Establishment of native and exotic grasses on mine overburden and topsoil in the Hunter Valley, New South Wales
C. H. A. Huxtable A D , T. B. Koen B and D. Waterhouse A CA Department of Natural Resources (DNR), PO Box 2185 Dangar, NSW 2309, Australia.
B DNR, PO Box 445, Cowra, NSW 2794, Australia.
C Current address: Plant Breeder’s Rights, Department of Agriculture, Fisheries and Forestry Australia, PO Box 858 Canberra, ACT 2601, Australia.
D Corresponding author. Email: Charles.Huxtable@dipnr.nsw.gov.au
The Rangeland Journal 27(2) 73-88 https://doi.org/10.1071/RJ05006
Submitted: 30 July 2004 Accepted: 15 October 2004 Published: 21 November 2005
Abstract
Native grasses have an important role to play in mine rehabilitation throughout Australia, but there have been few scientifically designed studies of field establishment of native grasses from sown seed in this country. Current recommendations for rehabilitation of open-cut coal mines in the Hunter Valley involve the sowing of exotic pasture species to reinstate mined land to Class IV and V under the Rural Land Capability System. Despite the importance of native grasses in the pre-mined landscape, they are currently not widely included in mine rehabilitation. To address this issue a project was conducted between 1994 and 2000 to research the use of native grasses for rehabilitation of open-cut coal mines in the Hunter Valley. This paper reports on 2 mine site experiments that aimed to assess establishment and persistence of a broad range of native and exotic grass species from an autumn sowing in both topsoil and raw spoil over a period of 61 months. The most promising natives in terms of early establishment, persistence and spread over time, included six C3 accessions (five Austrodanthonia spp. and Austrostipa bigeniculata) and one C4 accession (Cynodon dactylon). Persistence of these accessions was better in raw spoil than topsoil, despite initial low numbers, due to a lack of weed competition and their ability to spread by self-seeding. In topsoil, and in the absence of any biomass reduction, native species were mostly out-competed by vigorous exotic perennial grasses which were sown in these experiments and from seed influx from adjacent rehabilitation areas or from the soil seed bank. The effects of climatic conditions and differences in soil physical, chemical and seed bank characteristics at the 2 mine sites are also discussed.
Additional keywords: germination, rehabilitation, weeds.
Acknowledgments
The authors thank the Australian Coal Association Research Program (ACARP), who funded the 5-year project of which this paper is part. The Hunter Coal Environment Group initiated the project and members of the steering committee (Peter Brennan, Tony Voller, Geoff Marschke, Greg Summerhayes, Doug Stewart, Brian Medhurst, James Bailey and Bruce Foster) provided direction for the project. Thanks go to Environmental Officers at Howick and Ravensworth South mines for providing and preparing sites. Valuable technical assistance in the field was provided by Marianne Close and Andrew Sawicki and was much appreciated. Thanks also go to Ken Reynolds, Steven Young, Glenda Holman and Kerry Hindle and others at the Scone Soils Laboratory for conducting soil analyses. Thanks to Bill Semple and Ian Cole for critical review and helpful suggestions to earlier drafts of this paper.
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