Characterising soil physical properties of selected Temperate Highland Peat Swamps on Sandstone in the Sydney Basin Bioregion

Abstract

Study region: Sydney Basin, New South Wales, Australia. Study focus: Some of Temperate Highland Peat Swamps on Sandstone of Sydney Basin overlie existing underground mining areas, which may impact the hydrological fluxes into and out of the swamps. Understanding and predicting these potential impacts and their consequences for swamps’ vegetation requires knowledge of the relevant physical properties of the soil, however such knowledge is almost completely absent from the literature. This study addresses this gap, and provides new insight into the degree and nature of variability between swamp sites, and between groups of swamps, the soil properties controlling these variabilities and the classification of these swamps in the context of peatland. Soil samples were collected up to a depth of 750 mm from ten sites in Upper Nepean and Newnes Plateau swamps. Samples were analysed for organic matter, bulk density, texture, saturated hydraulic conductivity and water retention characteristics. New hydrological insights: Not only the organic matter, but also bulk density and sand content control soil physical properties of the swamps. Soil properties vary between swamps; however, the variabilities were not large relative to those found in peatlands globally. These THPSS of the Sydney Basin cannot be classified as peatland and so their soil parameters cannot be estimated through the generalisation of peatland soil physical properties. It is concluded that the insights into soil properties provide new scope for developing hydrological models to assist in hydrological and ecological impacts analysis of the swamps.

Keywords

• Organic matter content
• Soil hydraulic parameters
• Upland swamps
• Van Genuchten parameters
• Wetlands