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

esulting from vulcanism would have periodically impacted on the vegetation (Rosegren 1999). Some secondary grasslands are
present, resulting from tree removal or suppression of tree regeneration by livestock, notably on stony rises (Kirkpatrick et al.
1995).
Grasslands in the Victorian Midlands are included in this category. Little is known about the original extent and composition of
the Midlands grasslands. They were mostly in the Dundas tablelands, an undulating area west of the Grampians, 90% of which
has now been cleared and which currently supports sheep and cattle grazing (DNRE 1997). The principal areas were in the
Glenelg and Wannon catchments west of Hamilton. Smaller areas were present in the Goldfields and Central Victorian Uplands
Bioregions. Remnants are are often degraded (DNRE 1997). Prior to European occupation the heavy clays in the Wannon region,
near the western end of the Volcanic Plains, were often occupied by grasslands (Lunt et al. 1998).
The flora of the Victorian volcanic plains as a whole is the most highly modified vegetation in the State (Willis 1964). The
grasslands were the first areas of Victoria occupied by squatters in the 1830s and 1840s for sheep and cattle grazing (Willis
1964, Turner 1968) and “conversion of tribal territory to sheep-runs was rapid and decisive” (Mulvaney 1964 p. 427). These
areas “were especially valuable because they required little or no clearing” (Wadham and Wood 1950 p. 84). According to
Marshall (1968 p. 165) “the native flora was virtually exterminated over hundreds of square miles”. Nevertheless there is still
high diversity in the area as a whole. Carr (1999) provided a checklist of the Victorian Volcanic Plains indigenous flora, listing
the conservation status of each taxon and the vegetation formations in which they occur. Treeless grasslands and grassy
woodlands were not considered to be separate formations. Stony Rise Complex, in many ways a similar floral assemblage to the
grasslands, was treated as a separate entity. Asteraceae and Poaceae were by far the richest families (Table 13). McDougall
(1987) provided a list of the common vascular plant species in the basalt plains tussock grassland in the eastern section of the
Plains (Melbourne region) and a list and brief description of 32 remnant sites on private and public land.
Table 13. Number of plant taxa in plant families with the greatest number of taxa in Victorian Volcanic Plains grasslands and
grassy woodlands. Derived from Carr (1999). Taxa doubtfully occuring in this vegetation formation are recorded as “Uncertain”.
Liliaceae is the combination of Carr’s Anthericaceae, Asphodelaceae, Colchichaceae, Hypoxidaceae and Phormicaceae.
Family
No. of taxa
Known Uncertain Total
Asteraceae 61 9 70
Poaceae 56 7 63
Orchidaceae 18 20 38
Liliaceae 23 1 24
Fabaceae 19 1 20
Chenopodiaceae 16 2 18
Cyperaceae 13 1 14
Juncaceae 10 1 11
Two main types of grassland occur, dominated respectively by T. triandra in the drier eastern portion and by Poa labillardieri in
the higher rainfall western portion, and grassy wetlands occurred in areas subject to seasonal inundation (Lunt et al. 1998,
Barlow and Ross 2001). The daisies Rutidosis leptorhynchoides and Senecio macrocarpus have been identified as subdominant
herbs on red-brown earth soils (Hills and Boekel 2003). T. triandra was the original main dominant over a high proportion of the
area, with subdominant Austrodanthonia and Austrostipa spp., forming discrete tussocks with a range of herbs in the intertussock
spaces (Lunt 1990a). In the eastern area Austrodanthonia spp. are occasionally locally dominant, and low lying areas are
dominated by this genus or P. labillardieri and are “usually species rich”, while Themeda-dominated areas may be depauperate
due to dense cover (McDougall 1987 p. 17).. The T. triandra tussocks are rarely taller than 30 cm (not including panicles) and
have a basal diameter of 5-15 cm (Specht 1970).
Kirkpatrick et al. (1995) considered that most of the basalt plains grassland was a T. trindra – Eryngium ovinum – Schoenus
apogon association, with other characteristic species including Acaena echinata (Rosaceae), Leptorynchos squamatus (Labill.)
Less. (Asteraceae) and Convolvulus spp., and at drier sites, Calocephalus citreus Less. (Asteraceae). Other areas were dominated
by a T. triandra - Austrodanthonia setacea community, similar to, and possibly a degraded form of the former. Stony rises were
occupied by a community dominated by T. triandra, Austrostipa semibarbata and Poa sieberiana, sometimes with scattered
shrubs of Bursaria spinosa or small trees (Acacia melanoxylon R.Br. and Allocasuarina verticillata (Lam.) L.A.S. Johnson),
possibly derived from woodlands. Another T. triandra community, occurring in the Merri Creek Valley and on the Keilor Plains,
is characterised by sparse shrubs of Acacia paradoxa DC., and commonly Austrostipa mollis (R.Br.) S.W.L. Jacobs and J.
Everett and Austrodanthonia carphoides Kirkpatrick et al. (1995). McDougall (1987) found that many early maps referred to
occasional ‘Honeysuckle’ trees in the grasslands to the north-west and west of Melbourne and concluded that these were
probably Banksia marginata Cav. (Proteaceae), a species which no longer existed in this formation in the region. Barlow and
Ross (2001) expanded this interpretation and considered this formation to be a Banksia marginata Cav./Allocasuarina
verticillata/Acacia implexa Benth. woodland, none of which survived into modern times (Barlow and Ross 2001).
The grasslands formed a complex mosaic with other vegetation types, including wetlands and riparian areas, grassy woodlands,
shrublands and herblands, which have been similarly degraded or destroyed (McDougall 1999, Barlow and Ross 2001). In the
western part of the plains, Grassy Woodland dominates wherever rainfall exceeds c. 700 mm per annum and trees naturally
occured on the most rocky areas througout the region (Kirkpatrick et al. 1995) and on scoria cones (Barlow and Ross 2001).
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