THE INDEPENDENT EFFECTS OF HEAT, SMOKE AND ASH ON EMERGENCE OF SEEDLINGS FROM THE SOIL SEED BANK OF A HEATHY EUCALYPTUS WOODLAND IN GRAMPIANS (GARIWERD) NATIONAL-PARK, WESTERN VICTORIA

The independent effects of smoke, ash, and wet and dry heat treatments on seedling emergence from the soil seed bank were tested for soils f rom fire-prone heathy woodlands in western Victoria. A total of 763 in dividuals from 56 species were recorded from the surface soil samples (which covered a total area of 1 m(2)). Both species richness and dens ity of seedlings was greater for smoke- and heat-treated samples than for controls and ash-treated samples. However, only the density differ ences were significant. Mean seed bank densities for the smoke and hea t treatments ranged from 855+/-70 m(-2) to 1080+/-58 m(-2) and are sim ilar to estimates obtained elsewhere in Australia for heat-treated soi ls from dry sclerophyll communities. Of the 56 species recorded, 46 oc curred in the smoke and heat treatments but only 33 in the control and ash treatments. The sudden increase in surface soil pH, exchangeable cations and extractable phosphorus which was associated with the ash t reatment did not act as a trigger for germination in any of the specie s recorded here. Chemical constituents from smoke do appear to provide a stimulus separate from the effects of heat, but were not identified with any particular taxa.