The legacy of mid‐Holocene fire on a Tasmanian montane landscape

Abstract

Aim To assess the long‐term impacts of landscape fire on a mosaic of pyrophobic and pyrogenic woody montane vegetation. Location South‐west T asmania, A ustralia. Methods We undertook a high‐resolution multiproxy palaeoecological analysis of sediments deposited in L ake O sborne ( H artz M ountains N ational P ark, southern T asmania), employing analyses of pollen, macroscopic and microscopic charcoal, organic and inorganic geochemistry and magnetic susceptibility. Results Sequential fires within the study catchment over the past 6500 years have resulted in the reduction of pyrophobic rain forest taxa and the establishment of pyrogenic E ucalyptus ‐dominated vegetation. The vegetation change was accompanied by soil erosion and nutrient losses. The rate of post‐fire recovery of widespread rain forest taxa ( N othofagus cunninghamii and E ucryphia spp.) conforms to ecological models, as does the local extinction of fire‐sensitive rain forest taxa ( N othofagus gunnii and C upressaceae) following successive fires. Main conclusions The sedimentary analyses indicate that recurrent fires over several centuries caused a catchment‐wide transition from pyrophobic rain forest to pyrophytic eucalypt‐dominated vegetation. The fires within the lake catchment during the 6500‐year long record appear to coincide with high‐frequency E l N iño events in the equatorial Pacific Ocean, signalling a potential threat to these highly endemic rain forests if E l N iño intensity amplifies as predicted under future climate scenarios.

Bibliographic Information