Distribution of potential macrofossils in Lake Dobson, Tasmania

Abstract

(1) Lake Dobson is a small lake in south-central Tasmania surrounded by tree- and shrub-dominated sub-alpine evergreen vegetation. (2) Most species present in the vegetation surrounding Lake Dobson were recovered as leaves from the lake sediment, but the proportions of species changed rapidly between samples, and an accurate reconstruction of the surrounding vegetation from these samples would be impossible except in terms of species present. (3) Epacris serpyllifolia, a small, lakeside shrub, was overwhelmingly dominant in most sediment samples, and was strongly over-represented in relation to its importance in the surrounding vegetation. Eucalyptus coccifera, the dominant canopy tree species, was common directly below overhanging trees, but as the leaves sank rapidly they were virtually absent from the rest of the lake. E. coccifera was thus strongly under-represented in relation to its importance in the surrounding vegetation. (4) Leaf remains were far more common in Lake Dobson than reproductive structures and could be more reliably identified. (5) The most important features affecting leaf deposition in the lake were the prevailing wind direction, the presence of lakeside or overhanging vegetation, and leaf sinking rates. Decomposition of leaves is relatively slow in the lake.