Small‐scale Dynamics in an Early Holocene Wet Sclerophyll Forest in Tasmania

Summary Pollen analysis of organic sediments in a small hollow at Tarraleah in central Southern Tasmania allows identification of some small‐scale patterns and processes withinEucalyptuswet sclerophyll forest during the early to middle Holocene. These events are related to a time scale of inferred ages (i.a.), based on three radiocarbon dates and stratigraphic constraints. Although relatively few tree and tall shrub taxa are involved, changes in relative abundance show that at least five floristically distinctive communities of understorey mesophytes have surrounded the hollow. Prior to i.a, 9125 B.P., subalpineEucalyptusopen forest or woodland formed the local vegetation: Pomaderris apetala– Compositae i.a. 8900 to 8325 B.P. Atherosperma moschatum – Dicksonia antarcticai.a. 8175 to 7775b.p. Phyllocladus aspleniifolius – (?)Nothofagus cunninghamiii.a. 7625 to 7350b.p. Pomaderris apetala– sclerophyll shrubs i.a. 7200 to 6925b.p. Dicksonia antarcticaafter i.a. 6925b.p. In most general terms the forest and mire species have behaved consistently with their modern ecological preferences and established trends in Holocene climate. With more detailed resolution, the influence of climate is less apparent and the shifts in community composition more likely to be due to fire frequency and edaphic effects. The results confirm the modern observation that canopy eucalypts and understorey species are only weakly correlated in the presence of fire. Fire has resulted in the separation ofPomaderris apetalacommunities into two ecological entities but in the absence of fire ‐ and fire‐promoting climates ‐ during the early Holocene,P. apetalaand associated mesophytic small trees may have been able to exclude competitively the canopy eucalypts. Similarly the data indicate early Holocene rainforests may have been enriched withA. moschatum. The marked increase in fire frequency at or after i.a. 6925b.p.is suggested to be due to migration into or increased utilization of the area by Aborigines.