Establishment of the Box-Ironbark ecological thinning trial in north central Victoria

An ecological thinning trial was established in 2003 in north-central Victoria as part of the development of an ecological management strategy to support the newly created Box-Ironbark Parks and Reserves System. The objective of the trial was to restore diversity of habitat structure to declining Box-Ironbark forests and woodlands. Three ecological thinning techniques were designed around several principles: reducing total basal-area of trees and retaining levels of patchiness whilst retaining large trees. Thinning treatments were implemented in 30 ha plots at four conservation reserves south of Bendigo, Victoria. A range of ecosystem components were monitored before and after thinning. A woody-debris removal treatment was also set-up at a 1 ha scale within thinning treatments. Prior to thinning, plots were dominated by high numbers of coppice regenerated trees with few of the trees sampled considered large, resulting in low numbers of tree hollows and low loadings of coarse woody debris. It is anticipated that the establishment of the ecological thinning trial (Phase I), is the beginning of long-term monitoring, as effects of thinning on key habitat values may not be apparent for up to 50 years or more. The vision for restoration of Box-Ironbark forests and woodlands is one of a mosaic landscape with a greater diversity of habitat types including open areas and greater numbers of larger, hollow-bearing trees. This paper summarises the experimental design and the techniques adopted in Phase I of this project during 2003-2008

Fire-related threats and transformational change in Australian ecosystems

Aim: Megafire events generate immediate concern for wildlife and human well-being, but their broader ecological impacts likely extend beyond individual species and single fire events. In the first mechanistic study of fire effects focussed on ecosystems, we aimed to assess the sensitivity and exposure of ecosystems to multiple fire-related threats, placing impacts in the context of changing fire regimes and their interactions with other threats. Location: Southern and eastern Australia. Time period: 2019–2020. Major species studied: Australian ecosystems. Methods: We defined 15 fire-related threats to ecosystems based on mechanisms associated with: (a) direct effects of fire regime components; (b) interactions between fire and physical environmental processes; (c) effects of fire on biological interactions; and (d) interactions between fire and human activity. We estimated the sensitivity and exposure of a sample of 92 ecosystem types to each threat type based on published relationships and spatial analysis of the 2019–2020 fires. Results: Twenty-nine ecosystem types assessed had more than half of their distribution exposed to one or more threat types, and only three of those were listed as nationally threatened. Three fire-related threat types posed the most severe threats to large numbers of ecosystem types: high frequency fire; pre-fire drought; and post-fire invasive predator activity. The ecosystem types most affected ranged from rain forests to peatlands, and included some, such as sclerophyllous eucalypt forests and heathlands, that are traditionally regarded as fire-prone and fire-adapted. Main conclusions: Most impacts of the 2019–2020 fires on ecosystems became apparent only when they were placed in the context of the whole fire regime and its interactions with other threatening processes, and were not direct consequences of the megafire event itself. Our mechanistic approach enables ecosystem-specific management responses for the most threatened ecosystem types to be targeted at underlying causes of degradation and decline