Letteratura scientifica selezionata sul tema "Grazing South Australia Far North Region Management"

Research was conducted in the mid-north of South Australia over the period 2000–05 to evaluate the effects of different grazing management cues on composition and production of a grassland. The management cues were based on calendar, plant phenology or herbage mass thresholds using grazing exclusion as a control. There were five grazing treatments: (i) regional practice (RP), where sheep grazed continuously for the period April–December; (ii) autumn rest, where sheep grazing was restricted to June–December; (iii) spring rest, where sheep grazing was restricted to April–August; (iv) high density and short duration (HDSD), where herbage mass thresholds determined when grazing occurred and for what duration; and (v) nil (NIL) grazing by domestic herbivores. Mean annual estimates of herbage mass were highest for NIL and HDSD and inclusion of the estimate of herbage consumption by sheep resulted in greatest primary plant production in HDSD. The contribution of perennial grasses to herbage mass declined with RP and seasonal grazing treatments. Frequency of perennial grasses was unaffected by grazing treatment but the number of perennial grass plants increased over time in RP and seasonal treatments. HDSD allowed maintenance of basal cover whereas bare ground increased with RP and seasonal treatments. Litter accumulated in NIL but this was associated with a decline in perennial basal cover. Seasonal grazing treatments did not provide an advantage over RP and there appeared to be no benefit from including phenology in management decisions. In contrast, HDSD resulted in a stable and productive grassland ecosystem, with stocking rate estimated at 78% greater than other treatments. These features offer a desirable mix for future industry adoption in the mid-north of South Australia.

The main weeds and weed management practices undertaken in broad acre dryland cropping areas of north-eastern Australia have been identified. The information was collected in a comprehensive postal survey of both growers and agronomists from Dubbo in New South Wales (NSW) through to Clermont in central Queensland, where 237 surveys were returned. A very diverse weed flora of 105 weeds from 91 genera was identified for the three cropping zones within the region (central Queensland, southern Queensland and northern NSW). Twenty-three weeds were common to all cropping zones. The major common weeds were Sonchus oleraceus, Rapistrum rugosum, Echinochloa spp. and Urochloa panicoides. The main weeds were identified for both summer and winter fallows, and sorghum, wheat and chickpea crops for each of the zones, with some commonality as well as floral uniqueness recorded. More genera were recorded in the fallows than in crops, and those in summer fallows exceeded the number in winter. Across the region, weed management relied heavily on herbicides. In fallows, glyphosate and mixes with glyphosate were very common, although the importance of the glyphosate mix partner differed among the cropping zones. Use and importance of pre-emergence herbicides in-crop varied considerably among the zones. In wheat, more graminicides were used in northern NSW than in southern Queensland, and virtually none were used in central Queensland, reflecting the differences in winter grass weed flora across the region. Atrazine was the major herbicide used in sorghum, although metolachlor was also used predominantly in northern NSW. Fallow and inter-row cultivation were used more often in the southern areas of the region. Grazing of fallows was more prominent in northern NSW. High crop seeding rates were not commonly recorded indicating that growers are not using crop competition as a tool for weed management. Although many management practices were recorded overall, few growers were using integrated weed management, and herbicide resistance has been and continues to be an issue for the region.

Every year, millions of migratory birds journey along the East Asian-Australasian Flyway (EAAF). The scope of the EAAF encompasses Asia Pacific nations like Australia, New Zealand, China, Japan, South Korea, Vietnam, Malaysia and Indonesia. The effective conservation of these birds rests upon the implementation of bilateral legal agreements as well as non-binding regional initiatives along this North-South nexus. This article evaluates the implementation of one of the most important bilateral bird agreements in the region – the China-Australia Migratory Bird Agreement (CAMBA). The main obligations in CAMBA are identified; as are the legal initiatives adopted by both China and Australia which reflect CAMBA's obligations. Whilst Australian law makes specific reference to CAMBA, Chinese law is far less direct, though perhaps no less effective. The argument is made that the findings in this article have relevance for an improved understanding of the mechanisms for transboundary governance of migratory birdlife, especially in the Asia Pacific.

In this paper we examine the forces that have shaped Australia’s far northern (north of 20° south) beef industry over the past 35 years. This is done for the purpose of tracing its transformation from a state of relative isolation to an integral part of the national beef industry. We note that integration is being accompanied by a greater focus, particularly by corporate producers, on specialised breeding in the far north and this is being assisted by innovations that increase herd fertility and raise the meat quality of the progeny, while retaining adaptation of the breeding herd to the local environment. Among a range of technologies, genetic improvement has significant potential to bring about rapid improvement in the meat quality of tropically adapted cattle. With respect to gene-based technology, however, independent producers will have to be convinced about the rigour of the technology and the prospects of economic gains before they make significant management changes. To this end, innovative marketing systems are needed that will reveal the link between expected meat returns and the offer prices applying to groups of growing cattle in any location. Accordingly, there is an urgent need to develop and introduce a descriptive and informative trading language for growing cattle that incorporates inherent qualities including those that influence meat quality. Innovations that will complement those applying to enhancement of meat quality are more general but will significantly raise herd productivity. We also compare the operating systems of both corporate and independent producers in the region.

In the Mallee region of north-western Victoria, Australia, there is very little grazing of crops that are intended for grain production. The success of dual-purpose crops in other regions in south-eastern Australia with higher and more evenly distributed rainfall has driven interest in assessing the performance of dual-purpose cereals in the region. Five experiments were established in five consecutive years (2009–13) in the southern Mallee to measure the forage production and grain yield and quality response in wheat and barley to grazing by sheep or mechanical defoliation. The first three experiments focused on spring cultivars sown from late April to June, and the last two on winter cultivars planted from late February to early March. Cereal crops provided early and nutritious feed for livestock, with earlier sowing increasing the amount of dry matter available for winter grazing, and barley consistently produced more dry matter at the time of grazing or defoliation than wheat. However, the grain-production response of cereals to grazing or defoliation was variable and unpredictable. Effects on yield varied from –0.7 to +0.6 t/ha, with most site × year × cultivar combinations neutral (23) or negative (14), and few positive (2). Changes in grain protein were generally consistent with yield dilution effects. Defoliation increased the percentage of screenings (grains passing a 2-mm sieve) in three of five experiments. Given the risk of reduced grain yield and quality found in this study, and the importance of grain income in determining farm profitability in the region, it is unlikely that dual-purpose use of current cereal cultivars will become widespread under existing grazing management guidelines for dual-purpose crops (i.e. that cereal crops can be safely grazed once anchored, until Zadoks growth stage Z30, without grain yield penalty). It was demonstrated that early-sown winter wheat cultivars could produce more dry matter for grazing (0.4–0.5 t/ha) than later sown spring wheat and barley cultivars popular in the region (0.03–0.21 t/ha), and development of regionally adapted winter cultivars may facilitate adoption of dual-purpose cereals on mixed farms.

The helminth fauna from 124 water-rats, Hydromys chrysogaster, collected from 33 localities in Queensland was analysed. A total of 45 species of helminths was found, comprising 2 acanthocephalans, 2 cestodes, 13 nematodes and 28 trematodes. The helminth community of the water-rats in the region north of latitude 18˚ (far north) was different from that of water-rats south of 18˚ (central); Sorensen’s Index 45·8% similarity, whereas Holmes and Podesta’s Index gave 32·1% similarity. Comparisons with data from water-rats from southern and Tasmanian regions showed that they were different from each other and from both Queensland regions. The helminth communities were characterised by high diversity, dominated by trematodes in the central and Tasmanian regions, but with nematodes becoming more prominent in the far northern and southern regions. No core or secondary species were found in the Queensland helminth communities, the southern community was suggestive of a bimodal distribution and the Tasmanian had two core species. A checklist of helminth species occurring in water-rats from eastern Australia is provided.

Microlaena (Microlaena stipoides var. stipoides (Labill.) R.Br.) is a C3 perennial grass that is native to areas of south-eastern Australia. In this region, perennial grasses are important for the grazing industries because of their extended growing season and persistence over several years. This series of experiments focused on the population biology of Microlaena by studying the phenology (when seed was set), seed rain (how much seed was produced and where it fell), seed germination, germinable seedbank, seed predation and seedling recruitment in a pasture. Experiments were conducted at Chiltern, in north-eastern Victoria, on an existing native grass pasture dominated by Microlaena. Seed yields were substantial (mean 800 seeds m–2), with seed rain occurring over December–May. Microlaena has two distinct periods of high seed rain, in early summer and in early autumn. Seed predation is high. Within a 24-h period during peak seed production, up to 30% of Microlaena seed was removed from a pasture, primarily by ants. Microlaena seedlings recruited throughout an open paddock; however, seedling density was low (5 seedlings m–2). Microlaena represented only low numbers in the seedbank (0.01–0.05% of total); hence, any seedlings of Microlaena that germinate from the seedbank would face immense competition from other species. Management strategies for Microlaena-dominant pastures need to focus on the maintenance of existing plants.

Following a sequence of favourable years in which pasture growth over much of the arid zone of Australia reached very high ievels, controlled burns were carried out on two contrasting vegetation types in the extreme north-west of New South Wales. A wheei-point apparatus was used to measure subse- quent changes in botanical composition and foliage cover over a four year period. On a pasture periodically dominated by Mitchell grass (Astrebla spp.) burning while growing conditions were favourable resulted in only a small long- term decrease in the cover of Mitchell grass. In the short-term all chenopod species were eliminated and a wider range and greater abundance of annual forbs were promoted in the following spring. On a similar area burned by wildfire in a year of low summer rainfall the response from Mitchell grass was much poorer and botanical composition of the pasture present in the following spring differed from that which developed in the spring following the controlled burn. It also differed from that of the unburnt pasture. The major differences were due to the response of forb species and are attributed to variation in seasonal rainfall. On a dune-system pasture the dominant grasses were species of Aristida and Enneapogon. These are relatively short-lived and appear to have little ability to regrow from the butt after fire. Their slow regeneration after the burn was reflected in the substantial increase in relative abundance of perennial forbs in the following autumn, and of annual forbs the next spring. Although fire appeared to have no long-term effect on the pasture it dramatically reduced tree and shrub numbers. It is suggested that during years in which abnormal quantities of Mitchell grass are present in this region, controlled burning could be a useful form of management. A mosaic of patches burnt at different times would reduce the potential for wide-scale wildfires, provide refuge areas for stock and wildlife in the event of wildfire, and promote a wider choice of plant material for grazing animals. However, in dune-systems vegetation, removal of the pasture cover and reduction of the tree and shrub density would constitute an erosion risk.

Water is a principal medium of exchange within communities facing changing climate patterns and the ‘new dry’. For some parts of the globe water has been taken-for-granted, uncontested, yet for others highly variable, scarce and a measure of global and national inequalities. Australia as a large and diverse landmass is emblematic of those varied water contexts, yet as a whole, and after the recent ‘100-year drought’, water has become heavily regulated and marketised, and its material and symbolic meanings transformed. This has led us to ask: “What happens when water becomes marked or recognised as a scarce resource for all, indeed a site of contest and potential human conflict? How do the attempts to control water, through its market currency and environmental value, change the character of communities, the identities and interpersonal relationships that constitute the regional context?” After all, water is about far more than a material resource, it is also a cultural medium that is implicated the most fundamental aspects of life. In this study we explore the ways in which South Australian's living in the arid north of the state, above the Goyder Line, live and identify through the changing relations of water. Those changing relations are the changing availability and governance of water, nested within an ever-present public concern about climate change. We draw upon interviews with settler community members from a 200 square kilometre region across 7 towns or stations. Alongside the growing dry has been the developing commodification of water, having the effect of reducing local autonomy in the management and decision making about water conservation, supply and use. This paper considers the ways that these changes have transformative effects upon the differences and solidarities within local community relations.

The impression has been given in previous studies that there are few bird conservation problems in the arid zone, particularly because not one of a total of 230 species has become extinct. In stark contrast, almost half of the native terrestrial mammalian fauna of the Australian arid zone has become extinct on the mainland since European occupation. Here we show that the status of one half of the avifauna has changed since European occupation, and conclude there are many threats to avian biodiversity at the regional scale in the arid zone. There are 19 species (8%) in the arid zone classified as rare and threatened nationally. Twelve more (5%) are uncommon species which have declined or are at risk in two or more regions. A further 40 species (17%) have declined in at least one arid region, although many of these remain common and some have increased elsewhere in arid Australia. At least 45 species (20%) have increased in range or abundance, including a suite of ground-feeding birds associated with degraded landscapes. Striking patterns emerged from analysis of 29 threatened and declining species: • birds associated with chenopod shrublands and grassy, riparian or floodplain environments have been most affected whereas mulga inhabitants and canopy-dwellers of riparian woodland have been little affected; • birds generally with a northem distribution have declined in the south of the arid zone and birds with a southern distribution have declined in the north of the arid zone, and these patterns contrast with many birds with a southern or continental distribution which have declined more in southern semiarid regions than within the arid zone itself; • birds which feed at ground and low shrub height have been most adversely affected; • sedentary bushbirds (passerines) are more at risk than nomads and their limited mobility seems to be a risk factor; • among non-passerines, parrots, cockatoos and pigeons are most at risk, while three passerine families stand out, namely wrens, quail-thrushes, and thornbills and allies; • contrary to findings for mammals, size does not generally appear to be an important risk factor. Land degradation and habitat alteration such as shifts in abundance or dominance of plant species caused by the introduction of exotic herbivores appear to be the principal factors causing change in status while the provision of reliable water sources in pastoral districts is also important. Introduced predators are implicated in some cases and altered fire regimes may have played a part in spinifex and mallee habitats. Competitive interactions between increasing and declining species, although not demonstrated, appear to be likely for some species. We have documented a hitherto unsuspected degree of change in avian biodiversity in the Australian arid zone. In the absence of widespread regeneration of dominant plant species in the southern arid zone, the decline of many arid zone birds will accelerate dramatically. Also, unless better management ensues, the next major drought could cause accelerated declines and extinctions. We advocate a range of measures designed to improve the conservation prospects for arid Australian birds, including lower stocking rates on pastoral properties, rehabilitation of critical habitats and their protection from exotic herbivores, experimental research on the impact of grazing and predation, and monitoring of both threatened species and a range of sedentary passerines typically associated with representative habitats in the arid zone.

Accompanying CD-ROM inside back cover, includes Appendices. Bibliography: leaves 242-266. This thesis examines the effects on vegetation at selected sites in northern South Australia of excluding various herbivores over a four and a half year period and of two intense but controlled grazing pulses over a six month period followed by an 18 month recovery period in a dune-swale land system. These changes are compared with changes recorded over an 11-year period at the Olympic Dam mine site. It found that short-term changes in vegetation revealed by ordination of periodical cover, density and species richness, are attributable to the periodicity of rainfall and that, under present grazing regimes, rainfall effects override grazing effects. Differences between the effects of sheep and cattle hoof damage are worthy of further investigation, as is the impact of kangaroo grazing. These two factors may have important implications for the management of Australian rangelands. System requirements for accompanying CD-ROM: IBM compatible computer with Pentium processor or higher and Windows 95, 98 or NT ; 4 MB or RAM. Other software: Acrobat Adobe Reader.

Pictures of Time Beneath examines three celebrated heritage landscapes: Adelaide’s Hallett Cove, Lake Callabonna in the far north of South Australia, and the World Heritage listed Willandra Lakes Region of New South Wales. It offers philosophical insights into significant issues of heritage management, our relationship with Australian landscapes, and an original perspective on our understanding of place, time, nation and science. Glaciers in Adelaide, cow-sized wombats, monster kangaroos, desert dunes littered with freshwater mussels, ancient oases and inland seas: a diverse group of deep-time imaginings is the subject of this ground-breaking book. Ideas about a deep past in Australia are central to broader issues of identity, belonging, uniqueness, legitimacy and intellectual community. This journey through Australia’s natural histories examines the way landscapes and landforms are interpreted to realise certain visions of the land, the nation and the past in the context of contemporary notions of geological heritage, cultural property, cultural identity and antiquity.