Native plant diversity in tropical savannas decreases when exotic pasture grass cover increases
A. S. Kutt A C and J. E. Kemp B
+ Author Affiliations
- Author Affiliations
A CSIRO Ecosystem Sciences, PMB PO, Aitkenvale, Qld 4814, Australia.
B Queensland Herbarium, Department of Environment and Resource Management, PO Box 5318, Townsville, Qld 4810, Australia.
C Corresponding author. Email: alex.kutt@bigpond.com; alex.kutt@ghd.com
The Rangeland Journal 34(2) 183-189 https://doi.org/10.1071/RJ11048
Submitted: 17 August 2011 Accepted: 8 May 2012 Published: 31 May 2012
Abstract
The invasion of exotic plants into savanna ecosystems can disrupt the natural pattern of vegetation. Indian couch Bothriochloa pertusa was introduced into Australia as a species for rehabilitation of degraded grazing land. In this study the effect of increasing B. pertusa cover on native plant diversity and possible mechanisms of its spread were examined. Forty sites were sampled in uncleared Queensland rangelands with a range of B. pertusa and Bothriochloa ewartiana (a native species) cover. The mean number of native species per quadrat declined with increasing B. pertusa cover but remained stable over sites with increasing B. ewartiana cover. Mean species richness accumulated at a significantly lower rate for sites with B. pertusa present. Canonical analysis of principle coordinates suggested that three groups of sites, ranging from low to high species richness and cover of native plants, were correlated along gradients of B. pertusa cover, grazing intensity and basal area of dead trees. Generalised linear modelling indicated significant negative relationships between B. pertusa cover and total ground cover, forbs and perennial grass richness and cover, and cover of nine native perennial tussock grasses (Aristida leptopoda, B. decipiens, B. ewartiana, Chrysopogon fallax, Dichanthium fecundum, D. sericeum, Heteropogon contortus, H. triticeus and Themeda triandra). This study suggests that an increase in B. pertusa is associated with a substantial change in the cover and species richness of native plant communities. This was considered to occur via competitive effects as well as a result of cattle grazing, rainfall deficit and tree death. Regardless of the mechanism, continued spread of exotic pasture species has the potential to cause significant changes to rangeland biodiversity.
Additional keywords: biodiversity conservation, Bothriochloa, drought, grazing pressure, tropical weed ecology.
References
Accad, A., Neldner, V. J., Wilson, B. A., and Niehus, R. E. (2006). ‘Remnant Vegetation in Queensland. Analysis of Remnant Vegetation 1997–1999–2000–2001–2003, including Regional Ecosystem Information.’ (Queensland Herbarium, Environmental Protection Agency: Brisbane.)Boer, M., and Stafford Smith, M. (2003). A plant functional approach to the prediction of changes in Australain rangeland vegetation under grazing and fire. Journal of Vegetation Science 14, 333–344.
| A plant functional approach to the prediction of changes in Australain rangeland vegetation under grazing and fire.Crossref | GoogleScholarGoogle Scholar |
Bostock, P. D., and Holland, A. E. (2010). ‘Census of the Queensland Flora.’ (Queensland Herbarium, Department of Environment and Resource Management: Brisbane.)
Butler, D. W., and Fairfax, R. J. (2003). Buffel grass and fire in a gidgee and brigalow woodland: a case study from central Queensland. Ecological Management & Restoration 4, 120–125.
| Buffel grass and fire in a gidgee and brigalow woodland: a case study from central Queensland.Crossref | GoogleScholarGoogle Scholar |
Clarke, K. R., and Gorley, R. N. (2006). ‘PRIMER v6 User Manual and Program.’ (PRIMER-E Ltd: Plymouth, UK.)
DERM (2011). Land Cover Change in Queensland 2008–09: A State-wide Landcover and Trees Study (SLATS) Report, 2011. Department of Environment and Resource Management, Brisbane.
Eldridge, D. J., and Freudenberger, D. (2005). Ecosystem wicks: woodland trees enhance water infiltration in a fragmented agricultural landscape in eastern Australia. Austral Ecology 30, 336–347.
| Ecosystem wicks: woodland trees enhance water infiltration in a fragmented agricultural landscape in eastern Australia.Crossref | GoogleScholarGoogle Scholar |
Eyre, T. J., Wang, J., Venz, M. F., Chilcott, C., and Whish, G. (2009). Buffel grass in Queensland’s semi-arid woodlands: response to local and landscape scale variables, and relationship with grass, forb and reptile species. The Rangeland Journal 31, 293–305.
| Buffel grass in Queensland’s semi-arid woodlands: response to local and landscape scale variables, and relationship with grass, forb and reptile species.Crossref | GoogleScholarGoogle Scholar |
Fensham, R. J., and Holman, J. E. (1999). Temporal and spatial patterns in drought-related tree dieback in Australian savanna. Journal of Applied Ecology 36, 1035–1050.
| Temporal and spatial patterns in drought-related tree dieback in Australian savanna.Crossref | GoogleScholarGoogle Scholar |
Fensham, R. J., and Skull, S. D. (1999). Before cattle: a comparative floristic study of Eucalyptus savanna grazed by macropods and cattle in north Queensland, Australia. Biotropica 31, 37–47.
Fensham, R. J., Fairfax, R. J., and Buckley, Y. M. (2008). An experimental study of fire and moisture stress on the survivorship of savanna eucalypt seedlings. Australian Journal of Botany 56, 693–697.
| An experimental study of fire and moisture stress on the survivorship of savanna eucalypt seedlings.Crossref | GoogleScholarGoogle Scholar |
Fensham, R. J., Fairfax, R. J., and Ward, D. P. (2009). Drought-induced tree death in savanna. Global Change Biology 15, 380–387.
| Drought-induced tree death in savanna.Crossref | GoogleScholarGoogle Scholar |
Foley, J. C. (1957). ‘Droughts in Australia. Review of Records from the Earliest Settlement to 1955.’ Bulletin No. 47. (Bureau of Meteorology, Commonwealth of Australia: Melbourne.)
Franks, A. J. (2002). The ecological consequences of Buffel grass, Cenchrus ciliaris, establishment within remnant vegetation of Queensland. Pacific Conservation Biology 8, 99–107.
Friedel, M. H., Sparrow, A. D., Kinloch, J. E., and Tongway, D. J. (2003). Degradation and recovery processes in arid grazing lands of central Australia. Part 2: Vegetation. Journal of Arid Environments 55, 327–348.
| Degradation and recovery processes in arid grazing lands of central Australia. Part 2: Vegetation.Crossref | GoogleScholarGoogle Scholar |
Garnett, S. T., Woinarski, J. C. Z., Crowley, G. M., and Kutt, A. S. (2010). Biodiversity conservation in Australian tropical rangelands. In: ‘Wild Rangelands: Conserving Wildlife While Maintaining Livestock in Semi-arid Ecosystems’. (Eds J. D. Toit, R. Kock and J. Deutsch.) pp. 191–234. (Blackwell Scientific: London.)
Houlder, D. J., Hutchinson, M. F., Nix, H. A., and McMahon, J. P. (2000). ‘ANUCLIM User Guide, 5.1 edn.’ (Centre for Resource and Environmental Studies, Australian National University: Canberra.)
Jackson, J. (2005). Is there a relationship between herbaceous species richness and buffel grass (Cenchrus ciliaris)? Austral Ecology 30, 505–517.
| Is there a relationship between herbaceous species richness and buffel grass (Cenchrus ciliaris)?Crossref | GoogleScholarGoogle Scholar |
Jeffrey, S. J., Carter, J. O., Moodie, K. B., and Beswick, A. R. (2001). Using spatial interpolation to construct a comprehensive archive of Australian climate data. Environmental Modelling & Software 16, 309–330.
| Using spatial interpolation to construct a comprehensive archive of Australian climate data.Crossref | GoogleScholarGoogle Scholar |
Jones, R. J. (1997). Steer gains, pasture yield and pasture composition on native pasture and on native pasture oversown with Indian couch (Bothriochloa pertusa) at three stocking rates. Australian Journal of Experimental Agriculture 37, 755–765.
| Steer gains, pasture yield and pasture composition on native pasture and on native pasture oversown with Indian couch (Bothriochloa pertusa) at three stocking rates.Crossref | GoogleScholarGoogle Scholar |
Kutt, A. S., and Fisher, A. (2010). Ant assemblages change with increasing dominance of an exotic pasture grass in a tropical savanna woodland. Ecological Management & Restoration 11, 67–69.
| Ant assemblages change with increasing dominance of an exotic pasture grass in a tropical savanna woodland.Crossref | GoogleScholarGoogle Scholar |
Kutt, A. S., and Fisher, A. (2011). Increased grazing and dominance of an exotic pasture (Bothriochloa pertusa) affects vertebrate fauna species composition, abundance and habitat in savanna woodland. The Rangeland Journal 33, 49–58.
| Increased grazing and dominance of an exotic pasture (Bothriochloa pertusa) affects vertebrate fauna species composition, abundance and habitat in savanna woodland.Crossref | GoogleScholarGoogle Scholar |
Kutt, A. S., and Woinarski, J. C. Z. (2007). The effects of grazing and fire on vegetation and the vertebrate assemblage in a tropical savanna woodland in north-eastern Australia. Journal of Tropical Ecology 23, 95–106.
| The effects of grazing and fire on vegetation and the vertebrate assemblage in a tropical savanna woodland in north-eastern Australia.Crossref | GoogleScholarGoogle Scholar |
Landsberg, J., Lavorel, S., and Stol, J. (1999). Grazing response groups among understorey plants in arid rangelands. Journal of Vegetation Science 10, 683–696.
| Grazing response groups among understorey plants in arid rangelands.Crossref | GoogleScholarGoogle Scholar |
MacDougall, A. S., and Turkington, R. (2005). Are invasive species the drivers or passengers of change in degraded ecosystems? Ecology 86, 42–55.
| Are invasive species the drivers or passengers of change in degraded ecosystems?Crossref | GoogleScholarGoogle Scholar |
MacLeod, N. D., Ash, A. J., and McIvor, J. G. (2004). An economic assessment of the impact of grazing land condition on livestock performance in tropical woodlands. The Rangeland Journal 26, 49–71.
| An economic assessment of the impact of grazing land condition on livestock performance in tropical woodlands.Crossref | GoogleScholarGoogle Scholar |
McIvor, J. G. (1998). Pasture management in semi-arid tropical woodlands: effects on species diversity. Australian Journal of Ecology 23, 349–364.
| Pasture management in semi-arid tropical woodlands: effects on species diversity.Crossref | GoogleScholarGoogle Scholar |
McIvor, J. G. (2004). Pasture management in semi-arid tropical woodlands: levels of germinable seeds in soil and faeces of cattle grazing Stylosanthes pastures. Tropical Grasslands 38, 129–139.
McIvor, J. G. (2007). Pasture management in semi-arid tropical woodlands: dynamics of perennial grasses. The Rangeland Journal 29, 87–100.
| Pasture management in semi-arid tropical woodlands: dynamics of perennial grasses.Crossref | GoogleScholarGoogle Scholar |
McIvor, J. G., and Gardener, C. J. (1994). Germinable soil seed banks in native pastures in North-eastern Australia. Australian Journal of Experimental Agriculture 34, 1113–1119.
| Germinable soil seed banks in native pastures in North-eastern Australia.Crossref | GoogleScholarGoogle Scholar |
Miller, G., Friedel, M., Adam, P., and Chewings, V. (2010). Ecological impacts of buffel grass (Cenchrus ciliaris L.) invasion in central Australia – does field evidence support a fire-invasion feedback? The Rangeland Journal 32, 353–365.
| Ecological impacts of buffel grass (Cenchrus ciliaris L.) invasion in central Australia – does field evidence support a fire-invasion feedback?Crossref | GoogleScholarGoogle Scholar |
Mueller-Dombois, D., and Ellenberg, H. (1974). ‘Aims and Methods of Vegetation Ecology’. (John Wiley & Sons: New York.)
Orr, D. M., and O’Reagain, P. J. (2011). Managing for rainfall variability: impacts of grazing strategies on perennial grass dynamics in a dry tropical savanna. The Rangeland Journal 33, 209–220.
| Managing for rainfall variability: impacts of grazing strategies on perennial grass dynamics in a dry tropical savanna.Crossref | GoogleScholarGoogle Scholar |
Ostoja, S. M., and Schupp, E. W. (2009). Conversion of sagebrush shrublands to exotic annual grasslands negatively impacts small mammal communities. Diversity & Distributions 15, 863–870.
| Conversion of sagebrush shrublands to exotic annual grasslands negatively impacts small mammal communities.Crossref | GoogleScholarGoogle Scholar |
Prior, L. D., Williams, R. J., and Bowman, D. (2010). Experimental evidence that fire causes a tree recruitment bottleneck in an Australian tropical savanna. Journal of Tropical Ecology 26, 595–603.
| Experimental evidence that fire causes a tree recruitment bottleneck in an Australian tropical savanna.Crossref | GoogleScholarGoogle Scholar |
Rogers, L. G., Cannon, M. G., and Barry, E. V. (1999). ‘Land Resources of the Dalrymple Shire.’ Vols 1 and 2 (and Appendices). (Department of Natural Resources, Queensland: Brisbane.)
Rossiter-Rachor, N. A., Setterfield, S. A., Douglas, M. M., Hutley, L. B., Cook, G. D., and Schmidt, S. (2009). Invasive Andropogon gayanus (Gamba grass) is an ecosystem transformer of nitrogen relations in Australian savanna. Ecological Applications 19, 1546–1560.
| Invasive Andropogon gayanus (Gamba grass) is an ecosystem transformer of nitrogen relations in Australian savanna.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BD1MnjvVSgsA%3D%3D&md5=2c90a272f41a5f187ad4eff22a84bef5CAS |
Schmidt, C. D., Hickman, K. R., Channell, R., Harmoney, K., and Stark, W. (2008). Competitive abilities of native grasses and non-native (Bothriochloa spp.) grasses. Plant Ecology 197, 69–80.
| Competitive abilities of native grasses and non-native (Bothriochloa spp.) grasses.Crossref | GoogleScholarGoogle Scholar |
Setterfield, S. A., Rossiter-Rachor, N. A., Hutley, L. B., Douglas, M. M., and Williams, R. J. (2010). Turning up the heat: the impacts of Andropogon gayanus (gamba grass) invasion on fire behaviour in northern Australian savannas. Diversity & Distributions 16, 854–861.
| Turning up the heat: the impacts of Andropogon gayanus (gamba grass) invasion on fire behaviour in northern Australian savannas.Crossref | GoogleScholarGoogle Scholar |
Smyth, A., Friedel, M., and O’Malley, C. (2009). The influence of buffel grass (Cenchrus ciliaris) on biodiversity in an arid Australian landscape. The Rangeland Journal 31, 307–320.
| The influence of buffel grass (Cenchrus ciliaris) on biodiversity in an arid Australian landscape.Crossref | GoogleScholarGoogle Scholar |
Truong, P. N., and McDowell, M. (1985). Indian bluegrass for soil conservation and land stabilization in Queensland. Journal of Soil Conservation of N.S.W. 41, 38–43.
Williams, D. G., and Baruch, Z. (2000). African grass invasion in the Americas: ecosystem consequences and the role of ecophysiology. Biological Invasions 2, 123–140.
| African grass invasion in the Americas: ecosystem consequences and the role of ecophysiology.Crossref | GoogleScholarGoogle Scholar |
