Sue Baker1, Nick Fountain-Jones, Mingxin Liu, Emanuela Cosma1

1University of Tasmania, Hobart, Tasmania, Australia

Biography:

Sue is a forest ecologist and conservation biologist at the University of Tasmania. After undergraduate, she worked as a research assistant on integrated pest management of leaf feeding beetles. Later, she did her Honours and PhD to follow her passion for conservation science, researching forestry impacts on ground-active beetles, finding them to be highly sensitive to subtle ecological gradients. Her research seeks to improve conservation of forest biodiversity through developing better timber harvesting practices and reserve networks. Her Future Fellowship aims to determine the optimal landscape-scale mix of management and reservation to maximise biodiversity outcomes for a given level of timber production.

Abstract:

Ground-active beetles are sensitive to disturbance and environmental conditions. A premise of ecologically sustainable forest management is to adapt timber harvesting practices to better emulate natural disturbance dynamics — wildfire in the case of Tasmanian eucalypt forests. No differences were found between beetles 33-years after wildfire vs. timber harvest, with current research examining recent wildfire/harvesting. Harvesting (and likely also wildfire) does have a profound impact on beetle community composition. Young (1-5 y.o.) clearfelled forests have distinctly different species composition compared to mature forest, with greater beetle abundance and richness in harvested sites. Beetle communities show succession following harvesting, with minimal differences from unharvested forest by ~40-60 years.  Beetles are sensitive to environmental gradients, including edge effects, riparian influences and biogeographic variation. Mature forest indicator species were less common in unharvested forest near clearfells. Beetle communities in unharvested riparian buffers responded to opposing riparian and edge effects, compromising habitat suitability for sensitive species in narrow reserves. Recognition of differences between clearfelling and wildfires led to development of the ‘aggregated retention’ harvesting system, where patches of unharvested forest are retained within coupes. Retained patches function as ‘lifeboats’ for mature-forest beetle communities. Nearby mature forest acts as a source population, facilitating re-establishment into harvested areas. Our research demonstrates benefits at site-scale of variable retention harvesting compared to clearfelling. Yet at landscape-scale there is a trade-off, for a set level of timber production, between the intensity of site-scale management and the amount of reserves in the landscape. Our current research aims to resolve this conundrum.