| Abstract: | Percentage and influx pollen analyses of a 9.17 m core from Dublin Bog give a post last glaciation vegetation history (-13.6 to 0 ka BP) for the upper Mersey Valley. Herbaceous vegetation of Gramineae, Compositae and Chenopodiaceae developed rapidly after deglaciation and lasted until 13.2 ka BP. Around 13 ka BP Eucalyptus woodland and forest developed rapidly on the valley floor. At the same time Pomaderris apetala became an important understorey shrub/tree, and Phyllocladus aspleniifolius rainforest developed in the gullies on the upper slopes of the Mersey Valley and in the valleys to the west The major change in climate from late glacial cold (and probably drier conditions) to warm humid conditions similar to present occurred between 13.2 and 13 ka BP. Wet sclerophyll Eucalyptus forest occupied the valley throughout the post glacial and attained its maximum development between 11.7 and 8.4 ka BP. Rainforest never occupied the valley floor extensively. Phyllocladus aspleniifolius sattained an early maximum about 13 ka BP. The peak of Pomaderris apetala and expansion of Dicksonia antarctica suggests that the climate was warmer and wetter between 10.3 and 8.4 ka BP than at other times. Nothofagus attained its maximum development between about 10.3 and 6 ka BP. Both sclerophyll and rainforest vegetation associations in the upper Mersey Valley appear to have been very stable and similar to their present floristic compositions during the Holocene. Aborigines occupied the valley by 10 ka BP. Fire was always present in this marginal area between the wet climate of western and the dry climate of eastern Tasmania. Fire did not cause replacement of rainforest by wet sclerophyll forest on the valley floor, though it could have prevented rainforest establishment |
