Showing papers in "Urban Ecosystems in 2015"

Assessing the effect of green cover spatial patterns on urban land surface temperature using landscape metrics approach

Abstract: The present study was aimed to investigate how and to what extent urban land surface temperature (ULST) is affected by spatial pattern of green cover patch in an urban ambient in Isfahan, Iran. To materialize the effects of spatial pattern of green cover on ULST, Landsat ETM + image data on May 5, 2002 was acquired to be processed for ULST estimation and to generate Land Use/Land Cover (LULC) classes. Given to five percent of total available cells with a randomized distribution across the built-up areas, the linkage between ULST and composition, configuration and structure of green cover class was quantified. Five patch level landscape metrics including nearest distance (ND), patch area (AREA), perimeter to area (PARA), shape index (SHAPE) and core area index (CAI) were chosen and applied as explaining variables in statistical analyses due to their potential effects on ULST. Results of the present study have revealed that all the landscape metrics values of the green cover class were significantly correlated to their nearest ULST sample points, amongst which a stronger linkage was observed between ND (r = 0.611, p <0.05) and ULST compared to others. Stepwise generalized additive modeling method-based multiple linear regression model was then fitted to dataset and resulted in developing the model (r2 = 0.41, p <0.05), explaining the relationship between spatial pattern of green cover and ULST. Finally, we concluded that the present study could provide additional level of knowledge through which urban planners can optimize composition, configuration and structure of green cover patches to mitigate the adverse impacts of LST phenomenon especially where urbanization is still ongoing.

Urbanization promotes non-native woody species and diverse plant assemblages in the New York metropolitan region

Abstract: The rapid urbanization of the world has significant ecological consequences that shape global biodiversity patterns. The plant communities now common in urban centers may represent new habitats with unique dynamics and the potential for highly modified ecological services. This study, joining extensive spatial and floristic data sets, examined current distribution patterns of non-native and native woody plant species in the New York metropolitan region, USA. We joined the New York Metropolitan Flora (NYMF) database of woody species with GIS data of urban land cover for 297 5 km by 5 km landscape blocks. We tested the relationship between urbanization and native and non-native species richness patterns, the extent of non-native species presence in the urban area, and the change in beta diversity across a gradient of urban land cover. We found that across the urban–rural gradient, native plant species richness decreased and non-native species richness increased with increasing urban land cover. Total richness does not change across the urban–rural gradient. Our analyses show that these patterns are highly correlated with urbanization, but vary across the New Jersey landscape. We also found an increase in beta diversity with urbanization; urban areas are not homogenized in plant species composition compared to rural areas. Here we show a species-rich flora dominated by non-native species which are differentiating the urban flora. These results can help guide appropriate conservation decisions for the maintenance of plant biodiversity in cities.

A comparison of the growth and cooling effectiveness of five commonly planted urban tree species.

Abstract: It is often claimed that evapotranspiration from urban trees can mitigate the urban heat island and adapt our cities to climate change; however, the relative effectiveness of different tree species has rarely been investigated. The current study addressed this shortcoming by comparing the growth and physiology of five commonly planted tree species: Sorbus arnoldiana, Crataegus laevigata, Malus ‘Rudolph’, Pyrus calleryana and Prunus ‘Umineko’. The study was conducted between March and November, 2011 in eight different streets of Manchester, UK where trees had been growing for 6 years in the same growing conditions. The study showed that evapotranspirational cooling is closely related to the growth and stress tolerance of tree species. Of the species tested, Prunus ‘Umineko’ and P. calleryana were the fastest growing and Malus ‘Rudolph’ was the slowest growing. In general faster growing species showed higher leaf area index (LAI) and higher stomatal conductivity and so provided more cooling. However, Prunus ‘Umineko’ had surprisingly low cooling and showed signs of drought stress. P. calleryana showed up to 100 % higher stomatal conductance than the other tree species. Combining the higher LAI and wider canopy, P. calleryana and C. laevigata provided cooling up to 2.2 kW tree−1, 3 to 4 times of cooling to that of Prunus ‘Umineko’ and S. arnoldiana and showed no signs of drought stress. Malus ‘Rudolph’ showed stress tolerance but provided low cooling. Prunus ‘Umineko’ and S. arnoldiana with their thin and sparse canopy provided low cooling and showed susceptibility to urban stress.

Effects of habitat structure, human disturbance, and habitat connectivity on urban forest bird communities

Abstract: As urbanization accelerates, urban biodiversity conservation is becoming a great concern for the maintenance of urban ecosystem functions. In particular, forest bird communities in urban areas have been recognized as a conservation target because of their functions in food webs and ecosystem services. But our understanding of which local- and landscape-scale factors influence native bird communities within urban green spaces is still insufficient to provide managers with information for effectively planning biodiversity management programs. Here we examine how local habitat characteristics, human disturbance, and habitat connectivity influence the diversity of forest bird communities in 44 small forest patches (0.5–20.0 ha) embedded in an urbanized landscape. Patch size exerted a positive influence on the diversity of most bird functional groups, and it had the greatest effects on total abundance and species richness. The second most important factor was human disturbance. Remnant patches with lower levels of human disturbance had higher diversity than newly established patches where intense human activities occurred more frequently. In addition, vegetation complexity and habitat connectivity were positively related to total species richness and abundance, respectively, but they were less important. Management strategies for the conservation of urban forest birds, therefore, should consider not only local improvements in habitat structure – through increased patch size, reduced human disturbance, and increased vegetation complexity – but also the maintenance of habitat connectivity.

Creating better cities: how biodiversity and ecosystem functioning enhance urban residents' wellbeing

Abstract: Cities concentrate risks and the adverse effects of dense populations, such as outdoor air pollution, chronic disease and the impact of extreme weather events. Governments and planning bodies struggle to heed and apply the abundance of unintegrated research that links aspects of the urban environment with urban residents’ wellbeing. In order to promote human wellbeing in cities, a number of key features of the urban environment should be promoted. The medical science, urban ecology and urban design research already recognises the importance of some aspects, including providing walkable spaces, community space and greenspace. We argue that in practice, the provision of these three features is insufficient for human wellbeing. Emerging research demonstrates the importance of biodiversity and ecosystem functions to wellbeing. This paper outlines the concept of wellbeing and provides a summary of the three established features of urban environments that enhance residents’ lives: the provision of walkable, community and greenspace. We then outline the importance of two vital but often overlooked links in the discussion of how urban planning contributes to wellbeing: biodiversity and ecosystem functioning. Until governments and policies recognise the importance of these two elements, urban design and management for wellbeing is at best simplistic. It is important for biodiversity and ecosystem function to be considered during the design decision process. Urban designers and ecologists should recognise that their work has the potential to contribute to human wellbeing by integrating biodiversity and ecosystem functioning in their research.

Effects of urban trees on local outdoor microclimate: synthesizing field measurements by numerical modelling

Abstract: In this study, we investigated the effects of trees on the local urban microclimate and human thermal comfort under different local weather conditions, in a small urban area in Assen, the Netherlands. In both summer and winter, continuous air temperature and relative humidity measurements were conducted at five selected sites having obviously different environmental characteristics in tree cover. Measurements demonstrated that in summer the microclimatic conditions at each observation site showed significant differences. The cooling effects of trees on clear and hot days were two times higher than on cloudy and cold days. In winter, air temperature was slightly reduced by the evergreen trees, and weather conditions did not cause a notable change on performance of trees on the microclimate. ENVI-met, a three-dimensional microclimate model was used to simulate the spatial distribution of temperature and humidity. After selecting representative days, we simulated the study site as it currently is and for a situation without trees. Spatial differences of trees’ effects were found to vary strongly with weather conditions. Furthermore, human thermal comfort is indicated by the Predicted Mean Vote model. During the hottest hours, trees improved the thermal comfort level via reducing ‘very hot’ and ‘hot’ thermal perception by about 16 % on clear days and 11 % on cloudy days. Generally, our findings demonstrate that urban microclimate and human thermal comfort convincingly varies in close geographical proximity. Both are strongly affected by the presence of local trees. Weather conditions play an important role on the trees’ performance on the summer-time microclimate.

Understanding preferences for tree attributes: the relative effects of socio-economic and local environmental factors

Abstract: Urban plant biodiversity is influenced by both the physical environment and attitudes and preferences of urban residents for specific plant types. Urban residents are assumed to be disconnected from their immediate environment, and cultural and societal factors have been emphasized over environmental factors in studies of landscaping choices. However, we postulate that local climatic and environmental factors can also affect preferences for plant attributes. Therefore, spatial and temporal patterns in urban tree biodiversity may be driven not only by the direct effect of environmental variables on plant function, but also by the effect of environmental variables on attitudes toward trees and associated choices about which types of trees to plant. Here, we tested the relative effects of socio-economic and local environmental factors on preferences toward tree attributes in five counties in southern California in and surrounding Los Angeles, based on 1,029 household surveys. We found that local environmental factors have as strong an effect on preferences for tree attributes as socio-economic factors. Specifically, people located in hotter climates (average maximum temperature 25.1 °C) were more likely to value shade trees than those located in cooler regions (23.1 °C). Additionally, people located in desert areas were less likely to consider trees to be important in their city compared with people located in naturally forested areas. Overall, our research demonstrates the inherent connections between local environmental factors and perceptions of nature, even in large modern cities. Accounting for these factors can contribute to the growing interest in understanding patterns of urban biodiversity.

Exotics on exotics: Pollen analysis of urban bees visiting Sedum on a green roof

Abstract: Numerous bee species were collected from a single green roof over the blooming period of the dominant exotic plant type, Sedum, a succulent stonecrop widely used in the green roof industry. As green roofs become more common in cities, an understanding of the potential positive and negative impacts of widespread use of this exotic but useful plant is needed. In this study we sampled bees visiting a green roof in downtown Toronto and compared the proportion of Sedum pollen in the loads they were carrying back to nesting locations. It was found that smaller bees (e.g. Lasioglossum, Hylaeus) were significantly less common on the roof compared with medium (e.g. Apis, Megachile) and large-sized bees (e.g. Bombus, Andrena). The proportion of Sedum pollen in the pollen loads of foraging bees collected was high amongst all bees (average of 80.5 % of total pollen load), but significantly greater for exotic bees compared to native bees. Moreover, native bees had significantly greater numbers of non-Sedum pollen types comprising more than >20 % of their pollen loads, meaning bees could be visiting flowers at ground level and on the roof in the same foraging bout. As the number of green roofs in cities increase, the characteristics of their designs, including the vegetation type and diversity, could have a significant impact in shaping local urban bee communities.

Window collisions by migratory bird species: urban geographical patterns and habitat associations

Abstract: Bird collisions with buildings are an increasing concern and yet understanding the factors contributing to collisions at the species level remains largely unknown. This gap in our knowledge of species-specific strike patterns hinders the development of accurate estimates for the impact of death-by-collision on bird populations and impedes on our ability to minimize its effects. Our study offers the first examination of the impact of environmental variables on bird- window collisions at the species level. The Fatal Light Awareness Program Canada collected bird-window collision data in three distinct regions of Toronto, Canada during the migratory season of the years 2009 and 2010. Our results indicated that building percent window cover, exposed habitat cover, and cover of built structures significantly affect bird-window collisions. Multivariate analyses showed that the bird species that collided with buildings surrounded by a high level of urban greenery are species that typically occur in forested habitats and are foliage gleaners. In contrast, species that collided with buildings surrounded by a higher level of urbanization are species that typically occur in open woodland and are ground foragers. These results suggest that the composition of bird species colliding with buildings across various regions of the Greater Toronto Area is influenced by the local bird species community composition, by the configuration of the surrounding landscape, and by the levels of greenery around the buildings.

Defining and measuring the social-ecological quality of urban greenspace: a semi-systematic review

Abstract: Various disciplines have examined the role of urban greenspace in delivering a wide array of social-ecological values to urban residents. This semi-systematic review of 50 studies assesses how links between the social and ecological qualities of urban greenspace have been measured to establish social-ecological values, and what qualities researchers have used to define greenspace type. Our review identified that differences in the definition and measurement of greenspace and its ecological and social qualities can have a profound impact on interpretations of greenspace value. We argue that it is critical to acknowledge the heterogeneity among different greenspace types, and to use suitable metrics of greenspace ecological and social quality accordingly. We present a heterarchical typology of greenspace qualities (rather than a hierarchical typology of urban greenspaces) that can be used to define greenspace type and identify research clusters, gaps and emerging lines of inquiry into the social-ecological values of greenspace.

Ecological design for urban waterfronts

Abstract: Urban waterfronts are rarely designed to support biodiversity and other ecosystem services, yet have the potential to provide these services. New approaches that integrate ecological research into the design of docks and seawalls provide opportunities to mitigate the environmental impacts of urbanization and recover ecosystem function in urban waterfronts. A review of current examples of ecological design in temperate cities informs suggestions for future action. Conventional infrastructures have significant and diverse impacts on aquatic ecosystems. The impacts of conventional infrastructure are reduced where ecological designs have been implemented, particularly by projects adding microhabitat, creating more shallow water habitat, and reconstructing missing or altered rocky benthic habitats. Opportunities for future research include expanding current research into additional ecosystems, examining ecological processes and emergent properties to better address ecosystem function in ecological design, and addressing the impact of and best practices for continuing maintenance. Planned ecological infrastructure to replace aging and obsolete structures will benefit from design feedback derived from carefully executed in situ pilot studies.

Pollination service to urban agriculture in San Francisco, CA

Abstract: Urban agriculture can increase the sustainability of cities by reducing their ecological footprint, conserving biodiversity, and improving quality of life in a city. Given the environmental, economic and social value of urban agriculture, it is important to understand the ecosystem services that sustain it. We experimentally investigated how pollination by wild bees affects tomato production on 16 urban agriculture sites in San Francisco, CA. By comparing four pollination service indicators (fruit set, fruit mass, yield, and seed set) in four pollination treatments (open, artificial-self, artificial-cross, control), we were able to determine that tomatoes pollinated by wild bees significantly outperform the control in terms of all four pollination service indicators measured. Furthermore, the results of this study indicate that urban areas can support adequate pollination service to urban agriculture, regardless of garden size, garden age, or proportion of impervious surface in the surrounding matrix, and that floral resource density is a major factor influencing pollination service.

Comparison of stormwater runoff from sedum, native prairie, and vegetable producing green roofs

Abstract: Stormwater retention is one of the well-studied benefits of green roofs. A roof’s ability to retain stormwater depends on factors such as the intensity and duration of the rain event as well as substrate depth, substrate moisture content at the start of the rain event, and vegetation type, health, density and water use efficiency. Extensive green roofs used for crop production differ from traditional Sedum and prairie-covered extensive green roofs in plant density and water use efficiency, but their impact on stormwater retention has not been well studied. Three vegetation types (unfertilized Sedum and native prairie species mixes, and a fertilized vegetable and herb species mix) were compared for stormwater runoff quantity over three growing seasons and stormwater runoff quality during one growing season. The prairie covered green roofs had the lowest increase in runoff as precipitation increased, almost half that of Sedum or vegetable producing green roof treatments. Vegetation type had no effect on runoff nitrate-nitrogen (NO3 −) concentrations, but NO3 − concentrations decreased over the course of the growing season. Runoff phosphorus (P) concentrations also decreased over time in the Sedum and prairie treatments, which were lower than P concentrations from the vegetable green roof throughout the growing season. This is likely a result of the difference between amounts of NO3 − and P applied to the vegetable green roof and the needs of the crop plants in that treatment. The similarities in water retention and water quality between vegetable producing extensive green roofs and Sedum green roofs suggest that vegetable production with careful nutrient management will not have a negative impact on stormwater retention or runoff water quality.

Eating locally: dance decoding demonstrates that urban honey bees in Brighton, UK, forage mainly in the surrounding urban area

Abstract: Urbanization is increasing worldwide. Urban habitats often support considerable biodiversity and so are of conservation value, even though they are highly modified ecosystems. Urban parks and gardens are rich in flowers that provide food for pollinators, including bees. Here, we use waggle dance decoding to investigate foraging by 3 honey bee hives located in the city of Brighton, UK, over almost an entire foraging season, April to October. Waggle dances were recorded using video cameras and decoded during framewise playback on a computer by measuring the angle and duration of the waggle phase. Foraging was mostly local (mean monthly distances 0.5–1.2 km) and mostly within the surrounding urban area (monthly means 78–92 %) versus the countryside (closest distance 2.2 km) even though this was well within the honey bee maximum foraging range (c. 12 km). These distances were lower than those from a previous study for hives located in a rural area 4.5 km away. Honey bees are very sensitive to foraging economics and foragers make waggle dances only after visiting high-quality feeding locations. Low distances advertised by dances, therefore, indicate sufficient forage nearby and show that urban areas can support honey bees year round. As a corollary, however, urban bees may provide little pollination service to agriculture especially in spring, which had the lowest foraging distances and is when the most economically important animal-pollinated UK crops, apple and oilseed rape, are in bloom.

Poor ecological quality of urban ponds in northern England: causes and consequences

Abstract: The value of ponds in urban areas historically has been overlooked While some recent studies have described considerable biodiversity in urban areas, it is unclear as to how far this extends to different urban habitats The aims of this study were to determine the condition of 21 urban ponds in Bradford (northern England) and to quantify the connectivity of wetlands in the district The study showed that macroinvertebrate and plant biodiversity was substantially lower than would be expected based on pristine reference sites Of the 21 ponds surveyed, 15 were found to be classified as having very poor ecological quality, with 5 being classed as poor and just 1 was classed as moderate The number of aquatic plant species found in the ponds ranged from 0 to 6 and the number of macroinvertebrate families found ranged from 4 to 13 It was suspected that the aquatic plant diversity was low due to management techniques such as the removal of emergent vegetation The average distance to a wetland was found to be higher in urban areas (533 m) compared to rural areas (448 m) although this difference was small, which indicates that the low diversity found in urban ponds is likely due to habitat variables

The influence of rainfall depth class and deciduous tree traits on stemflow production in an urban park

Abstract: The growing recognition of trees’ value in urban environments is resulting in increased investment in “green infrastructure.” However, generalizations that deciduous canopies reduce stormwater are based largely on closed-canopy forests, highlighting the need for more detailed study of isolated urban trees. We systematically studied the effect of canopy traits on stemflow percent and funneling ratios for isolated deciduous trees in a semi-arid climate characterized by mostly small precipitation events. High stemflow production was generally associated with high branch angles (single- and multi-leader trees) small diameter-at-breast-height (single-leader trees), furrowed bark in single-leader trees for rain events ≥ 10 mm, and smooth bark in multi-leader trees for all except the lowest rain depth class. Higher numbers of leaders converging at the base were associated with high stemflow yields. Individual-tree stemflow percent and funneling ratio values were variable, even for similar rain depths, suggesting that meteorological factors play a role. Event maximum stemflow percent was 22.8 % (25.6 mm rain depth) for a columnar English oak and event maximum funneling ratio was 196.9 (5.6 mm) for a Riversii European beech. Our findings highlight the importance of infiltration capacity at the base of urban trees and of designing for the rainfall regime when integrating stormwater management with vegetation and soils in cities.

Soil heavy metal contamination in residential neighborhoods in post-industrial cities and its potential human exposure risk

Abstract: This study assessed the extent of potential human risk to heavy metal exposure by comparing concentrations of arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb) and zinc (Zn) in soil in 43 vacant lots in two low income neighborhoods, Hough (Cleveland, Cuyahoga County, Ohio) and Weinland Park (Columbus, Franklin County, Ohio) in USA to the US Environmental Protection Agency (EPA)’s Soil Screening Levels (SSLs) and to regional background concentrations. At least one soil sample in all the lots in Weinland Park and 27 out of 28 (96%) of the lots in Hough exceeded the natural background concentration of Pb in Franklin (14 to 25 mg/kg soil) and Cuyahoga (56 to 136 mg/kg soil) counties, respectively. When compared to the USEPA’s SSL for Pb for human ingestion of soil, soil from only 1 out of 15 (6.6%) lots in Weinland Park and 15 out of 28 (54%) in Hough neighborhood exceeded the SSL of 400 mg Pb/kg soil. All sites in both neighborhoods exceeded the SSL for As (0.4 mg/kg soil); however only 1 lot (6.6%) in Weinland Park and 3 (11%) in Hough exceeded the background concentrations of As in Franklin (9 to 33 mg/kg soil) and Cuyahoga (5 to 20 mg/kg soil) counties. Thirteen (86%) lots in Weinland Park and 25 (89%) in Hough had soil Zn concentration higher than the background in Franklin County (71 to 177 mg/kg soil) and Cuyahoga County (56 to 137 mg/kg soil) respectively, however they were all within the SSL of 23,000 mg Zn/kg soil. Significant correlations were observed within metals, soil properties, and between metals and soil properties including texture, moisture, pH, organic matter and active carbon suggesting unique associations in the two neighborhoods. Results indicate that Pb is a metal of concern in 54% of the vacant lots in Hough neighborhood. The study highlights the need for comparing vacant lot heavy metal concentrations to both USEPA’s SSLs and natural background concentrations in the area for establishing safety of a lot prior to its use for urban agriculture.

Assessing aquatic biodiversity of zooplankton communities in an urban landscape

Abstract: Aquatic ecosystems are common in urban environments. A solid understanding of aquatic species’ distributions in urban habitats will both advance urban ecology and preserve biodiversity in cities. In particular, zooplankton are central components of aquatic food webs and their biodiversity patterns thus warrant further characterization and understanding. We examined sources of variation and biodiversity patterns of zooplankton communities across eighteen waterbodies in the urban landscape of Canada’s large island city of Montreal. We report a total of 80 zooplankton taxa of which rotifers and cladocerans were major contributing taxa to biodiversity. We found a lack of agreement between contributions of individual waterbodies to rotifer and cladoceran beta diversity. Littoral vegetated zones proved to be important habitats for zooplankton biodiversity, contributing considerably to the species richness pool, often with a different species composition. Further variation in zooplankton community composition was attributable to local factors such as waterbody size, algal biomass and composition, and macroinvertebrate predators, but also to urban management practices such as waterbody draining during winter. We show that urban waterbodies can represent important reservoirs of biodiversity. Management practices favoring a large diversity of permanent and temporary habitats with littoral vegetated zones should be incorporated in urban design and conservation plans.

Multi-taxonomic diversity patterns in a neotropical green city: a rapid biological assessment

Abstract: The growing number of urban ecology studies has raised concern about the importance of comprehending the ecological patterns and processes of urban areas in order to manage and plan them properly. In this study, we performed a rapid descriptive ecological assessment of the biodiversity patterns in a neotropical mid-sized urban area from a multi-taxonomic approach, contrasting seven taxonomic groups (i.e., vascular plants, fungi, ants, butterflies, beetles, amphibians, birds) in areas with different degree of urbanization intensity. Results of this study show that diversity patterns differ depending on the taxonomic group; thus, it was not possible to generalize specific trends in species richness, abundance, and species composition because each taxon seems to respond differently to the process or level of urbanization. Our results also highlight the relevance of using multi-taxonomic approaches to understand the relationship between biodiversity and urban environments, and underline potential benefits and limitations of using each of the studied groups when considering rapid biodiversity assessments. Based on our results, we suggest the following recommendations when performing rapid biological assessments in urban areas: evaluate as many taxa as possible, choosing the set of taxonomic groups in relation to the objectives of the study, wide the temporal and spatial survey window as much as possible, focus on several biodiversity measures, and interpreting results cautiously, as rapid assessments do not necessarily reflect ecological patterns, but just part of the history.

Privatizing the commons: impact on ecosystem services in Bangalore’s lakes

Abstract: The incipient megapolis of Bangalore, India, has historically been dependent on ecosystem services provided by an extensive network of lakes. Today, many of these lakes have disappeared or been degraded due to pressures of development and urbanization. This paper assesses the impact of governance through Private-Public-Partnerships (PPPs) in three lakes, by examining the impacts on provisioning and cultural ecosystem services, by comparison with adjacent, state managed (public) lakes. Public lakes support a greater diversity of traditional livelihoods, non-commercial uses and cultural services as compared to privatized lakes. PPPs thus appear to exacerbate inequities in access, in particular for users dependent on traditional livelihood services and cultural ecological services from lakes. Results indicate that implementation of PPP approaches need reconsideration from an equity perspective in cities of the global South.

A specialist in the city: the diet of barn owls along a rural to urban gradient

Abstract: We investigated the variations in the diets of barn owls (Tyto alba) along a rural to urban gradient in the Lower Fraser Valley of southwestern British Columbia, Canada. Our objectives were to determine the food preferences of barn owls in different habitat types and to assess both seasonal and annual variations in their diets. In particular, given the increased incidences and concentrations of second generation anticoagulant rodenticide (SGAR) residues in barn owls, we were interested in determining whether there was any relationship between the degree of urbanization surrounding their nest/roost sites and the proportion of commensal rodents (Rattus norvegicus, Rattus rattus, Mus musculus) in their diet. In total, 8,941 individual prey remains were identified. The proportion of rats consumed increased significantly with the amount of urbanization within home ranges. However, voles (primarily field voles, Microtus townsendii) were the main prey item for all sites irrespective of surrounding land use within home ranges. Shrews were the second most consumed prey species (10.8 ± 8 %), and were found predominantly in the diet of barn owls nesting in more rural landscapes. The dominance of field voles in the diet was also reflected in the food-niche breadth, which was consistently low for all sites across the rural to urban gradient. Interestingly, barn owls were found nesting in highly urban environments (66–95 % urbanization), where bait stations containing SGARs were regularly used. This, combined with the increased consumption of rats in more urban environments, illustrates why the SGAR exposure rate in barn owls is substantial and rising.

A check list of plant species in the urban forestry of Fortaleza, Brazil: where are the native species in the country of megadiversity?

Abstract: Although Brazil is recognized as a country of megadiversity many Brazilian cities have an overwhelming number of exotic street trees in their urban environments. Here we investigate this situation in the city of Fortaleza, Brazil’s fifth largest city. Through an extensive qualitative survey, complemented by published quantitative surveys, we developed the most complete inventory done to date in Fortaleza. We registered the largest possible number of plant species which we could record in the public treescape of the city. We recorded 219 tree species, of which 158 were exotic to Fortaleza’s ecosystems. Of the 61 native species, some were represented only by relictual individuals spared during urban growth and only 39 native species were cultivated plants. Most of these 39 cultivated natives are represented by a small number of individuals in the city, while most of common trees are exotic species. We show that many native plants that are potentially suitable for ornamental use in urban settings are being ignored and argue that exotics are overvalued, including some plants that are invasive. We also discuss the consequences of the predominance of alien species for the public perception of native biodiversity. We advocate that increasing the number of native plants in cities has many advantages from an ecological perspective.

High diversity in an urban habitat: are some animal assemblages resilient to long-term anthropogenic change?

Abstract: Urbanization is thought to lead to the loss of biodiversity both because of habitat disturbance and the increased abundance of invasive species. However, most studies of biodiversity in cities are conducted on a short time scale, usually less than 3 years, and so miss the long-term dynamics of communities inhabiting these ecosystems. Here we use a study performed in the early 70’s on North Carolina State University (Raleigh, USA) as a baseline to evaluate the long term effects of disturbance and introduced species on native ant communities. Ant species were sampled almost 40 years later using a variety of sampling techniques in order to maximize species collection. Our results show that while the number of exotic species increased, including three major invasive ants, native ant species richness remained high. Furthermore, our survey was able to add several new records for the area considered, in comparison of the 70’s study, for a total of 89 species known from NCSU campus. After comparison with other studies, our results represent one of the most species-rich urban environments monitored and thus open encouraging perspective on how urban ecosystems could contribute to the preservation of the biodiversity of small-bodies organisms such as ants.

How much is that birdie in my backyard? A cross-continental economic valuation of native urban songbirds

Abstract: Human-wildlife interactions in urban areas, both positive and negative, often involve people and birds. We assess the economic value placed on interactions with common native songbirds in two different urban areas (Berlin, Germany and Seattle, Washington, USA) by combining a revealed preference (recalled expenditures on bird feed) and a stated preference approach (determining willingness to pay for conservation or reduction of birds). Residents in both cities purchase bird food, engage in a range of bird-supporting activities and are generally willing to pay a small amount for native songbird conservation. Demographic, cultural and socio-economic factors, as well as specific attitudes towards birds and general attitudes about conservation were found to influence these decisions. This study presents the first attempt at estimating the economic value of enjoying common native urban songbirds and estimates the lower bound to be about 120 million USD/year in Seattle and 70 million USD/year in Berlin.

Conservation of fragmented grasslands as part of the urban green infrastructure: how important are species diversity, functional diversity and landscape functionality?

Abstract: Natural remnants, such as fragmented grasslands form an integral part of the urban green infrastructure in the Grassland biome of South Africa. Nearly 30 % of natural grasslands are transformed with only 1 % formally conserved. Since grassland habitats are globally regarded as a biodiversity conservation priority, protection should be accorded outside formal conservation areas as well. However, urban grassland fragments are often regarded as highly transformed, and are therefore targeted for development rather than conservation. The aim of this study was to compare plant species composition, −diversity and -functional diversity, as well as the fine-scale biophysical landscape functionality of grassland fragments in urban and exurban areas in the vulnerable Rand Highveld Grassland vegetation type in the Tlokwe Municipal area of South Africa. Thirty selected grassland fragments were investigated along an urbanisation (urban-exurban) gradient that was quantified using several demographic- and physical variables as well as landscape metrics, each reflecting a pattern or process associated with urbanisation. Plant species composition, −diversity, and -life history traits were determined in randomly selected sample plots. Functional diversity indices were also calculated to describe the composition and distribution of plant functional traits in the selected grassland fragments. Additionally, landscape functionality, in terms of how effectively the landscape is functioning as a biophysical system, was determined using the Landscape Function Analysis (LFA) method. LFA provides information such as fine-scale resource conserving patchiness, soil surface stability, infiltration, and nutrient cycling. The fine-scale biophysical landscape function of urban and exurban landscapes are comparable, indicating that urban grassland fragments are worthy of conservation on a biophysical landscape function scale. However, differences in plant species diversity, functional trait composition, and plant functional diversity were evident.

Living wall systems: evaluating life-cycle energy, water and carbon impacts

Abstract: There is little doubt that covering the facade of a building with a vertical garden can achieve numerous environmental benefits, such as reducing the energy consumption and the overall carbon footprint. However, there remains a need to assess these advantages on a more comprehensive basis. This study investigates the energy use, water use, and greenhouse gas emissions from a vertical garden throughout its life-cycle phases (manufacture, transportation, use, and disposal). This includes a payback period analysis of the energy savings provided by the vertical garden over an assumed lifetime of 20 years. The primary findings of this study were that the use phase has the greatest impact, and that reducing energy and water consumption at this phase has significant impact on the total life-cycle burden. Suggestions were given for future design and evaluation of vertical gardens.

Urban heat island mitigation strategies and lizard thermal ecology: landscaping can quadruple potential activity time in an arid city

Abstract: A global warming of 2 °C is predicted to drive almost half the world’s lizard populations to extinction. Urban heat island (UHI) effects may further exacerbate the impacts of climate change on organisms that are sensitive to small changes in temperature. Currently, the Phoenix metropolitan region in Arizona, USA, is an average of 3 °C warmer than the surrounding desert. With continuing urbanization and climate change, thermal stress will become an increasingly important facet of urban ecology in coming decades. The main objective of our study was to investigate which landscaping styles and microhabitat variables can most effectively reduce the surface temperatures experienced by lizards. Using a bare lot as a control, we placed copper lizard models with data loggers in several vegetation and irrigation treatments that represent the dominant backyard landscaping styles in Phoenix (grassy mesic with mist irrigation, drip irrigated xeric, unirrigated native, and a hybrid style known as oasis). Our lizard models recorded 6915 estimates of potential body temperatures. We show that lizard activity time in summer was restricted to a few hours in un-irrigated native desert landscaping, while heavily irrigated grass and shade trees allowed for continual activity during even the hottest days. Shade, humidity, and sky view factor explained the majority of variation in temperature at a sub-meter scale. We suggest that maintaining the existing diversity of landscaping styles (as part of an ongoing UHI mitigation strategy targeted at humans) will be beneficial for lizards.

Urbanization and the temporal homogenization of bird communities: a case study in central Argentina

Abstract: Urban expansion to rural and natural areas is a global process. Although several studies have analyzed bird community attributes along urbanization gradients, little is known on the impact of urbanization on temporal variability of bird communities. Rural areas show higher seasonal and interannual variability in environmental conditions and resources than do urban areas. Our objectives are to determine how seasonal and interannual variability in bird assemblages change along an urban–rural gradient, and how interannual variability in bird assemblages changes with season. Low seasonal and interannual variability of bird communities is expected in urbanized areas that show a process of temporal homogenization. Seasonal variability of bird richness and abundance were positively related to the percent cover of crops. Seasonal and interannual variability in community composition were positively related to coverage of herbaceous vegetation and crops, and negatively related to coverage of impervious areas. Interannual variability of bird richness and abundance were highest during the non-breeding season. We conclude that highly urbanized areas allow bird communities to have a more stable composition over time, promoting temporal homogenization. Our results emphasize that urbanization alters the temporal dynamics of resources and, therefore, the temporal variability of bird communities.

Urbanization affects frog communities at multiple scales in a rapidly developing African city

Abstract: Urbanization is worldwide among the biggest threats to amphibian populations. However, hardly any studies have been conducted on the effects thereof in developing countries. Amphibian distribution and community assemblages are not well understood in aquatic and terrestrial habitats that are rapidly changing due to human modification. We conducted four surveys using three detection methods for both anuran larvae and predatory fish in 61 ponds in and around the city of Potchefstroom, South Africa. Tadpoles of eight anuran species and seven fish species were detected during the field surveys. The common river frog (Amietia quecketti) was the most abundant species, occurring in 39 % of the sites, whereas the bubbling kassina (Kassina senegalensis) was detected in only one pond. The remaining six species were detected in 6.6–26.2 % of the sites. Predatory fish were detected in 64 % of the wetlands with mosquitofish (Gambusia affinis) and the banded tilapia (Tilapia sparrmanii) detected respectively in 44 and 43 % of the sites. High species richness was associated with well-vegetated wetlands, low urban CBD surface area and conductivity, large pond areas and steeper bank slopes. Conductivity and pH showed only weak negative effects on species richness. This is the first study to quantify the effects of urbanization on frog communities in a developing city on the African continent. Our results demonstrate that both local and landscape variables affect amphibians in a small but rapidly developing city. Accordingly, management practices need to adopt a multi-scale approach if we are to conserve amphibians in African cities.

A genet drive-through: are large spotted genets using urban areas for “fast food”? a dietary analysis

Abstract: Knowledge of an urban carnivore’s foraging behavior is vital to understanding its ecology. This is particularly important as urbanization continues to convert natural habitats into human-altered landscapes. Over the past few years there have been increasing reports of large spotted genets (Genetta tigrina) foraging within suburbs of towns and cities in KwaZulu-Natal, South Africa. Consequently, we investigated the dietary composition of urban G. tigrina using scat analyses, and the influence of predictable supplementary feeding stations on their feeding behavior in the suburbs of Kloof/Hillcrest, KwaZulu-Natal. Prey items with the highest relative frequency of occurrence were invertebrates (42.5 %). In particular, their scats found in anthropogenic structures such as roofs and out buildings were dominated by cockroaches (Blattodea). Small mammals also formed an important component of the diet. Significant seasonal variation in diet was recorded. The highest recorded relative frequency of occurrence of reptiles in scats was during spring (8.6 %). The highest recorded relative frequency of occurrence of anthropogenic refuse in the scats was in winter (12.7 %) with pieces of plastic, elastic bands and cardboard present in the scats. Uncommon genet behavior recorded at artificial feeding stations included diurnal feeding patterns and multiple individuals feeding with no signs of aggression. The presence of pet food, invertebrates associated with anthropogenic structures, and anthropogenic pollution/waste in the diet of urban genets, as well as their ability to use supplemental feeding stations highlights their adaptability to make use of temporally or locally available food resources within the urban environment.