Changes in alpine vegetation related to geomorphological processes and climatic change on Hill One, Southern Range, Tasmania, 1989–2000

Abstract

Photographs of 84 plots in alpine vegetation, largely consisting of fjaeldmark and bolster heath, on Hill One, Southern Range, Tasmania, were taken in both 1989 and 2000 to compare cover characteristics. Between these two observations, vegetation cover declined in the fjaeldmark, largely as a result of erosion. Declines also occurred on the active depositional lobes, through burial of bolster heath. Within the parts of Hill One where vegetation cover was not lost, graminoids decreased and Pterygopappus lawrencei increased in the bolster heath and tall shrubs displaced bolster heath. Thirty-six per cent of the rocks visible in the 1989 photographs had moved by 2000, the mean area of the individual rocks that moved being 95 cm². Larger rocks were moved on the exposed western slope than on the leeward eastern slope. Analyses of climatic data from nearby stations for 1979–2000 indicated a decline in both precipitation and temperatures and an increase in the frequency of the highest wind speeds, all of which are consistent with the nature of vegetation and geomorphological changes that occurred on the mountain, although a climatic cause is far from proven. Localised cooling and drying, in the two hottest and wettest decades recorded for the globe, emphasises the importance of local data in determining the possible impacts of climatic change on biota.