What is Para grass?

Para grass was introduced to Australia in the 1800s as a ponded pasture species for cattle grazing. It is probably native to Africa. Along with other wetland weeds, such as hymenachne and giant sensitive plant (mimosa), para grass poses a major threat to natural wetland environments in northern Australia.

Why is Para grass a problem?

Para grass competes strongly with native plant species and, in many cases, the wetland vegetation becomes a virtual monoculture. Many of the species depending on the diversity of wetland plant communities decline as a result.
For example, the brolgas relient on the bulbs of sedges such as bulkuru ( Eleocharis dulcis ), and the magpie geese who nest and feed in the wetlands.

Restoration of seasonal wetlands: Town Common

Town-Common-birds-at-hole

The Townsville Town Common Conservation Park is a seasonal wetland of national significance for birds. Declared a Conservation Park in the late 1970s, the wetland habitat has degraded significantly over the past 50 years due to weed infestation, dominated by para grass ( Brachiaria mutica , also known as Urochloa mutica ). The increase of para grass on the Townsville Town Common has dramatically altered water bird habitat, especially for brolgas and magpie geese.

Para grass is an exotic weed, capable of destroying ecosystem structure and function. Introduced to Australia from Africa in the late 1800s to increase pasture productivity, para grass has since spread outside grazed areas where it monopolises large areas of land by out-competing complex mosaics of native vegetation. In many cases, the wetland vegetation becomes a virtual monoculture. Many of the species depending on the diversity of wetland plant communities decline as a result. For example, the brolgas are reliant on the bulbs of sedges such as bulkuru ( Eleocharis dulcis ), and the magpie geese nest and feed in the wetlands.

This project commenced in 2004 and is examining how various combinations of fire and grazing by cattle can reduce the abundance of para grass. Twelve 6 ha plots were established in an area of the Townsville Town Common Conservation Park that was dominated by para grass. Plots were allocated to one of four treatments:

  1. Unburned and ungrazed control plots
  2. Burned and ungrazed plots
  3. Unburned and grazed plots
  4. Burned and grazed plots

The project is documenting changes in wetland vegetation and the animal communities dependent on it, and we are working with community groups to translate the results into recommendations for the management of coastal wetlands in northern Australia.

Project Update:

So far fires have occurred in August 2004, October 2005, and November 2006. Sites were grazed soon after the fires and cattle were removed from these sites before the on-set of the wet season. Significant increases in para grass abundance have been observed in control plots which were ungrazed and unburnt. Patch “burning” and “burning plus grazing” treatments each year for three consecutive years have led to a marked decrease in para grass weed infestation. Importantly, two food species (wild rice and bulkuru) important for wetland birds have increased in the treated areas. With more food and more free water, it is not surprising that more and more bird species have been surveyed in the “burned” plots, although bird usage varies greatly between seasons regardless of treatment. We have also been encouraged by the findings that the patch “burning” treatment does not result in major problems for other faunal groups (mammals, reptiles and amphibians). This is being investigated more thoroughly in the para grass, amphibians and reptiles project.

EPA/QPWS are using the results of the research to develop management strategies to control para grass in the Town Common. Developing and promoting methods for maintaining and restoring the Town Common is of regional significance, as a model for restoring para grass-infested seasonal wetlands throughout North Queensland.


Key References:

Campbell, SD; Grice, AC. 2000. Weed Biology: a foundation for weed management. Tropical Grasslands 34 (3-4): 271-279.

Choy, S, Ramage, D, Jones, G & Barratt, P 2002, Prioritising research on inland aquatic ecosystems in Queensland. Consortium for Integrated Resource Management, Department of Natural Resources and Mines, Coorparoo.

Douglas, MM; O'Connor, RA. 2003. Effects of the exotic macrophyte, para grass (Urochloa mutica), on benthic and epiphytic macroinvertebrates of a tropical floodplain. Freshwater Biology 48 (6): 962-971.

Ferdinands, K; Beggs, K; Whitehead, P. 2005. Biodiversity and invasive grass species: multiple-use or monoculture?. Wildlife Research 32 (5): 447-457.

Grice, AC; Martin, TG. 2006. Rangelands, weeds and biodiversity. Rangeland Journal 28 (1): 1-2.

Grice, AC. 2006. The impacts of invasive plant species on the biodiversity of Australian rangelands. Rangeland Journal 28 (1): 27-35.

Grice, AC. 2004. Weeds and the monitoring of biodiversity in Australian rangelands. Austral Ecology 29 (1): 51-58.

Grice, AC; Campbell, SD. 2000. Weeds in pasture ecosystems - symptom or disease?. Tropical Grasslands 34 (3-4): 264-270.

Grice, AC; Barchia, I. 1992. Does grazing reduce survival of indigenous perennial grasses of the semiarid woodlands of western New-South-Wales. Australian Journal of Ecology 17 (2): 195-205.

Guenni, O., Marin, D. and Baruch, Z. 2002. Responses to drought of five Brachiaria species. I. Biomass production, leaf growth, root distribution,water use and forage quality. Plant and Soil 243, 229-41.

Humphries, S.E., Groves, R.H. and Mitchell, D.S. 1991. Plant invasions of Australian ecosystems: a status review and management directions. Report to the Australian National Parks and Wildlife Service, Endangered Species Program and CSIRO. Kowari 2 (Canberra).

Martin, TG; Grice, AC. 2006. Management of weeds in Australian rangelands: a basis for evaluating projects. Rangeland Journal 28 (1): 77-81.

Williams, P.R., Collins, E.M. and Grice, A.C. 2005. Cattle grazing for para grass management in a mixed species wetland of north-eastern Australia. Ecological Management and Restoration 6, 75-6.

 

Town-Common-paddock

Administration

Funding: approx $200,000

Contact: Dr. Bronwyn Houlden, BDTNRM Programme Coordinator

Email: bronwyn.houlden@bdtnrm.org.au

Project Identification Number: SWW3002

Key Management Action Targets:

SWW2.1.2 “By 2006, implement waterway/wetland rehabilitation/conservation programs for priority systems .

BVH2.3.1 “By 2010, establish a rehabilitation program to rehabilitate priorities for critical fragmented, riparian and threatened remnant native vegetation.”

BVH2.3.2 “By 2010, ensure 40% of land managers, including local, state and federal governments are utilizing land management techniques that improve land and biodiversity condition.”

Partners: CSIRO, EPA/QPWS, Commonwealth Department of Defence, James Cook University, Australian Airports Corporation, Townsville Enterprise, Townsville City Council, Greening Australia, pastoral industry representatives, Conservation Volunteers, Bird Observers’ Club of Australia, the Townsville–Thuringowa Landcare Group, Wetland Care Australia and Traditional Owners.

Project Manager: Tony Grice, CSIRO

Links: Tony.Grice@csiro.au