| Andropogon gayanus | |
|---|---|
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Scientific classification 
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Clade: | Commelinids |
| Order: | Poales |
| Family: | Poaceae |
| Subfamily: | Panicoideae |
| Genus: | Andropogon |
| Species: | A. gayanus |
| Binomial name | |
| Andropogon gayanus Kunth | |
Andropogon gayanus, commonly known as gamba grass, Rhodesian blue grass, tambuki grass, and other names, is a species of grass native to most of the tropical and subtropical savannas of Africa.
History and naming
Andropogon gayanus was recognised and named by 1833. Its common names include gamba grass, bluestem (Africa, Australia); Rhodesian andropogon (southern Africa); Rhodesian blue grass (Zimbabwe); onga, tambuki grass (north-west Africa); and sadabahar (India).
Description
This tufting perennial bunchgrass can grow 4 m (13 ft) tall and 70 cm (2.3 ft) in diameter, and has hairy leaves. Most of its roots are fibrous, spreading close to the surface of the soil for up to 1 m (3 ft 3 in), but it also has thick cord roots which store starch and anchor the plant as well as vertical roots able to extract water from a greater depth during the dry season.
It produces large numbers of light, fluffy seeds (up to 244,000 seeds each year, with 65% viability), which can be spread by wind, animals or machinery. It spreads rapidly where vegetation is disturbed, but most seeds fall within 5 m (16 ft) of the parent plant.
Habitat
The grass is native to most of the tropical and subtropical savannas of Africa, also extending southwards into Mozambique, Botswana, Namibia and South Africa in regions with long dry seasons. It occurs naturally in xerophytic grasslands on doleritic, sandy or clay soils, at altitudes of up to 1,500 m (4,900 ft), and is very drought-tolerant. However it does not do well where mean minimum temperatures dip below 4.4 degrees Celsius, and it is not frost-tolerant. It has also been introduced around the world as a pasture crop in Australia and Brazil.
Uses
A. gayanus was introduced as a pasture crop in many parts of the world, including Australia, tropical countries of the Americas, as well as naturalising in Brazil It has also been introduced in Nigeria to reclaim land that has been overgrazed.
Strips of the grass are also planted in millet fields help to reduce wind erosion of the soil.
In some African countries, the stems are also used as thatch and for making pen.
Environmental impacts
Gamba grass forms dense patches, out-competing native species and altering ecosystems. Areas of dense infestation have a significantly higher fire risk than native pastures. It is highly resistant to both cutting and fire, and ungrazed tussocks can generate very intense fires, leading to loss of tree cover and long-term environmental damage. It replaces native grasses, reducing natural biodiversity on ungrazed land. Being highly invasive, it can move into conservation areas, semi-urban residential land and mining leases.
This has led to its declaration as a noxious species, officially being declared a "Weed of national significance" in Australia since 2012. Western Australia, the Northern Territory and Queensland all have state legislation which prohibits planting of new plants and requires land managers to control infestations.
Northern Territory
Gamba grass was introduced into the Northern Territory of Australia in 1931 for trial as cattle feed. There are now large swathes of the plant over 532,900 hectares between Darwin and Katherine. Gamba grass already accounts for as much as 20% of Litchfield National Park, around 30,000 hectares of the 144,000-hectare park, contributing to worsening fire seasons. Researchers estimate that this will increase to as much as 30% by 2033, a major threat to the park's future due to extreme fire risk. Conservationist Mitch Hart has described gamba grass as a "triple threat" to people's lives, the economy and the potential destruction of Australia's northern savanna. Two zones of management have been declared. Class A requires eradication and class B requires growth and spread to be controlled. The Gamba Army, a partnership between the Northern Territory Government and Territory NRM are working to control spread in priority areas.
Queensland
Gamba grass was imported into the state of Queensland as a pasture grass in 1942, but was not planted on a large scale until about 1983. Almost all known locations in Queensland are in areas below 980 m (3,220 ft) altitude that receive 400–1,500 mm (16–59 in) annual rainfall. It is declared a class 2 pest under the Land Protection (Pest and Stock Route Management) Act 2002, making it an offence to introduce, keep or supply the species without a permit and requiring land managers to keep land free of the species.
Western Australia
Gamba grass has effectively been eradicated from Western Australia, where infestations were not as widespread as the NT and Queensland. The Gamba Grass Eradication Program, a collaborative project supported by the Department of Biodiversity, Conservation and Attractions, the Department of Primary Industries and Regional Development, El Questro Station and Kimberley Rangelands Biosecurity Association began in 2011 and has been highly successful. It reduced the number of plants to 3,000 by 2018, leaving just 23 by 2020. They found only eight plants in the 2021 wet season. However it currently receives no funding from the federal government and monitoring is necessary for a further five years to ensure that there is no future spread.
References
- Kunth, Karl Sigismund (1833). Enumeratio plantarum omnium hucusque cognitarum : secundum familias naturales disposita, adjectis characteribus, differentiis et synonymis. Vol. v.1 (1833). Stutgardiae,et Tubingae: sumtibus J.G. Cottae.
- ^ "Andropogon gayanus". Tropical Forages. Archived from the original on 26 February 2017. Retrieved 21 June 2013.
- ^ "Gamba grass (Andropogon gayanus)". Business Queensland. Restricted invasive plants. Queensland Government. 30 October 2015.
Text may have been copied from this source, which is available under a Attribution 4.0 International (CC BY 4.0) licence.
- Bowden, B.N. (July 1964). "Studies on Andropogon gayanus Kunth: III. An outline of its biology". Journal of Ecology. 52 (2): 255–271. doi:10.2307/2257594. JSTOR 2257594.
- Lister, Ben (13 March 2019). "Gamba grass | Cape York Natural Resource Management". capeyorknrm.com.au. Retrieved 6 April 2024.
- Lesley Head, Jennifer Atchison. 2015. Governing invasive plants: Policy and practice in managing the Gambagrass (Andropogon gayanus) – Bushfire nexus in northern Australia. Land Use Policy 47: 225–234
- Neale, Timothy (2 October 2019). "A Sea of Gamba: Making Environmental Harm Illegible in Northern Australia". Science as Culture. 28 (4): 403–426. doi:10.1080/09505431.2018.1552933. ISSN 0950-5431.
- ^ "Invasive pasture grasses in northern Australia - Gamba grass". Department of Agriculture, Water and the Environment. Australian Government.
- ^ Snow, Madison (21 February 2022). "WA on cusp of eradicating gamba grass as Queensland and Northern Territory battle to contain it". ABC News. Australian Broadcasting Corporation. Retrieved 23 February 2022.
- ^ "Weed Management Plan Gamba Grass 2020-2030 (2024 Revision)" (PDF). Northern Territory Government. January 2024. Retrieved 6 April 2024.
- "This highly flammable weed is taking over Litchfield National Park. Experts say urgent action is needed". ABC News. 26 February 2023. Retrieved 6 April 2024.
- "Plea to eradicate highly flammable invasive weed in Litchfield National Park 'before someone gets hurt'". ABC News. 21 August 2023. Retrieved 6 April 2024.
- "RIEL researcher warns of gamba grass threat to Litchfield National Park | Charles Darwin University". www.cdu.edu.au. 23 February 2023. Retrieved 6 April 2024.
- "Gamba Army | Territory NRM". territorynrm. Retrieved 6 April 2024.
- "Invasive pasture grasses in northern Australia - Gamba grass". Department of Climate Change, Energy, the Environment and Water. Australian Government. Retrieved 6 April 2024.
External links
- Andropogon gayanus. National Weeds Strategy.
| Taxon identifiers | |
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| Andropogon gayanus |
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