Paleoenvironments of Tasmania inferred from a 5–75 ka marine pollen record

Abstract

Pollen and oxygen isotope analyses of sediments from deep‐sea core SO36–7SL (42°18’ S, 144°40’ E; 1085‐m water depth) provide a chronostratigraphically‐controlled paleoenvironmental record of the last 75,000 years from southeastern Australia. During the early Holocene and later part of the preceding period of deglaciation (post‐14,000 yr B.P.), the vegetation of coastal central western Tasmania consisted mainly of Phyllocladus‐Eucalyptus mixed forest with a mesic understory, implying warm and humid climate. Grassy herbland communities with scattered Athrotaxis and Lagarostrobos were widespread during the last major phase of highland glaciation (∼25,000–14,000 yr B.P.), and reflect much lower temperatures than at present. During much of the last glaciation (∼63,000–25,000 yr B.P.), the vegetation was a mosaic of Eucalyptus woodland, shrubland, herbland and sedgeland communities that developed under generally cool and moist climate. Very high Asteraceae and low Eucalyptus, Phyllocladus and Dicksonia/Cyathea pollen and spore values indicate colder and probably drier environments ∼70,000–63,000 yr B.P. The basal Eucalyptus‐Dicksonia/Cyathea‐Phyllocladus forest assemblage, deposited ∼75,000–70,000 yr B.P., signifies a rapid transition from a moderately warm and moist interglacial‐like climate to the colder conditions and open environments that characterized much of the last glacial period. The results of the past 50,000 years are broadly consistent with paleoenvironmental reconstructions inferred from radiocarbon dated lowland pollen sequences in western Tasmania and further afield.