Holocene palaeoenvironments of salt lakes in the Darling Anabranch region, south-western New South Wales, Australia

Abstract

Abstract Aim Fossil pollen preserved within small salt lake basins in the Australian interior is used to reconstruct mid- to late Holocene vegetation. The study aims to identify the origin of problems such as woodland decline and salinization within present ecosystems. Location Warrananga and Tooperoopna salt lakes, south-western New South Wales, Australia. Methods Pollen, carbonized particle and sedimentological analyses of cores taken from salt lakes. Results Prior to c. 4500 years ago, the region supported a dense cover of Casuarinaceae woodlands. It is possible that the subhumid zone species Allocasuarina luehmannii comprised some of the Casuarinaceae element. In the late Holocene, A. luehmannii disappeared from the record and chenopodiaceous low shrublands expanded. About 2000 years ago, Callitris representation decreased. Woodland contraction also occurred after European settlement. Main conclusions Increasing aridity or greater seasonal variation in the climate during the late Holocene caused a contraction of woodland vegetation. Increased proportions of Chenopodiaceae may indicate soil salinization around the basins. A decrease in Callitris was possibly due to heightened severity or frequency of drought events after 2000 years ago. Decline in woodland pollen in the uppermost samples is explained by the preferential clearing of Callitris glaucophylla, Callitris gracilis and Casuarina pauper for timber and their limited regeneration because of browsing by stock and rabbits.