Cities are hotspots for threatened species Ives, Christopher D; Lentini, Pia E; Threlfall, Caragh G ...
Global ecology and biogeography,
January 2016, Volume:
25, Issue:
1
Journal Article
Peer reviewed
Open access
AIM: Although urbanization impacts many species, there is little information on the patterns of occurrences of threatened species in urban relative to non‐urban areas. By assessing the extent of the ...distribution of threatened species across all Australian cities, we aim to investigate the currently under‐utilized opportunity that cities present for national biodiversity conservation. LOCATION: Australian mainland, Tasmania and offshore islands. METHODS: Distributions of Australia's 1643 legally protected terrestrial species (hereafter ‘threatened species’) were compiled. We assessed the extent to which they overlapped with 99 cities (of more than 10,000 people), with all non‐urban areas, and with simulated ‘dummy’ cities which covered the same area and bioregion as the true cities but were non‐urban. We analysed differences between animals and plants, and examined variability within these groups using species accumulation modelling. Threatened species richness of true versus dummy cities was analysed using generalized linear mixed‐effects models. RESULTS: Australian cities support substantially more nationally threatened animal and plant species than all other non‐urban areas on a unit‐area basis. Thirty per cent of threatened species were found to occur in cities. Distribution patterns differed between plants and animals: individual threatened plant species were generally found in fewer cities than threatened animal species, yet plants were more likely to have a greater proportion of their distribution in urban areas than animals. Individual cities tended to contain unique suites of threatened species, especially threatened plants. The analysis of true versus dummy cities demonstrated that, even after accounting for factors such as net primary productivity and distance to the coast, cities still consistently supported a greater number of threatened species. MAIN CONCLUSIONS: This research highlights that Australian cities are important for the conservation of threatened species, and that the species assemblages of individual cities are relatively distinct. National conservation policy should recognize that cities play an integral role when planning for and managing threatened species.
•We examine bee communities in three dominant urban green spaces.•Bee assemblages in residential neighbourhoods were dominated by Apis mellifera.•Suitable bee habitat was infrequently managed, and ...dominated by native vegetation.•Simple changes to green space management can assist native bee conservation.
Networks of urban green space can provide critical resources for wild bees, however it is unclear which attributes of green spaces provide these resources, or how their management can be improved to benefit a diversity of bee species. We examined bee communities in three dominant urban green space habitats: (1) golf courses (2) public parks and (3) front gardens and streetscapes in residential neighbourhoods in Melbourne, Australia and assessed which local and landscape attributes influenced bee communities. There was a greater abundance and richness of bee species in public parks compared to golf courses and residential neighbourhoods, where the latter habitat was dominated by European Honeybees (Apis mellifera). The occurrence of A. mellifera was positively associated with increases in flowering and native plants. Ground-nesting Homalictus species occurred more frequently in older golf courses and public parks surrounded by low impervious surface cover, and with a low diversity of flowering plants. Cavity nesting, floral specialists within the Colletidae family occurred more often in green space habitats with greater native vegetation, and occurred infrequently in residential neighbourhoods. The lack of appropriate nesting habitat and dominance of exotic flowering plants in residential neighbourhoods appeared to positively impact upon the generalist A. mellifera, but negatively affected cavity and ground nesting floral specialist bee species (e.g. Halictidae and Colletidae). Our results highlight the need to include urban areas in pollinator conservation initiatives, as providing resources critical to diverse bee communities can assist in maintaining these key pollinators in urban landscapes.
Urban biodiversity conservation is critical if cities are to tackle the biodiversity‐extinction crisis and connect people with nature. However, little attention has been paid to how urban ...environmental managers navigate complex socio‐ecological contexts to conserve biodiversity in cities. We interviewed environmental managers from Australian cities to identify (1) the breadth of conservation actions undertaken and (2) the barriers and enablers to action. We found current practice to be more diverse, innovative, and proactive than previously described (318 actions across nine categories). Conversely, priority actions identified by the literature are yet to be “mainstream” in practice (e.g., designing for human–nature connection, securing space for nature in cities). Further, we identified a suite of levers to overcome barriers. Our research provides scientists and practitioners with an understanding of the multiple facets of conservation in cities and emphasizes the importance of interdisciplinary approaches in future research and practice.
Urban environments are being subject to increasing temperatures due to the combined effects of global climate change and urban heat. These increased temperatures, coupled with human planting ...preferences and green space management practices, influence how urban plants grow and survive. Urban community gardens are an increasingly popular land use, and a green space type that is influenced by unique climate-human behavior interactions. Despite ongoing rapid temperature changes in cities, it is unknown how gardeners are adapting to these changes, and to what extent changes influence planting decisions and patterns of urban plant diversity. In this study, we monitored the variation in daily air temperatures and measured plant species richness at the garden and garden plot scale in 11 community gardens in Melbourne, Australia. We surveyed >180 gardeners to better understand the relationships between temperature variation, garden plant species diversity, and gardener management practices. We found that garden scale temperature variability is driven by regional context, and temperatures are more stable in landscapes with higher impervious surface cover. Gardeners agreed that climatic/temperature changes are influencing their watering behavior, but not their plant selection. Instead plant selection is being driven by desired food production. Yet, when comparing two bioregions, temperature did have a measurable relationship with garden plant composition in the region with more temperature variation. Temperature variability negatively related to plant species richness within garden plots, providing evidence that plant survival is related to climate at this scale in such regions. Although gardeners may be able to water more in response to regional climate changes, gardeners are unlikely to be able to completely control the effects of temperature on plant survival in more variable conditions. This suggests the inner city with more stable temperatures (albeit potentially hotter for longer due to heat island) may accommodate more species diverse gardens.
Display omitted
•Temperature variability affects urban garden management and resource use.•Three scale approach examined drivers of variability and social-ecological effects.•Landscape affects temperature variability to effect plant richness in plots.•Climate changes prompt gardeners to adjust water use, but not plant selection.•Plant survival mitigation strategies may still be climate-dependent in cities.
Abstract
Rapid urbanization and the global loss of biodiversity necessitate the development of a research agenda that addresses knowledge gaps in urban ecology that will inform policy, management, ...and conservation. To advance this goal, we present six topics to pursue in urban biodiversity research: the socioeconomic and social–ecological drivers of biodiversity loss versus gain of biodiversity; the response of biodiversity to technological change; biodiversity–ecosystem service relationships; urban areas as refugia for biodiversity; spatiotemporal dynamics of species, community changes, and underlying processes; and ecological networks. We discuss overarching considerations and offer a set of questions to inspire and support urban biodiversity research. In parallel, we advocate for communication and collaboration across many fields and disciplines in order to build capacity for urban biodiversity research, education, and practice. Taken together we note that urban areas will play an important role in addressing the global extinction crisis.
1. Cities are rapidly expanding world-wide and there is an increasing urgency to protect urban biodiversity, principally through the provision of suitable habitat, most of which is in urban green ...spaces. Despite this, clear guidelines of how to reverse biodiversity loss or increase it within a given urban green space is lacking. 2. We examined the taxa- and species-specific responses of five taxonomically and functionally diverse animal groups to three key attributes of urban green space vegetation that drive habitat quality and can be manipulated over time: the density of large native trees, volume of understorey vegetation and percentage of native vegetation. 3. Using multi-species occupancy-detection models, we found marked differences in the effect of these vegetation attributes on bats, birds, bees, beetles and bugs. At the taxa-level, increasing the volume of understorey vegetation and percentage of native vegetation had uniformly positive effects. We found 30-120% higher occupancy for bats, native birds, beetles and bugs with an increase in understorey volume from 10% to 30%, and 10-140% higher occupancy across all native taxa with an increase in the proportion of native vegetation from 10% to 30%. However, increasing the density of large native trees had a mostly neutral effect. At the species-specific level, the majority of native species responded strongly and positively to increasing understorey volume and native vegetation, whereas exotic bird species had a neutral response. 4. Synthesis and applications. We found the probability of occupancy of most species examined was substantially reduced in urban green spaces with sparse understorey vegetation and few native plants. Our findings provide evidence that increasing understorey cover and native plantings in urban green spaces can improve biodiversity outcomes. Redressing the dominance of simplified and exotic vegetation present in urban landscapes with an increase in understorey vegetation volume and percentage of native vegetation will benefit a broad array of biodiversity.
Landscape preferences shape decision-making and drive the ecological outcomes of urban landscapes. We investigate how people's landscape preferences are shaped by the green space context (public park ...vs private residential garden landscapes) and by physical features such as vegetation complexity. A postal questionnaire was sent to households near seven urban parks in Melbourne, Australia. Results showed that landscapes were grouped into four categories based on patterns of preference response. Landscapes with moderate vegetation complexity were placed in separate categories distinguished by green space context (parks vs gardens), while very simple and very complex landscapes were placed in different categories irrespective of green space context. Surprisingly, dense vegetation was highly preferred by respondents. As areas of dense vegetation also provide complex habitats for wildlife, this highlights the possibility of developing policies and designing landscapes that can benefit both people and nature.
Urban landscapes are often located in biologically diverse, productive regions. As such, urbanization may have dramatic consequences for this diversity, largely due to changes in the structure and ...function of urban communities. We examined the influence of landscape productivity (indexed by geology), housing density and vegetation clearing on the spatial distribution of nocturnal insect biomass and the foraging activity of insectivorous bats in the urban landscape of Sydney, Australia. Nocturnal insect biomass (g) and bat foraging activity were sampled from 113 sites representing backyard, open space, bushland and riparian landscape elements, across urban, suburban and vegetated landscapes within 60 km of Sydney's Central Business District. We found that insect biomass was at least an order of magnitude greater within suburban landscapes in bushland and backyard elements located on the most fertile shale influenced geologies (both p<0.001) compared to nutrient poor sandstone landscapes. Similarly, the feeding activity of bats was greatest in bushland, and riparian elements within suburbs on fertile geologies (p = 0.039). Regression tree analysis indicated that the same three variables explained the major proportion of the variation in insect biomass and bat foraging activity. These were ambient temperature (positive), housing density (negative) and the percent of fertile shale geologies (positive) in the landscape; however variation in insect biomass did not directly explain bat foraging activity. We suggest that prey may be unavailable to bats in highly urbanized areas if these areas are avoided by many species, suggesting that reduced feeding activity may reflect under-use of urban habitats by bats. Restoration activities to improve ecological function and maintain the activity of a diversity of bat species should focus on maintaining and restoring bushland and riparian habitat, particularly in areas with fertile geology as these were key bat foraging habitats.
The city as a refuge for insect pollinators Hall, Damon M.; Camilo, Gerardo R.; Tonietto, Rebecca K. ...
Conservation biology,
February 2017, Volume:
31, Issue:
1
Journal Article
Peer reviewed
Open access
Research on urban insect pollinators is changing views on the biological value and ecological importance of cities. The abundance and diversity of native bee species in urban landscapes that are ...absent in nearby rural lands evidence the biological value and ecological importance of cities and have implications for biodiversity conservation. Lagging behind this revised image of the city are urban conservation programs that historically have invested in education and outreach rather than programs designed to achieve high-priority species conservation results. We synthesized research on urban bee species diversity and abundance to determine how urban conservation could be repositioned to better align with new views on the ecological importance of urban landscapes. Due to insect pollinators' relatively small functional requirements—habitat range, life cycle, and nesting behavior—relative to larger mammals, we argue that pollinators put high-priority and high-impact urban conservation within reach. In a rapidly urbanizing world, transforming how environmental managers view the city can improve citizen engagement and contribute to the development of more sustainable urbanization. Las investigaciones sobre los insectos polinizadores urbanos están cambiando las percepciones sobre el valor biológico y la importancia ecológica de las ciudades. La abundancia y la diversidad de las especies nativas de abejas en los paisajes urbanos, que además están ausentes en los terrenos rurales cercanos, evidencian el valor biológico y la importancia ecológica de las ciudades y tienen implicaciones para la conservación de la biodiversidad. A paso lento detrás de esta imagen revisada de las ciudades están los programas de conservación urbana que históricamente han invertido en la educación y el alcance en lugar de los programar diseñados para adquirir resultados de conservación para especies de prioridad alta. Sintetizamos las investigaciones sobre la diversidad de especies de abejas urbanas y la abundancia para determinar cómo la conservación urbana podría ser reposicionada para alinearse de mejor manera con las nuevas visiones sobre la importancia ecológica de los paisajes urbanos. Debido a los requerimientos funcionales relativamente pequeños de los insectos polinizadores - extensión del hábitat, ciclo de vida, comportamiento de anidamiento - en relación con los mamíferos más grandes, argumentamos que los polinizadores colocan a la conservación urbana de alta prioridad y alto impacto dentro de nuestro alcance. En un mundo rápidamente urbanizado, transformar la forma en que los administradores ambientales ven a las ciudades puede mejorar la participación ciudadana y contribuir al desarrollo de una urbanización más sustentable.
The evidence base for the benefits of urban nature for people and biodiversity is strong. However, cities are diverse and the social and environmental contexts of cities are likely to influence the ...observed effects of urban nature, and the application of evidence to differing contexts. To explore biases in the evidence base for the effects of urban nature, we text-matched city names in the abstracts and affiliations of 14 786 journal articles, from separate searches for articles on urban biodiversity, the health and wellbeing impacts of urban nature, and on urban ecosystem services. City names were found in 51% of article abstracts and 92% of affiliations. Most large cities were studied many times over, while only a small proportion of small cities were studied once or twice. Almost half the cities studied also had an author with an affiliation from that city. Most studies were from large developed cities, with relatively few studies from Africa and South America in particular. These biases mean the evidence base for the effects of urban nature on people and on biodiversity does not adequately represent the lived experience of the 41% of the world's urban population who live in small cities, nor the residents of the many rapidly urbanising areas of the developing world. Care should be taken when extrapolating research findings from large global cities to smaller cities and cities in the developing world. Future research should encourage research design focussed on answering research questions rather than city selection by convenience, disentangle the role of city size from measures of urban intensity (such as population density or impervious surface cover), avoid gross urban-rural dualisms, and better contextualise existing research across social and environmental contexts.
PDF
