Добірка наукової літератури з теми "Sand dunes Victoria"

The New Holland mouse (Pseudomys novaehollandiae) was first recorded at Wilson?s Promontory in 1972 in heathland vegetation, but has not been located in this habitat subsequently. The species was not trapped again until 1993 when it was found in calcarenite dune woodland on the Yanakie Isthmus. The aims of this study were to assess the population dynamics and habitat use of the species in this dune habitat. Mark-recapture trapping was conducted at three sites from 1999 to 2002. One site was located on low (0 - 5 m), flat sand dunes and open swales, another on medium (5 ? 10 m) vegetated dunes, and the third on high (20 m) steep vegetated dunes. The three sites had not been burnt for 30 to 50 years. The abundance of P. novaehollandiae was related to understorey vegetation density and differences in population densities on the sites are likely to be related to the primary succession stages on the sand dunes, rather than fire history. The maximum density (24 ha-1) recorded at one site was very high compared to other Victorian populations, however this was followed by a substantial decline in numbers within the year. At another site a small population declined to extinction. Populations on the isthmus are thus capable of achieving high densities but may decline quickly. Rainfall patterns may have affected the population fluctuations, but further research is required to elucidate fully the factors involved in the long-term dynamics of this species.

Most of Australia’s desert dune fields are stable; however, wildfires may reduce vegetation and biological soil crust cover so that sand movement may take place until vegetation recovers. In this study, we aimed to study the recovery rate of vegetation cover in spinifex (Triodia)-dominated desert dunes following wildfires using satellite imagery-derived spectral indices to: (1) determine for how long after fire these dunes may be active until critical levels of vegetation cover are attained; (2) determine which spectral index is the most suitable for monitoring vegetation recovery in this area. We have used a combination of MODIS, Landsat, Aster and QuickBird images to analyse vegetation cover following fire at various spatial and temporal scales, in the Great Victoria Desert, WA. The following spectral indices were compared: Brightness Index, Biological Soil Crust Index (BSCI), Crust Index, Enhanced Vegetation Index, Normalised Burn Ratio, Normalised Difference Vegetation Index, Soil Adjusted Vegetation Index and the Stress-related Vegetation Index. The BSCI was found to outperform the other spectral indices in monitoring vegetation cover in this area. Whereas full recovery of vegetation following wildfires in the study area was attained only after 25–30 years, critical thresholds of vegetation cover limiting sand movement were attained after just 1–5 years. The frequency and intensity of wildfires is therefore an important factor controlling dune activity in Australia’s deserts.

Pseudomys novaehollandiae is ‘Endangered’ in Victoria, where it is presently considered to be extant at only three localities Loch Sport, Providence Ponds, and Wilsons Promontory. This study aimed to determine indicators of suitable habitat for the species that could assist in identifying potential habitat and sites for planned re-introductions as part of a recovery program. Vegetation and site data (soils, topography, rainfall, fire age-time since fire) were assessed at localities where P. novaehollandiae was recorded. The species occurred in five structural vegetation groups - open-forest, woodland, heathland, shrubland, grassland, with the most common being open-forest and woodland. Grassland and shrubland were restricted to coastal sand-dunes in south Gippsland. Understorey vegetation at most sites was dominated by sclerophyllous shrubs ranging in cover from 10 - 70%. Classification of quadrats produced eight floristic groups in which the trend was for quadrats to cluster according to geographical location. Ordination confirmed the classification pattern and vector-fitting produced significant correlations between vector points and five variables: species richness, latitude, longitude, fire age and annual rainfall. The study identified a range of vegetation communities where P. novaehollandiae occurs and provided evidence that the species is not restricted to floristically rich and diverse heathlands. The findings can be used to determine further localities with suitable habitat. However, factors other than vegetation are also likely to be important in predicting suitable habitat.

The present paper completes a taxonomic revision of Cassinia subg. Cassinia, a group of 35 species separated from subg. Achromolaena by the structure of its inflorescence (capitula arrangement approximately dichasial, giving rise to flat- or round-topped compound inflorescences, as opposed to the irregular or alternate arrangement of capitula in subg. Achromolaena, where the overall shape of the inflorescence is conical or elongate). The seven species of Cassinia sect. Cassinia (C. aculeata, C. thinicola, C. wilsoniae, C. longifolia, C. aureonitens, C. trinerva and C. cinerea) are keyed, described and illustrated, with discussion of ecology, distribution and variation. Cassinia aculeata subsp. nova-anglica Orchard, C. thinicola Orchard, C. wilsoniae Orchard and C. cinerea Orchard are described as new. Cassinia aculeata is a variable and widespread species. Four morphological variants are described and discussed, although not formally named. Previously suggested hybridisation between C. aculeata and Ozothamnus obcordatus is discussed, and dismissed. A new subspecies, narrowly endemic to the New England region of New South Wales (NSW), and separated by 350 km from subsp. aculeata, is described. Cassinia longifolia is similarly widespread and variable, particularly in indumentum and leaf shape. Again, four more or less distinct local morphological variants are described, but they are not formally named because of problems with satisfactory circumscription. Cassinia thinicola is newly segregated from C. aculeata. It is a strikingly distinct species, confined to coastal habitats north and south of Newcastle, distinguished by its (usually) lack of hairs on the upper leaf surface, ochre-coloured inflorescences and compact habit. Cassinia wilsoniae, confined to Wyperfeld National Park in western Victoria, has hitherto been largely overlooked, with specimens assigned to a broadly circumscribed ‘C. uncata’, or C. aculeata or C. longifolia. It is geographically widely separated from all of these taxa. It is unusual in the genus, in being confined largely to the summits of consolidated sand dunes. It has rather small inflorescences with few capitula, and these are ochre-coloured. The leaf margins are strongly revolute, almost completely covering the midrib below, unlike related taxa where the midrib remains uncovered. Cassinia cinerea is a rare species confined to south-eastern Queensland, and hitherto confused with C. laevis and C. collina, both in subg. Achromolaena (and thus with conical inflorescences). It also differs from both in a range of indumentum and leaf characters. The remaining, previously recognised, species are redescribed in detail, and their nomenclature, variation, ecology and distribution are discussed as required.

The Pleistocene Bridgewater Formation is well exposed at Cape Bridgewater and surrounding areas in south-western Victoria, where field studies, mineralogical and isotopic analyses and OSL dating have shown that it can be divided into three members, here named (in stratigraphic order) the Descartes Bay, Bats Ridge and Duquesne members. Each member consists of aeolian calcarenite deposited as a coastal dune, that was karstified (with solution pipe development) and then overlain by a red or purple palaeosol. The aeolianites were deposited in three distinct phases corresponding to interglacials MIS 11, MIS 9 and MIS 7, respectively, when the shoreline was near present sea level. Karstification occurred as a result of the high effective precipitation characteristic of the transition between interglacial and glacial periods, followed by aeolian dust accession and palaeosol formation during the drier, windier glacial climates. Comparison with the coeval Tamala Limestone in south-western Western Australia shows simultaneous changes in palaeoclimate: high effective precipitation during the transition from MIS 11 to MIS 10, and a relatively dry transition from MIS 9 to MIS 8. Abundant rainfall during MIS 5 caused extensive limestone dissolution (solution pipes in Victoria, pinnacles in Western Australia) and the resulting quartz sand residue was redeposited during MIS 2-4.

Abstract Dasyurids are small mammals that can conserve energy and water by using shelters that insulate against extreme conditions, prevent predation, and facilitate torpor. To quantify the diurnal sheltering requirements of a poorly known, endangered dasyurid, the sandhill dunnart, Sminthopsis psammophila, we radiotracked 40 individuals in the Western Australian Great Victoria Desert between 2015 and 2019. We assessed the effect of habitat class (broad habitat features), plot-level (the area surrounding each shelter), and shelter characteristics (e.g., daily temperature ranges), on shelter selection and sheltering habitat preferences. Two hundred and eleven diurnal shelters (mean of 5 ± 3 shelters per individual) were located on 363 shelter days (the number of days each shelter was used), within mature vegetation (mean seral age of 32 ± 12 years postfire). Burrows were used on 77% of shelter days and were typically concealed under mature spinifex, Triodia spp., with stable temperature ranges and northern aspects facing the sun. While many burrows were reused (n = 40 across 175 shelter days), spinifex hummock shelters typically were used for one shelter day and were not insulative against extreme temperatures. However, shallow scrapes within Lepidobolus deserti hummock shelters had thermal advantages and log shelters retained heat and were selected on cooler days. Sminthopsis psammophila requires long-unburned sheltering habitat with mature vegetation. Summer fires in the Great Victoria Desert can be extensive and destroy large areas of land, rendering them a key threat to the species. We conclude that the survey and conservation of S. psammophila requires attention to long-unburned, dense lower stratum swale, sand plain, and dune slope habitats, and the tendency of S. psammophila to burrow allows the species to survive within the extreme conditions of its desert environment.

Mineral-sands mining in the semiarid and arid zone of south-eastern Australia is now a widespread disturbance that may adversely affect large areas of remnant vegetation, including mallee (Eucalyptus spp.) with hummock grass or spinifex (Triodia scariosa) understorey. No broad-scale restoration projects have been undertaken to revegetate mallee Eucalyptus species with spinifex. We report on the survivorship and relative importance (spatial coverage) of hand-planted tubestock 10 years after establishment in 2001, which included mallee Eucalyptus, Triodia scariosa, Acacia spp. and Hakea spp. These taxa are the dominant plants in a semiarid dune–swale system on a former mineral-sands mine licence area in semiarid, north-western Victoria. Mean survivorship of tubestock was 0.58 ± 0.04. Spinifex (Triodia scariosa), needlewood (Hakea) and several mallee species (Eucalyptus spp.) survived substantially better than the average of all tubestock-planted species, although Acacia spp. had low survivorships. Although the plantings were undertaken in the early stages of the most severe drought in the instrumental record (the ‘Millennium drought’), several taxa survived well and species such as spinifex established and developed ground coverage greater than the benchmark values for the ecological vegetation class of the location. We conclude that hand-planting of tubestock can achieve restoration objectives for this component of spinifex–mallee vegetation, even under extremely arduous conditions associated with long-term drought. We also herald the importance of taking a long-term view to the assessment of revegetation success, in this case 10 years.

It has long been hypothesized that the last glacial maximum (LGM) oversaw cold, arid, windy climates across southern Australia, and that these were driven by intensification and northward expansion of mid-latitude westerly circulation. Moreover, it was recently suggested that Australia experienced an extended LGM which began several millennia before the global peak. Aeolian sedimentary deposits provide key evidence for these hypotheses, and climate modelling an alternative means to test them. As yet, however, combined approaches to reconstructing glacial environments on the continent are scarce. Here we provide new evidence for westerly wind regimes across glacial southeastern Australia. We confirm active transverse lunette deposition at c. 29 ka and c. 23–19 ka in the semi-arid Willandra Lakes, and identify aeolian sand incursions to Spring Creek on the temperate Western Victorian Volcanic Plains from c. 29 ka. The Spring Creek deposits contain a surprising quantity of sand-sized quartz given the basalt setting, which we propose to be allochthonous and likely transported some distance. The site lies more than 50 km east and south of dunefields which were active at the same time and may have contributed sediment via long distance transport. We investigate the hypothesis for northward glacial expansion of westerly winds by combining our sediment records with aeolian particle transport simulations. We find that LGM near-surface winds were dominated by stronger, more focussed westerly air flow across southeastern Australia, compared with presently more diffuse wind regimes. Our results suggest stronger potential for LGM eastward distal sand transport onto the basalt plains, coeval with enhanced aeolian activity in the semi-arid Australian dunefields. Our combined reconstruction of aeolian deposition and trajectory modelling confirms the extended LGM hypothesis and indicates a northward migration of westerly winds over southeastern Australia during this period.