and Mission grass can have major effects of savanna plants, animals and important ecosystem processes including nutrient and water cycling and fire regimes.

Drivers of landscape change: Aaron Petty

Tropical savannas extend across nearly one third of the Earth’s — and Australia’s — surface. Although the biome is principally defined by a climate condition — highly seasonal but regular rainfall patterns — the name “savanna” is also given to the dominant feature of tropical savannas: open woodlands characterised by the coexistence of grasses and trees.

Under classical successional theory this is a paradox: either conditions do not support trees, or trees eventually supplant grasses. There has been much debate over the factors that lead to grass-tree coexistence in savannas, but a consensus is forming that disturbance, particularly from grazing and fire, is the key structuring factor. Because tropical savannas are disturbance dependent systems, they can be particularly impacted by seemingly subtle changes in disturbance regime.