Effective fire management is critical for successful rehabilitation of minesites in northern Australia.
Tropical savannas need fire for rehabilitation
Fire is typically excluded from minesites undergoing rehabilitation in order to protect the developing vegetation. However, frequent fire is a feature of the savanna landscapes of northern Australia and active fire exclusion from rehabilitating minesites leads to the development of very different ecosystems.
The goal of creating ecosystems similar to that of surrounding unmined areas is therefore not achieved. Moreover, a lack of fire results in the build-up of unusually high litter loads, which creates a serious fire risk to the vegetation.
Working with the mining industry to improve rehabilitation success
For more than two decades CSIRO has been helping the mining industry across northern Australia assess rehabilitation success. Much of this work has involved the use of ants as bio-indicators, where the extent of convergence of ant communities at rehabilitation sites with those of surrounding unmined areas is used as a measure of rehabilitation success.
More recently, CSIRO has been working with the mining industry to help improve fire management on minesites undergoing rehabilitation.
Fire needs to be part of minesite rehabilitation
Ant surveys have repeatedly shown that minesites undergoing rehabilitation are failing to converge on the ecosystems of surrounding unmined sites. Ant species of older rehabilitation sites are characteristic of long-unburnt forest habitats, and species of surrounding open savanna habitats are absent.
Recent work at the Alcan Gove bauxite mine in north-east Arnhem Land in the Northern Territory has shown that in the long-term absence of fire, leaf litter in rehabilitated sites can increase to many times the levels found in surrounding savanna habitats. Fire exclusion can thereby create a serious fire management problem – when fires inevitably occur they can be very intense, killing most trees. Incorporation of fire from an early stage of the rehabilitation process is required to confer fire resilience and to create the open habitats preferred by savanna species.
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