Succession in Bird and Plant Communities over a 24-Year Chronosequence of Mine Rehabilitation in the Australian Monsoon Tropics

Abstract

We compared the bird and woody plant communities of 2 to 24-year-old rehabilitation areas at Gove bauxite mine (20 km2) in the seasonal tropics of northern Australia, where Alcan has maintained a consistent rehabilitation program since it began operation in 1974. Birds were censused every second month over 2 years in 30 widely separated 0.25-ha plots, representing five chronosequence stages. These were also compared with six (off-mine) plots adjacent to the mine, which represented the annually burnt open forest typical of the region. Short-lived Acacias dominated the early chronosequence stages, whereas eucalypts dominated in later stages. Mean avian species richness and abundance increased significantly along the chronosequence, with values for the oldest rehabilitation plots being very similar to those for the off-mine plots. However, analyses of similarity revealed that the bird communities of the oldest rehabilitation plots were distinct from those of the off-mine plots, indicating that succession in rehabilitation areas is not following a direct trajectory toward the native open forest surrounding the mine. Several hollow-nesting bird species were scarce or absent in the rehabilitation areas, probably reflecting the absence of older hollow-bearing trees. Many differences between the rehabilitation and the off-mine areas in vegetation structure, woody flora, and avifauna appear to be related to the exclusion of fire from the minesite. We recommend the initiation of experiments designed to assess the effects of fire on the biota but caution against the use of fires for the majority of rehabilitation areas.