VEGETATION OF AN ALKALINE PAN ACIDIC PEAT MOSAIC IN THE HARDWOOD RIVER VALLEY, TASMANIA

The vegetation associated with sandy alkaline pans and surrounding acidic peats in southwest Tasmania is described. The upper margins of the pans are characterized by sharp environmental discontinuities, with pH changes of more than 3 units in only 20 cm being recorded. Classification and ordination of quadrats by plant species associated with a typical pan showed that 5 distinct communities are evident, but that these form a gradational series which reflects the altering edaphic status of the sites during infilling of the pans. The pH, drainage and redox characteristics of the substrates are among the factors determining the frequency of particular species at any stage of the progression. Frequency histograms for plant species in and around the pans indicate that many of the species respond individually to changing pH.