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

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Grasslands of the Gippsland Plains have substantially disappeared and are now largely restricted to small linear remnants (DNRE 1997) (Tables 11 and 12). Those at Safety Beach are on small urban blocks destined for housing (Sinclair 2007). Threats include weed invasion, livestock grazing and roadworks (DNRE 1997). Exotic grasses are the most serious weeds at Safety Beach and include Anthoxanthum odoratum, Paspalum dilatatum, Pennisetum clandestinum, Holcus lanatus, Festuca arundinacea, Sporobolus africanus, Phalaris spp. and Stenotaphrum secundatum (Walter) Kuntze (Sinclair 2007). Fire is now believed to be less frequent and more intense than in pre-European times (DNRE 1997). Northern Plains Grasslands Much of the Murray Valley Riverine Plains were reputedly covered with grassland at the time of European settlement. The Victorian Riverina plains grasslands are ecologically similar to those on the floodplains of the Lachlan and Murrumbidgee Rivers in New South Wales. The Northern Plains Grasslands largely occupied gently sloping, Quaternary alluvial stream deposits, often very deep, built of sedimentary and igneous materials derived from the Victorian highlands, deposited on flat plains with residual volcanic hills (Hills 1967, Rosengren 1999). The soils are
Foreman (1997) investigated the effects of livestock grazing, cultivation and burning on a long-grazed species-rich remnant. Only the diminuitive annual species were not grazed and they increased in abundance under grazing by exploiting the increased gaps. Cultivation increased the abundance and species richness of exotic species, and the abundance of some native annuals (probably because they had a soil seed bank). Fire reduced the abundance of exotics, particularly annuals, presumably by destroying surface seeds. He also found that drought had a very significant effect on the flora, causing a substantial drop in above-ground species richness and abundance, and that native annuals were more abundant when winter rainfall was high. Irrigated agriculture is the major landuse in the Riverina and salinity is a widespread problem, while other threats include cultivation, irrigation, inappropriate grazing and fire regimes, weed invasion, feral animals and increased fertiliser use (DNRE 1997). The Northern Plains Grasslands are listed as a threatened community under the Flora and Fauna Guarantee Act. (Department of Sustainability and Environment 2009a). Terrick Terrick National Park near Mitiamo, a former grazing property, is the largest and most important conserved remnant of this ecosystem in Victoria (Lunt et al. 1998). Victorian Basalt Plains Grasslands The grasslands of the Victorian basalt plains were a very large area of grassland at the time of European settlement (Tables 11 and 12). The grassy ecosystems of the plains extended from Melbourne to Hamilton (Stuwe and Parsons 1977) or to “beyond the South Australian border, broken only in a few places by deeply dissected ranges” (McDougall 1987 p. 17), at altitudes from less than 100 m to over 600 m (Stuwe and Parsons 1977). The Volcanic Plains as a land unit occupies c. 22,000 km 2 of which about 37% or 8,260 km 2 (or over 10,000 km 2 according to Williams 2007) was occupied by grassland complexes and most of the remainder by grassy woodland (28%) and herb-rich woodland (14%) complexes (DNRE 1997, Barlow and Ross 2001). Numerous other vegetation types occurred, including wetland, forest and swamp scrub, forming a complex mosaic, in which, judging by the maps of early surveyors, “treeless areas occurred as discrete ‘openings’ in the landscape”, which they identifed as “Plains” (Barlow and Ross 2001 p. 26). The majority of the Victorian Volcanic Plains terrain is composed of Newer Volcanics, a series of lava flows and tuff plains with extinct volcanic cones (commonly scoria cones but also lava domes) aged from 46 million years ago, peaking at about 2.4 million years and ceasing about 7,000 years ago, i.e. Middle Pliocene to recent (Hills 1967, Dahlhaus et al. 2003), although radiocarbon evidence indicates that the most recent volcanic activity was >20,000 years ago (Rosegren 1999). The most recent lava flows are represented by stony rises of ropy lava (Hills 1967). Smaller volcanoes, such as Mt Cottrell, produced the majority of the geological material, mostly highly fluid, basalt lava, that spred in thin sheets 20-200 cm thick, with overlapping flows to 60 m thick in some areas (Rosengren 1999). Eruptions were infrequent and there was little pyroclastic material and ash in most areas, so vegetation would have survived widely beyond the edges of the lava flows (Rosengren 1999). Despite common parent materials, the soils are highly variable, ranging from gradational clayey chocolate soils and kraznozems on the younger basalts, to coarsely structured duplex soils on the older rocks (Dahlhaus et al. 2003). Much of the lava plains was “originally rough and stony, resulting in an irregular topography with many small depressions” (McDougall 1987). In areas that have not been worked, there is still abundant surface rock (Hills 1967), and in areas with developed soils, basalt corestones (‘floaters’) are common at the surface. Much of the rock in developed areas has been cleared, and many kilometres of dry stone walls were built (Patton 1935). The rock is fine-grained, blue-grey in colour and not very hard (Patton 1935) and underlying rock is very close to the surface in many areas (Sutton 1916-1917). The development of watercourses is generally poor, with lava flows often resulting in blockages and substantial areas of internal drainage to ephemeral wetlands, swamps and lakes (Dahlhaus et al. 2003), many of which have been drained (McDougall 1987) Waterlogging is widespread (Dahlhaus et al. 2003), partly because the soils are so shallow (Patton 1935), but much of the area is well drained due to strong fracturing of the underlying rocks (McDougall 1987). The eastern areas are Miocene to recent lava plains, with two dominant soil types, formed in situ: grey cracking clays, Northcote classification Ug 5.2, and hard alkaline red soils Northcote classification Dr 2.13, ranging in surface texture from sandy loam to clay, but mostly clay loams or light clays, and in colour from black to grey, brown and reddish brown (Stuwe and Parsons 1977). Patton (1935) thought the darker soils characteristic of more low-lying areas, the colour attributable to leaching or organic matter from upslope, and considered that soils higher up the slope had lower clay content. The clays have a high water-holding capacity (45% according to Patton 1935) and high shrink:swell ratio so become waterlogged with poor aeration in winter and deeply cracked in summer (Stuwe and Parsons 1977). With a moisture content of 19%, the soil is “definitely sticky” (Patton 1945 p. 185). Patton (1935) provided a generalised soil profile of a red-brown earth on the Keilor Plains and noted that the B horizon, extending from c. 40-85 cm depth, is not generally penetrated by roots and rests directly upon bedrock. It contains abundant calcium carbonate giving it a white colour. “Most of the richest aricultural and pastoral land in the Western District is composed of ... recent tuffs” (Hills 1967). For Australian soils, the clays are relatively nutrient rich, particularly in phosphorus (Barlow and Ross 2001). The Victorian Volcanic Plain has average annual rainfalls of 500-700 mm (Dahlhaus et al. 2003) and western Victorian grasslands between 450-850 mm (Jones 1999b) , with some areas in the east in rain shadow (between Melton and Werribee) receiving slightly less (Dahlhaus et al. 2003), the areas between Anakie and Melbourne with a range of c. 400-600 mm (McDougall 1987), and areas at higher altitude receiving up to 1000 mm, and is evenly distributed throughout the year (Stuwe and Parsons 1977) or with a late winter peak (Jones 1999b). Eight major droughts occurred in the eastern area between 1887 and 1987 (McDougall 1987). Average monthly temperatures are 7-20ºC (Jones 1999b). February is hottest, with maxima sometimes exceeding 40ºC and annual frost days in the eastern area range from 16 to 53 (McDougall 1987). Evaporation is very high in the summer (December to February). The precipitation to evaporation ratio appears to have fallen over the last 100 years, so the area seems to be drying (Dahlhaus et al. 2003). Much of the western area is severely affected by rising water tables and dryland salinity, predicted to dramatically worsen (Dahlhaus et al. 2003). Mean daily minimum and maximum temperatures are 5-12ºC in July and 12-26ºC in January (Stuwe and Parsons 1977). Victorian western plains grasslands a result of both soil and climate factors, not aboriginal burning (Cook and Yugovic 2003). Treelessness is explained by seasonal aridity,cold temperature and heavier clay soils (Willis 1964 p. 398). Fires and ash falls 135
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Literature review: Impact of Chilea
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Fire 49 Other disturbances 50 Shade
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Conventions and standards Botanical
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neesiana appears to be a habitat ge
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population densities of existing sp
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elated plants have similar defences
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For invasion to occur there must be
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As yet there appears to be no evide
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experimental manipulation of specie
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species tend to be those which tran
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Taxonomy and nomenclature Stipeae N
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Vernacular names ‘Needlegrass’
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to Bouchenak-Khelladi et al. 2009).
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1 m (Walsh 1994), ca. 90 cm (Verloo
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Figure 2. Anatomy of the seed of N.
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are the seeds larger/smaller, longe
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also based on a misunderstanding of
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Table 2. Modified Feekes Scale for
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Argentina, in the provinces of Chac
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Figure 3. Recorded distribution of
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1994). Only 3 of 186 exotic grasses
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According to Morfe et al. (2003) th
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populations have been found in the
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(Honaine et al. 2006). The flechill
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In Australia the altitudinal range
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Proximity to urban development appe
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In the southern Brazilian campos of
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arundinacea (Gardener et al. 2005).
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al. 2008). Cues for masting may be
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Approximately 200 alien grass speci
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Dispersal of seed in contaminated s
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In New Zealand, Hurrell et al. (199
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No emergence was observed in undist
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and high impact (“ability to caus
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also noted that despite a wide rang
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a small reduction in seedhead produ
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Slashing and mowing Slashing can re
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Themeda re-establishment McDougall
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species (Lawton and Schroder 1977 p
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y increased importance of ant grani
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BIODIVERSITY “Biodiversity ... on
Page 83 and 84: According to Woods (1997 p. 61) “
Page 85 and 86: 2004, Richardson and van Wilgen 200
Page 87 and 88: negative depending on the particula
Page 89 and 90: Competition with native plants Comp
Page 91 and 92: asexual seed production, so local f
Page 93 and 94: GRASSLANDS Grasses: “... the most
Page 95 and 96: susceptible to N. neesiana invasion
Page 97 and 98: Floristic composition, vegetation s
Page 99 and 100: proportion of the flora then presen
Page 101 and 102: tussock space (Stuwe and Parsons 19
Page 103 and 104: Like vascular plant diversity, comm
Page 105 and 106: Opinions differ on the nature and i
Page 107 and 108: Species Common Name Family Aust ACT
Page 109 and 110: in shifting the distribution, exten
Page 111 and 112: of these systems is largely explain
Page 113 and 114: pasture. The least understood trans
Page 115 and 116: tend to benefit more from relaxed c
Page 117 and 118: Bovids crop their food between the
Page 119 and 120: are therefore less likely to distur
Page 121 and 122: esult in a “short-term flush” o
Page 123 and 124: Fire effects on weeds Moore (1993 p
Page 125 and 126: Table 8. Typical nutrient levels in
Page 127 and 128: grasses produced sigificantly more
Page 129 and 130: Fossorial vertebrates are or were o
Page 131 and 132: (Rosengren 1999). Approximately one
Page 133: Table 12. Areal extent and conserva
Page 137 and 138: Willis (1964) considered that the f
Page 139 and 140: Austrostipa-Enneapogon) from around
Page 141 and 142: Woodlands and New England Grassy Wo
Page 143 and 144: Thylogale billardierii), Peramelida
Page 145 and 146: Its original habitat on the mainlan
Page 147 and 148: Table 17. Endangered reptile specie
Page 149 and 150: equirement, but unlike plants and v
Page 151 and 152: e assigned the same biodiversity sc
Page 153 and 154: Nematodes are mostly minute animals
Page 155 and 156: found in all mainland states, O. co
Page 157 and 158: Keyacris scurra, Melbourne (1993) o
Page 159 and 160: was once widespread in south- easte
Page 161 and 162: eing sluggish and wingless, and exi
Page 163 and 164: estoration and, if Australia follow
Page 165 and 166: close to the plant are able to bury
Page 167 and 168: Species *Chirothrips mexicanus Craw
Page 169 and 170: Table A2.1 (continued) Species Life
Page 171 and 172: Table A2.1 (continued) Species *Het
Page 177 and 178: Nematodes of grasses and grasslands
Page 179 and 180: REFERENCES Aceñolaza, F.G. (2004)
Page 181 and 182: Benson, D. and McDougall, L. (2005)
Page 183 and 184: Chan, C.W. (1980) Natural grassland
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DNRE (Department of Natural Resourc
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Fuhrer, B. (1993) A Field Companion
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Groves, R.H. and Whalley, R.D.B. (2
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Iaconis, L. (2004) Chilean needle g
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Levine, J.M., Adler, P.B. and Yelen
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McDougall, K.L. (1987) Sites of Bot
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Morfe, T.A., McLaren, D.A. and Weis
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Perelman, S.B., León, R.J.C. and O
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Saunders, D.A. (1999) Biodiversity
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Thellung, A. (1912) La flore advent
Page 205 and 206:
Weiss, J. and McLaren, D. (2002) Vi
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