Application of Iversen's glacial-interglacial cycle to interpretation of the late last glacial and holocene vegetation history of western Tasmania

Abstract

The Iversen glacial-interglacial cycle of vegetation change is modified and applied to glacial, Lateglacial and Holocene age pollen records from western Tasmania. Cryocratic conditions occurred at high altitude (ca. 500 m+) during glacial and Lateglacial time. Transition from cold humid to cool humid climate occurred on the lowlands by 13 ka BP and in the mountains by 10 ka BP. There is regional parallelism of vegetation development from grassland-herbland-sedgeland through alpine-subalpine scrub and woodland to temperate rainforest dominated by Nothofagus cunninghamii. However, radiocarbon dating shows that changes in the vegetation succession and Nothofagus rainforest maximum were non-synchronous. Although climate change from glacial to interglacial conditions directed the general succession, variations in dates for similar vegetation changes show that biological and physical variables were important for local vegetation development. Some sites show late Holocene vegetation changes that could be interpreted as revertance. Aboriginal fire and lake infilling were probably responsible. There is no evidence for an Allerød-type warm phase between 13 and 11 ka BP or a Younger Dryas-type cold phase between 11 and 10 ka BP. The climate was cool temperate between 13 and 0 ka BP, and neither temperature nor precipitation change was sufficient to cause vegetation change of regional significance.