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Advice to the Minister for the Environment, Water, Heritage and the Arts from the Threatened Species Scientific Committee (the Committee) on Amendments to the List of

Key Threatening Processes under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)

1. Name and description of the threatening process

1.1 Title of the Process

Ecosystem degradation, habitat loss and species decline due to invasion of northern Australia by introduced Gamba Grass (Andropogon gayanus), Para Grass (Urochloa mutica), Olive Hymenachne (Hymenachne amplexicaulis), Mission Grass (Pennisetum polystachion) and Annual Mission Grass (Pennisetum pedicellatum).

1.2 Name Changes

The original title of the nomination was ‘Ecosystem degradation, habitat loss and species extinction due to invasion of Top End NT by introduced Gamba Grass (Andropogon gayanus)’. The Committee changed the name of the nomination to ‘Ecosystem degradation, habitat loss and species decline due to invasion of northern Australia by introduced Gamba Grass (Andropogon gayanus), Para Grass (Urochloa mutica), Olive Hymenachne (Hymenachne amplexicaulis), Mission Grass (Pennisetum polystachion) and Annual Mission Grass (Pennisetum pedicellatum)’ to reflect that there are other invasive grass species in northern Australia impacting on native ecosystems and that Gamba Grass also occurs in Queensland and Western Australia.

1.3 Description of Process All of the introduced grasses in this threatening process are high biomass pasture grasses that out-compete native grasses and increase fuel loads which promote intense, late, dry season fires. For example, Gamba Grass has fuel loads up to seven times higher than native grasses (Rossiter et al., 2003). This produces fires that are eight times more intense than those produced by native grasses (Rossiter-Rachor et al., 2008). Research by Rossiter-Rachor and others found that the mean rate of spread of fires in Gamba Grass plots was 5 times that of native grass plots (Rossiter-Rachor et al., 2008). These factors modify ecosystem processes and have a detrimental effect on trees and other native flora and fauna allowing exotic grass monocultures to dominate. See section 1.6 for details of each introduced grasses status under state and territory legislation. Gamba Grass Gamba Grass is a large, perennial, highly productive introduced grass which forms tall (to 4 m), dense stands (Csurhes, 2005). These stands cure later than native annual grasses of the Top End, and provide increased fuel loads which promote intense, late, dry season fires. Native grass typically has a fuel load of 3-5 tonnes/ha, while Gamba Grass typically has fuel loads of 11-15 tonnes/ha and may be as high as 30 tonnes/ha (Williams et al., 2003; Rossiter et al., 2003; Douglas and Setterfield, 2005). This produces fires that are eight times more intense than those produced by native grasses (Rossiter-Rachor et al., 2008). It has been estimated that the mid-dry season fires in Gamba Grass have a fire intensity of up to 48, 000 kW m as opposed to native grasses that produce an estimated 2, 000 k W m (Rossiter-Rachor et al., 2008). Gamba Grass is native to the tropical and sub-tropical savannas of Africa, from Senegal in the west to Sudan in the east, south to Mozambique, Botswana, Namibia and South Africa (Csurhes, 2005). It was first introduced into Australia in 1931 by the CSIRO Division of Land Research but was not widely released as a pasture grass until 1983 when commercial

Invasion of northern Australia by Gamba Grass and other introduced grasses listing advice — of 22

quantities of the seeds became available (Csurhes, 2005). The spread of Gamba Grass has been accelerated by transportation of seed in hay, road maintenance activities and the run of above average wet seasons during the mid to late 1990’s. The success of Gamba Grass as a weed invader can be attributed to its ability to colonise a range of habitats from wetland margins and riparian corridors through to open woodlands and more closed forests (Flores, 1999; Flores et al., 2005). Gamba Grass can colonise undisturbed savanna ecosystems and does not need disturbed sites to become established, however, disturbance will increase its ability to colonise sites and does promote its survival in the first year (Setterfield et al., 2005). The spread of Gamba Grass has principally followed roadsides and other disturbance corridors (Barrow, 1995; Kean and Price, 2003). Once established it can spread over long distances from roadsides into undisturbed savanna areas (Price and Baker, 2003). Gamba Grass invasion can increase fire frequency as land managers need to burn more frequently to reduce the large fuel loads. Gamba Grass also has the potential to support fires more than once per year due to its high tolerance to fire and its ability to resprout shortly after fire (Bowden, 1963). Such fires have a detrimental effect on native habitat and ecosystems. Fires in Gamba Grass dominated ecosystems produce flame heights that are higher than typical fires causing canopy fires which affect the whole tree crown (Rossiter-Rachor et al., unpublished data.). Research has shown that these fires can lead to a 50% reduction in tree cover over 12 years (Ferdinands et al., 2006). In addition, in areas dominated by Gamba Grass the number of regenerating tree seedlings is reduced by approximately 4 times (Clifton et al., unpublished data.). Stands of Gamba Grass may also adversely affect native plant regeneration by creating an unfavourable microclimate. It out-competes native species, reduces biodiversity, and also affects the ecosystem by increased water use and a reduction in soil nitrogen. Gamba Grass is able to displace or out-compete many native species as it has higher photosynthetic rates, higher growth rates, greater biomass and a high seed output of up to 244 000 seeds per plant (Flores et al., 2005; Rossiter, 2001). Gamba Grass can reduce plant diversity to 1 or 2 ground cover species (Beggs, unpublished data), reduce frog and lizard populations (Beggs, unpublished data; Beggs and Ferdinands, 2003), cause the decline of grain-eating birds and mammals (Cook, 1991), Gamba Grass is considered an ‘ecosystem transformer’ whereby it converts eucalypt woodlands into exotic grasslands (Miller, 2006; Navie and Adkins, 2007). Gamba Grass is currently at an early stage of invasion, but will be increasingly difficult to control if action is not taken within the next few years (P. Robertson 2005, pers. comm.). Mission Grass Mission Grass is a large tussock-forming, long-lived grass which grows to between 2 and 3 m. It produces yellowish or brownish coloured seed-heads during late summer and autumn and dies back during the dry season. Mission Grass is believed to be native to tropical and sub-tropical Africa (Ethiopia, west tropical Africa and south to Mozambique) and tropical Asia (India, Malay Peninsula, Indo-China, Indonesia and the Philippines) (Parsons and Cuthbertson, 2001; Miller, 2006). It was first introduced into Australia in the 1940’s and 1950’s, but did not become widely established until the 1970’s (Miller, 2006). Mission Grass is a common weed on roadsides that also invades summer crops, pastures and native plant communities in the coastal districts of northern Australia. This species often grows with Gamba Grass. Once established, it has a competitive advantage over shorter-lived grasses and replaces native species (Miller, 2006). Because Mission Grass has a high fuel load, it can significantly change the fire regime in invaded areas. This results in extremely hot fires that


can cause the death of trees and transform natural savanna communities into exotic grasslands (Miller, 2006; Navie and Adkins, 2007). Annual Mission Grass Annual Mission Grass incorporates two sub-species: Pennisetum pedicellatum ssp. pedicellatum; and Pennisetum pedicellatum ssp. unispiculum. Annual Mission Grass is native to northern tropical Africa and India (FAO, 1974). It was brought into northern Australia from Uganda in the 1940’s and became widespread by 1970 (Setterfield et al., 2006). Annual Mission Grass is a tufted, drought tolerant introduced grass that grows to 1.5 m. It is found in dry savanna regions in sandy and fertile loamy soils and dominates on disturbed land including road reserves. It is of low grazing value, but is very palatable to sheep and cattle. It is predominantly used for grazing in times of scarcity. It produces a high seed output and occurs in high densities (Setterfield et al., 2006). Given its high biomass it appears to have a similar impact on the environment as Gamba Grass and Mission Grass in dominating the understorey, competing with native grasses, increasing fuel loads and promoting more intense, late, dry season fires that can transform eucalypt woodlands into grasslands (Woinarski, 2002a, 2002b; DPIF, 2008, pers. comm.). Para Grass Para Grass Urochloa mutica is also known as Brachiara mutica. It is a creeping, prostrate grass which grows to 1 m. The leaf blades are hairy, dark green and up to 15 cm long tapering to a fine point. Flower heads are up to 18 cm long and made up of several spikes approximately 5 cm long. It is often found in moist areas such as drains, but may also be found in drier deep soils. Para Grass is native to tropical Africa and South America and was brought into Australia in 1880 (Cameron and Lemcke, 2002). Para Grass affects approximately 40,000 ha of the Northern Territory (Low, 1997). It is a potential threat to natural wetland ecosystems (Department of Primary Industries and Fisheries, 2007). Para Grass has been shown to change plant community composition as well as reducing biodiversity (Douglas et al., 2002; Ferdinands et al., 2005). It outcompetes many native plants and its high productivity, fast growth and allelopathic effect on other plants allow it to form dense monocultures (Northern Territory Department of Natural Resources, Mines and Water, 2006). For example, Para Grass inhibits germination of native wild rice (Oryza australiensis) seed (Wurm et al., 2006), and displaces native wild rice plants. Fish and bird communities are also known to be affected by Para Grass (Douglas et al., 2002; Ferdinands et al., 2005), as well as ecosystem processes such as nutrient cycling (Douglas et al., 2002) and carbon flow (Douglas et al., 2002, 2005). Para Grass also changes the fuel load and increases the intensity of floodplain fires which can damage or kill native woody plants (Douglas and O’Connor, 1999). Olive Hymenachne Olive Hymenachne is a Weed of National Significance. It is a perennial semi-aquatic grass which commonly grows to between 1 and 2.5 m. Olive Hymenachne is native to southern and central America and was first introduced to central Queensland in the 1970’s. It later escaped cultivation and has established in tropical wetlands in North Queensland and the Northern Territory, where it threatens natural wetlands, riparian zones and waterways. Olive Hymenachne produces dense floating mats which out-compete native species by smothering nearby plants. It also produces a large number of seeds. Recent studies have indicated that each flower head produces as many as 4000 seeds, which gives Olive Hymenachne a competitive advantage over surrounding plant species. These characteristics reduce biodiversity and available habitat for native animals and can cause the loss of wildlife


resources such as fish and waterfowl. Olive Hymenachne can impede water flow and increase the likelihood of flooding in low-lying areas. It can also affect the recruitment of native trees and exclude native grasses and sedges which provide foraging resources and nesting habitat for native wildlife (Department of Natural Resources, Mines and Water, 2006).

1.4 Geographic Extent Gamba Grass was first introduced to pastoral land in the Northern Territory. It has since colonised large areas of non-pastoral land such as conservation reserves. Gamba Grass is found in the Top End of the Northern Territory, northern Queensland and the Kimberley region of Western Australia. In the Northern Territory it is estimated that the potential distribution of Gamba Grass would include all savanna areas, wetland and rainforest margins north of Daly Waters (15ºS), representing an area of approximately 380 000 km2 (S. Wingrave, pers. comm., cited in P. Robertson 2005, pers. comm.).

Mission Grass is predominantly found in the Top End of the Northern Territory and northern Queensland. It is also known to occur in central and south-eastern Queensland and in the southern parts of the Northern Territory (Navie & Adkins, 2007).

Annual Mission Grass is found on Cape York in northern Queensland, the Top End of the Northern Territory and north-eastern Western Australia (Global Biodiversity Information Facility, 2008).

Para Grass occurs in the Top End of the Northern Territory, north-eastern and south-western Western Australia (Department of the Environment, Water, Heritage and the Arts, 2008).

Olive Hymenachne is found in sub tropical and tropical Queensland. It also occurs on the coastal plains of northern Queensland and in small populations in the Northern Territory (Navie, 2007).

1.5 Threats to Native Species A variety of threatened and non-threatened native species of the tropical savannas, rainforests and wetlands of northern Australia are affected by this threatening process. The following threatened species are affected by this threatening process:

Yellow-snouted Gecko - High biomass exotic grasses such as Gamba and Mission Grass adversely affect the Yellow-snouted Gecko by increasing the mortality of geckoes and their eggs, decreasing the leaf litter in which they reside, and increasing their predation;

Gouldian Finch - High biomass exotic grasses affect the Gouldian Finch by modifying their habitat, reducing nesting hollows, reducing foraging resources by smothering native grasses and promoting extremely hot, late, dry season fires which destroy food sources;

Gove Crow Butterfly - This species is adversely affected by Mission Grass in that it threatens its habitat as a result of increasing intense, late, dry season fires; and


The Yellow Chat (Alligator Rivers) - This species is threatened by the invasion of exotic weeds such as Para Grass, Gamba Grass, and Olive Hymenachne which modify the species’ habitat and alter local fire regimes, making it unsuitable for the Yellow Chat (Alligator Rivers).

Other threatened species that may be affected by this threatening process include:

Dasyurus hallucatus (Northern Quoll); Notomys aquilo (Northern Hopping Mouse); Psephotus chrysopterygius (Golden-shouldered Parrot); Geophaps smithii smithii (Eastern Partridge Pigeon); Helicteres sp. Glenluckie Creek (N.Byrnes 1280) (a shrub).

The following non-threatened species are also affected by this threatening process:

Cycas armstrongii (a cycad); Fire sensitive plants such as Acacia shirleyi (Lancewood) and Callitris columellaris

(Blue Cypress Pine); Phascogale tapoatafa pirata (Northern Brush-tailed Phascogale).

In addition, the broader impact on the ecosystems of northern Australia can be demonstrated by the effect of Para Grass on native wild rice plants. Para Grass displaces native wild rice plants Oryza sp. which may affect other species in the food chain (Douglas et al., 2002). Australian Magpie Geese and rodents such as the Rattus colleti (Dusky Plains Rat) rely on the seeds of native wild rice plants (Whitehead and Dawson, 2000; Wurm, 1998). A reduction in rat populations may also affect their predators such as Liasis fuscus (Water Pythons) (Shine and Madsen, 1997) and Canis familiaris (Dingoes) (Corbett, 1995).


1.6 Listing Status Under State and Territory Legislation Weed State Status Legislation Gamba Grass Northern Territory Declared – this

means that it cannot be introduced into the Northern Territory (Class C), it must be eradicated in certain areas (Class A), and its growth and spread must be controlled in other specified areas (Class B).

Weeds Management Act 2001

Queensland Declared as a class 2 pest - this means that it cannot be sold in Queensland and landholders must control it on their land.

Land Protection (Pest and Stock Route Management) Act 2002

Western Australia Declared - this means that it cannot be bought or sold in Western Australia, and all known plants must be eradicated.

Agriculture and Related Resources Protection Act 1976

Mission Grass Northern Territory Declared as a Class B and C weed - which means that it cannot be introduced into the Northern Territory and its growth and spread must be controlled.


Queensland nil Western Australia nil Annual Mission Grass

Northern Territory nil

Queensland nil Western Australia nil Para Grass Northern Territory nil Queensland nil Western Australia nil


Olive Hymenachne Northern Territory Declared as a Class B

and C weed - which means that it cannot be introduced into the Northern Territory and its growth and spread must be controlled.


Queensland Declared as a class 2 pest - this means that it cannot be sold in Queensland and landholders must control it on their land.

Land Protection (Pest and Stock Route Management) Act 2002

Western Australia Declared – this means that it cannot be bought or sold in Western Australia, and all known plants must be eradicated.

Agriculture and Related Resources Protection Act 1976

2. How judged by the Committee in relation to the EPBC Act criteria

Section 188(4) of the EPBC Act states: A threatening process is eligible to be treated as a key threatening process if: a) it could cause a native species or an ecological community to become eligible for

listing in any category, other than conservation dependent; or b) it could cause a listed threatened species or a listed threatened ecological community

to become eligible to be listed in another category representing a higher degree of endangerment; or

c) it adversely affects 2 or more listed threatened species (other than conservation dependent species) or 2 or more listed threatened ecological communities.

A. Could the threatening process cause a native species or an ecological community to become eligible for listing as Extinct, Extinct in the Wild, Critically Endangered, Endangered or Vulnerable?

All of the introduced grasses in this threatening process are high biomass grasses that out-compete native grasses and increase fuel loads which promote intense, late, dry season fires. Consequently, all of the introduced grasses included in this threatening process have the potential to cause a variety of native species or ecological communities to become eligible for listing as threatened under the EPBC Act. However, there are currently insufficient data available to demonstrate this in all cases. There is evidence, however, that both Gamba Grass and Mission Grass are likely to cause Cycas armstrongii (a cycad) to become eligible for listing as threatened (D.T. Liddle 2004, pers. comm.). The eligibility of C. armstrongii for listing under the EPBC Act can be assessed using relevant criteria set out in the Environment Protection and Biodiversity Conservation


Regulations 2000. The species would be considered to be rated in the lowest category of threatened species (vulnerable) if it met any one of the criteria set out in the Regulations. The criterion most relevant in the case of C. armstrongii is:

‘It has undergone, is suspected to have undergone or is likely to undergo in the immediate future, a substantial reduction in numbers’.

Cycas armstrongii C. armstrongii is a medium-sized cycad which grows to between 3 and 6 m with a narrow trunk 6 - 12 cm in diameter. It has glossy, bright green, leaves and orange, pollen cones. It is endemic to the Northern Territory and forms dense and numerous populations on sandy soils in Eucalyptus miniata/ E. tetradonta forests around Darwin. It is known from the Adelaide River west to the Finniss River and south to the settlement at Adelaide River, with several occurrences further south, almost to Hayes Creek. It also occurs on the Tiwi Islands and Cobourg Peninsula (Department of Natural Resources, Environment and the Arts, 2006a; Royal Botanical Gardens Sydney, 2008). Dr David Liddle in his doctoral thesis ‘The ecology of C. armstrongii and management of fire in Australia’s tropical savannas’ modelled the impact of alien grasses such as Gamba Grass and Mission Grass on fire regimes in northern Australia and the resultant impact on C. armstrongii. In this report, he states that Gamba Grass and Mission Grass increase the fuel load and cure later in the dry season than native grasses, increasing the likelihood of later, hotter, fire events (Bowman, 1999; Rossiter et al., 2003). Liddle concluded that the increased fuel loads caused by these high biomass introduced grasses lead to fires which cause higher mortality rates of C. armstrongii, which are now considered threatened (Kerrigan et al., 2006). He also concluded that introduced grasses such as Gamba Grass and Mission Grass are spreading rapidly and have the potential to extend over the full range of C. armstrongii. Further modelling by Liddle indicated that there is a 50 % probability that C. armstrongii would meet thresholds for listing as threatened with extinction under IUCN red list criteria with intense fires at > 1 in 5 years. From this it is concluded that the current fire regime combined with invasion by introduced grasses and projected land clearance, is likely to cause the species to decline significantly (D.T. Liddle 2004, unpublished data.). Summary of Assessment Gamba Grass and Mission Grass currently occur in the range of occurrence of C. armstrongii and it is estimated that they will extend over the full range of occurrence of C. armstrongii unless they are successfully controlled. Gamba Grass and Mission Grass increase the likelihood of more frequent and intense fire events and such events will adversely impact on C. armstrongii. Currently, intense fires caused by the spread of these high biomass introduced grasses are occurring at a frequency that will directly threaten C. armstrongii and it is likely to undergo in the immediate future, a substantial reduction in numbers. Conclusion for Criterion A: The Committee considers that the threatening process is eligible under this criterion as the process is likely to cause the native species C. armstrongii to become eligible for listing as vulnerable. B. Could the threatening process cause a listed threatened species or a listed threatened ecological community to become eligible to be listed in another category representing a higher degree of endangerment?


Conclusion for Criterion B: The Committee considers that the threatening process is not eligible under this criterion as there is insufficient information to judge whether this process is likely or not likely to cause a listed threatened species or a listed threatened ecological community to become eligible to be listed in another category representing a higher degree of endangerment. C. Does the threatening process adversely affect two or more listed threatened species (other than conservation dependent species) or two or more listed threatened ecological communities? The majority of research to date has focused on the impact of Gamba Grass on threatened native species. However, all of the introduced grasses in this threatening process have similar threatening characteristics in that they are high biomass grasses that outcompete native grasses and increase fuel loads which promote intense, late, dry season fires. Therefore, all of the introduced grasses in this threatening process have the potential to adversely affect a variety of threatened species or ecological communities. The following species listed as threatened under the EPBC Act have been selected to demonstrate the impact of introduced grasses on listed threatened Australian native species. This list has been selected as a sample of species being affected. As discussed in section 1.5 ‘Threats to Native Species’, there are a number of additional threatened species (not listed below) being impacted by this threatening process.

Diplodactylus occultus (Yellow-snouted Gecko) Erythrura gouldiae (Gouldian Finch) Euploea alcathoe enastri (Gove Crow Butterfly) Epthianura crocea tunneyi (Yellow Chat - Alligator Rivers)

Yellow-snouted Gecko The Yellow-snouted Gecko is a small ground dwelling lizard. It is predominantly dark brown with a reddish head and white spots on its flanks and limbs. It is endemic to the Northern Territory and is found in lowland open forests in the Mary, Wildman and West Alligator catchments (Department of Natural Resources, Environment and the Arts, 2006b). It is listed as endangered under the EPBC Act. In the Wildman Reserve the Yellow-snouted Gecko is only found in well developed leaf litter in Eucalyptus miniata/ E. tetradonta forests (Beggs and Martin, 2001, cited in S. Setterfield and M. Douglas 2006, pers. comm.) and does not occur in any areas with a dense understorey (Beggs, Phd data, pers. comm., cited in S. Setterfield and M. Douglas 2006, pers. comm.). Fire studies in the region where this species is found have shown that the area is now characterised by fire regimes with a greater extent, frequency and intensity of fires than in areas dominated by native grasses (Anderson et al., 1998, 2003). This fire regime is considered too frequent for the conservation of biodiversity (Pardon et al., 2003; Woinarski et al., 2004 Anderson et al., pers. comm.). The habitat of the Yellow-snouted Gecko is likely to decline due to the altered fire regimes in the area, and the invasion of exotic grasses (Department of the Environment, Water, Heritage and the Arts, 2006). Studies of these exotic grasses in the Wildman River Reserve (Northern Territory) suggest that fuel loads are increasing by 3-5 times and fire intensities by 8 times greater than those in comparable open


forests with native grasses (Rossiter et al., 2003). Much of the Yellow-snouted Gecko’s habitat has been invaded by exotic grasses such as Gamba Grass and Mission Grass. These exotic grasses increase fire fuel loads and promote intense, late, dry season fires as they have a higher biomass than native grasses and cure later in the dry season than native grasses. Mapping by the NT Government shows that the climate and soil type that supports the Yellow-snouted Gecko are also suited to Gamba Grass infestations (S. Setterfield and M. Douglas 2006, pers. comm.). Gamba Grass is currently invading one of the few sites where the Yellow-snouted Gecko occurs in the Wildman and Mary River catchments (Robertson, pers comm., 2005). Current fire regimes are likely to increase the mortality of geckoes and their eggs and decrease the leaf litter in which they reside, as well as increase their predation (Department of the Environment, Water, Heritage and the Arts, 2006). Gouldian Finch The Gouldian Finch is a small, multi-coloured granivorous bird that is found in the northern savannas of Australia (O’Malley, 2006). They occur in northern Australia within the Northern Territory, Western Australia and Queensland. The Gouldian Finch is listed as endangered under the EPBC Act. The spread of Gamba Grass will threaten the Gouldian Finch as it will lose food resources, as their habitats will be dominated by a single introduced grass which provides seeds at only one time of the year as opposed to a mix of grasses that provide seeds differentially over a longer period (Cook, 1991). The restricted diet of the Gouldian Finch makes it susceptible to seed shortages. The spread of Gamba Grass and the subsequent increased frequency and intensity of late, dry season fires may also threaten the Gouldian Finch by reducing the number of nesting hollows (Tidemann, 1996; Dostine, 1998) and vegetative cover, resulting in the species having an increased exposure to radiant heat. The Gouldian Finch has a low tolerance to intense heat and is known to abandon water holes that have been exposed to extreme fires in the dry season (Tidemann, 1996; Burton and Weathers, 2003). In addition, the Gouldian Finch is known to have a more restricted diet than other seed eating birds (Garnett & Crowley, 1994, 1995, 1999; Fraser, 2000; Dostine et al., 2001; Dostine & Franklin, 2002; Todd et al., 2003), and a moulting period that is considered to be energetically demanding and coincides with a period when food availability is low (Franklin et al., 1998). Consequently, the Gouldian Finch may also be susceptible to seed shortages caused by an increase in the intensity and frequency of fire in northern Australia (Crowley and Garnett, 2001; Dostine et al., 2001; Dostine and Franklin, 2002). In its submission to the Department, the CRC for Weed Management provided supporting information that Gamba Grass is having a negative impact on the Gouldian Finch in Queensland (R. McFadyen 2006, pers. comm.). It stated that the Gouldian Finch is found in the Georgetown area of Queensland where it is threatened by Gamba Grass. For example, Gamba Grass has spread around the Mareeba Wetlands where it is directly threatening a newly established population of Gouldian Finches. The CRC for Weed Management also stated that the Gouldian Finch relies on short native grasses for foraging and are eliminated from areas infested with Gamba Grass which are affected by intensely hot, late, dry season fires (R. McFadyen 2006, pers. comm.). Gove Crow Butterfly


The Gove Crow Butterfly is a large, black-brown butterfly with white spots on the edge of its wings. It is listed as endangered under the EPBC Act and the Territory Parks and Wildlife Conservation Act 2000. It is only found on the Gove Peninsula, north-east of Arnhem Land, in the Northern Territory (Department of Natural Resources, Environment and the Arts, 2006c). Mission Grass has only recently been established on the Gove Peninsula and is currently found within the Gove Crow Butterfly's distribution. The more frequent and intense fires generated by Mission Grass can have a detrimental effect on tropical rainforest patches leading to a decrease in their size and eventually to their complete demise (Department of Natural Resources, Environment and the Arts, 2006c). Tropical rainforest (Evergreen Monsoon Vine-forest) provides critically important habitat for the Gove Crow Butterfly. As a result, it is expected that if Mission Grass is not adequately controlled, tropical rainforest on the Gove Peninsula will decline and so will the Gove Crow Butterfly (Department of Natural Resources, Environment and the Arts, 2006c). Yellow Chat (Alligator Rivers) Another example of a species that is being adversely affected by high biomass exotic grasses is the Yellow Chat (Alligator Rivers), which is listed as endangered under the EPBC Act and the Territory Parks and Wildlife Conservation Act 2000. The Yellow Chat (Alligator Rivers) is a mainly insectivorous, small bird in the Honeyeater family. It commonly forages on the ground in dense grasslands or shrublands near water sources in semi-arid areas. The male is a striking golden-yellow colour and has a black chest band. The female is a pale lemon-yellow colour and has no chest banding. It is endemic to the Northern Territory and is found in a limited geographic area encompassing the floodplains from the Adelaide River to the east Alligator River. This species is being threatened by the invasion of exotic weeds such as Para Grass, Gamba Grass, and Olive Hymenachne, which modify the species’ habitat by increasing the density of the grass and shrub layer, smothering native grasses and increasing fuel loads which promote intense, late, dry season fires. These changes in the species’ habitat make it unsuitable for the Yellow Chat (Alligator Rivers) (Garnett and Crowley, 2000; Woinarski, 2002c). Conclusion for Criterion C: The Committee considers that the threatening process is eligible under this criterion as the process is likely to adversely affect at least four species that are listed as endangered under the EPBC Act. These are the:

Yellow-snouted Gecko - High biomass exotic grasses such as Gamba and Mission Grass adversely affect the Yellow-snouted Gecko by increasing the mortality of geckoes and their eggs, decreasing the leaf litter in which they reside, and increasing their predation;

Gouldian Finch - High biomass exotic grasses affect the Gouldian Finch by modifying their habitat, reducing nesting hollows, reducing foraging resources by smothering native grasses and promoting extremely hot, late, dry season fires which destroy food sources;

Gove Crow Butterfly – This species is adversely affected by Mission Grass in that it threatens its habitat as a result of increasing intense, late, dry season fires; and

The Yellow Chat (Alligator Rivers) - This species is threatened by the invasion of exotic weeds such as Para Grass, Gamba Grass, and Olive Hymenachne which modify


the species’ habitat and alter local fire regimes, making it unsuitable for the Yellow Chat (Alligator Rivers).

CONCLUSION: The threatening process does not meet s188(4)(b) of the EPBC Act. However the threatening process meets s188(4)(a) and s188(4)(c) of the EPBC Act and is therefore eligible to be listed as a Key Threatening Process. 3. Threat Abatement Plan 3.1 Degree of Threat All of the introduced grasses in this threatening process are high biomass grasses that out-compete native grasses and increase fuel loads which promote intense, late, dry season fires. In the case of Gamba Grass and the Mission Grasses, these intense fires are killing trees and converting eucalypt woodlands into exotic grasslands. The Committee considers that this is a current and widespread threat to a variety of native species. 3.2 Potential for Threatened Species to Recover The threats posed by the introduced grasses in this threatening process can be controlled by preventing further spread into new habitats, eradicating weeds and rehabilitating the ecosystems where these weeds have invaded. The majority of the weeds in this threatening process are in the relative early stages of invasion. Consequently, a coordinated, timely response to the threat posed by these invasive weeds could abate the threat this process poses to a variety of species. Threatened species have the ability to recover from the impacts of introduced grasses. Local eradications of other introduced grasses in northern Australia have led to re-colonisation of habitats by native endemic species. For example, in the Epping Forest National Park in Queensland the removal of Buffel Grass (Cenchrus ciliaris) has lead to the re-establishment of native grasses such as Kangaroo Grass (Themeda australis). The slashing of strips of Buffel Grass around Northern Hairy-nosed Wombat burrows in the park may be one of the factors that has contributed to the increase in this nationally endangered species’ numbers from 90 in 2002 to 115 in 2006 (A. Dinwoodie 2008, pers. comm.).


3.3 Current Threat Abatement Actions There are a number of national and state-based initiatives in place to address this threatening process. These are instructive when considering the need for a national Threat Abatement Plan. National Initiatives

AusBIOSEC is a policy framework that provides for national collaboration on biosecurity issues. This includes managing pests (including weeds) and diseases in terrestrial, freshwater and marine environments. It aims to provide a coordinated national approach to prevention, emergency response to new incursions, and management of established invasive species. AusBIOSEC builds on existing strategies, including The Australian Weeds Strategy.

The Australian Weeds Strategy provides guidance to all stakeholders involved in weed

management and identifies priorities for weed management across Australia. The goals of the strategy are: preventing new weed problems; reducing the impact of existing priority weed problems; and enhancing Australia's capacity and commitment to solve weed problems. Under the strategy, priority is given to control and management of 20 plant species identified as Weeds of National Significance. This includes Olive Hymenachne, but does not include the other weed species covered by this threatening process. The Australian Weeds Committee supports the implementation of the Australian Weeds Strategy by facilitating and coordinating consistent national action on weed tasks.

State and Territory Initiatives Northern Territory

The Territory Weeds Management Strategy (1996-2005) aims to: prevent the spread of weeds within, into and out of the Northern Territory; provide guidance on the integration of control methods including physical, chemical, ecological and biological control methods; and promote cooperative weed management amongst landholders at a catchment level.

Report on Invasive Species and Management Programs in the Northern Territory by the Legislative Assembly of the Northern Territory. The aim of this inquiry was to prevent new incursions of invasive species in the Northern Territory and to implement effective eradication and management programs for existing invasive species. One of the recommendations of this report was that Gamba Grass and other improved pasture species with weedy characteristics should be subject to legislative control in the Northern Territory (Legislative Assembly of the Northern Territory, 2008).

The Northern Territory Government in collaboration with Charles Darwin University has developed a Weed Risk Management system. The aim of this process was to assess the degree of threat posed by various weeds and to quantify the government’s ability to manage them. A ranking system was developed for prioritising weeds for control in the Northern Territory.

Queensland

Pest management plan: Areas managed by Queensland Parks and Wildlife Service July 2003 - July 2008. The aim of the plan is to: prevent the introduction or spread of any declared plant or animal on the Queensland Parks and Wildlife Service estate; undertake pest control programs in cooperation with neighbouring landholders, other


State agencies and local governments; and protect natural and cultural values, including threatened species and ecosystems, by eradicating pests or significantly reducing impacts.

The Queensland Weeds Strategy 2002–06 establishes a state-wide planning

framework, providing clear direction to government, community, industry and individuals for the management of weeds across Queensland. This strategy is linked to the National Weeds Strategy and various individual weed management plans.

Western Australia

Environmental Weed Strategy for Western Australia 1999 and the associated environmental weed database, is a tool to prioritise the weeds of Western Australia and provide control options and revegetation strategies once the weeds have been adequately controlled.

3.4 Efficient and Effective Use of Resources The Australian Weeds Strategy and AusBIOSEC provide for national coordination for the control of weeds. However, with the exception of Olive Hymenachne, these strategies don't include specific control and management actions for the weed species identified in this threatening process. A threat abatement plan for this threatening process would be consistent with the goals of these overarching strategies and would complement current on-ground work. However, it would focus specifically on actions required for abatement of these five species within northern Australia. Where programs are already in place for Olive Hymenachne (as one of the Weeds of National Significance), a threat abatement plan would refer to and build on existing actions as appropriate. The development of a national Threat Abatement Plan would be a feasible, effective and efficient way to abate this threatening process at this time. The majority of the weeds in this threatening process are in the relatively early stages of invasion. Consequently, a coordinated, timely response to the threat posed by these invasive weeds will have a greater chance of success. The extent of these invasive weeds is still at a level that makes management and control possible and practical. For example, Gamba Grass currently only occupies a small portion of its potential distribution, although it is expanding rapidly. Therefore, timely action may prevent it from spreading across all savanna woodlands and open forests, riparian zones, floodplain margins and monsoon vine thickets in Northern Australia (Flores et al., 2003, cited in S. Setterfield and M. Douglas 2006, pers. comm.). A national Threat Abatement Plan would provide a framework for prioritising investment in actions to abate the threat of this threatening process. This threatening process covers the jurisdictions of Queensland, Western Australia and the Northern Territory. A national Threat Abatement Plan would allow for coordinated control, funding, and knowledge sharing across these jurisdictions to improve management. As the invasive weeds in this threatening process are not all declared weeds across all of the jurisdictions that they occur, a national Threat Abatement Plan would assist in encouraging consistency of management across all jurisdictions.


The five high biomass grasses in this threatening process can be effectively controlled in small patches using current methods such as removal by hand, spraying with herbicide, ploughing, grading, slashing, burning and grazing. However, dense infestations are more difficult to manage and large infestations may require coordination between local, state and Commonwealth agencies and landowners for effective control. In northern Australia there is a high level of awareness of the threats posed by these invasive weeds and strong community support for action to control these weeds (S. Setterfield and M. Douglas 2006, pers. comm.). Key features of a national Threat Abatement Plan could include:

a review of current control methods; an assessment of the efficacy of different control mechanisms; determining the pathways of spread of these invasive weeds; prioritising the threat abatement actions to eliminate, control or limit further spread of

the invasive weeds included in this threatening process; containing and eradicating isolated infestations in areas of high biodiversity; minimising further spread of these weeds into weed-free areas and areas considered to

be environmentally significant; the development of a national management strategy that includes regional

coordination of control programs across the NT, QLD and WA; developing a mapping and monitoring database to inform management; an outline of possible incentives for removal of the invasive weeds included in this

threatening process; developing and implementing an education and engagement strategy to mobilise

management action from landholders; addressing the social and economic impacts of the process in terms of the significant

threat it poses to people, property, agricultural production and tourism.

CONCLUSION: The Committee considers a Threat Abatement Plan to be a feasible, effective and efficient way to abate the process at this time. The majority of the weeds in this threatening process are in the relatively early stages of invasion and still at a level that makes management and control possible and practical. In addition, this threatening process covers the states and territories of Queensland, Western Australia and the Northern Territory and abatement action would benefit from national coordination. At the national level, a Threat Abatement Plan would complement the work of the Australian Weeds Strategy and AusBIOSEC.


4. Recommendations

A. The Committee recommends that the list referred to in section 183 of the EPBC Act be

amended by including in the list as a key threatening process: ‘Ecosystem degradation, habitat loss and species decline due to invasion of northern Australia by introduced Gamba Grass (Andropogon gayanus), Para Grass (Urochloa mutica), Olive Hymenachne (Hymenachne amplexicaulis), Mission Grass (Pennisetum polystachion) and Annual Mission Grass (Pennisetum pedicellatum)’.

B. The Committee recommends that a Threat Abatement Plan is considered a feasible,

efficient and effective way to abate the process at this time. Associate Professor Robert J.S. Beeton AM FEIANZ Chair Threatened Species Scientific Committee


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