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Fauna Habitat Return
Before mining, all timber and rock materials are removed. Some of the large logs and boulders are left on the forest edge following clearing operations for construction of fauna habitats after mining is complete. During landscaping, front-end loaders pile the large rocks and boulders up to build fauna habitats. Habitats are placed evenly throughout the pit, avoiding steep areas, which can lead to soil erosion problems. All effort is made to vary the size, shape and material used to construct the habitats. A combination of different habitat materials such as rocks, logs, tree stumps and soil provide a variety of shelters to suit all the fauna of the jarrah forest.
We have begun investigating the potential of using smaller pieces of wood (50 cm maximum length) as habitat material. Previously all timber waste from clearing was burnt before mining. We now harvest as much wood residue as possible for charcoal production. In 2007 50,000 tonnes were used for charcoal production by a silicon smelting operation in the south of the state. Trials have been conducted in recent years utilising some of this remaining wood residue to either scatter across the soil surface or applied in small piles of 10-12 tonnes. Once the vegetation in these trial pits has begun to establish, botanical and fauna monitoring results will reveal whether these methods of wood residue distribution are beneficial to both botanical diversity and fauna movement in pit rehabilitation. A small scale experiment recently revealed that small piles of snipped wood close to the edge of mined pits encourages habitat specialists such as Napoleon’s skinks that are slow to colonise rehabilitation to move into restored areas.
Alcoa’s completion criteria and working arrangements with DEC require one constructed habitat per two hectares; however Alcoa has an internal standard of one constructed habitat per hectare. Increasing the number of fauna habitats in the rehabilitation results in more animals recolonising. We have found that mardo (a small native marsupial) numbers increase with more log piles, and it is likely this is true for many animals of the jarrah forest.
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