On the equivocal fate of Late Pleistocene Callitris Vent. (Cupressaceae) woodlands in arid South Australia

Abstract

Fossil pollen assemblages suggest Callitris (Cupressaceae)-dominated woodlands were prominent elements in landscapes near Lake Frome and Lake Eyre during latest Pleistocene times. Callitris woodlands were present at Lake Eyre before 30,000 BP but became fragmented and disappeared in the lead up to the last glacial maximum. Callitris was again prominent from approximately 10,000 BP until about 5000 BP after which time it vanishes from the pollen record and, presumably, the region. At Lake Frome, Callitris was abundant between 16,000 BP and 13,000 BP before declining to low modern levels from 11,000 BP. At both sites, the latest Pleistocene or Holocene decline in Callitris occurrence, and its eventual extinction in the vicinity of Lake Eyre, broadly corresponds with archaeological indications of increasing human presence in the landscape. In the absence of evidence of significant climatic changes at the times in question, these observations lend tentative support to arguments that the composition and structure of modern zone vegetation has been significantly modified by Aboriginal land management practices. Although the charcoal record is ambiguous, fire is argued to be the principle agent of the changes wrought during human re-colonisation of lands around Lake Frome and Lake Eyre.