The Litchfield Savanna SuperSite represents high rainfall, frequently burnt, tropical savanna. At 1.9 million km2, tropical savanna is the dominant ecosystem type across northern Australia. Understanding biogeochemical cycles, impacts of fire on sequestration, vegetation and fauna is a national priority.
The site is a 5 km x 5 km block of relatively uniform open-forest savanna inside the park, and about 80 km south of Darwin. The infrastructure being put in place will help scientists understand the dynamics of vegetation structure and floristics (the kinds and numbers of plant species in an area, and their distribution and relationships) by linking field observations with infrastructure measuring fluxes (or exchanges) of carbon, water and energy. The fluxes will be linked to remotely sensed observations of vegetation cover and leaf area taken from the ground, aircraft and space.
Impacts of fire
In the Northern Territory, savanna ecosystems are largely intact in terms of tree cover, with only modest levels of land use change. Despite this, there is evidence of a loss of biodiversity, most likely due to shifts in fire regimes and a loss of patchiness in the landscape. Approximately 40% of the savanna burn every year and understanding fire impacts on fauna and flora is essential for effective land management. Vast areas, limited infrastructure and human resources makes the role of remote sensing all the more important for land management in north Australia and this SuperSite aims to address these needs by establishing infrastructure at a significant savanna site of uniform topography within a managed national park (Lichfield NP) that makes it ideal for remote sensing as well as flux studies.
Key research questions
- What are the impacts of prevailing fire regimes (primarily frequency, but also intensity, extent, heterogeneity) on vegetation structure and composition, habitat quality, fragmentation and vertebrate faunal biodiversity?
- How does vegetation structure, climate drivers and fire regime influence savanna carbon sequestration rate?
- How can fire management contribute to greenhouse gas abatement and carbon sequestration in savanna ecosystems?
- What are the impact of climate change on fire regimes and subsequent feedbacks to savanna carbon and water cycles?
Comparison Research Sites
TERN Australian Long Term Ecological Research Network
Fauna and vegetation monitoring will be continued at five sites. All of these monitoring sites are components of the LTERN Three Parks Savanna Fire-Effects Plot Network, a 17 year monitoring program of the three major national parks of the Northern Territory — Kakadu, Nitmiluk and Litchfield — in which the effects of fire frequency on vegetation structure and woody growth rates are being examined (discussed in the 2010 paper by Murphy et al in Global Change Biology). Because fauna and flora have been monitored at these sites for some time, Litchfield Savanna SuperSite provides an excellent site history to help scientists interpret biophysical observations of fluxes (exchanges of gases) and radiative surface properties (the radiation that emanates from the surface of whatever object is being measured, e.g. soil, leaves). A fire history at Landsat scale (30 m) is also available.
Observations through time are particularly important in savannas because of the huge seasonal range in vegetation biomass (between wet season and dry season) and the common occurrence of fires and other processes that have significant impacts on long-term fauna and vegetation dynamics and create short- to medium-term changes to carbon, water and radiative properties.
TERN OzFlux at the Litchfield Savanna SuperSite
OzFlux maintains the flux tower instrumentation that continuously measures exchanges of carbon dioxide, water vapour and energy between the terrestrial ecosystem and atmosphere.
Flux data is available from the OzFlux data portal.
Recent data from the flux tower sensors can be viewed at the University of Western Australia's Land Ecosystem Atmosphere Program website.
TERN AusCover activities at the Litchfield Savanna SuperSite
In 2013, AusCover ran airborne LiDAR and hyperspectral and ground LiDAR campaigns at Litchfield Savanna SuperSite with ground calibration. Phenocams are installed on the flux towers to Integrate flux measurements and phenology to understand the impacts of climate change on Australian landscapes. Analysis of ground-based and airborne LIDAR and radar missions will give scientists detailed maps of topographic and vegetation structure. This infrastructure will provide a collection of intermediate remote-sensing products from the Litchfield Savanna SuperSite that will provide the data needed, in conjunction with flux measurements, to calibrate and validate higher-level products – and these may be used to help us understand regional changes in the ecosystem.
Evaluation of various fire regimes will also be undertaken to examine their impact on the surface energy balance and carbon sequestration, essential data for the development of better savanna burning practices and the various carbon farming options that are being looked as part of the Carbon Farming Initiative . By doing this, Litchfield Savanna SuperSite will become a verification site for future land-management opportunities in north Australia.
The agencies involved in the Litchfield Savanna SuperSite are Charles Darwin University, Bushfires NT, and NT Government’s Department of Natural Resources, Environment, The Arts and Sport (NRETAS) and The University of Western Australia.