A QUANTITATIVE ESTIMATE OF HOLOCENE CLIMATE USING A BIOCLIMATIC PROFILE OF NOTHOFAGUS-CUNNINGHAMII (HOOK) OERST

A climate profile of Nothofagus cunninghamii (Hook.) Oerst. generated by the bioclimatic prediction system (BIOCLIM) is applied to fossil pollen data from eight sites at different altitudes in the Central Highlands of Victoria, Australia, to derive palaeoclimatic estimates. Altitude-related changes in the distribution of N. cunninghamii over time, with peak distribution between c. 4000-7000 years BP, earlier at the lower altitude sites and later at the higher altitude sites, suggest that summer temperatures were c. 2-degrees-C lower and winter temperatures slightly higher than present, and with higher effective precipitation. Some reassessment of the above estimates may prove necessary as the model does not take into account the effects of factors such as microtopography, short-term climatic conditions, fire, and the ecological and ecophysiological characteristics of a taxon. The results of Victoria are generally similar to BIOCLIM predictions obtained from northeastern Queensland and Tasmania, but differ from climate estimates derived from certain fossil pollen assemblages. Identification of pollen, particularly of key indicator taxa, to lower taxonomic levels may help resolve this disparity.