Suchergebnisse

Habitat loss as a result of land conversion for agriculture is a leading cause of global biodiversity loss and altered ecosystem processes. Restoration plantings are an increasingly common strategy to address habitat loss in fragmented agricultural landscapes. However, the capacity of restoration plantings to support reproducing populations of native plants and animals is rarely measured or monitored. This review focuses on avifaunal response to revegetation in Australian temperate woodlands, one of the world's most heavily altered biomes. Woodland birds are a species assemblage of conservation concern, but only limited research to date has gone beyond pattern data and occupancy trends to examine whether they persist and breed in restoration plantings. Moreover, habitat quality and resource availability, including food, nesting sites and adequate protection from predation, remain largely unquantified. Several studies have found that some bird species, including species of conservation concern, will preferentially occupy restoration plantings relative to remnant woodland patches. However, detailed empirical research to verify long-term population growth, colonisation and extinction dynamics is lacking. If restoration plantings are preferentially occupied but fail to provide sufficient quality habitat for woodland birds to form breeding populations, they may act as ecological traps, exacerbating population declines. Monitoring breeding success and site fidelity are under-utilised pathways to understanding which, if any, bird species are being supported by restoration plantings in the long term. There has been limited research on these topics internationally, and almost none in Australian temperate woodland systems. Key knowledge gaps centre on provision of food resources, formation of optimal foraging patterns, nest-predation levels and the prevalence of primary predators, the role of brood parasitism, and the effects of patch size and isolation on resource availability and population dynamics in a restoration context. To ensure that restoration plantings benefit woodland birds and are cost-effective as conservation strategies, the knowledge gaps identified by this review should be investigated as priorities in future research.

Domestic livestock grazing is one of the dominant forms of land use globally. However, there are variable findings concerning the impacts of different grazing regimes on soil condition. We quantified the impacts of contrasting livestock grazing regimes on soil properties within nationally endangered temperate box-gum woodlands in south-eastern Australia. We sampled total soil nitrogen, phosphorus, carbon and bulk density at 65 woodland sites with a history of either continuous, strategic or rotational livestock grazing, as well as livestock grazing exclusion. We evaluated the influence of both historical and current management practices upon soil properties in the context of broad-scale soil forming factors such as climate, geology and topography. We found evidence of a strong relationship between total soil phosphorus and nitrogen, while phosphorus also was influenced by site-scale native tree cover. Total soil phosphorus and nitrogen were related to the combined effects of pasture type and long-term fertilizer history (>10 years prior to sampling). No significant differences in soil nutrients or bulk density were detected between different grazing treatments, likely due to the importance of total grazing pressure (i.e. from all exotic and native herbivores) and the level of environmental variation between sites. However, total soil phosphorus was significantly higher in soils sampled in the season following a grazing event, irrespective of grazing intensity or duration. Total soil nitrogen and carbon exhibited a similar pattern. This is likely a result of multiple processes such as direct input of organic matter to the soil and stimulation of soil microbial communities. These findings have important implications for the strategic management of woodland understorey vegetation as soil nutrients have been identified as important drivers of native plant diversity. ; This work was supported by the Australian Government Environmental Stewardship Programme, the National Environmental Research Program (NERP), an Australian Research Council (ARC) Linkage Project (Grant number: LP100100467), the Ian Potter Foundation, the Vincent Fairfax Family Foundation, the Calvert-Jones Foundation, and an ARC Laureate Fellowship (Grant number: FL120100108) awarded to David Lindenmayer.

Culling of overabundant and invasive species to manage their ecological impacts on target species is widely practised but outcomes are unpredictable and monitoring of effectiveness often poor. Culling must improve ecosystem function, so clear, measurable goals, such as improved breeding potential of target species, are necessary. Many overabundant and invasive species are also nest predators and nest predation is the principal cause of breeding failure of many birds of conservation concern. It is important for managers to know the likely effects on nest predation when culling one species among a suite of nest predatory species. We tested the effect of culling a hyperaggressive, overabundant bird and known nesting disruptor, the noisy miner (Manorina melanocephala), on artificial nest predation rates in remnant eucalypt woodlands in a highly fragmented agricultural landscape of eastern Australia. Culling of noisy miners is already practised to manage this key threatening process, but evidence of improved breeding outcomes for target species is lacking. We found no significant change in artificial nest predation rates following the treatment, despite a 28% reduction in noisy miner abundance in treatment compared to control sites. We identified five other nest predatory bird species, the noisy miner being responsible for 18.3% of total predation. Our findings suggest a compensatory nest predation model, which is problematic for management. It means that, where culling is done with a view to improving breeding potential of target species by reducing nest predation, removing one nest predatory species may not result in a commensurate reduction in nest predation. ; This work was supported by Birdlife Australia, Holsworth Wildlife Endowment, Australian Government's National Environmental Science Program Threatened Species Recovery Hub.