The effects of temperature and salinity on Acacia harpophylla (brigalow) (Mimosaceae) germination
S. M. Reichman A D , S. M. Bellairs B and D. R. Mulligan CA Division of Agriculture and Life Sciences, Lincoln University, Lincoln 7647, New Zealand.
B School of Science and Primary Industries, Charles Darwin University, Darwin NT 0909, Australia.
C Centre for Mined Land Rehabilitation, University of Queensland, St Lucia, Qld 4072, Australia.
D Corresponding author. Email: s.reichman@lincoln.ac.nz
The Rangeland Journal 28(2) 175-178 https://doi.org/10.1071/RJ06027
Submitted: 27 March 2006 Accepted: 16 June 2006 Published: 9 November 2006
Abstract
Acacia harpophylla F. Muell. (brigalow) used to naturally occur over a range of about 50 000 km2 in Queensland and New South Wales, Australia. Large scale clearing for agriculture has reduced the area to less than 20 000 km2 and it is estimated that 20–25% of vertebrate fauna living in brigalow communities will become locally extinct as a result of the current clearing induced loss of habitat. Some coal mining companies in central Queensland have become interested in providing habitat for the endangered bridle nail-tailed wallaby that lives in brigalow vegetation. However, there is little known about establishment techniques for brigalow on mine sites and other disturbed ground; an understanding of brigalow biology and ecology is required to assist in the conservation of this threatened vegetation community and for re-creation of bridled nail-tail wallaby habitat in the post mining landscape. Brigalow is an unusual species of Acacia because it is not hard-seeded and germinates readily without the need to break seed-coat imposed dormancy. Germination trials were undertaken to test the ability of brigalow seed to germinate with a range of temperatures and salinity levels similar to those experienced in coal mine spoil. Optimum germination was found to occur at temperatures from 15 to 38°C and no germination was recorded at 45°C. Brigalow was very tolerant of high salt levels and germinated at percentages greater than 50% up to the highest salinity tested, 30 dS/m. Germination of greater than 90% occurred up to an electrical conductivity of 20 dS/m. The results indicate brigalow seed can be sown in summer when rains are most likely to occur, however, shading of the seed with extra soil or mulch may ensure the ground surface does not become too hot for germination. Because of its ability to germinate at high salinity levels, brigalow may be suitable for use in saline mine wastes which are common on sites to be rehabilitated after mining.
Additional keywords: Australia, mined land, rehabilitation, revegetation, seed germination.
Acknowledgments
Thank you to Trish Madsen, Greg Browne and other staff and students of the Centre for Mined Land Rehabilitation and School of Land and Food Sciences at the University of Queensland who provided technical assistance and advice.
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