Major progress in understanding biological invasions has recently been made by quantitativelycomparing successful and unsuccessful invasions. We used such an approach to test hypotheses about the role of climatic suitability, life history, and historical factors in the establishment and subsequent spread of 40 species of mammal that have been introduced to mainland Australia. Relative to failed species, the 23 species that became established had a greater area of climatically suitable habitat available in Australia, had previously become established elsewhere, had a larger overseas range, and were introduced more times. These relationships held after phylogeny was controlled for, but successful species were also significantly more likely to be nonmigratory. A forward-selection model included only two of the nine variables for which we had data for all species: climatic suitability and introduction effort. When the model was adjusted for phylogeny, those same two variables were included, along with previous establishment success. Of the established species, those with a larger geographic range size in Australia had a greater area of climatically suitable habitat, had traits associated with a faster population growth rate (small body size, shorter life span, lower weaning age, more offspring per year), were nonherbivorous, and had a larger overseas range size. When the model was adjusted for phylogeny, the importance of climatic suitability and the life-history traits remained significant, but overseas range size was no longer important and species with greater introduction effort had a larger geographic range size. Two variables explained variation in geographic range size in a forward-selection model: species with smaller body mass and greater longevity tended to have larger range sizes in Australia. These results mirror those from a recent analysis of exotic-bird introductions into Australia, suggesting that, at least among vertebrate taxa, similar factors predict establishment and spread. Our approach and results are being used to assess the risks of exotic vertebrates becoming established and spreading in Australia. Resumen:Recientemente se ha logrado un progreso importante en el entendimiento de invasiones biológicas al comparar invasiones exitosas y no exitosas cuantitativamente. Utilizamos ese método para probar hipótesis acerca de la adaptabilidad climática, historia de vida y factores históricos en el establecimiento y extensión posterior de 40 especies de mamíferos que han sido introducidas en Australia. En relación con especies no exitosas, las 23 especies que se establecieron tenían una mayorárea de hábitat adecuado climáticamente en Australia, se habían establecido en otras partes, tenían un mayor rango y fueron introducidas más veces. Después de controlar para filogenia, estas relaciones se mantuvieron, pero las especies exitosas también fueron significativamente no migratorias. Un modelo de selección anterior incluyó a sólo dos de las nueve variables 558 Establishment and Spread of Exotic MammalsFor...
Field experiments were carried out at seven sites in southern Australia from 2002 to 2006 to measure changes in plant frequency, root characteristics and summer activity for a range of grass and herb species or cultivars. Annual rainfall during the experimental period was on average 75 mm lower than the long-term average. Plant frequency differed significantly between species and between sites. Temperate grasses generally had higher frequencies than subtropical grasses, native grasses and herbs. Cocksfoot (Dactylis glomerata cvv. Currie, Porto), tall wheat grass (Thinopyrum ponticum cv. Dundas), winter-active tall fescue (Festuca arundinacea cvv. Fraydo, Resolute MaxP) and phalaris (Phalaris aquatica cvv. Atlas PG, Australian) were the most persistent of the temperate perennial species over the experimental period. The frequency of most cultivars declined from year 2 to year 4 after establishment, but the frequency of kikuyu (Pennisetum clandestinum cv.Whittet) and wallaby grass (Austrodanthonia richardsonii cv. Taranna) increased by over 5% from year 2 to year 3, and cocksfoot (cv. Currie) increased from year 3 to year 4. At two sites where measurements were made, there were significant differences in rooting depth between species. Whittet kikuyu was the deepest among all species with a rooting depth of up to 2 m, followed by phalaris, tall fescue, grazing brome (Bromus stamineus) and tall wheat grass. Root density was affected by plant genotype and soil structure. Root density of the species varied significantly in the subsoil (0.1–1.1 m) and deeper subsoil (1.1–2 m) but not in the topsoil (0–0.1 m). Green-leafiness over summer was generally higher for subtropical grasses, native grasses, herbs and some summer-active temperate grasses, than most temperate grasses with high summer dormancy.
Deep-rooted perennial pasture plants can play an important role in solving the environmental problems of rising watertables, dryland salinity and soil acidification in the wheatbelt of southern Australia. These problems are attributed to the extensive clearing of perennial native vegetation and its replacement with shallow-rooted winter-growing annual crops and pastures. Deep-rooted, herbaceous perennial legumes, particularly lucerne (Medicago sativa L.), are seen as making an increasing contribution in the cropping zones where high rates of symbiotic nitrogen fixation and increased water use are high priorities. This paper reviews the current use and the potential of a range of temperate perennial legumes for the wheatbelt of southern Australia. The genera examined include Medicago, Hedysarum, Trifolium, Onobrychis, Lotus, Galega, Astragalus, Lathyrus, Anthyllis, Psoralea, Dorycnium, Lespedeza and Securigera. There is considerable scope to expand the use of lucerne; however, there is also a need for alternative perennial species to increase biodiversity and to fill niches where lucerne is less suited. Based on current knowledge, the species with the most promise to complement lucerne include sainfoin (Onobrychis viciifolia Scop.) and sulla (Hedysarum coronarium L.) on alkaline soils, strawberry clover (Trifolium fragiferum L.) in wet or mildly saline niches and Lotus and Dorycnium spp. on waterlogged and/or acid soils.
Ninety-one perennial legumes and herbs (entries) from 47 species in 21 genera were evaluated at sites in New South Wales, South Australia and Western Australia over 3 years from 2002 to 2005 to identify plants with superior herbage production, persistence and the potential to reduce ground water recharge. Evaluation was undertaken in three nurseries (general, waterlogged soil and acid soil). Medicago sativa L. subsp. sativa (lucerne) cv. Sceptre was the best performing species across all sites. In the general and acid soil nurseries, Cichorium intybus L. (chicory) cv. Grasslands Puna was the only species comparable with Sceptre lucerne in terms of persistence and herbage production. Trifolium fragiferum L. cv. Palestine and Lotus corniculatus L. SA833 were the best performing species on heavy clay soils prone to waterlogging. Three Dorycnium hirsutum (L.) Ser. accessions persisted well on acid soils, but were slow to establish. Short-lived perennial forage legumes, such as Onobrychis viciifolia Scop. cv. Othello, and three Hedysarum coronarium L. entries, including cv. Grasslands Aokou, had high herbage production in the first 2 years and may be suitable for short-term pastures in phased pasture-crop farming systems. T. uniflorum L. and M. sativa subsp. caerulea SA38052 were highly persistent and could play a role as companion species in mixtures or ground cover species for undulating landscapes. Cullen australasicum (Schltdl.) G.W. Grimes SA4966 and Lotononis bainesii Baker cv. Miles had poor establishment, but were persistent. Chicory, T. fragiferum and L. corniculatus were identified as species, other than lucerne, with the most immediate potential for further selection to increase the diversity of perennial legumes and herbs adapted to southern Australian environments.
To review pasture species for regions with 465-680 mm average annual rainfall, 22 perennial grasses and herbs were evaluated for pasture establishment and productivity in four states at seven locations where the arrest of groundwater recharge is considered necessary to ameliorate dryland salinity. Species represented introduced and native, temperate and subtropical grasses, chicory (Cichorium intybus L.) and plantain (Plantago lanceolata L.). This report describes establishment and yield; the following paper describes persistence and root characteristics. Yields were measured over 2-3 years except at one site, which suffered severe drought. Perennial ryegrass (Lolium perenne L., cv. Avalon) and tall fescue (Festuca arundinacea Schreb. = syn. Lolium arundinaceum. (Schreb.) Darbysh., cvv. AU Triumph and Resolute MaxP), cocksfoot (Dactylis glomerata L., cv. Porto) and phalaris (Phalaris aquatica L., cv. Holdfast and Australian) were the most productive species, with dry matter (DM) yields of 13.6-15.1 t/ha. For summer growth, Porto and Rhodes grass (Chloris gayana Kunth, cv. Katambora) were the most productive species; relative to Australian in summer, Porto and Katambora produced 41% and 26% more DM, respectively (95% confidence). Perennial ryegrass (cv. Avalon), tall fescue (cv. Resolute MaxP) and chicory (cv. Grouse) were particularly valuable for autumn growth; Avalon was 30% more productive than Australian. Tall fescue (cv. Resolute MaxP) was 32% more productive than Australian in winter. Avalon and AU Triumph were the most productive grasses and herbs in spring. Based on natural rainfall over the 2-3 years of measurement, the mean water use productivity, ignoring any runoff, was 10.5 kg DM/ha.mm for the three most productive species. Apart from kangaroo grass (Themeda triandra Forssk), native grasses gradually established, but over a prolonged period weeping grass (Microlaena stipoides (Labill.) R.Br., cv. Wakefield) was the most rapid. Perennial ryegrass, tall fescue, cocksfoot and phalaris maintained productive yields across a diverse range of soils and climates. Exploration of the diversity within these species in a nationally coordinated program of genetic improvement appears warranted for improving reliability and expanding the zone of adaptation.
As a result of a workshop held at Täljöviken, Åkersberga, Sweden, on 27–29 May 1991, a multicentre collaborative research project was established, with the purpose of developing the concept of integrated in vitro toxicity testing. The first priority was the selection of tests within eight appropriate areas: basal cytotoxicity, irritancy, developmental toxicity, hepatotoxicity, nephrotoxicity, immunotoxicity, neurotoxicity and biokinetics. An ideal battery of tests for each area was identified. Since it was realised that it would not be feasible to include the full ideal list of tests in the project, a minimum test list was also agreed. For each area, ten calibration chemicals were selected. From these 80 compounds, 30 were selected for inclusion, together with 20 of the OECD test programme chemicals, in a first test set of chemicals. The toxicity of these 50 test set chemicals will be investigated in the minimum integrated test scheme. The aim of the project is to employ non-animal methods to assess the toxicological properties of chemicals, and to improve this assessment through the use of knowledge about mechanisms of toxic action. The information produced will contribute to the establishment of a more-scientific and more-efficient toxicological procedure for hazard assessment. Questions concerning which parameters need to be investigated and combined to make hazard assessments, and which parameters relevant to in vivo toxicity can be determined in non-whole animal test systems, will also be addressed.
Keynote paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.There is considerable interest from Western Australian (WA) pastoralists on the potential role of leucaena (Leucaena leucocephala) in northern WA, where the potential area for dryland production of species of the genus Leucaena is high. Although it is highly regarded for animal production in other countries and in Queensland, leucaena is a contentious species since its status as an environmental weed precludes it from use on pastoral leases in the Kimberley and Pilbara regions of WA. Development of sterile/seedless forms would overcome risks of spread of the species as a weed. The key environmental constraints to growth of leucaena are likely to be the length of the dry season and low fertility of most soils other than the grey/black cracking clays (vertosols). Psyllid resistance and cool temperature tolerance are likely to be of secondary importance. Opportunities for irrigated production are also emerging and may allow leucaena species to be used in environments previously considered well outside their home-range. It is desirable now to re-examine the diversity of the wider leucaena genus for adaptation to WA conditions generally and for the purpose of selecting elite parent material for use in a sterile/seedless leucaena breeding program. These perennial species that can be under production for 30 to 40 years need to be evaluated in the target environments for at least 3‒5 years to fully understand their potential as adult plants.
The agricultural region of south-west Western Australia (WA) has a Mediterranean climate, characterised by a winter-dominant rainfall pattern. Perennial subtropical grasses are increasingly being grown to increase productivity and reduce erosion on infertile sandy soils in the northern agricultural region (NAR) of WA, an area with mild winters and dry, hot summers. However, little information exists on the persistence of different species or their expected seasonal production and feed quality. On the south coast of WA, an area with dry, warm summers and a maritime influence, kikuyu (Pennisetum clandestinum) has been widely sown, but there is little information on the potential of other subtropical grasses. To address these issues, five trials were established across the agricultural area of south-west WA to measure the seasonal production, feed quality and persistence of the main, commercially available subtropical grasses over 3–4 years. This study demonstrates that subtropical grasses have a long-term role in the NAR in areas with mild winters and/or where the rainfall is >400 mm. The best performing subtropical grasses across a range of sites were panic grass (Megathyrsus maximus) and Rhodes grass (Chloris gayana). These species can be expected to have a water-use efficiency of ~10 kg ha–1 mm–1 over a 12-month period, provided there is a good perennial grass density. On the south coast, panic grass, Rhodes grass and setaria (Setaria sphacelata) persisted well and produced significantly more biomass than kikuyu. These grasses could complement kikuyu by increasing out-of-season production. At Kojonup, a more inland site, most of the subtropical grasses died over winter from a combination of occasional frosts and cold, wet soils. However, kikuyu re-grew from rhizomes in spring and maintained >90% ground cover 4 years after sowing. The results from these experiments are likely to be applicable to other regions across the globe with Mediterranean climates and similar soil types.
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