Research
Current Research at ARCUEPlant Extinctions from Urban Areas Around the World Characterising Urbanisation using Quantitative Measures Ecological Effects of Roads and Traffic on Flora, Fauna and Ecological Processes Urban Ecology of the Grey-headed Flying-fox See also: Archived Research Commercial Research and ConsultingThis section is under construction. We apologise for any inconvenience.Please feel free to contact us with any questions about Commercial Activities at ARCUE. Plant Extinctions from Urban Areas Around the WorldAmy K. Hahs1,2, Mark J. McDonnell1,2, Michael A. McCarthy2,3, Peter A. Vesk2, Richard T. Corlett4, Briony A. Norton1,2, Steven E. Clemants* 5, Richard P. Duncan6, Mark W. Schwartz7, Ken Thompson8 and Nicholas S.G. Williams9 1 Australian Research Centre for Urban Ecology, Royal Botanic Gardens Melbourne, Melbourne, Victoria, Australia; 2 School of Botany, University of Melbourne, Victoria, Australia; 3 Applied Environmental Decision Analysis, c/o School of Botany, University of Melbourne, Victoria, Australia; 4 Department of Biological Sciences, National University of Singapore, Singapore; 5 Brooklyn Botanic Garden, Brooklyn, NY, USA; 6 Bioprotection and Ecology Division, Lincoln University, Lincoln, New Zealand; 7 Department of Environmental Science and Policy, University of California, Davis, Davis, CA, USA; 8 Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK; 9 Melbourne School of Land and Environment, University of Melbourne, Victoria, Australia. Urbanisation is rapidly proceeding around the world. The consequences of urbanisation on the native plant communities are not well understood, particularly in terms of local extinctions of native species. We examined the relationship between the history of urban development, and the current extent of native vegetation on the extinction rate of plant species from 22 urban areas around the world, and found that 67% of the variability in our data can be explained by these two factors. Extinction rates were highest in those cities that were founded after 1600, but which experienced major landscape transformation prior to the first plant survey. Extinction rates were lower in those cities that experienced intensive agrarian settlement prior to 1600. The lowest extinction rates were present in those cities that had relatively extensive native vegetation at the time of the first survey. Our findings suggest the presence of an extinction debt, with up to 44% of the original flora predicted to be lost from recent cities with less than 20% of native vegetation remaining. The impacts of urbanisation can act over hundreds of years. This highlights the need to preserve native vegetation in urban areas to minimize the local extinction of plant species. The extinction debt in urban areas provides us with an opportunity to restore habitat and implement management strategies that will minimize potential plant extinctions while also serving as a warning that action is required now. Characterising urbanisation using quantitative measuresA. Hahs and M. McDonnell Over the past 15 years, the urban-rural gradient approach has been widely used to study the influence of urbanisation on ecological patterns and processes. Most of these studies have characterised the urban-rural gradient using either demographic information, physical or chemical attributes of the landscape or quantitative landscape metrics. The study sites at the urban and rural ends of the gradients have generally been treated as classes (e.g., “urban” patches), which does not capture the variability between sites within that class. Our research investigates how the concept of the urban-rural gradient can also be used to quantify variability within the urban end of the gradient; which measures can be used most effectively to characterise urbanisation gradients around the world; and how these measures can be used to better inform our understanding of the ecological patterns and processes present in urban areas. Reptile and Amphibian EcoolgyThe response of herpetofauna to urbanisation: inferring patterns of persistence from wildlife databasesAndrew J. Hamer and Mark J. McDonnell We analysed sighting records held in wildlife databases to infer the probability of persistence of reptiles and amphibians (‘herpetofauna ’) within Melbourne, Australia. Throughout greater Melbourne, 81% (13) of the 16 frog species recorded had ≥ 95% probability of being extant in 2006, compared with 56% (22) of the 39 species of reptiles recorded. The impact of urbanisation on reptiles in greater Melbourne appears to have been greater than the impact on frogs. To conserve herpetofauna in urban areas we need to maintain structural complexity in remnant habitat patches, and implement strategic policies and management actions that protect habitat remnants and habitat corridors. Local habitat quality assembles anuran metacommunities in urban pondsAndrew J. Hamer I assessed the breeding distribution of frogs in ponds across an urban-rural gradient in greater Melbourne, Australia, and examined the relationship with habitat quality. I sampled frog larvae at 65 ponds on four separate occasions, and collected data on aquatic vegetation cover, presence of non-native fish, hydroperiod, pond shading and water conductivity. Using Bayesian Poisson regression modelling I found that species richness increased at ponds with low water conductivity and without non-native fish. Aside from draining ponds to eradicate non-native fish, I suggest planting aquatic vegetation to ameliorate the negative impact of non-native fish on frog metacommunities in urban ponds. I also recommend retrofitting stormwater drainage systems to improve the water quality in urban ponds and therefore increase their suitability for amphibian reproduction. Ecological effects of roads and traffic on flora, fauna and ecological processesR. van der Ree In fragmented landscapes, wildlife need to move between habitat patches to exchange genes, increase the size of declining populations and recolonise areas were animals have become extinct. For many species, roads may act as barriers that prevent or limit dispersal, potentially isolating some habitats and populations. The disruption to normal movement patterns and behaviour may increase the risk of mortality, as well as threatening populations and species with extinction. Roads are clearly critical to the social and economic health of all Australians. However, conflict often arises in rural and regional Australia where highways dissect relatively intact habitat (e.g. through National Park or wilderness area) or in areas where the cumulative effect of numerous relatively minor roads (e.g. in areas of high road density such as urban or urban-rural fringe areas) exceeds threshold levels. Dr Rodney van der Ree with colleagues Prof Mark Burgman, Dr Paul Sunnucks, and Dr Andrea Taylor have recently received funding from the Australian Research Council to study the ecological effects of roads and traffic on wildlife. In collaboration with VicRoads, they aim to quantify the extent to which major highways in regional Australia form a barrier to the movement of different groups or species of wildlife that include vertebrates and invertebrates. They will then test the effectiveness of measures that may facilitate safe crossing by measuring their rate of use, reduction in road kill and increase in population viability. This information can then be used to construct major roads that are more environmentally sustainable. More InformationThe Ecology of River Red Gum Woodlands in Northern MelbourneThe Sanitisation of Urban Ecological Systems: a study of the distribution and management of leaf litter in eucalypt woodlandsBriony Norton and Mark J. McDonnell Leaf litter is a critical resource in ecosystems. Humans, however, have been shown to prefer ‘tidy’ landscapes where ground-layer resources such as leaf litter are cleared away, leading to ‘sanitised’ ecosystems. This tendency is most notable in human-dominated landscapes such as cities and towns. Despite its importance, we know very little about leaf litter in Australian urban environments, or about the impacts of its removal on urban ecosystems. In this project the distribution of leaf litter in Eucalyptus camaldulensis woodlands in remnants and parklands across Melbourne is documented, and its role in maintaining invertebrate biodiversity is being measured in parks and remnants, and also in an experimental garden plot. This project is Briony's Ph.D. research. Plant community composition and leaf litter decomposition of river red gum woodlands in northern MelbourneAmy K. Hahs and Mark J. McDonnell River red gum (Eucalyptus camaldulensis) woodlands in the Melbourne area of the Victorian Volcanic Plain bioregion extend from the centre of the city up to Yan Yean Reservoir. This research used an urban-rural gradient approach to investigate the current plant community composition within remnant patches of River red gum woodlands; the composition of the soil seed bank within these plant communities, and also how the urbanisation gradient influences the rate of leaf litter decomposition at these sites. The main findings from this research indicate that the composition of the existing vegetation and the soil seed bank shows very little difference between the remnant patches. Average annual rainfall was often a better predictor of differences between remnant patches, particularly for total species diversity and indigenous species diversity. Although the number and abundance of non-indigenous species was quite high, these remnant patches still support populations of at least 123 indigenous plant species. Thus, these remnant patches play an important role in enhancing the overall diversity of northern Melbourne. Leaf litter decomposition is an important step in the process of nutrient cycling within ecological systems. Patterns of leaf litter decomposition recorded in this study showed very little difference between remnant patches, although there was some indication that the rates of decomposition may vary between patches surrounded by different amounts of urban land-cover. However, this trend was relatively subtle and needs to be investigated in greater detail before any firm conclusions can be reached. Urban ecology of the Grey-headed Flying FoxARCUE has been investigating the causes of the extension of the geographic range of the Grey-headed Flying-fox (Pteropus poliocephalus) into Melbourne. Data are being collected on the diet of the species, the availability of food resources in Melbourne, and the influence of climate change (e.g., increased winter temperatures, increased humidity in summer) in inner Melbourne. This research contributes to our understanding of the ecology of Grey-headed Flying- foxes and assists RBG and the Department of Natural Resources in the management of in Melbourne's Flying-Fox population.
Spotted Gum (Corymbia maculata), a widely Phenology of fruit and flower resources for wildlife in urban and suburban MelbourneKelly D. Holland, Rodney van der Ree, Amy K. Hahs, Lauren D. Keim and Mark J. McDonnell We have been monitoring flowering and fruiting of trees and shrubs in order to determine the abundance and seasonality of suitable food resources for Grey-headed Flying-fox and other nectar-, pollen-, and fruit-feeding wildlife. A wide variety of planted species are present in the urban environment, providing a range of potential resources for wildlife that were not present historically. Phenology is also potentially useful as a measure of biological impacts of environmental change. Urban areas are typically warmer than the surrounding region, and may therefore act as indicators of future, broader impacts of climate change. Archived ResearchModels and Quantitative Assessment Tools |
