English

Abstract

An investigation of litter decomposition was undertaken at the Kidston Gold Mine in north Queensland, Australia with the aim of assessing the status of nutrient cycling capacity on a directly-revegetated tailings dam. Weight losses from leaf litter contained in litterbags placed in a 5-year old revegetated section of the dam were not significantly different from losses observed at two unmined reference sites over the 18 month study period, representing a rapid improvement in nutrient cycling capacity in the reconstructed ecosystem. However, fitted decay curves for each site predicted a slower decay constant and a longer litter half-life on the dam, which indicated that full pre-mining capability had not yet been achieved. Weight loss in the reconstructed system was most constrained by the low build-up of microbial biomass within the surface soil, which is expected to take at least 10 years to achieve pre-mining levels. In contrast, weight losses in the unmined sites appeared more related to the abundance of invertebrate fauna rather than microbial content. The results presented here of a developing system suggest that the importance of different factors affecting decomposition will reflect those that are most limiting over the course of ecosystem recovery. Additional