Australia: The Land Where Time Began

A biography of the Australian continent 

Kurnell Fen Coastal Wetland - Holocene Vegetation, Sea-level & Aboriginal Use

This is a residual fenland at the eastern end the of Kurnell Peninsula. According to the author¹ it is shown by analysis of a 3.4 m pollen core from the residual fenland that losses from the woodland cover, Eucalyptus spp, Angophora costata, Banksia integrifolia/B. serrata and Casuarina spp., occurred about 5,000 BP following the destabilisation of a nearby coastal protobarrier by rising sea level. Oxygen-depleted, algal and FeS-rich fine detritus gyttja was replaced by rapidly-formed fen peat. Up to this time the frequency of fire was low.

Over the next 2,000 year period the woodland partly recovered, in spite of heavier or more frequent firing that coincided with the arrival of Aboriginal people. Marsh ferns came to dominate the peatland, formerly sedge/Triglochin, between 4,000 and 2,000 BP. During a major change to a peat that was more acid these were largely replaced, with the expansion of Sphagnum bog elements, associated with acidiphilous diatoms. At about 1,700 BP there was minor destabilisation of local duneland that brought fine sand into the fen basin. After 1,700 BP there was an increase of dryland plant cover, mainly dominating locally by a more seral Monotoca/Leptospermium scrub. Possibly as the result of recent salt spray access, bog has reverted to Baumea rubiginosa/Triglochin procera fen in which there were few diatoms. The author¹ suggests there may be a link between this and the more seral vegetation, and higher population density or greater continuity of occupation of later (Bondaian) Aboriginal peoples after 2,000 BP.

Sources & Further reading

1. Martin, A. R. H. "Kurnell Fen: An Eastern Australian Coastal Wetland, Its Holocene Vegetation, Relevant to Sea-Level Change and Aboriginal Land Use." Review of Palaeobotany and Palynology 80, no. 3–4 (2// 1994): 311-32.