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

Roofing tiles were found to be regularly used as artificial shelters and determined to be a useful survey and population
monitoring tool. She also developed an objective pictorial method of identifying individual animals based on head scale patterns.
D. impar is listed as Vulnerable at the national level (Hadden 1995, Webster et al. 2003), Vulnerable in the ACT (Sharp 1997)
and NSW and Endangered in South Australia and Victoria (O’Shea 2005).
Tympanocryptis pinguicolla (Mitchell) Grassland Earless Dragon (Agamidae)
Tympanocryptis Peters is an endemic Australian genus of small, terrestrial dragons distributed through most of mainland
Australia (Cogger 1983). T. pinguicolla was originally described as T. lineata pinguicolla Mitchell in 1948 and raised to species
status in 1999 with a change of common name from Eastern (ACT Government 2005) or Southern Lined Earless Dragon
(Brereton and Backhouse 2003). The vernacular name refers to the absence of an external ear opening, and of a functional
tympanum (ACT Government 2005) which is “hidden below the skin of the head” (Cogger 1983 p. 250). It was once abundant in
the ACT and was recorded from near Cooma in the Southern Tablelands and Bathurst in NSW (ACT Government 2005). In
Victoria, anecdotal evidence indicates it was once not uncommon in basalt plains grasslands north and west of Melbourne. All
Victorian records with habitat data were from areas of rocky, open T. triandra grassland, including sites on the Jackson Creek at
Holden Flora Reserve near Diggers Rest, the upper reaches of the Merri Creek, north of Donnybrook, and the Little River Gorge
west of Werribee. All sites where it was observed between 1988 and 1990 were T. triandra grasslands with Red-leg Grass
Bothrichloa macra and Silky Blue-grass Dichanthium sericeum (R.Br.) A. Camus in ungrazed or lightly grazed paddocks
(Brereton and Backhouse 2003). In the ACT it is known from seven sites in natural temperate grassland and appears to prefer
sites with little disturbance and grasslands that are short and open (ACT Government 2005). T pinguicolla is a diurnal, wholly
terrestrial, insectivorous(Brereton and Backhouse 2003) and arachnivorous (ACT Government 2005)species which shelters in
small burrows (Brereton and Backhouse 2003) including those of invertebrates, under rocks and within Austrostipa tussocks
(ACT Government 2005). It is an oviparous species and females are believed in the main to breed only once, and to die after 1
year (ACT Government 2005). Loss and modification of habitat is probably largely responsible for its great decline (Brereton
and Backhouse 2003).
Other species
The Pink Worm Lizard Aprasia parapulchella Kluge was known only from Coppins Crossing on the Molongo River, ACT and
from near Tarcutta and Bathurst, NSW, the type specimens recorded under weathered granite rocks on a grazed, grassy riverside
(Cogger 1983) and was listed as nationally endangered (Sharp and Shorthouse 1996). A recovery plan for the species in the ACT
was published in 1995 (Sharp and Shorthouse 1996). The Corangamite Water Skink Eulamprus tympanum marnieae (Lvnnberg
and Andersson) is endemic to the Victorian Volcanic Plain (DNRE 1997, Department of Sustainability and Environment 2007).
Its inhabits rocky areas on the margins of wetlands in a limited area of the Victorian volcanic plains so exists on the margins of
grasslands. “Weed invasion” is one threat to this species (Department of Sustainability and Environment 2007). The Pygmy
Bluetongue, Tiliqua ?adelaidensis (Peters) is another grasslands species that may be threatened. Cogger (1983 p. 388) recorded
that its distribution was “not known” with most recorded specimens from the Adelaide region. It was listed as ‘Indeterminate’ in
the IUCN Red List of Threatened Vertebrates (IUCN 1988) with not enough information available to determine whether it was
enadangered or rare. The Pygmy Bluetongue reportedly “depends on spider holes for shelter in the grasslands around Burra in
South Australia’s Mid North” (Lunt et al. 1998).
Invertebrates
Plant invasions have the potential to modify interactions amongst species at all trophic levels. Changes to the composition,
structure and functioning of communities caused by alien plant invasions have a major impact on native insects (Samways 2005).
These effects include alteration of species richness and the composition of the fauna. The mechanisms include displacement of
indigenous food plants, alterations to solar insolation by shading, and to shelter characteristics of the vegetation (Samways
2005). The impacts are generally complex, with individualistic responses by the range of taxa.
On a world basis, ungulate mammals are the dominant herbivores in tropical grasslands whereas in temperate grassland this role
is taken by insects (Tscharntke and Greiler 1995). Insects consume a greater proportion of the plant biomass compared to their
own biomass than mammals (Tscharntke and Greiler 1995). Several features of grasses play a role in determining their insect
fauna: lack of secondary thickening (woody tissue), simple architecture, protected buds, almost complete lack of secondary
compounds with herbivore deterrence properties, but an abundance and great variety of silica bodies (phytoliths) in the epidermis
that increases their resistance to invertebrate herbivory (Stebbins 1986, Tscharntke and Greiler 1995,Witt and McConnachie
2004).
Invertebrates are the major component of biodiversity in temperate native grasslands in Australia (Yen 1999, Gibson and New
2007). New South Wales grasslands “have abundant herbivorous insects” (Keith 2004 p. 104). But surveys of grassland
invertebrates in Australia had barely begun by the mid-1990s when Driscoll (1994) stated that the invertebrates of south eastern
Australian grasslands had “never been surveyed’. Keith (2004 p. 104) exaggerated the exent of knowledge when he stated that
the “invertebrate fauna of the grasslands before their modification and use as pastures is poorly documented”. Wapshere’s (1993
p. 344) statement that “nothing” was known about the nematode, mite and insect faunas of Austrostipa spp., despite their
economic importance in native pastures, while not strictly correct (see the section above on the curculionid predators of Nassella
species in Australia), nicely reflects the general paucity of information. Gibson and New (2007) considered remnant lowland
native grasslands to be “among the least investigated” ecosystems entomologically in south-eastern Australia. Nevertheless it is
has been “presumed widely” that loss of native plants in these systems has been accompanied by similar loss of invertebrate
diversity (New 2000 p. 154).
Invertebrate diversity appears to be particularly suitable for study and assessment of remnants because most of the vertebrate
diversity has been lost from native grasslands, and because invertebrates are highly diverse, abundant and easy to collect (Yen
1995). It has been suggested that the suites of macroinvertebrates present are most appropriate for characterising grasslands for
conservation, and can act as flagship taxa, and that microinvertebrates may be superior for monitoring ecological functioning
(Yen 1995). However invertebrates hardly offer direct approaches to biodiversity assessment. Inventory studies are a primary
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