Vegetation and climate change during the Last Interglacial-Glacial cycle in western Tasmania, Australia

Abstract

Cool temperate Phyllocladus aspleniifolius-Nothofagus cunninghamii rainforest occurred in western Tasmania during Isotope Substage 5e. During most of the Last Glacial Stage (Substage 5d to Stage 2) the vegetation was subalpine woodland and shrubland, or alpine grassland, herbland, and heathland. Montane and subalpine rainforest existed at mid-altitude (516 m) during Substages 5a and 5c. During Stage 2, the Late Wisconsin Glacial Maximum, most of western Tasmania had alpine grassland and herbland vegetation, with areas of sclerophyll woodland and rainforest taxa below 100 m on valley floors near the coast. Cool temperate rainforest developed again during late glacial times (after 14 k 14C yr BP), with maximum development of Nothofagus cunninghamii rainforest in the early Holocene. Estimates of temperature depression, based on depression of the altitudinally zoned vegetation communities, a lapse rate of 0.65 °C/100 m, and comparison with marine core RC 11–120 from the southwestern sub-polar Indian Ocean, indicate that the early stadials (Substages 5b and 5d) were cold, and the early interstadials (Substages 5a and 5c) were cool. Stage 4 was cold and probably fully glacial. Temperature increased early in Stage 3 but then decreased, with some fluctuations, towards Stage 2, the late Wisconsin Glacial Maximum. An abrupt increase in temperature of ca. 6°C occurred after 14 k 14C yr BP.