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