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

proportion of the flora then present on the Victorian basalt plains (including non-grassland formations) had distributions outside
the plains, many being ecological ‘wides’, with only c. 10 spp. restricted to the region. Similarly many plants of the New
England Tablelands grasslands have very wide ranges, with the flora as a whole having low habitat specificity (McIntyre and
Lavorel 1994a), and it is generally agreed that only a very small number of vascular species are restricted to Australian
temperate grasslands (Kirkpatrick et al. 1995). The few native annuals present are often very small plants which tend to occur in
wet depressions (Lunt et al. 1998) and are ephemeral, growing in early spring (Sharp 1997).
Phenology
Most of the plant species in south-eastern temperate grasslands flower mainly in spring, and a substantial proportion also in
autumn, “presumably” responding to day length and day temperatures of c. 20ºC (Groves and Whalley 2002), along with soil
moisture. A high proportion of the perennials flower and fruit in spring-early summer and have no living parts above ground for
much of the year (Lunt et al. 1998). All the Orchidaceae fit this pattern, with no above-ground living material during the warmer
months (Smith et al. 2009). Patton (1935) considered October-November to be the peak flowering period for grasses and other
plants in the Coburg to Melton area of the Victorian basalt plains. He and Willis (1964) noted that the major flowering period
corresponds with the time that evaporation begins to exceed precipitation. Sutton (1916-1917) observed that many species were
in flower long before the end of winter (31 August). Groves (1965) found that nearly half the species present at St Albans
flowered in October and November, with similar patterns for exotic and native species. Most of the grasses in the Victorian
basalt plains flower in November (Willis 1964). Yellow-flowered daisies were a prime feature in spring (Sutton 1916-1917) but
are now greatly depleted. Chan (1980) recorded the flowering periods of 61 native species at Yarrumundi Reach, ACT, and
found that 33 species flowered in September, 51 in October, 49 in November, 32 in December, 28 in January and 7 or fewer
species in every other month. Exotic species also showed a marked flowering peak in October and November.
As moisture levels decline the flowering period rapidly ends and “most of the vegetation passes into a resting stage until the
following autumn” (Patton 1935 p. 172), being practically dormant from December to April (Willis 1964), with vegetative
growth recommencing after autumn rains and continuing slowly during the winter. Summer rains may stimulate growth of many
species. Morgan (1995b) for example observed rapid growth of juvenile Rutidosis leptorhynchoides after summer rains.
Information on the germination and establishment periods of most species appears to be lacking , possibly because recruitment
events are rare. Morgan (1995b) found that Rutidosis leptorhynchoides seeds germinated 8-12 days after the first major autumn
rains and continued to germinate through until early July.
Plant species richness
The richest terrestrial plant communities in Australia include the kwongan of south-western Australia with up to 103 vascular
species in 0.1 ha and the herb-rich woodlands of western Victoria with up to 96 spp. in 0.1 ha, 93 species in 128 m 2 , and 45 spp.
m -2 (Lunt 1990d). The richest communities in the world have traditionally been considered to be the European chalk grasslands,
with a maximum of 54 spp. m -2 (Lunt 1990d). One recently burnt grassland in the vicinity of Porto Alegre, southern Brazil, had
maxima of 28 vascular spp. per 0.25 m -2 , 34 per 0.75 m -2 and approximately 450 spp. in 220 ha (Overbeck et al. 2007).
Vascular plant species richness in Australian temperate grasslands shows considerable variation across the range of spatial
scales, but native richness is strongly related to the historical disturbance regime, particularly burning and grazing (Kirkpatrick et
al. 1995, Dorrough et al. 2004). At the regional scale, Willis (1964) considered the Victorian Basalt Plains flora to be
floristically ‘deficient’ in comparison with other regions of the State. However communities in this region can nevertheless be
species rich at a small scales (Morgan 1998e). Sutton (1916-1917 p. 117) considered that the vegetation of typical Keilor Plains
grasslands contained “some hundred or more species”.
Patton (1935) calculated a species/area curve for basalt plains grassland and found an average of c. 8-9 species present in 1 m 2 ,
rising to c. 14 spp. in 5 m 2 , and to c. 17 spp. in 10 m 2 with a total of 45 spp. in all quadrats, and 73 species comprising the whole
flora. A relatively high proportion of species occurred infrequently, or were only very sparsely present. Stuwe and Parsons
(1977) found species richness of c. 12-18 m -2 in Victorian basalt plains grasslands. Kirkpatrick et al. (1995) considered it
common for more than 40 native species to occur in an area of 100 m 2 . Morgan (1998e) recorded 22 spp. in 0.25 m -2 and 27 spp.
m -2 in some species-rich Victorian basalt plains remnants and total species data for two ungrazed roadside sites – 71 native and
22 exotic species in annually burnt site and 67 native and 19 exotic spp. in a bienially burnt site. Other data includes Groves
(1965) study along the railway line at St Albans - 101 spp. including 64 natives; Evans St., Sunbury, c. 11-17 species m -2
(Morgan 1998d) and c. 103 species present in quadrats with 48 additional spp. recorded in 3.5 ha (Morgan and Rollason 1995);
Derrimut Grassland Reserve, a 154 ha “species-poor” remnant with “a long history of domestic stock grazing and little or no
recent burning” (Morgan 1998c) 102 native and 78 exotic species in the above-ground vegetation (Lunt 1990a) with 1 additional
native species and 3 exotics found only in the soil seed bank (Lunt 1990b); five Victorian volcanic plains T. triandra grasslands
with a range of historical fire frequencies (1 y, 3 y, >10y) and a total area of 32 ha surveyed in 1993-95 (Morgan 1998c) – 61
native and 30 exotic spp. in the vegetation, 32 native and 28 exotic in the soil seed bank of which 11 were not present in the
vegetation; the same five sites plus an additonal one, all surveyed in August 1998 (Morgan 2004) – a total of 69 spp. from a
single 150 m 2 quadrat at each site; New England tablelands an average of 19.9 native species in 30 m 2 , with a maximum of 28
and minimum of 1 (McIntyre 1993); native pasture on the New England Tablelands (Chiswick) 124 species in 2.4 ha of which 26
were grasses, 11 Cyperaceae + Juncaceae and 87 other forbs, with a range of 4-26 spp. and means of 11-16 spp /0.25 m 2 in
grazed areas and range of 1-9 and means of 3-4 spp./0.25 m 2 in grazed areas (Trémont 1994); 39 natural grasslands in the ACT -
191 spp., 56% forbs, including 10 native grass spp., with a range of 23-56 spp. in ten 1m 2 quadrats (Sharp 1997). On the Monaro
Tablelands of New South Wales Dorrough et al. (2004) found mean plant species richness of 11.7, 12.6 and 15.7 species 0.25 m -
2 in native pastures, on roadsides and in travelling stock routes respectively, with the richness of native species being 5.0, 7.8 and
8.6 and of exotic species 6.7, 4.8 and 7.1 respectively, with a total of 120 species in 100 m 2 . Kirkpatrick et al. (1995) calculated
a total of 771 vascular species in 77 families in the south-eastern lowland grasslands. In high-richness sites natives grasses are
always the dominant species, whereas low-richness sites may be dominated by exotic or native Poaceae (New England
tablelands, McIntyre 1993). The grasslands of the Victorian Volcanic Plains were generally floristically rich (DNRE 1997) but
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