How well do Immediate Protection Areas conserve biodiversity in Victorian forests?

Context. Protected areas are necessary to conserve biodiversity. Their locations, design and management can have major impacts on their effectiveness. In timber and pulpwood production forests of Victoria, Australia, Immediate Protection Areas (IPAs) were established by the Victorian Government to conserve biodiversity. IPA identification has overlooked much of 30 years of reserve selection science. This has resulted in poor selection of locations for protection, lack of attention to habitat suitability for target species, and a destructive past land use history that has eroded current habitat suitability. Aims. Our aim was to assess the suitability IPAs for threatened species, including Leadbeater's Possum (Gymnobelideus leadbeateri) and the Southern Greater Glider (Petauroides volans). Methods. We assessed aspects of effectiveness of IPAs for forest-dependent species of conservation concern. We compared the IPAs to a prioritised protected area network using Marxan accounting for past forest disturbances, including logging and high severity wildfires. Key results. We found IPAs failed to include the most suitable habitat areas, capturing only 11.7% of modelled habitat for Leadbeater's Possum and 5.3% for the Southern Greater Glider. Our analyses also revealed large parts of the IPA network had been clearcut logged, eroding habitat value for many species. Conclusions. Given IPAs do not protect substantial amounts of important habitat for threatened species such as Leadbeater's Possum and Southern Greater Glider, we conclude the current IPAs are unlikely to adequately protect biodiversity from logging. Implications. The IPAs need to be better designed to improve their effectiveness for biodiversity conservation. We provide recommendations on how this might be done.