Arid South Australia Research Articles

Estimation of the Density of Feral Goats in Part of Arid South Australia by means of the Peterson Estimate

The density of feral goats in about 234 km2 of arid rangeland used for sheep grazing in South Australia was estimated by means of a mark-resight technique. Marking and subsequent resighting were done at watering points. The Petersen estimate was 4.4 goats per square kilometre; adjustment to allow for nonrandom behaviour raised this estimate to 5.0 km-1. Maximum allowable sheep density is 12 km-2. The goat density we observed imposes an added burden on the vegetation. The densities of red and western grey kangaroos, when added together, approximate that of the goats. Rabbits are virtually absent. The long-term effects of the total grazing pressure on the vegetation cannot be predicted in detail but will probably be deleterious.

Late Quaternary piedmont sedimentation, soil formation and paleoclimates in arid South Australia

Late Quaternary piedmont sedimentation, soil formation and paleoclimates in arid South Australia

Radiocarbon Dating of Arid-Zone Calcareous Paleosols

Field study and radiocarbon dating of authigenic carbonate in arid-zone paleosols and calcretes have been carried out in Australia to determine the reliability of this method of soil dating. Three calcareous paleosols of late Quaternary age are developed within alluvial and eolian deposits on the Lake Torrens plain in arid South Australia. Dates for organic carbon obtained from the sediments show that soil-forming episodes took place shortly after 30,000 yrs B.P., between about 16,000 and 12,000 yrs B.P., and between 6,000 and 1,500 yrs B.P. Respective mean radiocarbon ages determined for pedogenic carbonate are (with approximate scatter) 27,450 (± 7,000) yrs B.P., 13,900 (± 2,000) yrs B.P., and 7,750 yrs (± 1,000) B.P. Although the great majority of the individual carbonate dates and the three mean dates are sound as relative ages, they are less reliable as absolute ages. A review of the literature reveals that most carbonate dates for arid-zone paleosols and calcretes which have been dated by coexisting organic carbon are from about 500 to 7,000 radiocarbon years too old. This is attributed to an initial low C 14 /C 12 ratio in soil carbonate, reflecting low C 14 content of source carbonate. Postformation contamination with C 14 commonly appears to be minimal in the arid zone, where dates for micritic carbonate from well-drained sites should approximate to or be up to several thousand years older than true ages of soil formation. Age correction based on δC 13 values for soil carbonate is invalid.

Optical properties of leaves of some species in arid South Australia

Reflection and transmission spectra were measured for the leaves of a number of species of South Australian arid zone vegetation, over the wavelength range 350- 1350 nm. Spectra were also obtained for several non-arid species for comparison. Coefficients of reflection, transmission, and absorption of solar radiation were calculated from these spectra, and also obtained from direct measurements made with a specially constructed reflecting hemisphere. The coefficients of reflection for the arid zone species covered a wide range of values, and the group as a whole could not be clearly separated from the comparison group on the basis of reflection or absorption coeficients. Of the species in the group, Atriplex vesicaria had the highest coefficient of reflection, and also the lowest coefficient of absorption.

Distribution of the Kangaroo-Tick ornithodoros Gurneyi in Arid South Australia

Distribution of the Kangaroo-Tick ornithodoros Gurneyi in Arid South Australia