Species selection for revegetation of the Goro Nickel project area in New Caledonia McCoy, Stephane G.; Kurpisz, D.; Newedou, S.
Peridotite ranges cover an important part of the Pacific island of New Caledonia and have been the focus of intense mine activity for nickel, chromium and iron ores. Mine overburden historically placed in valleys causing subsequent coastal sedimentation is now the focus of revegetation operations. These activities aim to produce a vegetation similar to native types because the peculiar properties of ultramafic soils preclude future agricultural or pastoral land use. Revegetation efforts have focussed on fast growing Casuarina collina and Acacia spirorbis, and more recently, a diverse assemblage of endemic species tolerant of mine site conditions to produce an initial vegetation suited to seedling colonisation from surrounding areas. Measures of relative growth indicate that species not native to ultramafics (Pinus, Casuarina, Acacia) grow faster than endemic species on laterite trials in the Goro Nickel project area. This would suggest that these species could produce suitable cover for vegetation development from seedling colonisation. However measures of seedling colonisation at a mature Casuarina and Acacia plantation indicate that they support significantly fewer colonists than younger endemic species plantations despite having a near continuous litter cover. Significantly fewer seedlings were found underneath Casuarina suggesting that deep litter is impeding colonist establishment. This phenomenon has been documented for Casuarinaceae in New Caledonia and elsewhere. Furthermore, Casuarina seedlings were absent underneath adult trees at the plantation suggesting that this species is unable to regenerate on laterites at Goro. The current revegetation program has focussed efforts on the flora of the Goro region and produced 130 endemic species as potential alternatives to Pinus, Acacia and Casuarina that would generate ecologically sustainable vegetation. Direct seeding techniques of native species are options currently being tested to determine their potential and economic viability.
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