Areas Of South-eastern Australia Research Articles

Rb/Sr evidence for the nature of the mantle, thermal events and volcanic activity of the Southeastern Australian continental margin

Rb/Sr isotopic data are presented for three different mantle-derived rock types from a single quarry in the Kiama area in southeastern Australia. These rocks comprise a latite (∼249 Ma), a basanitic dyke (∼191 Ma) and mantle-derived xenoliths entrained in the basanitic dyke. Interpretation of the Rb/Sr data with other geochemical results shows that significant crustal contamination of either the latite or the basanite is unlikely. It is suggested that metasomatic mantle events may closely coincide with the production of basaltic magma. Basaltic activity in this area in the late Permian, early Jurassic and Tertiary would imply that a high heat flow may have persisted in southeastern Australia over this time span. 87 Sr/ 86 Sr values of the rocks studied are within the range of intraplate basalts worldwide and support the concept of a REE-enriched upper mantle beneath eastern Australia.

The prevalence of anti-leptospiral agglutinins in sera of wildlife in southeastern Australia.

Anti-leptospiral agglutinins were found in the serum from 18 (7 species) of 419 (25 species) animals sampled from various areas of southeastern Australia. Positive serologic reactions were observed in 5 of 25 (20%) brush-tailed possum (Trichosurus vulpecula), 1 of 26 (3.8%) tammar wallaby (Macropus eugenii), 2 of 12 (16.7%) swamp wallaby (Wallabia bicolor), 1 of 3 (33.3%) koala (Phascolarctos cinereus), 3 of 41 (7.3%) common wombat (Vombatus ursinus), 2 of 100 (2%) bush rat (Rattus fuscipes) and 4 of 12 (25%) rusa deer (Cervus timorensis). The majority (55.5%) of serologic reactions were to serovar hardjo. No serologic reactions were observed in samples from echidna (Tachyglossus aculeatus), brown antechinus (Antechinus stuartii), swainson's antechinus (Antechinus swaisonsii), long-nosed bandicoot (Perameles nasuta), brown bandicoot(Isoodon obesulus), common ringtail (Pseudocheirus peregrinus), greater glider (Schoinobates volans), eastern grey kangaroo (Macropus giganteus), red-necked wallaby (Macropus rufogriseus), rabbit (Oryctolagus cuniculus), water rat (Hydromys chrysogaster), black rat (Rattus rattus), eastern swamp rat (Rattus lutreolus), broad-toothed rat (Mastacomys fuscus), fox (Vulpes vulpes), sambar deer (Cervus unicolor), hog deer (Axis porcinus) and fallow deer (Dama dama).

The effect of nitrogen fertilizer and irrigation frequency on a semi-dwarf wheat in south-east Australia. 2. Water use

The semi-dwarf wheat WW15 was grown under four irrigation frequencies and two nitrogen rates in the Murrumbidgee Irrigation Area of south-eastern Australia. The irrigation treatments, which were scheduled using pan evaporation and rainfall, ranged from natural rainfall alone to seven flood irrigations. Water use was determined using the water balance equation, and measurements or irrigation water applied, rainfall, change in soil-stored moisture, and surface drainage. The water-use figures were high in comparison with values obtained overseas, ranging from 408 mm with no irrigation to 818 mm at the highest irrigation frequency. Despite the high water use, water-use efficiency was comparable with that for semi-dwarf wheat in other parts of the world, with a mean value of 10.4 kg grain ha-1 mm-1. Nitrogen fertilizer had little effect on plant growth and no effect on crop water use.

Skilliostrobusgen. nov., a new lycopsid cone from the Early Triassic of Australia

Skilliostrobus australis gen. et sp. nov. is a large, ovoid, pedunculate cone present in rocks of Early Triassic age in three areas in southeastern Australia and Tasmania. The cone is heterosporous and its unisporangiate sporophylls are wedge-shaped with long horizontal limbs. Microsporophylls occur above megasporophylls in the cone and the sporangia are adaxial. Large trilete megaspores similar to the dispersed megaspore genus Horstisporites Potonié are present in the megasporangia of the cone and the microsporangia contain small monolete spores similar to the dispersed microspore genus Aratrisporites Leschik. Skilliostrobus is placed in the family Lepidodendraceae in the order Lepidodendrales. The size of the cone suggests that the parent plant was comparable in size with small arborescent Palaeozoic lycopsids and with some species of Pleuromeia. The discovery of this cone is another indication that arborescent lycopsids did not become extinct at the end of the Paleozoic.

Endogone Spores in a Heathland Area of South-Eastern Australia

An area of heath occurring on sandy podzolic soil at Cranbourne in Victoria has been studied. Relative spore numbers of vesicular-arbuscular mycorrhizal fungi have been monitored over a period of 2 years at sites containing disturbed and undisturbed native vegetation, as well as recolonizing areas of mixed indigenous and introduced species. A large number of 'Endogone' spores were found, and some correlation between peak spore numbers and periods of high rainfall was recorded at the disturbed sites. No such correlation was found in undisturbed heath. Many spores of varying morphology were examined, and eight spore types belonging to the non-sporocarpic members of the Endogonaceae have been described in detail. The viability of a white, bulbous-based spore type was investigated following storage in different conditions for varying lengths of time.

Wild Rabbit (Oryctolagus cuniculus (L.)) Populations in a High Rainfall Area of Victoria, Australia

The wild rabbit (Oryctolagus cuniculus (L.)) in Australia inhabits a wide range of environments from alpine to arid. Although most of the rabbit's range has an average annual rainfall of less than 750 mm it has successfully colonized river valleys and forest fringes in the higher rainfall area of south-eastern Australia. In this area rabbits impose an erratic but occasionally severe grazing pressure on pastures and on native plants. An inter-departmental impact study on the construction of a dam at Dartmouth, which is in a high rainfall area in Victoria, included the investigation of rabbit populations in the valley of the Mitta Mitta River which is reported here. The primary aim of the work was to determine whether distinct sub-populations were likely to be present and, if so, to differentiate them on the basis of readily observed parameters. Initial investigations suggested that differences related to environment did occur. This paper reports on the occurrence of sub-populations and on several parameters which were used to distinguish them.

Utilization of Appetite for Sodium Salts to Control Rabbit Populations by Poisoning.

Rabbits in subalpine areas in south-eastern Australia show a marked avidity for sodium salts during the spring and early summer months. During that period rabbit populations may be controlled by allowing access to soft wooden meranti pegs impregnated with sodium chloride and sodium luoroacetate (poison 1080). If the pegs are left out as permanent bait stations they produce long-term effective control. The method should be applicable to other areas in Australia where soil sodium is very low.

Topologically random channel networks in the presence of environmental controls

The occurrence of topologically random channel networks in the presence of strong environmental controls does not necessarily indicate that network topology is insensitive to such controls. In areas where environmental controls have a preferred orientation, certain topologically distinct channel networks may be promoted where networks of a given magnitude flow in one direction and inhibited where they flow in another; but these biases in network topology may compensate for one another so effectively that they do not give rise to identifiable systematic deviations from topological randomness. This theme is illustrated by analyses of magnitude-4 channel networks from three areas in southeastern Australia. Goodness-of-fit tests indicate that the exhaustive samples of networks from these areas could have been drawn from topologically random populations. However, similar tests applied to subsamples selected according to network flow direction reveal biases in network topology in two of the areas. These biases, which are apparently due to microclimatic controls, signify that, although the networks in each area may belong to a topologically random population, they are not composed of randomly merging stream channels.

The Allocation and Pricing of Water in a River Basin

AbstractA spatio‐temporal equilibrium model that incorporates intraseasonal demands for irrigation water is developed for the situation with a (constrained) competitive market for water. An application of the quadratic programming model, which utilizes demand and supply estimates relating to an intensive irrigation area in southeastern Australia, is used to derive optimal short‐run allocation and pricing patterns for the resource. Extensions of the model to cover multiple dam river basins and additional water uses seem conceptually straightforward, but the limitations imposed by its deterministic partial equilibrium character should be recognized.

Portable Rainfall Simulator and Plot Unit for Use in Field Studies of Infiltration, Runoff and Erosion

The simulation of rainfall for studies of infiltration, surface runoff and erosion is not new. Early methods of applying rainfall used hand-operated watering cans (e.g. Duley & Hays 1932). In later work rainfall was delivered to the plots through specially designed upturned nozzles; here the spray also wets a variable area surrounding the plots and protective tents are commonly necessary to minimize wind effects. The most familiar are the Types F and FA Infiltrometers (Wilm 1943) and the Rocky Mountains Infiltrometer (Dortignac 1951). These units have proved of value in elucidating the contribution of rainfall, soil, vegetation and management effects to infiltration, runoff and soil loss (Meyer 1960), but there are several disadvantages for convenient and realistic use. The Type F Infiltrometer, for example, is bulky, due largely to the large water requirements and the need for protective tents when up-turned nozzles are used. On the other hand, the Type FA and Rocky Mountains Infiltrometers have a plot size of only 2-5 ft2, which restricts the development of surface runoff and soil erosion. Laboratory studies of the infiltration, runoff, and erosion processes generally utilize elaborate mechanical devices which are unsuitable for field use (cf. Turner 1964). The equipment described in this paper was developed progressively in the course of catchment studies in subalpine and alpine (Costin, Wimbush & Kerr 1960), forest (Gilmour 1965), and pasture (Costin & Gilmour, in preparation) areas in south-eastern Australia. Because the terrain is often rough and staff limited, the equipment had to be compact, robust and easily handled by one person. Other requirements were ease of assembly, operation and dismantling, and rapid movement from site to site enabling a large number of replicated plots (up to ten) to be examined before site conditions changed materially during any one day. A relatively large plot size (10 x 6 ft) helped to overcome problems of small scale soil variability and three-dimensional infiltration along the plot boundaries frequently encountered when small diameter infiltrometer rings are used, and to make the runoff and erosion effects more realistic. In erosion studies using simulated rainfall it is often desirable to reproduce the stress conditions most likely to be experienced in the area under investigation (Costin et al. 1960). A summer storm rainfall of about 80 points in 15 min occurs approximately every second year in the study area and was selected as the stress rain to be simulated.

The high mountain vegetation of Australia

An account is given of the high mountain vegetation of the Australian Alps. This vegetation is naturally defined as that situated above the level of the winter snow-line (4500–5000 ft); it occupies an area in south-eastern Australia of about 2000 sq. miles. The high mountain environment can be divided into subalpine and alpine tracts, on the basis of average duration of the winter snow cover and related effects. Relevant climatic data are given, together with information on physiography, geology, flora, fauna, soils, and land use. The plant communities identified earlier in the Snowy Mountains area are found to provide a generalIy satisfactory basis for the rest of the high mountain areas. The various fjaeldmark, alpine herbfield, sod tussock grassland, heath, subalpine woodland, and bog and fen alliances are enumerated, with details of distribution and rariation in Australia and comparisons with homologous vegetation in Europe. Five broad ecological types of high mountain are recognized and the characteristic associations of communities are described. Almost all of the Australian high mountain vegetation has been modified by land use. Few of the existing communities are regarded as stable and the direction of change will depend largely on how they are henceforth managed by man.

Cyclic salt as a dominant factor in the genesis of soils in South-Eastern Australia.

A theory is presented suggesting that during the Recent Arid Period the rainfall was approximately half that of the present day and enabled cyclic salt to be accumulated in areas in south-eastern Australia, where it does not 'accumulate at present. The salinization and subsequent desalinization during the wetter conditions since the Arid Period have operated with varying degrees of intensity to produce solods, solodic and solonized soils over large areas. However, irrespective of the degree of intensity, some of the pre-Arid soils because of their chemical or physical properties have been able to resist these processes and remain unaffected. Five "pedogenetic zones" have been defined according to the degrees of intensity with which the salinization and desalinization processes are thought to have operated, and it is found that soil distribution and morphology is correlated with these defined zones. The zone in which the effect has been most intense has an average annual rainfall at present of between 20 and 30 in., and the most widespread soils, those formerly called red and yellow podzolics, are solodic soils and solods. The theory provides a reasonable explanation for the anoxalous distribution of soils within the "podzol" zone where those showing the greatest degree of horizon differentiation (solods and solodic soils) occur in the driest parts. In addition, the postulated processes for the formation of the soils provide a reason why molybdenum deficiency is so common on these soils in zone 3.