Still a million wild acres: unlocking environmental archives in the Pilliga Forest

Land use and management in Australia can be broadly categorised into two distinct periods; pre- and post-European settlement in 1788. The Pilliga Forest is the largest remnant woodland in western NSW. It has been proposed that a shift in management regime in the post-European period caused a trophic cascade and instability in the landscape. However, these scenarios have been subjected to minimal scientific investigation. Three continuous cores were taken from three ephemeral wetlands, part of a declared ‘Endangered Ecological Community’ in the Pilliga National Park. Through the application of a multi-proxy approach that incorporates surveying catchment and wetland topography, limnology, sedimentology, geochronology and geochemistry, this project found that sedimentation rates have increased over one order of magnitude in the European period in Old Boo wetland. The wetland was formed ca. 15,000 years ago, as an ephemeral shallow water body and has progressively become wetter and home to a more complex aquatic community. Threats to the wetland appear to be accelerated sedimentation from forestry service tracks, rather than drying or water quality. Management plans should therefore aim at minimising sediment inputs. These findings give partial support to Rolls’ model but do not point to catastrophic change as claimed.