Literature review: Impact of Chilean needle grass ... - Weeds Australia

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