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

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Hispidon sp. (Perissodactyla: Equidae), Hemiauchenia sp., Lama gracilis, Lama guanacoe (Artiodacytla: Camelidae) and various Cervidae (Carlini et al. 2004, Norriega et al. 2004). The herbivorous megafauna of South America was comparatively large compared to other continents, and went extinct from the late Pleistocene into the Holocene (Johnson 2009). It appears probable that these animals strongly influened the distribution of grasslands and had strong selective effects on the grassland flora, although knowledge of these palaeoecological relationships is currently very deficient (Johnson 2009).. Its ancestors may have subject to predation by dinosaurs and probably Gondwanatheria, about which little is known, but which had teeth which indicate that grasses may have been major components of their diets (Prasad et al. 2005). Before Spanish occupation in the 14th century, the pampas lacked bovids (cattle and sheep) (Mack 1989) and large herbivores were scarce from the end of the Pleistocene until European colonisation (Fernández et al. 2009). An array of medium sized mammals was present, of which the the largest grazers were deer (Darwin 1845), and the camelids, the most important of which was the guanaco Lama guanicoe (Müller). Large herds of grazing animals were absent at least from the Tertiary until the arrival of Europeans (Coupland 1992). The camelids have broad, spreading, soft-padded feet that do not compact the soil (Castillo-Ruiz and Lundrigan 2007) and a digestive system with foregut fermentation, similar to ruminants (Siebert and Newman 1989). The Guanaco is a moderate sized herbivore about 1 m tall at the shoulders, which commonly forms herds of 4-18 with males troops of up to 200, and is a grazer and browser, consuming grasses, lichens, forbs, seeds, fruits, rushes and sedges. It has narrow foot pads and a more hoof-like nails than camels. The Alpaca Lama pacos (L.) and the Llama L. glama (L.) are domesticated forms, probably of the Vicuna L. vicugna (Molina) and the guanaco respectively, and all four of these taxa will interbreed. Recent evidence indicates that domestication of the wild species occurred 6000-7000 years ago. There were probably 10 million alpacas and several million llamas on the continent when the Spanish arrived in the 14th century, along with similar numbers of the undomesticed species, but within 100 years the populations collapsed, probably largely as a result of competition with domestic livestock (Long 2003), but no doubt greatly propelled by the destruction of the indigenous human cultures. The Vicuna is now restricted to the central and southern Andes in arid and montane grasslands at altitudes of 3500-4800 m, but it formerly had a more extensive range now occupied by exotic sheep and goats (Long 2003, Castillo-Ruiz and Lundrigan 2007). It too feeds on grasses and forbs (Long 2003). The reported diet of the alpaca in highland Chile is dominated by grasses including Festuca spp., Deschampia caespitosa and Agrostis tolucensis (Castillo-Ruiz and Lundrigan 2007). Darwin (1845) reported that the only large indigenous mammal still common in the extensive grasslands of the Maldonada region of Uruguay (near Montevideo) by 1852 was the Pampas Deer Ozotoceros bezoarticus L., but rheas Rhea americana (L.) were also common. The Pampas Deer is now extinct throughout the Rio de la Plata grasslands except in a few small reserves and ranches (Soriano et al. 1992, Cosse et al. 2009) while rhea populations have sharply decreased due to uncontrolled hunting and wire fences (Soriano et al. 1992). Cosse et al. (2009) investigated the diet of Pampas Deer on a ranch in south-eastern Uruguay and found that cultivated rice and Lolium sp. were the most important food plants in this agricultural environment, that the dietary overlap with sheep was complete, but that there was limited competition for food with cattle. Various grasses were recorded in the diet, not including Nassella or other Stipeae, although unidentified monocots generally comprised about one third of material found in faeces. Wild cattle Bos taurus L. and horses Equus caballus L. became established in Argentina after the abandonment of Buenos Aires by the Spanish in 1537 (Long 2003). 80,000 horses were present around Buenos Aires by 1585, large numbers of cattle were present by 1609 (Soriano et al. 1992) and millions of cattle and horses were present on the pampas by 1699 (Long 2003). According to Darwin (1845 p. 120): “The countless herds of horses, cattle and sheep, not only have altered the whole aspect of the vegetation, but ... have almost banished the guanaco, deer, and ostrich” (Rhea). Horses and cattle were introduced east of the Uruguay River by Jesuit missionaries in the 17th century and rapidly proliferated in the feral state (Overbeck at al. 2007). The whole of the campos and pampas have been grazed by sheep, cattle or horses “generally for centuries” (Soriano et al. 1992 p. 380). Cattle grazing and other agricultural pursuits have greatly altered the landscape, with agricultural ecosystems replacing native grasslands in most of the region, and large areas of native grassland surviving only in Buenos Aires province due to wetter, more saline soils (Pedrano et al. 2008). As with other major grasslands lacking a recent history of grazing by hardhooved livestock (Mack 1989) the pampas grasslands were invaded by a large suite of exotic species after European colonisation. Livestock grazing in the Flooding Pampas has actively promoted these invaders, 75% of which are annuals and 74% forbs (Perelman et al. 2001). Livestock grazing of natural grasslands and improved pastures is a major economic activity in the Rio de la Plata grasslands (Soriano et al. 1992) as is cattle ranching in the natural grasslands of southern Brazil, where 13.2 million head were present in Rio Grande do Sul state in 1996 (Overbeck at al. 2007). In Brazilian campos, grazing is “often considered the prinicpal factor maintaining the ecological properties and physiognomic characteristics of the grasslands” (Overbeck at al. 2007 p. 104). N. neesiana may have existed through much of the Quaternary period and into early historical times under grazing pressure from large mammals that was relatively light, and was then subjected in much of its core range to unprecedented grazing by feral livestock. Limited evidence indicates that N. neesiana declines under livestock grazing in its native range in Argentina. After exclusion of large ungulates from Flooding Pampa grasslands the relative basal cover of the major grass species (Briza subaristata Lam., Danthonia montevidensis (DC.) et Lam., Sporobolus indicus (L.) R.Br. and N. neesiana) more than doubled to 97% after 4 years, while annual and broad-leaved herbs disappeared (Soriano et al. 1992). Under a management regime of grazing and winter burning in the Tandilia Range of Buenos Aires province, the major grass components of the flechillar grassland (including N. neesiana) decreased and the broadleaved Achillea millefolium. and Carduus acanthoides began to dominate, while under grazing alone C. acanthoides, Cirsium vulgare, Dactylis glomerata L., Vulpia dertonensis (All.) Gola. and Bothriochloa laguroides became more dominant (Honaine et al. 2009) The situation appears to be different in Australia where N. neesiana is generally considered to be tolerant of heavy grazing by sheep and cattle (Storrie and Lowien 2003, McLaren, Stajsic and Iaconis. 2004, Grech 2007a), in part because of its relatively low palatability to these animals compared with desirable pastures grasses (Bourdôt and Hurrell 1989a, Grech 2007a). It has relatively low herbage production compared to some such desirable pasture grasses used in Australia, notably Festuca 54
arundinacea (Gardener et al. 2005). N. neesiana tillers profusely when grazed (McLaren, Stajsic and Iaconis. 2004) and produces large amounts of unpalatable flower stalks and very little leaf material during flowering and fruiting (Gardener et al. 1996b, Gardener 1998, Grech et al. 2004, Grech 2007a). Stock avoid eating it in the reproductive stage even at stocking rates of 300 DSE ha -1 (Grech 2007a). However plants are palatable to livestock during much of the year (Grech et al. 2004, Grech 2007a). Slay (2002a) reported observations that ewes grazed N. neesiana in preference to Dactylis glomerata and Lolium perenne in winter near Napier, New Zealand. It can be reduced by appropriately timed grazing at high intensity, but the stocking rates and practices required are generally unrealistic for Australian conditions (Grech 2007a). The impact of goats on N. neesiana is unknown, but goats are able to substantially reduce infestations of N. trichotoma (McGregor 2003). Goats and alpacas have been considered as potential control agents in Australia (Bedggood and Moerkerk 2002) but no trials appear to have been undertaken and no observations of N. neesiana herbivory by these species in Australia appear to be on record. Studies of biotic resistance (e.g. Parker et al. 2006a) suggest that alpacas would preferentially utilise Australian native plants or European grasses rather than N. neesiana or other South American grasses with which they may have coevolved. No studies of marsupial grazing of N. neesiana appear to have been undertaken. It is not recorded whether it is eaten by kangaroos and whether they prefer it to native grasses, as predicted by the biotic resistance hypothesis. Studies of the feeding preferences of Eastern Grey Kangaroos by Robertson (1985) indicate that species of Austrostipa and other grasses with sharp and long-awned seeds are avoided when their inflorescences are present, and that narrow-leaved species that develop substantial standing biomass of dead foliage that resticts selective foraging for green shoots suffer less damage. Thus macropod grazing of N. neesiana is probably similar to that by domestic livestock, in that it is avoided when in flower and fruit and has partial protection of green shoots resulting from retention of dead biomass, but will be selectively consumed when it is comparatively more palatable and accessible. Mammal grazing selects for prostrate or low-growing ecotypes of Stipa (Peterson 1962) and many other perennial grasses, but the low-growing forms of many grasses are the result of phenotypic plasticity (Cox 2004). The so called ‘sward form’ of N. neesiana in Australia (Randall Robinson pers. comm.) characterised by a large number of semi-prostrate stems and more limited development of an uptright tussock form, appears to occur where mowing is frequent as well as in heavily grazed situations, but whether the plants resume a more normal form if these pressures are relaxed is unclear. Grazing of various European pasture grasses has been found to lead to the development of ecotypes characteristed by small size and increased silica concentrations (Tscharntke and Greiler 1995). The relationships between the silica defences of grasses and grazing are as yet poorly understood, but it may be presumed that the altered grazing pressures in the introduced environment will select for different leaf hairiness and phytolith profiles characters. The possibility that such selection has altered the morphology or other characteristics of N. neesiana in Australia has not been investigated. Physiology and biochemistry The dominant native grasses in Australian temperate lowland grasslands are all C 3 species except for the major dominant Themeda triandra. Various other C 4 species commonly occur (e.g. Aristida spp., Dichanthium sericeum, Panicum spp.) and some form dense subdominant populations (e.g. Bothriochloa macra ) but none are dominant over wide areas. N. neesiana is a C 3 grass. C 3 and C 4 plants possess different biochemical pathways of photosynthetic carbon acquistion and consequently have markedly different leaf anatomy, different ratios of carbon isotopes in their tissues ( 13 C/ 12 C ratios or δ 13 C) and different responses to climatic factors (Hattersley 1986). The biochemistry of these differences is complicated and will not be explained here. In the simplest terms, the species that produce acids with four C atoms as the main initial stable product of CO 2 fixation are C 4 species, while those that produce the three-C acid 3-phosphoglyceric acid as the primary product are C 3 species (Salisbury and Ross 1992). There are three biochemical variants of C 4 photosynthesis in grasses, that differ in the main enzymes that catalyse the decaroboxylation of the four-C acids, the output products of that process and, with some additional compications, the leaf anatomy that supports the biochemistry (Hattersley 1986). Those that form malate utilise PEP carboxykinase and are called PCK species, while the two types that form aspartate utilise either NADP malic enzyme or NAD malic enzyme and are NADP-ME and NAD-ME species respectively (Hattersley 1986). Eleven differing biochemical/structural combinations have been identified. Andropogonanae have the classic structural NADP-ME type (Hattersley 1986), possessed also by T. triandra. C 3 grasses generally have a lower optimum temperature for photosynthesis, and grow better in cooler environments with less light than C 4 grasses, which often have temperature optima in the 30-40ºC range and are mostly native to unshaded environments (Monson 1989, Salisbury and Ross 1992, Sinclair 2002, Jessop et al. 2006), although some have a large ecological range (Christin et al. 2009). C 3 species are most numerous in areas with a cool, wet spring and become dormant in summer (Sinclair 2002). In contrast C 4 grasses grow mostly in summer and are more efficient users of water and N, in terms of CO 2 assimilation, in high-light environments (Monson 1989). C 4 species have a competitive advantage when photorespiration costs become important, and are more efficeint in high temperatures and arid and saline environments (Christin et al. 2009) and much more efficient at producing biomass in warm environments with high light intensity (Salisbury and Ross 1992). The variations in the evolved biochemical-structural types of C 4 grasses likely have other ecophysiological and ecological implications, for instance differential leaf digestibility (Hattersely 1986). C 3 grasses tend to have shallower root systems than C 4 grasses, which require water for growth in summer when it is generally less available, so widespread replacement of C 4 with C 3 species may increase deep drainage to water tables, and contribute to dryland salinity (Sinclair 2002). Reactions of C 3 and C 4 species to increasing atmospheric CO 2 are complex, with neither group necessarily advantaged (Sinclair 2002). The C 4 species grow more rapidly under elevated CO 2 levels and it is likely that they will expand southwards, but this is dependant on the N usage of C 3 spccies under the changed conditions (Keith 2004). Little is known of the specific biochemistry of N. neesiana, however a photosystem IIA protein, A9YFV6, has been described from N. neesiana chloroplasts (Boeckmann et al. 2003). Yeoh and Watson (1986) included N. neesiana in a study of the 55
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Literature review: Impact of Chilea
Page 3 and 4: Fire 49 Other disturbances 50 Shade
Page 5 and 6: Conventions and standards Botanical
Page 7 and 8: neesiana appears to be a habitat ge
Page 9 and 10: population densities of existing sp
Page 11 and 12: elated plants have similar defences
Page 13 and 14: For invasion to occur there must be
Page 15 and 16: As yet there appears to be no evide
Page 17 and 18: experimental manipulation of specie
Page 19 and 20: species tend to be those which tran
Page 21 and 22: Taxonomy and nomenclature Stipeae N
Page 23 and 24: Vernacular names ‘Needlegrass’
Page 25 and 26: to Bouchenak-Khelladi et al. 2009).
Page 27 and 28: 1 m (Walsh 1994), ca. 90 cm (Verloo
Page 29 and 30: Figure 2. Anatomy of the seed of N.
Page 31 and 32: are the seeds larger/smaller, longe
Page 33 and 34: also based on a misunderstanding of
Page 35 and 36: Table 2. Modified Feekes Scale for
Page 37 and 38: Argentina, in the provinces of Chac
Page 39 and 40: Figure 3. Recorded distribution of
Page 41 and 42: 1994). Only 3 of 186 exotic grasses
Page 43 and 44: According to Morfe et al. (2003) th
Page 45 and 46: populations have been found in the
Page 47 and 48: (Honaine et al. 2006). The flechill
Page 49 and 50: In Australia the altitudinal range
Page 51 and 52: Proximity to urban development appe
Page 53: In the southern Brazilian campos of
Page 57 and 58: al. 2008). Cues for masting may be
Page 59 and 60: Approximately 200 alien grass speci
Page 61 and 62: Dispersal of seed in contaminated s
Page 63 and 64: In New Zealand, Hurrell et al. (199
Page 65 and 66: No emergence was observed in undist
Page 67 and 68: and high impact (“ability to caus
Page 69 and 70: also noted that despite a wide rang
Page 71 and 72: a small reduction in seedhead produ
Page 73 and 74: Slashing and mowing Slashing can re
Page 75 and 76: Themeda re-establishment McDougall
Page 77 and 78: species (Lawton and Schroder 1977 p
Page 79 and 80: y increased importance of ant grani
Page 81 and 82: 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
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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 and 134:
Table 12. Areal extent and conserva
Page 135 and 136:
Foreman (1997) investigated the eff
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
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Its original habitat on the mainlan
Page 147 and 148:
Table 17. Endangered reptile specie
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equirement, but unlike plants and v
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e assigned the same biodiversity sc
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Nematodes are mostly minute animals
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found in all mainland states, O. co
Page 157 and 158:
Keyacris scurra, Melbourne (1993) o
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was once widespread in south- easte
Page 161 and 162:
eing sluggish and wingless, and exi
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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
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Table A2.1 (continued) Species Life
Page 171 and 172:
Table A2.1 (continued) Species *Het
Page 173 and 174:
Page 175 and 176:
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
Page 185 and 186:
DNRE (Department of Natural Resourc
Page 187 and 188:
Fuhrer, B. (1993) A Field Companion
Page 189 and 190:
Groves, R.H. and Whalley, R.D.B. (2
Page 191 and 192:
Iaconis, L. (2004) Chilean needle g
Page 193 and 194:
Levine, J.M., Adler, P.B. and Yelen
Page 195 and 196:
McDougall, K.L. (1987) Sites of Bot
Page 197 and 198:
Morfe, T.A., McLaren, D.A. and Weis
Page 199 and 200:
Perelman, S.B., León, R.J.C. and O
Page 201 and 202:
Saunders, D.A. (1999) Biodiversity
Page 203 and 204:
Thellung, A. (1912) La flore advent
Page 205 and 206:
Weiss, J. and McLaren, D. (2002) Vi
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