Heather M. McGinness

Woodland bird declines in the Murray–Darling Basin: are there links with floodplain change?

Woodland bird population declines in Australia have been attributed to various factors including habitat loss, fragmentation, and degradation. However, the influence of altered water availability in the landscape upon woodland bird populations has not been examined, particularly in terms of changes in flood regimes and subsequent loss of floodplain productivity. In this review, we examine the importance to woodland birds of floodplains, floods, and associated vegetation communities, highlighting potential links between declining water availability, habitat degradation, and bird populations. Floodplain woodlands and forests may be important refuges for woodland bird populations because (1) floodplain woodlands and forests comprise some of the largest and most continuous vegetation remnants in south-east Australia; and (2) floods intermittently supply water, sediment and nutrients that drive greater primary and secondary productivity than found in woodlands not subject to flooding. However, floodplains in south-east Australia have been subject to substantial flow regime change, driven predominantly by dams and irrigation water use. Consequently, habitat quality for woodland birds has been degraded, potentially exacerbating population declines. We suggest that despite such change, floodplain communities and their requisite floods remain of great importance for the persistence, productivity and diversity of woodland birds in Australian drylands. We hypothesise that (1) the influence of flooding upon primary and secondary productivity in floodplain and riparian zones is a key driver of resident bird populations, and a key determinant of nomadic/migratory bird use of a site; (2) alterations in flooding and consequent changes in productivity and condition of floodplain vegetation have contributed to observed declines in resident woodland birds in Australian drylands; and (3) the influence of flooding upon productivity extends beyond local populations of floodplain residents to non-floodplain populations via dispersal, and that floodplain woodlands often act as a source population for surrounding non-floodplain woodlands. We make several testable predictions regarding these hypotheses.

Confronting the risks of large-scale invasive species control

Large-scale invasive species control initiatives are motivated by laudable desires for native species recovery and economic benefits, but they are not without risk. Management interventions and policies should include evidence-based risk-benefit assessment and mitigation planning.

Floodplain amphibian abundance: responses to flooding and habitat type in Barmah Forest, Murray River, Australia

Abstract Context. Frog species are now targets for delivery of high-value managed environmental flows on floodplains. Information on the drivers of frog presence and abundance is required to support adaptive management, including analysis of the roles of flood frequency, flood timing and habitat type. Aims. This paper describes frog species richness and abundance responses to flooding and habitat type in the Barmah Forest, part of the largest river red gum forest in the world. Methods. Surveys were conducted at 22 sites over 6 years, to determine species presence, relative abundance, and evidence of breeding. Data were then used to examine temporal patterns within and between wet and dry years and spatial relationships with site geomorphology, vegetation form and wetting frequency. Key results. Six species were common and widespread, and three were rare. The seasonal timing of peak numbers of calling males differed among species. The seasonal pattern of calling for each species did not differ between wet and dry years; however, significantly lower numbers of frogs were recorded calling in dry years. The number of frogs calling was significantly higher in well vegetated grassy wetlands. Evidence of a positive relationship between wetting frequency and numbers of calling males was found for Limnodynastes fletcheri, Crinia signifera and Limnodynastes dumerilii. The abundance of tadpoles was significantly higher in wet years. Conclusions. The seasonal timing of flooding in Barmah Forest will influence the breeding success of individual species with different preferences. Flooding from September to December is required to cover most preferred breeding seasons, but longer durations may be required to maximise recruitment. This, together with regular flooding of well vegetated grassy wetland habitat, will increase the likelihood of species persistence and maximise diversity. Insufficient flooding frequency will result in reduced frog species richness and abundance. Implications. Managed flooding is important for frog abundance and species richness. This study emphasises the value of key habitats such as well vegetated grassy wetlands and reinforces the need to make their preservation a priority for management. It has identified knowledge gaps to drive future data collection for improved modelling, including a need for further research on flow-regime change and frog communities.

Does structural connectivity facilitate movement of native species in Australia's fragmented landscapes?: a systematic review protocol

BackgroundHabitat fragmentation and accompanying isolation effects are among the biggest threats to global biodiversity. The goal of restoring connectivity to offset these threats has gained even greater urgency under the looming spectre of climate change. While linear corridors have been the most commonly proposed solution to these issues, it has become increasingly recognised that structural connectivity exists in different forms with a variety of characteristics. We previously conducted a systematic review from 2008-2010 to collate and synthesise evidence regarding the relationship between these different types of structural connectivity and the actual movement of native Australian plants and animals (i.e., functional connectivity). Our previous review produced a number of management recommendations but also identified significant knowledge gaps. Given that empirical research into connectivity has become even more common since the original review and that it has been more than five years since the original literature searches, the time is ripe for an update of that review.MethodsWe will update our previous systematic review by repeating a thorough search for both published and unpublished evidence on the effects of structural connectivity on animal and plant movement through heterogeneous landscapes. We will slightly broaden the scope of the original review by including data on semi-aquatic species as well as terrestrial ones. Studies will be included if they: 1) contain data on a terrestrial or semi-aquatic native Australian species; 2) have at least one study site that contains some form of structural connectivity between otherwise isolated patches of habitat; and 3) include data on movement of species through the connectivity or data that allow inference of movement (or the lack thereof). We will repeat the analyses carried out for the original review which used hierarchical linear modelling to assess the effects of numerous sources of heterogeneity (e.g., type of connectivity, width of connection, ecosystem type, taxonomic group, and many other characteristics of the species, habitat, and connectivity) on the amount of movement observed in a landscape. If increased sample sizes allow we will also carry out additional meta-analyses, which were not possible with the original dataset.

Climatic Drivers of Revegetation Management Practices in Australia: Analysis of a Social Survey

Investment in small and large-scale revegetation in Australia is growing in response to concerns regarding the sustainability and productivity of agricultural landscapes. Site preparation and management––such as soil cultivation, weed control, fertilising, mulching, use of treeguards and watering––are major costs associated with small-scale revegetation. The aim of this study has been to investigate local revegetation knowledge and practices to determine the usefulness of each management practice for achieving success and to determine whether some practices are more suited to particular climatic zones. A national online revegetation survey was conducted to ascertain current small-scale revegetation practices and the factors that drive these choices. Management practices were found to be strongly associated with climate. Mulch, fertiliser, weed control and watering were applied more frequently in higher rainfall and higher temperature zones. Soil cultivation and treeguards were used more frequently in lower rainfall and lower temperature zones. These findings suggest that there may be some benefit in modifying existing revegetation guidelines to reflect climatic zones and management flexibility.

Flood regimes driving vegetation and bird community transitions in semiarid floodplain woodlands

Ecohydrology. 2018;11:e1954. https://doi.org/10.1002/eco.1954 Abstract Water resource development in many parts of the world has resulted in serious reductions in the frequency, extent, and duration with which floodplain woodlands are inundated, resulting in significant habitat change and loss of productivity. Yet few studies have attempted to assess the effects of different flood regimes upon floodplain vegetation and fauna communities together, particularly during the terrestrial phase. We use new space‐for‐time substitution data from south‐eastern Australia to describe the nature of Eucalyptus largiflorens floodplain woodland communities under different flood regimes, from which inferences may be made about the consequences of water management decisions. We explore the hypothesis that differences in flood regime drive dissimilarities in vegetation structure and condition as well as variation in woodland bird abundance. Overall, insufficient floodingwas associated with degradation of floodplainwoodland condition and structure, as well as shifts in the relative abundance of key woodland bird groups. The results suggest that changes in flooding frequency are associatedwith significant shifts in site character and ultimately transitions in community composition, even within the same broad vegetation type. Importantly, these transitions are the result of interactions between water availability, vegetation changes, fauna habitat preferences, and interspecific interference competition. In addition, they indicate the influence of altered flood regimes upon terrestrial fauna of floodplain ecosystems rather than just aquatic components—a link that is relatively neglected by both scientists andmanagers to‐date. Such transitions and links have far‐reaching implications for ecosystem function at multiple scales and for how floodplains are understood, valued, and managed.