Abstract

Hill One is a wind-exposed, alpine environment in southern Tasmania. The prevailing wind-stream is westerly. However, high intensity south-westerly winds associated with frost events appear to control the patterning of fjaeldmark. These winds cause necrosis of prostrate Richea scoparia and cushion plants on their south-western side and induce migration of individual plants in a north-easterly direction. Fjaeldmark is confined to the exposed mountain summit and terrace and step treads. Mosaic cushion heath occurs in more exposed and poorly drained areas than other heath communities. The horizontally bedded sediments of Hill One have been worked by erosional and depositional agents into a complex morphology. Large terraces and non-sorted steps are likely to have formed from altiplanation processes, that is, differential erosion of interbedded sediments, with accumulation of erosional debris at the foot of the risers. Depositional lobes and erosional washout features are actively forming in localised areas of concentrated drainage. The distribution of plant communities is closely associated with rockiness, wind exposure and drainage.