Late holocene fire history and palaeoecological conditions at Dunphy Lake, Warrumbungle National Park, New South Wales, Australia

Konayasji, T; Ralph, TJ; Lobb, J; Gadd, PS; Theischinger, G

Late holocene fire history and palaeoecological conditions at Dunphy Lake, Warrumbungle National Park, New South Wales, Australia

Date

2015-11-26

Authors

Publisher

New Zealand Freswater Sciences Society and Australian Society for Limnology

Abstract

There is a significant geographical and temporal gap in the Holocene environmental record of fire, hydrology and palaeoecological conditions in the region of the Warrumbungle Mountains in eastern Australia. Dunphy Lake (-31.3076°S, 149.0149°E) is a small, ephemeral freshwater wetland within Warrumbungle National Park, and the only example of its kind in this temperate -semiarid region. Late Holocene fire history and palaeoecological conditions at Dunphy Lake were determined using a multiproxy approach that incorporates geochronological, limnological and geochemical techniques. The sediment profile at Dunphy Lake is dominated by mud (< 63 µm) and the macrocharcoal record indicates that the largest local fire events have occurred since 1,793±28 years BP. Some distinct peaks in macrocharcoal are coincident with peaks in sand (63-2000 µm) content, suggesting that some fires occurred at similar times to episodes of significant runoff and sediment flux from the catchment. Recent palaeoecological conditions were conducive to a relatively complex aquatic food web, as shown by the presence of micro- and macro-invertebrate and diatom remains in the upper sediment facies. A geochemical record derived from ITRAX core scanning shows facies with elevated pedogenic (e.g. Mn, Ca) and detrital (e.g. Si, Ti) elements, but does not show a significant increase in anthropogenic elements at the surface. Altogether, this multiproxy approach yields a record of fire and aquatic conditions that can be used to place historical and contemporary fires and vegetation changes in this region into context.

Keywords

Fires, Historical aspects, Quaternary period, Lakes, Sediments, New South Wales, Australia, Fresh water, Wetlands, Watersheds, Runoff, Sand, Mountains, Plants

Citation

Kobayashi, T., Ralph, T., Lobb, J., Ingleton, T., Gadd, P., & Theischinger, G. (2015). Late holocene fire history and palaeoecological conditions at Dunphy Lake, Warrumbungle National Park, New South Wales, Australia. Paper presented at the "The changing freshwater landscape: collaboration, communication and communities" joint Conference for the New Zealand Freshwater Sciences Society and Australian Society for Limnology, 23-26 November 2015, Wellington, New Zealand.