Literature review: Impact of Chilean needle grass ... - Weeds Australia
Literature review: Impact of Chilean needle grass ... - Weeds Australia
Literature review: Impact of Chilean needle grass ... - Weeds Australia
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Austrostipa-Enneapogon) from around New Norfolk to south <strong>of</strong> Launceston. Frequent frosts appear to be the main cause <strong>of</strong><br />
treelessness (Lunt et al. 1998). Secondary <strong>grass</strong>lands resulting from tree clearance are present in near-coastal areas where<br />
frequent burning prevent encroachment by Melaleuca ericifolia (Lunt et al. 1998). Poa labillardieri <strong>grass</strong>lands on Cape Barren<br />
and Flinders Islands were probably formed by repeated burning <strong>of</strong> forest (Kirkpatrick et al. 1995). Austrodanthonia, Austrostipa,<br />
Poa, Microlaena stipoides and T. triandra are the dominant <strong>grass</strong>es, the latter probably the major dominant at the time <strong>of</strong><br />
European settlement (Lunt et al. 1998). Almost all <strong>of</strong> Tasmania’s remnant are grazed by livestock (Kirkpatrick 2007). Exotic<br />
plants have been reported to comprise 23% <strong>of</strong> the <strong>grass</strong>land vascular flora (Kirkpatrick et al. 1995).<br />
Several plant communities comprise the Tasmanian <strong>grass</strong>lands (Kirkpatrick et al. 1995):<br />
1. Austrodanthonia – Astroloma humifusum East Coast Tasmanian Grassland, a derived formation dominated by sparse A.<br />
caespitosa (Gaudich) H.P. Linder, A. pilosa (R.Br.) H.P. Linder and A. racemosa (R.Br.) H.P. Linder with other <strong>grass</strong>es, and<br />
intertussock spaces occupied by herbs and the epacrid A. humifusum (Cav.) R.Br.<br />
2. Poa labillardieri – Lomandra longifolia – Acaena novae-zelandiae Tasmanian Valley Grassland, mainly in the Midlands,<br />
dominated by P. labillardieri and L. longifolia Labill. (Xanthorrhoeaceae), with various components including Juncus spp. and<br />
A. novae-zelandiae Kirk (Rosaceae).<br />
3. P. labillardieri – Microlaena stipoides – Solenogyne dominii Tasmanian Valley Grassland, characterised by sparse Poa<br />
tussocks interspersed with <strong>grass</strong>es and herbs including the Flat Daisy, S. dominii L.G. Adams.<br />
4. P. labillardieri – Juncus – Hypericum japonicum Tasmanian Flood Plain Grassland, with large Poa tussocks, found on alluvial<br />
flats.<br />
5. Poa rodwayi – Astroloma humifusum Tasmanian Rock Outcrop Grassland, found on shallow sandy clay loams around dolerite<br />
outcrops.<br />
6. Themeda – Hibbertia hirsuta – Astroloma humifusum Tasmanian Grassland, widespread in the Midlands and on the east coast,<br />
much <strong>of</strong> it probably derived from <strong>grass</strong>y woodland.<br />
7. Themeda – Stipa stuposa – Chrysocephalum apiculatum Tasmanian Grassland, on fertile, well-drained sites in the Midlands.<br />
8. Themeda – Solenogyne gunnii – Microlaena stipoides Tasmanian Grassland, also in the Midlands and on the east coast, many<br />
remnants probably derived from woodlands.<br />
New South Wales and <strong>Australia</strong>n Capital Territory<br />
For convenience, discussion <strong>of</strong> the NSW and ACT native <strong>grass</strong>lands is subdivided into three geographical regions. This ignores<br />
the occurrence <strong>of</strong> Temperate Montane Grasslands in outliers around Braidwood, Goulburn, Bathurst and the Albury area, and the<br />
whole Austrostipa aristiglumis-dominated Western Slopes Grasslands on the North West and Central West Slopes and Plains<br />
(Keith 2004). The previous extent <strong>of</strong> ‘natural’ <strong>grass</strong>lands in New South Wales remains controversial. There are large areas <strong>of</strong><br />
derived <strong>grass</strong>land. Based on a survey <strong>of</strong> 126 selected landholders Garden et al. (2000) estimated that nearly 1.4 m ha (40%) <strong>of</strong><br />
Central, Southern and Monaro Tablelands pastures (excluding the ACT) contained significant amounts <strong>of</strong> native perennial<br />
<strong>grass</strong>es, representing 48%, 31% and 40% respectively <strong>of</strong> the area <strong>of</strong> these regions. It was assumed that “cleared and undisturbed<br />
areas were essentially dominated by native perennial <strong>grass</strong>es” and that timbered areas and areas disturbed by cultivation or<br />
hebicides to sow pastures or crops were not (Garden et al. 2000 p. 1085). The figures probably significantly underestimate the<br />
true extent <strong>of</strong> native <strong>grass</strong> dominance, since many disturbed area have been recolonised and some sowing <strong>of</strong> exotic pastures has<br />
occurred amongst native <strong>grass</strong>es (Garden et al. 2000). Groves et al. (1973) considered that except for frost hollow areas the<br />
Themeda/Poa <strong>grass</strong>lands <strong>of</strong> south-eastern NSW were derived from woodland, and maintained by sheep grazing and regular<br />
burning.<br />
Compared to other States, large areas <strong>of</strong> native <strong>grass</strong>land in New South Wales exist in Travelling Stock Routes and Reserves,<br />
linear reserves up to 400 m wide, that are leased by Rural Land Protection Boards for grazing (Kirkpatrick et al. 1995).<br />
Southern Tablelands (NSW and ACT)<br />
The Murrumbateman (South Eastern Highlands 6) bioregion covers the <strong>Australia</strong>n Capital Territory and surrounding areas in<br />
NSW and includes the Monaro Tablelands. Grassy woodlands are the major native vegetation type in the region but <strong>grass</strong>lands<br />
occurred throughout, especially on clay substrates in lower rainfall areas, in frost hollows and land with poor drainage (Lunt et<br />
al. 1998). The soils are typically fertile clays and are derived from basalt, limestone or other sedimentary rocks (Keith 2004).<br />
The <strong>grass</strong>lands in the region are included in Benson’s (2004) and Keith’s (2004) Temperate Montane Grasslands, which include<br />
the <strong>grass</strong>lands <strong>of</strong> the ACT, Southern Tablelands and Monaro Plains. According to Keith (2004) they occur at 550-1500 m<br />
altitudes in areas with 500-750 mm annual rainfall and are closely related to Tableland Clay Grassy Woodlands, widespread on<br />
both the Northern and Southern Tablelands <strong>of</strong> NSW. On clay soils they are dominated by T. triandra and Poa spp., on lighter<br />
soils and drier upper slopes by Austrostipa, Austrodanthonia and Bothriochloa and along drainage lines by Poa labillardieri. The<br />
inter-tussock spaces are occupied by erect, scrambling and rosette herbs, and geophytes including orchids and lilies (Keith 2004).<br />
Benson (2004) and to a lesser extent Keith (2004) include alpine <strong>grass</strong>lands dominated by Poa spp. in this class, although Keith<br />
acknowledges a gradation into Poa costiniana Vickery alpine herbfield/<strong>grass</strong>land. Temperate Themeda/ Austrodanthonia/<br />
Austrostipa <strong>grass</strong>land was one <strong>of</strong> the dominant ecosytems in the region (Lunt et al. 1998, Sattler and Creighton 2002), with pre-<br />
European extent in the ACT <strong>of</strong> about 14,000 ha, or 20,000 ha if sparsely treed areas (