Fire management in the VRD

By Jeremy Russell-Smith, Bushfires Council of the Northern Territory & Tropical Savannas CRC

Fire research in the VRD

The Natural Heritage Trust (NHT) and the Tropical Savannas CRC have funded a regional study on fire management in the VRD that has already led to changes in the way fire is managed in the District. This has only been possible through cooperation from a wide range of people and organisations, and more importantly, through the active encouragement and participation of the Bushfires Regional Council and land managers in the VRD.

The study first ignited interest in the district when historical photos of the area taken back in the early 1900s were compared with current scenes showing an apparent increase in woody vegetation. Interviews with landholders and further comparison of aerial photography confirmed initial impressions and indicated that in some areas a 30% increase in vegetation cover had occurred. Such a thickening of vegetation obviously has a range of implications for natural resource management, some of which are being explored by other Tropical Savannas CRC projects.

Use of remote sensing technology

Much more recent technology is being used, however, to develop a picture of how past fire management practices have impacted on savanna ecology. Satellite information dating back to 1983 is being used to develop a fire history map over most of the VRD. This mapping has shown that pastoral country in the district has been subject to very little burning, while rugged sandstone country has in some cases been burnt up to eight times in 15 years. Unfortunately, much sandstone vegetation (especially where it comprises healthy shrubs) is sensitive to too frequent burning. Work undertaken so far indicates that different management practices will need to be adopted in the future to conserve these habitats.

Bradshaw study

Detailed fire mapping has been undertaken for the Department of Defence on the Bradshaw Field Training Area. Both this and more general regional mapping have been undertaken mainly using LANDSAT Multi-Spectral Scanner (MSS) satellite data that is fairly detailed in nature but which only passes over the Earth every nine days. Information from the LANDSAT Thematic Mapper and NOAA AVHRR (National Oceanic and Atmospheric Administration—Advanced Very High Resolution Radiometer) devices has also been used. The latter has a more coarse resolution, but gathers information on a daily basis. It is particularly useful for finding thermal 'hot-spots' (active fires) and therefore has potential for locating fires before they spread large distances or become unmanageable.

Another element of the VRD regional study is an investigation into curing rates and how field-based indications of available fuel loads, curing rates and fire risk can be related to estimations derived from NOAA satellite data. So far, the correlations look very promising and may enable the development of a satellite-based assessment of regional fire risk.

Broader land management applications

A range of projects is nearing completion within the district focusing on different aspects of fire management. This includes field-based studies that explore the relationship between fire and pasture development and the impacts of fire on vertebrate and invertebrate fauna. In total, there are about 200 fire monitoring plots within the VRD that are being used for a variety of related projects. In addition, a modelling approach is being used to simulate the trade-off between fire and grazing and to develop a better regional understanding of long-term vegetation dynamics.

While the findings of each of these projects will have implications for smaller scale fire management, they will also contribute to a regional assessment of the costs and benefits associated with various fire regimes. This will in turn contribute to the development of strategic guidelines for improved fire management in the district that completed by the end of 2001.

To view and make your own fire history maps of the VRD, click on the link to our Savanna Map Maker on this page.