Local environmental correlates of variability in the organic soils of moorland and alpine vegetation, Mt Sprent, Tasmania

Abstract

Data on soils, vegetation and environment were collected between 510 and 1050m a. s. l. on Mt Sprent, southwestern Tasmania, traversing the Gymnoschoenus sphaerocephalus sedgeland-alpine vegetation boundary. One or more of the following horizons were found in almost all soil pits (downwards from the surface to the bed rock) fibric peat, hemic peat, sapric peat, organic sand, sand and clay. Mean total soil depth, mean organic soil depth, mean humification of the soil surface horizon, pH and mean organic content of the surface horizon all decline with altitude, while the redness of the soil and the mean depth of the mineral and gravel layers increase. At four intensively studied sites at 620, 850, 930 and 1040 m the relationships between phytosociological, topographic and water-table variables, and soil characteristics were determined. The pH of the topsoil was significantly positively related to water-table depth at three sites, but there were no other relationships between local environmental variation and soil characteristics that were consistent between most of the four sites, despite a large number of locally significant relationships. The alpine and sedgeland soils differ most markedly in colour, number of horizons and degree of humification of the surface horizon. The vegetation at each site was separated into communities along a drainage gradient. The mesoscale differences in soils seem most likely to be attributable to a vegetation productivity gradient.