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

in shifting the distribution, extent and composition of grasslands. All these major factors are compounded, their individual
influences are difficult to determine from the limited palaeecological records (Hope 1994) and existing remnants may have little
resemblance to their pre-European condition (Trémont and McIntyre 1994). The palaeontolgy of temperate Australian grasslands
is discussed in the section on grasslands origins (above), while the pre-European influences of aboriginal grassland management,
grazing and fire, and the post European disturbance and management factors are discussed in sections on these topics below.
Aboriginal management
In south-eastern Australia, apart from the coast, grassland was the main habitat occupied by aborigines (Kirkpatrick et al. 1995).
The earliest undisputed evidence for aboriginal occupation of Australia remains at around 40,000 ypb in the Kimberley of
Western Australia, close to the limit of resolution of radiocarbon dating, but evidence using other techniques indicates first
occupation may have occurred c. 60 kybp (Kershaw et al. 2000). Coutts (1982) claimed that aboriginal people were present in
Victoria at least as long ago as 40 kybp, but the oldest south-eastern mainland site known, at Willandra Lakes, is dated at c. 36
kybp (Kershaw et al. 2000). Most of Australia, including Tasmania was probably occupied by 35 (Hope 1994) or 32 kybp, all
major environments were certainly occupied by 22 kybp, and occupational intensities increased after c. 5 kybp (Kershaw et al.
2000). Aborigines coexisted for many thousands of years with the extinct marsupial megafauna in the early prehistoric period
(Coutts 1982, Kershaw et al. 2000).
Aboriginal people managed the land over many thousands of years (Zola and Got 1992) and would have witnessed the assembly
of many Australian grasslands, notably on the Victorian Volcanic Plains, where the most recent terrain was formed several
thousand years ago. The total aboriginal population of Victoria in 1788 has been estimated at 15,000 (Coutts 1982) but actual
population is very uncertain. Mulvaney (1964) suggested a population density of one person per 13 km 2 in the western district of
Victoria prior to European settlement, with a total population of 1,800. Mulvaney’s estimate is probably much too low, since
800-1,000 western district aborigines were known to gather annually at Lake Bolac (Jones 1999b). The South East of South
Australia supported an “unusually large population, perhaps numbering 2000” (Pretty et al. 1983 p. 116). The population in that
region is estimated to have declined by half every five years, from the beginning of settlement in 1840 (Pretty et al. 1983).
Numerous archaeological sites are recorded on the Victorian Basalt Plains including campsites, earthen mounds (probably long
occupied campsites), burials, canals and weirs of basalt rocks used as fish traps, basalt block walls probably roofed with timber
and used as huts, etc. (Coutts 1982). Indications are that some populations were more or less sedentary, rather than nomadic.
Digging and burning of the vegetation were probably the most important aboriginal activities in terms of grassland ecology, and
areas of grassland appear to have been extended by aboriginal activities (Kirkpatrick et al. 1995). However in the mid to late
Holocene some societies in more arid areas developed economies based on systematic harvesting and processing of grass seed
(Kershaw et al. 2000, Gammage 2009). One species exploited was Barley Mitchell Grass, Astrebla pectinata (Lindl.) F. Muell.,
a common and very widespread species of the summer rainfall semi-arid and arid zones. It has “relatively large seeds that
separate easily from the chaff” and “at one time provided an important part of the diet of the Aborigines” (Cribb and Cribb 1974
p. 101). Another grain, with distribution extending into more temperate winter rainfall areas of south-eastern Australia, was
Native Millet or Windmill Grass, Panicum decompositum R.Br., a species “often associated with temporarily wet places such as
creek beds and flood plains” (Jessop et al. 2006 p. 461). It was a major foodplant (Jessop et al. 2006), extensively cultivated
(Gammage 2009), the seeds being ground into a paste and baked to form bread (Cribb and Cribb 1974). Another arid zone
species harvested was Woollybutt, Eragrostis eriopoda Benth. (Jessop et al. 2006), which has abundant, readily husked, soft,
easily-ground seed that is held on the plant for months (Low 1989). Other Panicum spp. were also used (Low 1989). Perhaps
Hairy Panic, Panicum effusum R.Br., a common associate of T. triandra in temperate south-eastern grasslands, was used in a
similar manner. Eragrostis tef (Zucc.) Trotter and Panicum miliaceum L. were amongst the grasses cultivated in pre-Islamic
civilisations in Arabia (Pohl 1986). Current consensus appears to be that grasses were not important in the diets of aborigines
living outside the dry interior, and Gammage (2009) has convincingly argued that they were little used in areas with a reliable
supply of edible tubers. However the possibility that aboriginal management of cereal grasses influenced the structure and
biodiversity of the temperate grasslands of south-eastern Australia should not be ignored.
Intensive digging took place in the temperate grasslands to harvest roots for food, particularly Murnong, Microseris spp., which
was stockpiled and traded (Gott 1983), and Turrac (probably Pelargonium rodneyanum) (Lunt et al. 1998). Numerous other
tuberous or bulbous grassland species were eaten (Gott 1999) including Vanilla and Chocolate Lilies Arthropodium spp.
(Wigney 1994, Zola and Gott 1992), Bulbine Lily Bulbine bulbosa (R.Br.) Haw., Milkmaids Burchardia umbellata R.Br. and a
range of other lilies and orchids (Zola and Gott 1992). Approximately one quarter of the vascular plant species recorded in the
Victorian Basalt Plains were used by aboriginals, of which approximately 20% were used as food (Gott 1999). Over 100 plant
species found in the grasslands and grassy woodlands of Tasmania are known to have been used by aborigines elsewhere in
Australia (Kirkpatrick et al. 1995). Harvesting of roots resulted in improved aeration and water infiltration into the soil and
nutrient incorporation from litter and ash, and would therefore have enabled better plant regeneration. Dug areas would have
increased the availability of regeneration niches for many plants (Gott 1999). Recent studies have confirmed that this occurs with
the orchid Diuris fragrantissima, where soil aeration, consisting of tilling to 20 cm depth, significantly increased the proportion
of spring-planted plants that emerged and flowered (Smith et al. 2009). Aborigine thinned patches of the tuberous and bulbous
food plants, deliberately replanted them and traded valued plant production between clans and tribes (Gott 1999).
Burning in the dry season in Victoria may have enhanced the abundance and distribution of some plants e.g. Microseris spp.
(Gott 1983). According to Flannery (1994) fire was critical in releasing nutrients into the system to enable regeneration of plant
foods, however this may have been of limited importance in grasslands because of the limited nutrient reserves in above ground
vegetation during a significant proportion of the fire season. Burning was probably more critical to keep grass biomass low: the
tuber feeding people burnt “to expose the tubers, to improve their taste, and to keep grass sparse and give tubers and herbs
space” (Gammage 2009 p. 286). Burning was frequent on the Victorian Volcanic Plain prior to European occupation, being used
by aborigines in hunting and to encourage new growth, and probably assisted in maintaining treelessness (Stuwe 1994, DNRE
1997). Fires were reported by early maritime travellers in Port Phillip region in all months from spring to autumn (Jones 1999b).
Aborigines would have increased fire frequency above the background rate as a result of deliberate burning, accidental escapes
from camp fires (Stuwe 1994) and possibily the use of fire as a weapon against invading non-indigenous people (Flannery 1994).
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