Kurnell Fen: an eastern Australian coastal wetland, its Holocene vegetation, relevant to sea-level change and aboriginal land use

Abstract

Pollen analysis of a 3.4 m core from residual fenland at the eastern end of Kurnell Peninsula shows that woodland cover of Eucalyptus spp., Angophora costata, Banksia integrifolia/B. serrata and Casuarina spp. suffered losses about 5000 BP when a nearby coastal protobarrier was destabilised by rising sea level, while rapidly-formed fen peat replaced slowly formed O 2-depleted, algal and FeS-rich fine detritus gyttja. Fire frequency was low up to this time. Woodland partly recovered over a 2000 yr period despite heavier or more frequent firing coincident with the entry of hunter-gathering aboriginal (Pre-Bondaian) people. The peatland, formerly sedge/ Triglochin, became dominated by marsh ferns between 4000 and 2000 BP; these were largely replaced during a major change to a more acid peat, with an expansion of Sphagnum bog elements, associated with acidiphilous diatoms. Minor destabilisation of local duneland ca. 1700 BP brought fine sand into the fen basin. Dryland plant cover increased after 1700 BP but mainly dominated locally by a more seral Monotoca/Leptospermum scrub. Bog has reverted to Baumea rubiginosa-Triglochin procera fen with few diatoms, possibly due to recent salt-spray access. This and the more seral vegetation may be linked to higher population density or greater continuity of tenure of later (Bondaian) aboriginal peoples, post-2000 BP.