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

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identified as Stipa. neesiana by Dr. J.R. Swallen but also referred to also as “Stipa sp.?”, had 2n = 60. It differed morphologically from the tetraploid specimens, “but it was not possible to clarify the identification” (Bowden and Senn 1962 p. 1122). According to Moraldo (1986) N. neesiana is tetraploid with 2n = 44. The lowest known chromosome count of a stipoid species is n =10 in a Piptatherum sp. and the highest are n = 41 and n = 48 (Barkworth and Everett 1986). In Stipa (sens. lat.) and Oryzopsis (sens. lat.) the chromosome numbers range from n = 11 to at least n = 41 (including n = 12, 16, 17, 18, 20, 21, 22, 23, 24, 32, 33, 34, 35), a situation that can be explained by recurrent amphiploidy, i.e. combinations of autopolyploidy (simple doubling of the number of chromosomes in an individual) and allopolyploidy (hybridisation of diploid and/or polyploid individuals), begining with n = 6 and n = 5 (Johnson 1972). In most European Stipa species that have been studied 2n = 44 (Tsvelev 1977, Moore 1982), derived through aneuploidy from a primary basic number of 2n = 22 (De Wet 1986). Of other European species, S. capensis Thunb. 2n = 34, 36, S. parviflora Desf. and S. bromoides (L.) Dörfler 2n = 28, and S. gigantea Link 2n = 96 (Moore 1982, Tsvelev 1984, Moraldo 1986). 2n = 24 in many Achnatherum spp. (Tsvelev 1977). Among other South American stipoids, 2n = 40 in Jarava plumosa (Spreng.) S.W.L. Jacobs and J. Everett, 2n = 42 and 44 in J.ichu Ruiz and Pavon and 2n = 40 and 44 in Amelichloa brachychaeta (Godr.) Arriaga and Barkworth (Bowden and Senn 1962). Of the North American species, 2n = 24 in Piptatherum pungens (Torrey) Dorn, 2n = 44 in Heterostipa comata (Trin. and Rupr.) Barkworth and 2n = 48 in Oryzopsis asperifolia Michaux and Piptatherum racemosa (Sm.) Barkworth (Barkworth 2006). Stipa sens. str. has a base number of 11, while the base number of Acnatherum is unclear but frequently cited as 11 or 12 (Vásquez and Barkworth 2004). Among the North American Nassella species, n = 11 in N. pungens E.Desv., n = 16 in N. tenuissima, n = 17 in N. lepida (Hitchc.) Barkworth, n = 23 in N. tucumana (Parodi) Torres, n = 32 in N. pulchra (Hitchc.) Barkworth, n =35 in N. cernua (Stebbins and Love) Barkworth and n = 41 in N. viridula (Trin.) Barkworth (Johnson 1972). However N. tenuissima material from Argentina examined by Bowden and Senn (1962) had a diploid number of 40, different from that of Texas plants. Of the South American species, 2n = 34 in N. hyalina, 2n = 36 in N. charruana, 2n = 36 and 38 in N. trichotoma, 2n = 42 in N. chilensis (Trin.) E. Desv., and N. exserta Phil., 2n = 64 in N. mucronata (Kunth) R.W. Pohl, 2n = 66 in N. lachnophylla (Trin.) Barkworth (Bowden and Senn 1962). But according to Watson and Dallwitz (2005) 2n = 38 in N. trichotoma. Genetic variation Grass species often possess wide racial or ecoytpic variation within their populations, partial discontinuities of phenotypes resulting from self-fertilisation, hybrid sterility between phenotypically similar populations, and other features, including polyploidy, that tend to obscure species boundaries (Stebbins 1972). Ecotype variation is known for N. trichotoma in Australia (Michalk et al. 2002) but has not been recorded for N. neesiana. Britt (2001) and Britt et al. (2002) sought evidence of genotypic variation in Australian populations. They compared four Victorian (Altona, Melton, Bacchus Marsh and Tarrawingee) and two New South Wales (Armidale and New England Tablelands) populations, using three molecular genetic profiling methods: 1. ITS – RFLP. Internal transcribed spacer - restriction fragment length polymorphism – a method for cutting the DNA at particular short sequences of nucleotides using restriction endonucleases – the polymorphisms in the restriction fragments are RFLPs and variation in the size of the RFLPs is dependent on the particular sequence recognised by each endonuclease. The ITS is a moderately conserved region of nuclear ribosomal DNA, and differences in its length and base pair pattern have revealed taxonomic patterns in grasses and enabled accurate scoring of their genotypes (Britt 2001). 2. ITS – PCR sequencing. Using the polymerase chain reaction (PCR) to generate large quantities of DNA to enable sequencing of the ITS region. 3. RAPD - PCR. Using PCR and random amplified polymorphic DNA (RAPD) analysis on the whole genome. The technique allows differentiation of closely related organisms or even single base changes by display of the DNA banding patterns using gel electrophoresis. DNA was extracted from between 18 and 10 plants grown from seeds collected in each geographical area (Britt 2001 p. 21), but no indication was provided of the number of individuals sampled from each population, their spatial arrangement in the source area, or the date of sampling (Britt 2001, Britt et al. 2002). The plants from which DNA were extracted were grown from seed collected in a particular area, but that seed could have been harvested from a single mother plant, and even if multiple mother plants were sampled a variable proportion of the seed from each would be cleistogamous. Thus all the individuals from which DNA was extracted for a particular area could have been genetically identical because of inadequate population sampling. No variation was found in the size of the ITS region (650 base pairs) or in the ITS-RFLP patterns tested. ITS sequencing revealed uniformity within the plants analysed from a particular area, but differences between plants from different areas, unrelated to their geographical proximity. All areas had shared homologies above 90%, suggesting conspecificity, except for Bacchus Marsh and Tarrawingee populations, but no one else appear to have suggested these populations are not N. neesiana. 98% homology – suggestive of convarietal status – was shared only by Altona and New England samples (Britt 2001). Jacobs et al. (2000) also analysed sequence data of the ITS region of nuclear rDNA and found no variation within the species tested, however, again, the number and intra-population source of their samples were not published. Britt’s (2001) RAPDs showed inter- but not intra-area variation but no consistent area groupings. Comparison of population differences using the two different methods produced two inconsistent ‘distance tree’ structures. ITS data indicated that the Melton population was most similar to N. leucotricha (Britt et al. 2002), suggesting the possibility that some hybridisation may be occurring. Jacobs et al. (2000) indicated that they are sister species. Britt (2001) and Britt et al. (2002) concluded that Australian N. neesiana possesses large genetic variation between areas (a number of subspecies/varieties – the terms were used interchangably – are present), that this may have arisen locally, and that local populations have no variation, so must have arisen via cleistogenes or seeds fertilised only by local pollen.The latter argument is flawed because Britt (2001) failed to demonstrate that the real population variation in each area was sampled. It is 32
also based on a misunderstanding of the breeding system (see Britt 2001 pp. 86-87): all the panicle seed is not necessarily crossfertilised (see the observations of floral anatomy by Burbidge and Gray (1970) and Vickery et al. (1986) above), the basal spikelets in a panicle are more or less cleistogamous, while cleistogamous spikelets can be found anywhere in the panicle. In order to reach such a concluison a methodology was required that ensured only the sampling of DNA from chasmogamous seeds. The local populations could also be the offspring of separate founder events involving different South American source populations, with the lack of local polymorphism (if it is not an artefact) resulting from genetic bottlenecking. As with most such studies these appear to be rather random probings of the genome, the genetic material examined is not necessarily expressed in the phenotype, nor is its functional role known. Future molecular genetical work in this area should start with an examination of South American populations ascribed to particular varieties and should also be integrated with a study of morphological variation, as suggested by Britt (2001). Phenology, growth and productivity Within the revised Raunkiaer plant life form spectrum (Mueller-Dombois and Ellenberg 1974), N. neesiana is classified as a hemicryptophyte (a perennial herb with periodic shoot reduction), subtype ‘caespitose graminoids’ (bunched or circular shoot arrangement with shoots more or less at the soil surface) and probably as 3.103 “sparingly evergreen during unfavourable season”. N. neesiana grows predominantly over the coooler months (Muyt 2001) with vegetative growth mainly from autumn to spring (Snell et al. 2007). Storrie (2006) considered it “one of the few” major weedy grasses in New South Wales “that produces green feed in winter”. In Argentina both agronomists and landholders agreed that it produced a large amount of good livestock feed during winter (Gardener et al. 1996b). High rainfall in spring promotes panicle proliferation (Cook 1999). Flowering and fruiting occurs from September to March in South America (Zanin 2008). In south-eastern Australia flowering occurs mainly during spring and early summer (September to December), but can occur at other times of the year when moisture and temperature conditions are suitable (Snell et al. 2007). At Inverleigh, Victoria, Gaur et al. (2005) recorded plants in the vegetative phase to 3 October 2003 and 1 October 2004, flag leaf swelling over the developing panicle on 13 October 2003, spiky stems on 18 October 2004 and full panicle emergence on 27 October 2003 and 28 October 2004. Pritchard (2002) recorded that plants at Laverton North had panicles still concealed in the sheath on 3 October 2000 and all the foliage was green, and that on 15 November there was a dense covering of emerged panicles. In Italy N. neesiana flowers and fruits from May to July (Moraldo 1986) approximately 6 months out of phase with Australia, where bolting generally begins in mid October and panicle seed drops in mid December (D. McLaren in Iaconis 2006b). Slay (2002c) reported a similar phenology in New Zealand: elongation of reproductive tillers in spring with the main flush of tiller production from mid-September to mid-October, flag leaf swelling in mid-October, then 24 days between the first emergence of the panicle and anthesis. Slay (2001) found the period from the boot stage to anthesis was 36 days and from anthesis to 100% viability of seed was 33 days. Slay (2001) identified: three phases of seeding: 1. basal cleistogene production during vegetative growth of the tiller, initiated in autumn and completed in spring before anthesis of panicle flowers; 2. cleistogamous and chasmogamous seed production in the panicle; 3. cleistogene production on the stems, initiated before anthesis of panicle flowers and completed after panicle seed maturation. In Victoria stems are brown and breaking down and cleistogenes form in mid to late summer, and by the end of February most stems have cleistogenes (McLaren in Iaconis 2006b). In New Zealand old culms are easily broken by late March (Slay 2001). The inactive period from mid summer to the time of autumn rain has been inadequately documented and summer dormancy appears to have been widely assumed. However flowering is indeterminate (Grech 2007a) and plants are known to flower in response to summer rain (Bedggood and Moerkerk 2002). Senescence of foliage and cessation of leaf growth occurs in all grasses in response to drought, but truly summer-dormant grasses display these traits despite summer irrigation (Norton et al. 2008). Across the range of pasture grass taxa there is a continuum of responses from full dormancy to non-dormancy, and the intensity of summer dormancy can be assessed by simulating a mid summer storm in the midst of drought, and measuring subsequent herbage production or senescence (Norton et al. 2008). Full dormancy is supposedly characterised by complete cessation of growth, full herbage senescence and dehydration of young leaf bases, whereas senescence and partial growth cessation may be just a dehydration avoidance strategy which can be expressed in any season under conditions of soil moisture stress. The possession of true summer dormancy is supposedly critical for pasture grass persistence in the drought prevalent pastures of south-eastern Australia, so a number of commonly utilised exotic grass cultivars have been assessed for this characteristic (Norton et al. 2008). Assessments of weedy and native Poaceae, including N. neesiana, would be informative. Average production in New England pasture was 2.3 t ha -1 y -1 (Gardener et al. 2005). Slay (2001) recorded production of 5.5±0.5 kg ha -1 of dry matter per day during the first 48 days after mowing in November in New Zealand. Grech (2004) found that plants that were regularly clipped to simulate grazing produced more digestible growth (significantly more crude protein, metabolisable energy and digestible dry matter) than unclipped plants. N fertiliser (100 kg ha -1 in two applications) increased the feed value only at the seedhead stage. Crude protein levels of green leaves (in South America) were 6.3-18.3% (Gardener et al. 1996b). Crude protein levels of winter foliage regrowth after clipping in Australia were 12.7-16.6% and digestible dry matter of green leaf material was c. 60% (range 58-66%), compared to Festuca arundinacea with crude protein of 13.0-18.8% and digestible dry matter 62-69% (Gardener, Storrie and Lowien 2003, Gardener et al. 2005). Culm material had a crude protein content of 4.5%. New Zealand data indicates a crude protein level of green leaves of plants in the vegetative phase of 14.5%, while leaves of plants early in the flowering stage had a crude protein level of 6.4%. The metabolisable energy value of vegetative phase leaves was 7.7 in early summer and of 7.5 in early flowering. Comparable crude protein and metabolisable energy (ME) levels were 9.9% and 11 for Lolium perenne L., while ME values in summer 1991 for D. glomerata, L. perenne, Phalaris aquatica L. and Festuca arundinacea were 8.3, 7.5, 33
Page 1 and 2: 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: are the seeds larger/smaller, longe
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 and 54: In the southern Brazilian campos of
Page 55 and 56: arundinacea (Gardener et al. 2005).
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
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 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
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 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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