Buffel grass in Queensland’s semi-arid woodlands: response to local and landscape scale variables, and relationship with grass, forb and reptile species
Teresa J. Eyre A D , Jian Wang A , Melanie F. Venz A , Chris Chilcott B and Giselle Whish CA Biodiversity Sciences Unit, Queensland Department of Resource Management, Forestry Building, 80 Meiers Road, Indooroopilly, Qld 4068, Australia.
B Department of Agricultural and Food, 3 Baron-Hay Court, South Perth, WA 6058, Australia.
C Department of Primary Industries and Fisheries, 203 Tor Street, Toowoomba, Qld 4350, Australia.
D Corresponding author. Email: teresa.eyre@derm.qld.gov.au
The Rangeland Journal 31(3) 293-305 https://doi.org/10.1071/RJ08035
Submitted: 11 August 2008 Accepted: 4 December 2008 Published: 28 August 2009
Abstract
Buffel grass [Pennisetum ciliare (L.) Link] has been widely introduced in the Australian rangelands as a consequence of its value for productive grazing, but tends to competitively establish in non-target areas such as remnant vegetation. In this study, we examined the influence landscape-scale and local-scale variables had upon the distribution of buffel grass in remnant poplar box (Eucalyptus populnea F.Muell.) dominant woodland fragments in the Brigalow Bioregion, Queensland. Buffel grass and variables thought to influence its distribution in the region were measured at 60 sites, which were selected based on the amount of native woodland retained in the landscape and patch size. An information-theoretic modelling approach and hierarchical partitioning revealed that the most influential variable was the percent of retained vegetation within a 1-km spatial extent. From this, we identified a critical threshold of ~30% retained vegetation in the landscape, above which the model predicted buffel grass was not likely to occur in a woodland fragment. Other explanatory variables in the model were site based, and included litter cover and long-term rainfall. Given the paucity of information on the effect of buffel grass upon biodiversity values, we undertook exploratory analyses to determine whether buffel grass cover influenced the distribution of grass, forb and reptile species. We detected some trends; hierarchical partitioning revealed that buffel grass cover was the most important explanatory variable describing habitat preferences of four reptile species. However, establishing causal links – particularly between native grass and forb species and buffel grass – was problematic owing to possible confounding with grazing pressure. We conclude with a set of management recommendations aimed at reducing the spread of buffel grass into remnant woodlands.
Additional keywords: clearing, fragmentation, grassy woodlands, invasive grass, thresholds.
Acknowledgements
We warmly thank the landholders and their families for kindly allowing access to their properties for this study. Many thanks to T. Hardaker, D. Ferguson and A. Kelly for assistance in the field. The project benefited from early discussions with D. Butler, S. McIntyre and A. Leverington. Thanks to A. Lawrence, M. Kraus and J. Thiessen for GIS assistance and generation of the landscape metrics, and J. Neldner and two anonymous reviewers for comments. This study was funded and supported by Land and Water Australia Native Vegetation Program (Project QNR28), Queensland Department of Natural Resources and Mines and the Queensland Environmental Protection Agency. Reptile surveys were conducted under Ethics Permit (Activity No. BRIBIE/6/99-1).
Andrén H.
(1994) Effects of habitat fragmentation on birds and mammals in landscapes with different proportions of suitable habitat: a review. Oikos 71, 355–366.
| Crossref | GoogleScholarGoogle Scholar |
(accessed 12 March 2006).
McIntyre S.,
Heard K. M., Martin T. G.
(2003) The relative importance of cattle grazing in subtropical grasslands: does it reduce or enhance plant biodiversity? Journal of Applied Ecology 40, 445–457.
| Crossref | GoogleScholarGoogle Scholar |
(accessed 25 June 2002).
Nurdin N., Fulbright T. E.
(1990) Germination of 2 legumes in leachate from introduced grasses. Journal of Range Management 43, 466–467.
| Crossref | GoogleScholarGoogle Scholar |
(accessed 15 February 2008).
Radford J. Q.,
Bennett A. F., Cheers G. J.
(2005) Landscape-level thresholds of habitat cover for woodland-dependent birds. Biological Conservation 124, 317–337.
| Crossref | GoogleScholarGoogle Scholar |
(accessed 25 June 2008).
Raftery A. E., Zheng Y. Y.
(2003) Discussion: performance of Bayesian model averaging. Journal of the American Statistical Association 98, 931–938.
| Crossref | GoogleScholarGoogle Scholar |
(accessed 25 June 2008).
Wintle B. A.,
Elith J., Potts J. M.
(2005) Fauna habitat modelling and mapping: a review and case study in the Lower Hunter Central Coast region of NSW. Austral Ecology 30, 719–738.
| Crossref | GoogleScholarGoogle Scholar |
Wintle B. A.,
McCarthy M. A.,
Volinsky C. T., Kavanagh R. P.
(2003) The use of Bayesian model averaging to better represent uncertainty in ecological models. Conservation Biology 17, 1579–1590.
| Crossref | GoogleScholarGoogle Scholar |
Zweig M. H., Campbell G.
(1993) Receiver-operating characteristic (ROC) plots: a fundamental evaluation tool in clinical medicine. Clinical Chemistry 39, 561–577.
| PubMed |
