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Showing papers in "Urban Ecosystems in 2018"


Journal ArticleDOI
TL;DR: Bee abundance declined by about 41% per °C urban warming, and temperature was among the best predictors of bee abundance and community composition, and local impervious surface and floral density were also important predictors, although only large bees appeared to benefit from high floral density.
Abstract: As cities expand, conservation of beneficial insects is essential to maintaining robust urban ecosystem services such as pollination Urban warming alters insect physiology, fitness, and abundance, but the effect of urban warming on pollinator communities has not been investigated We sampled bees at 18 sites encompassing an urban warming mosaic within Raleigh, NC, USA We quantified habitat variables at all sites by measuring air temperature, percent impervious surface (on local and landscape scales), floral density, and floral diversity We tested the hypothesis that urban bee community structure depends on temperature We also conducted model selection to determine whether temperature was among the most important predictors of urban bee community structure Finally, we asked whether bee responses to temperature or impervious surface depended on bee functional traits Bee abundance declined by about 41% per °C urban warming, and temperature was among the best predictors of bee abundance and community composition Local impervious surface and floral density were also important predictors of bee abundance, although only large bees appeared to benefit from high floral density Bee species richness increased with floral density regardless of bee size, and bee responses to urban habitat variables were independent of other life-history traits Although we document benefits of high floral density, simply adding flowers to otherwise hot, impervious sites is unlikely to restore the entire urban pollinator community since floral resources benefit large bees more than small bees

94 citations


Journal ArticleDOI
TL;DR: It is found that dominant and subordinate carnivores exhibited strong and often opposing spatio-temporal responses to the probability of human encounter and urban development, which underscores the complex and pervasive nature of human influence over the sympatry of competing carnivores inhabiting urban systems.
Abstract: Humans can profoundly shape animal community dynamics, but such effects have rarely been evaluated for terrestrial carnivores. Humans affect carnivores in both spatial and temporal dimensions via the chance of human encounter and alteration of the landscape through urban development. We investigated three hypotheses regarding how humans mediate the sympatry of larger, dominant carnivores with their smaller, subordinate counterparts. We tested these hypotheses by examining the spatio-temporal dynamics of a dominant carnivore (coyote Canis latrans) and its subordinate competitor (red fox Vulpes vulpes) across an extensive urban park system. We found that dominant and subordinate carnivores exhibited strong and often opposing spatio-temporal responses to the probability of human encounter and urban development. Spatially, coyotes visited more highly developed sites less frequently while red foxes exhibited an opposing response. Temporally, both species avoided humans via nocturnal activity. Spatio-temporally, red foxes avoided coyotes at all sites and avoided humans at highly developed sites, whereas coyotes showed a positive association with humans at such sites. Our analysis indicates that areas with higher urban development might act as spatial refugia for some subordinate carnivores against interference from larger, dominant carnivores (a “human shield” effect). Our findings also reveal that broad-scale spatial avoidance is likely a crucial component of coexistence between larger, dominant carnivores and humans, whereas finer-scale spatio-temporal avoidance is likely a key feature of coexistence between humans and smaller, subordinate carnivores. Overall, our study underscores the complex and pervasive nature of human influence over the sympatry of competing carnivores inhabiting urban systems.

69 citations


Journal ArticleDOI
TL;DR: It is demonstrated that a large and diversified city park may be a favourable habitat for bees, comparable to the natural fauna both in terms of the number and abundance of bee species.
Abstract: Urbanisation is an expansive process and a majority of insects live in human-modified areas. At the same time, a decrease in pollinator species richness and abundance has recently been observed in Europe, which in turn may have serious ecological and economic consequences. This study investigates the abundance, species richness and functional traits of wild bees in urban city parks in comparison to natural areas. The aim of this research was to assess the potential conservation values of urban green areas for bees. The present study demonstrates that a large and diversified city park may be a favourable habitat for bees, comparable to the natural fauna both in terms of the number and abundance of bee species. However, the study also showed that there were differences in the occurrence of species with different functional traits in the city parks investigated and in the natural landscape.

66 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the relationship between attributes of urban green spaces (size, vegetation, isolation, urbanization) and bird species richness, and found that species richness increased with size of green spaces and presence of native forest, but did not decrease towards the city centre.
Abstract: Understanding what determines wildlife species richness and community composition in urban green spaces is important for wildlife management and urban planning. Numerous studies have assessed the relationships between attributes of urban green spaces (size, vegetation, isolation, urbanization) and bird species richness, but little is known about how these factors influence community composition. I censused breeding land birds in 93 urban green spaces in Oslo, Norway, and species were grouped according to ecology (habitat preference, nest site, migration, diet, and red-list status). I analysed how species richness and, in particular, how community composition (relative proportion of different ecological groups) was influenced by size of urban green spaces, presence of native forest, isolation (i.e. distance from the periphery of the city) and urban zone (i.e. centre or periphery of city). Species richness increased with size of green spaces and presence of native forest, but did not decrease towards the city centre. Community composition was affected most strongly by presence of native forest, but site size and urbanization affected some ecological groups. Specifically, sensitive ecological groups of birds (in particular forest species, ground-nesters, migratory species, and species with a specialist diet) depended in particular on the presence of native forest in urban green spaces, with additional positive effects of increasing size of urban green spaces and location close to the periphery of the city.

58 citations


Journal ArticleDOI
TL;DR: In this article, the authors examined the decline of bee diversity and abundance in the city of Curitiba by comparing a bee assemblage sampled in the 1980s and again in 2015.
Abstract: Urban ecosystems are growing rapidly and urbanization is an important cause of the loss of biodiversity. Bees are declining in abundance worldwide, including urban areas, and this decline is alarming because of their global importance as plant pollinators. Here we examine that decline by comparing a bee assemblage sampled in the 1980s and again in 2015, in an urban area of the city of Curitiba. Both studies sampled assemblages with hand-nets every two weeks during one year of study. Bee species richness has declined by 45% (112 species then, 63 today). Two species that have disappeared, Gaesischia fulgurans (Holmberg, 1903) and Thectochlora basiatra (Strand, 1910), have also disappeared elsewhere in the city. Also, relative abundances of species have changed, notably with the increase of social bees. Large bees that nest in cavities have also increased relative to small bees that nest in the ground. These findings are similar with previous reports indicating the sensibility of bees to urbanization. The increase in paved areas, in urban population and in exotic plants are all probably responsible for the sharp decline in bee diversity and abundance.

48 citations


Journal ArticleDOI
TL;DR: This study demonstrates that ΨP0 gives strong evidence for a species’ capacity to tolerate dry growing conditions and is a trait that varies substantially across species, which should give those specifying trees confidence to recommend non-traditional species for challenging urban environments.
Abstract: High species diversity is argued to be the most important requisite for a resilient urban forest. In spite of this, there are many cities in the northern hemisphere that have very limited species diversity within their tree population. Consequently, there is an immense risk to urban canopy cover, if these over-used species succumb to serious pests or pathogens. Recognition of this should motivate the use of less commonly used species. Analysis of plant traits, such as the leaf water potential at turgor loss (ΨP0), can provide useful insights into a species’ capacity to grow in warm and dry urban environments. Therefore, the aim of this study was to evaluate ΨP0 of 45 tree species, the majority of which are rare in urban environments. To help evaluate the potential for using ΨP0 data to support future decision-making, a survey of professionals engaged with establishing trees in urban environments was also used to assess the relationship between the measured ΨP0 and the perceived drought tolerance of selected species. This study demonstrates that ΨP0 gives strong evidence for a species’ capacity to tolerate dry growing conditions and is a trait that varies substantially across species. Furthermore, ΨP0 was shown to closely relate to the experience of professionals involved in establishing trees in urban environments, thus providing evidence of its practical significance. Use of plant traits, such as ΨP0, should, therefore, give those specifying trees confidence to recommend non-traditional species for challenging urban environments.

45 citations


Journal ArticleDOI
TL;DR: A systematic review of the relationship between urban agriculture and biodiversity in the scientific literature can be found in this paper, where the authors define urban agriculture as areas in cities that grow produce specifically for human consumption.
Abstract: Urban agriculture is a unique form of agriculture that can provide fresh, local produce for urban residents, and may benefit biodiversity by decreasing the need to expand agriculture into natural areas as well as enhancing biodiversity in urban areas. However, although urban agriculture is also often cited as promoting biodiversity in urban areas, the extent of empirical evidence for such claims has not been studied. Here we systematically review the relationship between urban agriculture and biodiversity in the scientific literature. We strictly define urban agriculture as areas in cities that grow produce specifically for human consumption. We examined 148 papers from 2000 to 2017, of which only 24 studies fit our definition of urban agriculture, and of those, only 18 both involved urban agriculture and measured biodiversity. Of the studies that did measure biodiversity, some showed increases in diversity compared to urban vacant lots, but other showed no difference. Moreover, these studies were mostly focused on plants and invertebrates and were conducted almost exclusively in North America. In order to use the generalization that urban agriculture will have a positive influence on urban biodiversity, more studies will need to be conducted across a wider geographic range worldwide (particularly in developing countries in the tropics) and on a greater diversity of species and taxa (e.g., herpetiles, birds and small mammals). Such studies will likely increase in conservation importance as urban expansion and agricultural demands increase globally.

40 citations


Journal ArticleDOI
TL;DR: In this paper, the authors analyzed how different environmental features affect bird biodiversity in one of the most urbanized areas of Italy (the metropolitan area of Milan) at different spatial scales and found that a mixture of land covers and the presence of water bodies inside urban parks favored species occurrence and abundance at landscape scale, but a surrounding dense urban matrix deflated biodiversity.
Abstract: A significant decline in biodiversity is associated with the current and upcoming degree of urbanization. A challenging strategy to address this conflict is to make urban growth compatible with biodiversity protection and in this context urban parks can play a crucial role. Urban systems are highly dynamic and complex human-shaped ecosystems, where the relationship between species and environment may be altered and make the preservation of biodiversity within them a challenging goal. In this study, we analysed how different environmental features affect bird biodiversity in one of the most urbanized areas of Italy (the metropolitan area of Milan) at different spatial scales. Bird surveys were conducted in fifteen urban and peri-urban parks and environmental variables at landscape and local scale recorded. Results showed that a mixture of land covers and the presence of water bodies inside urban parks favoured species occurrence and abundance at landscape scale, but a surrounding dense urban matrix deflated biodiversity. At local scale, woodland cover and presence of water bodies were key determinants in ensuring overall high biodiversity but local-specific vegetation management produced an unusual pattern for forests species. In particular, the maintenance of large trees may not result in biodiversity support for forest bird species if large trees are not located in woodland areas with a significant tree density. To understand biodiversity patterns and provide useful information for urban planning and design, we need to provide insights into species/environment relationships at multiple scales in the urban environment.

40 citations


Journal ArticleDOI
TL;DR: In this article, the authors deployed an online survey to residents of the two mostpopulous cities in both Australia and New Zealand to measure self-reported wellbeing via three indices used widely in the literature: general wellbeing (WHO-5), personal wellbeing, and psychological wellbeing.
Abstract: In recent decades, empirical evidence has demonstrated that nature can enable urban environments to support human wellbeing. Research into links between nature and human wellbeing is often carried out with one wellbeing index or in single locations, which can limit our understanding of findings. To further this work, we deployed an online survey to residents of the two most-populous cities in both Australia and New Zealand. The survey measured self-reported wellbeing via three indices used widely in the literature: general wellbeing (WHO-5), personal wellbeing, and psychological wellbeing. We compared results with two biodiversity indicators: bird species richness and the Normalised Difference Vegetation Index (NDVI) of respondents’ postcodes. We also asked respondents to rate the amount of nature they view from their immediate environment: both at home and at work or other frequent location. Our results support a link between local nature and human wellbeing across all four cities, significantly in the two Australian cities. Qualitative data reveals that urban life can challenge human wellbeing by creating a unique suite of stresses that residents strive to balance. There is the potential for nature to support human wellbeing in typically degraded urban environments. While this work corroborates existing literature demonstrating links between human wellbeing and nature, our qualitative research extends our understanding of these links by providing more detailed and nuanced information.

40 citations


Journal ArticleDOI
TL;DR: In this article, the authors synthesize understanding of the relative abilities of different tree species to provide urban cooling in temperate regions of the world and thereby develop a pragmatic approach for choosing those trees that have greatest potential in that regard.
Abstract: Increasing urbanisation poses numerous challenges to human quality of life. Cities are particularly vulnerable to the urban heat-island effect, which will be amplified by climate change. Increasing tree cover may be one of the most cost-effective ways of moderating urban temperatures. Trees cool their surroundings by casting shade, reflecting solar radiation, transpiring, and intercepting rainfall that subsequently evaporates. However, the potential of trees to reduce the urban heat-island effect is underutilised. The aim of this study was to synthesise understanding of the relative abilities of different tree species to provide urban cooling in temperate regions of the world and thereby develop a pragmatic approach for choosing those trees that have greatest potential in that regard. Based on a literature review and semi-structured interviews with leading experts, we developed a series of scenarios to illustrate the impacts of a tree’s cooling mechanisms and tree species’ attributes on components of the surface-energy balance equation. This enabled us to select parameters and propose simple equations that can be used to compare the relative abilities of tree species in relation to each of the cooling mechanisms. The parameters selected were for: transpiration – crown diameter, Leaf Area Index (LAI), canopy aspect ratio, and stomatal conductance or growth rate; reflection – albedo, crown diameter and LAI; shading – canopy aspect ratio, crown diameter, LAI and tree height. The approach is intended for use by urban planners and managers who wish to make informed decisions about which tree species to select for planting to counter the urban heat-island effect.

40 citations


Journal ArticleDOI
TL;DR: It is concluded that wild bee diversity and abundance on green roofs are enhanced by floral resources, and the installations of areas with finer and deeper substrates benefit ground nesting and eusocial wild bees.
Abstract: Green roofs are potentially valuable habitats for plants and animals in urban areas. Wild bees are important pollinators for crops and wild plants and may be enhanced by anthropogenic structures, but little is known about wild bees on green roofs in cities. This study investigates the effects of green roof qualities (floral resources, substrate character and depth, roof height and age) on wild bee diversity, abundance and traits (nesting type, sociality, pollen specialisation, body size) on green roofs in Vienna. Nine green roofs were sampled monthly between March and September 2014 by a semi quantitative approach. Wild bees were collected in pre-defined sub-areas for the same amount of time and floral resources were recorded. Over all green roofs, 992 individuals belonging to 90 wild bee species were observed. Wild bee diversity and abundance was strongly positively affected by increasing forage availability and fine substrates. Wild bees on roofs were characteristically solitary, polylectic and 8.3–11.2 mm. Regarding nesting type, the percentage of above-ground nesting bees was higher compared to the common species composition in Middle Europe. Ground-nesting wild bees were mainly eusocial, smaller (6.4–9.6 mm) and positively affected by roofs with fine substrates. During June, when forage availability by wildflowers on roofs was “low” (5–15% flower coverage), flowering Sedum species were an important forage resource. We conclude that wild bee diversity and abundance on green roofs are enhanced by floral resources. Furthermore, the installations of areas with finer and deeper substrates benefit ground nesting and eusocial wild bees.

Journal ArticleDOI
TL;DR: It is suggested that for insect-natural enemy interactions, urbanization may affect some groups, while not influencing others, and that local effects will also be key determinants of how urban ecological communities are formed.
Abstract: Urbanization can alter the composition of arthropod communities. However, little is known about how urbanization affects ecological interactions. Using experimental colonies of the black bean aphid Aphis fabae Scopoli reared on Vicia faba L, we asked if patterns of predator-prey, host-parasitoid and ant-aphid mutualisms varied along an urbanization gradient across a large town in southern England. We recorded the presence of naturally occurring predators, parasitoid wasps and mutualistic ants together with aphid abundance. We examined how biotic (green areas and plant richness) and abiotic features (impervious surfaces and distance to town center) affected (1) aphid colony size, (2) the likelihood of finding predators, mutualistic ants and aphid mummies (indicating the presence of parasitoids), and (3) how the interplay among these factors affected patterns of parasitoid attack, predator abundance, mutualistic interactions and aphid abundance. Aphid abundance was best explained by the number of mutualistic ants attending the colonies. Aphid predators responded negatively to both the proportion of impervious surfaces and to the number of mutualistic ants farming the colonies, and positively to aphid population size, whereas parasitized aphids were found in colonies with higher numbers of aphids and ants. The number of mutualistic ants attending was positively associated with aphid colony size and negatively with the number of aphid predators. Our findings suggest that for insect-natural enemy interactions, urbanization may affect some groups, while not influencing others, and that local effects (mutualists, host plant presence) will also be key determinants of how urban ecological communities are formed.

Journal ArticleDOI
TL;DR: In this article, a survey with questions related to strategic and operational perspectives of municipal tree inventories, together with questions relating to budget and potential use of consultants, was sent to all 290 Swedish municipalities.
Abstract: Urban trees are an essential component of urban ecosystems, and management of this resource constitutes an essential element of urban open space management. However, municipal tree inventories in Sweden and elsewhere have received limited attention. It is unknown how common municipal tree inventories are in Sweden, factors governing whether a municipality has an inventory and what the inventories are used for. This study therefore sought to: Create an overview of the state of Swedish municipal tree inventories and determine how municipality size, green space budget and management organisation affect the presence and scope of municipal tree inventories. The research questions examined were: What is the current state of Swedish municipal tree inventories? and what affects the status of these municipal tree inventories? A survey with questions related to strategic and operational perspectives of municipal tree inventories, e.g. how they are conducted and used, together with questions relating to budget and potential use of consultants, was sent to all 290 Swedish municipalities. The response rate was 55.5%. The main findings were that municipality size affects whether a municipality has an urban tree inventory and that the municipal organisation form affects how inventories are used. The existence of an inventory also increased the probability of the municipality having a tree management plan. Based on these results we recommend further research related to strategic management perspectives of tree inventories.

Journal ArticleDOI
TL;DR: DNA barcoding was used to identify digested plant materials and seeds in the faeces of frugivorous bats to investigate whether C. brachyotis in urban and agricultural areas exploit cultivated and exotic plants as a novel food resource and as a consequence, potentially facilitate the invasion of cultivated and foreign plants.
Abstract: The expansion of cities and agricultural plantations have unpredictable impacts on biodiversity and ecosystem services. Yet some species are capable of tolerating anthropogenic impacts and continue to provide ecological services in highly disturbed landscapes. The objective of this study was to use DNA barcoding to identify digested plant materials and seeds in the faeces of frugivorous bats (Cynopterus brachyotis) and investigate whether (1) C. brachyotis in urban and agricultural areas exploit cultivated and exotic plants as a novel food resource and as a consequence, potentially facilitate the invasion of cultivated and exotic plants, or whether (2) C. brachyotis exploit native plants and as a consequence, potentially promote forest regeneration. A native species, Ficus fistulosa, was the most frequently detected plant and the seeds were found in bat faeces from all sampling sites suggesting the potential of fruit bats in dispersing seeds. However, we also detected several exotic plants in the faeces of C. brachyotis which suggests that the fruit bats exploit novel food resources at all sites. We recorded a diverse diet of C. brachyotis at an oil palm plantation which indicated that the fruit bats are not predominantly feeding on oil palm fruits. By using DNA barcoding, we detected plants that have not been reported in previous studies of the diet of C. brachyotis, although we could not identify which part of the plant was being consumed by the fruit bats. Given the varied diet of C. brachyotis, the potential of this bat to adapt to changing landscapes is high and they are likely dispersing seeds of native pioneer plants (Ficus).

Journal ArticleDOI
TL;DR: In this paper, the effects of local habitat parameters (management, plant diversity) and urban matrix variables (urbanisation, isolation) on carabid beetle and spider diversity and traits in informal urban green spaces in Berlin, Germany.
Abstract: Urbanisation is a growing global phenomenon having multiple ecological consequences. However, the effects of urbanisation on biodiversity remain ambiguous, and some evidence exists that cities provide valuable secondary habitats for many species, possibly mitigating regional biodiversity loss. Therefore, the value of urban sites for biodiversity depends on local habitat conditions and the configuration of the surrounding landscape. We aimed to disentangle the effects of local habitat parameters (management, plant diversity) and urban matrix variables (urbanisation, isolation) on carabid beetle and spider diversity and traits in informal urban green spaces in Berlin, Germany. Habitat management and isolation were the most important influences on carabid beetle and spider species and trait compositions. Spider communities of irregular managed sites contained 2.5 times more species of conservation concern than extensive (regular) managed sites. Moreover, irregular managed sites contained larger species (both for carabid beetles and spiders) and affected the hunting mode of spiders. Isolated sites tended to have lower spider species richness and number of spider species of conservation concern. Moreover, isolated sites were characterised by small, mobile and herbivorous carabid beetles. In contrast, urbanisation and local plant diversity had no effect on carabid beetles and spiders. We conclude that urban grasslands within residential areas – even if not targeted for conservation plans – can provide important habitats for conserving biodiversity, including species of conservation concern. Reducing the intensity of habitat management and increasing the connectivity of urban grassland sites can promote diverse arthropod communities and should therefore be considered in urban planning.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the extent (if any) to which householders in urban and suburban areas of KwaZulu-Natal provide supplementary food to African woolly-necked storks.
Abstract: African woolly-necked storks (Ciconia microscelis) depend on wetland habitats for foraging and nesting in natural environments. Recently, they have started colonising urban environments in KwaZulu-Natal, South Africa, and are now a common sight in suburban areas in particular. There have been some anecdotal reports on supplementary feeding of this species by households in some urban areas where they are common. However, these reports have never been confirmed and therefore the extent of feeding and lack thereof is unknown. Using a questionnaire survey, we therefore investigated the extent (if any) to which householders in urban and suburban areas of KwaZulu-Natal provide supplementary food to African woolly-necked storks. We also determined the feeders’ provisioning habits, and identified the motivation behind and attitudes toward feeding. We found that a significant number of householders fed African woolly-necked storks on a daily basis throughout the year. The majority of respondents provided meat while others provided inappropriate food such as bread. Respondents were most often motivated to feed for personal pleasure. Our results showed that this species is successfully utilising and exploiting anthropogenic food – a novel behaviour. The observations and narratives from respondents strongly suggest that the African woolly-necked stork is present throughout the year, contrary to the perception that this species is migratory during winter. Based on the results obtained in this study, supplementary feeding of African woolly-necked stork by householders is relatively common, widespread and established in suburban areas of KwaZulu-Natal, South Africa. However, reported inappropriate feeding may create concerns regarding the health status of African woolly-necked storks in urban population. Therefore, to prevent further detrimental effects and potential human-wildlife conflicts we recommend that suitable feeding guidelines be formulated.

Journal ArticleDOI
TL;DR: Zhang et al. as discussed by the authors conducted correlation analyses between urban forest structure and its location attributes, and carried out quantitative regression analyses between them, finding that urban forest could create urban cool islands, which were higher in summer than those in autumn.
Abstract: Urban forest can help decrease land surface temperature (LST) and create urban cooling effect (UCI) to mitigate urban heat island (UHI). However, it is still unclear how urban forest structure and its location affect UCI, particularly under different seasons. In this study, with plot-based urban forest structure and UCI intensity extracted from Landsat-7 Enhanced Thematic Mapper Plus (ETM+) thermal data, we first conducted correlation analyses between UCI and different forest structures (crown closure, tree height, leaf area index, basal area, stem density and diameter at breast height, etc.) and spatial location (distances from buildings and from water bodies and elevation) attributes, and we then carried out quantitative regression analyses between them. Our results indicate that (1) Urban forest could create “urban cool islands”, which were higher in summer than those in autumn.(2) UCI could be significantly affected by urban forest structural attributes, especially by crown closure and LAI. All urban forest structural attributes had positive linear relationships with UCI except for LAI and basal area which had positive non-linear relationships with UCI.; (3) UCI in urban forest could also be affected by its spatial location but not by its elevation. The UCI non-linearly decreased with decreasing distance from buildings and with increasing distance from water bodies. The threshold values of DB for significantly affecting UCI variation is approximately between 100 m and 300 m in summer and autumn, respectively; and (4) the relationships between UCI and urban forest structure and its location attributes were complex and seasonal dependent. Urban forest attributes had greater effects on increasing UCI in summer than those in autumn. These findings would deepen our understanding of interactions between UCI and urban forest attributes and provide urban planners with useful information about how to design urban forest to effectively mitigate UHI effects.

Journal ArticleDOI
TL;DR: In this paper, the authors collected 12,153 individual land snails from 54 city parks along an urban gradient to understand impacts of urbanization on snail communities and found that urbanization greatly alters land snail community structure.
Abstract: Urbanization has tremendous impacts on most native species. This is especially true in land snails, which are surprisingly understudied organisms. Due to their low mobility and dispersal potential, land snails are valuable indicators of ecosystem disturbance. For this study, land snails were collected in 54 city parks along an urban gradient to understand impacts of urbanization on snail communities. Sampled parks include small extensively landscaped downtown parks, neighborhood and community parks, district parks, and large nature parks, each with variable vegetation, soil characteristics, disturbance regimes, and human activities. Sampling recovered 12,153 individual snails, representing 20 families, 43 genera, and 95 species. Seven new Tennessee state and 87 new county occurrences were recorded. Five non-native and one extra-limital non-native species were found, four of which are new Tennessee state records. Results show that urbanization greatly alters land snail community structure. Nature and district parks have significantly greater species richness, species diversity and species evenness than community, neighborhood, and downtown parks. Degradation of parks, distance from the park to the commercial city center and percent of coarse woody debris accounted for most of the variation between park types. Non-metric multidimensional scaling and pairwise Jaccard indices indicate that downtown snail communities are more similar whereas snail communities in nature parks are more distinct. This suggests that urbanization promotes homogenization among land snail communities. We also show that this homogenization is thus far driven mainly by synanthropic, broadly adapted native species rather than non-native snail species.

Journal ArticleDOI
TL;DR: Street trees are an important part of urban vegetation due to their provisioning of different types of ecosystem services such as local climate regulation and contribution to aesthetical and recrea....
Abstract: Street trees are an important part of urban vegetation due to their provisioning of different types of ecosystem services such as local climate regulation and contribution to aesthetical and recrea ...

Journal ArticleDOI
TL;DR: In this article, the authors used a patch-landscape approach in an urbanizing region of the Brazilian Atlantic Forest to test whether the increase in landscape urbanization reduces plant species density, phylogenetic richness and divergence, and increases the relatedness among co-occurring individuals and species.
Abstract: Urbanization causes species loss around the world, but its effects on phylogenetic diversity are poorly known in tropical forests. Using a patch-landscape approach in an urbanizing region of the Brazilian Atlantic Forest, we tested whether the increase in landscape urbanization reduces plant species density, phylogenetic richness and divergence, and increases the relatedness among co-occurring individuals and species. We assessed plant responses to urbanization in adult (diameter at breast height > 10 cm) and sapling communities (2.5–10 cm diameter) separately, as saplings are proxies of the future flora. We sampled 2860 woody plants belonging to 155 species in nine circular landscapes with urbanization level varying from 0% to 45%, and estimated the relatedness among the species that have increased and decreased in relative abundance in more urbanized landscapes (winner and losers, respectively). As expected, species density and phylogenetic richness decreased with the increase in urbanization. These responses were consistent for adult and sapling communities, suggesting a persistent loss of species and lineages in more urbanized landscapes. Contrary to our expectations, phylogenetic divergence and structure did not respond to urbanization, indicating that the more urbanized landscapes still retain much evolutionary history. However, because the relatedness among winners was greater than among losers, it is likely that the phylogenetic divergence gradually reduces and the relatedness increases, resulting in impoverished forests with uncertain ability to provide ecosystem services such as carbon storage and pest control. This environmental cost should be taken into account to align urban sprawl with biodiversity conservation.

Journal ArticleDOI
TL;DR: In this article, the authors evaluated the contribution of native and exotic species in urban parks of a Latin American city, and assessed the related role of park area, age and socio-economic status.
Abstract: Plant diversity and composition in urban parks is determined by socio-economics, environmental, and ecological drivers. These drivers give rise to urban spaces with unique compositions of flora, consisting of planted and spontaneous species. The present study aimed to determine the contribution of native and exotic species in urban parks of a Latin American city, and to assess the related role of park area, age and socio-economic status. We also evaluated administration type (public or private) and the effect of environmental factors on plant richness. We hypothesized that the composition of park vegetation differs according to urban-rural gradient. To determine flora composition, two transects (100 m long by 1–3 m wide) per park were selected in 49 parks. In each of these, we identified all the vascular plants found (woody and herbs, planted and spontaneous), which were then classified as native or exotic. We conducted ANCOVAs in order to determine the effect of five independent variables and one factor, on native and exotic plant richness. Of 550 recorded species, 16.2% were native and 83.8% exotic. Number of plant species per park varied between 42 and 146. The parks are known urban habitats containing the highest planted and spontaneously occurring exotic diversity in the city of Santiago, contrasting with other types of habitats. Likewise, parks in Santiago are habitats with low levels of planted and spontaneously occurring native diversity, compared to the parks of Europe, America North and Asia. Ours results show that park area and age affected native plant richness, while exotic plant richness was determined only by park age. We rejected all other possible drivers. Finally, according to the low frequency of native species, we propose that Santiago’s parks could be gradually reoriented towards ex-situ conservation of native plants.

Journal ArticleDOI
TL;DR: In this article, a stochastic eco-hydrological model that couples two existing models for water and nutrients in urban soil at the single street-tree scale is proposed, which is used to estimate the potential for ecosystem services like tree cooling effects, soil carbon sequestration or storm-water management.
Abstract: Urban green spaces have been recognized as an important source of ecosystem services, whose quantification requires the determination of quantities related to energy, water, carbon and soil nutrient content. In this paper we propose a stochastic ecohydrological model that couples two existing models for water and nutrients in urban soil at the single street-tree scale. The model input are rainfall and irrigation, for water, and deposition and fertilization, for nitrogen, while the output are evapotranspiration, runoff and deep percolation, for water, and plant uptake and leaching, for nitrogen. The various terms are related to the amount of paved and impervious surfaces that surround the tree trunk and regulate the water and nutrient fluxes in and out the soil. Particular attention is paid to the effects of seasonal variations on plant water and nutrients through a temporal variation of the hydrologic variables (i.e., temperature and rainfall intensity and frequencies). The average model outputs are preliminarily compared with the scant existing literature data, supporting the model application to cities with different climatic conditions. The model results are used to estimate the potential for ecosystem services like tree cooling effects, soil carbon sequestration or storm-water management. Because of the minimal structure of the proposed model, it requires a very low amount of data, while accounting for the stochastic input of rainfall. In the context of climate change and increasing urbanization, the model may offer useful indications to urban planners to enhance ecosystem services while minimizing irrigation, fertilization and their related costs.

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TL;DR: This paper assesses the main constraints and challenges regarding the urban field and describes the major steps to be considered when planning research on urban rats, allowing researchers to answer long-standing key questions about urban rat ecology.
Abstract: Nowadays, the majority of human beings live in urban ecosystems, with this proportion expected to continue increasing in the future. With the growing importance of urban rat-associated issues (e.g. damages to urban infrastructures, costs of rat-control programs, rat-associated health risks), it is becoming indispensable to fill the identified gaps in knowledge on the urban brown rat regarding, among others, its density, home range, genetic structure, and infectious status. In this context, live-trapping is a crucial prerequisite to any scientific investigation. This paper assesses the main constraints and challenges regarding the urban field and describes the major steps to be considered when planning research on urban rats. The primary challenges are i) the characterization of the urban experimental unit; ii) the choice of a trapping design: the use of live-trapping in capture-mark-recapture design, in association with modern statistics, is highly recommended to answer ecological questions (although these methods, mostly developed in natural ecosystems, need to be implemented for the urban field); iii) the potential ethical considerations with regard to animal welfare and field-worker safety; iv) the building of mutually-beneficial collaborations with city stakeholders, pest control professionals, and citizens. Emphasis must be put on communication to the public and education of field-workers. One major need of modern urban rat research is a peer-validated field methodology allowing reproducibility, repeatability, and inference from urban field studies and enabling researchers to answer long-standing key questions about urban rat ecology.

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TL;DR: In this paper, the authors evaluated the mechanisms by which structural habitat changes associated with urbanization alter the available vegetation and substrates on which two species of Anolis lizards perch in urban and natural forest sites in Miami, FL.
Abstract: Persistence of animals in urban habitats, a stark environmental contrast to natural habitats, can be explained through evaluating the mechanisms behind organism-habitat interactions. One of the most notable effects of urbanization is the change in structural habitat; vegetation is removed and modified, favoring large trees and adding artificial structures in cities, which may alter how organismal preferences for aspects of the habitat are realized. We evaluated the mechanisms by which structural habitat changes associated with urbanization alter the available vegetation and substrates on which two species of Anolis lizards perch in urban and natural forest sites in Miami, FL. We also experimentally assessed habitat preference in the lab to establish the mechanism behind habitat selection. We found that vegetation was broader in urban areas compared to natural habitats, and artificial structures in urban areas were more than twice the diameter of available natural perches. Lizards expressed their preference for broad perches by selecting broader vegetation and artificial structures compared to their availability in both habitats. With the increased availability of broad substrates in urban areas, perch diameters selected by lizards resulted in an expansion of this aspect of the structural habitat niche for both species. The two species differed, however, in other responses to altered urban habitats. Anolis cristatellus tended to avoid artificial substrates, whereas A. sagrei used both natural and artificial structures in proportion to their availabilities. This study provides a mechanistic explanation for how urbanization alters structural habitats, leading to niche expansion for organisms living in cities.

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TL;DR: In this paper, the authors present a synthesis of the state of knowledge of ground beetle communities from green roofs in Switzerland and highlight patterns of species occurrence and composition across green roofs and cities, and suggest improving the design of green roofs (composition and configuration of vegetation, as well as soil depth and substrate composition) to increase their ecological value for species with the most different ecological needs, and to integrate green roofs into urban planning to make them more efficient as biodiversity supports.
Abstract: Green roofs have recently gained recognition for their potential contribution to urban ecosystems by providing, among other services, habitat for plants and animals, and stepping stones for mobile organisms, thereby enhancing permeability among habitat patches across densely built cities. In Switzerland, investigations over the past 20 years on more than one hundred distinct green roofs across six cities have provided an unprecedented dataset on ground beetles, albeit with information that is scattered across unpublished reports and local databases. We present here for the first time a synthesis of the state of knowledge of ground beetle communities from green roofs in Switzerland. We describe 91 ground beetles species (19,428 individuals) and highlight patterns of species occurrence and composition across green roofs and cities. Most of the roofs host ground beetle communities dominated by five common mobile species with quite diversified ecological requirements. In addition, we observed nine species (10% of all species collected) that are conservation concerns in Switzerland and Central Europe as well as numerous stenotopic species (from grasslands and pioneer vegetation). This indicates that, besides sustaining local populations of common species, green roofs can also offer suitable ecological conditions of high conservation interest. We suggest both improving the design of green roofs (composition and configuration of vegetation, as well as soil depth and substrate composition) to increase their ecological value for species with the most different ecological needs, and to integrate green roofs into urban planning to make them more efficient as biodiversity supports.

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TL;DR: In this paper, the authors used mobile acoustic monitoring to determine when bat species were active in a single night in urban and non-urban sites and if nightly bat activity patterns differed in urban versus nonurban sites.
Abstract: Time of peak bat activity during the night differs among bat species due to temperature, prey availability, habitat availability, and/or interactions between species. Habitat availability is altered in urban areas, which may affect insect prey availability and interspecies interactions. Our objectives were to use mobile acoustic monitoring to determine when bat species were active in a single night in urban and nonurban sites and if nightly bat activity patterns differed in urban versus nonurban sites. Bat echolocation call sequences were recorded using Anabat acoustic detectors while driving transects through the night at five sites (three “urban” and two “nonurban”) located in the Piedmont region of north-central North Carolina from May through August 2016. Transects were driven three times per night starting 45 min, 180 min, and 300 min after sunset. Recorded echolocation call sequences were analyzed manually using AnalookW and automatically using Bat Call Identification and Echoclass software. Total bat activity was not different between urban and nonurban sites. However, total bat activity was lower later in the night in urban sites, but stayed the same in nonurban sites. Species specifically, there were more Eptesicus fuscus, Lasionycteris noctivagans, and Tadarida brasiliensis call sequences and fewer Lasiurus borealis, Nycticeius humeralis, and Perimyotis subflavus call sequences in urban sites than nonurban sites. There were also fewer E. fuscus, L. noctivagans, and N. humeralis call sequences later in the night in both urban and nonurban sites. Only Lasiurus borealis activity in urban sites later in the night reduced and L. borealis activity in nonurban sites remained at the same. These results suggest that bats in urban areas partition time differently, which is important to consider for urban conservation efforts and planning.

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TL;DR: In this article, the authors investigate the social and cultural drivers shaping front yard vegetation composition and configuration at two study sites with consistently low native bee species diversity and abundance, and find neighborhood public-facing landscaping is shaped by various socio-cultural influences: aesthetics, norms, reference-group behavior, institutions, socioeconomics, and identity.
Abstract: In the United States, residential yards are typically overlooked for biodiversity conservation, yet they account for a significant portion of urban green space. Yard vegetation can serve as valuable habitat patches for insect pollinator populations in cities, providing important foraging and nesting resources. Based on long-term native bee sampling data, we investigate the social and cultural drivers shaping front yard vegetation composition and configuration at two study sites with consistently low native bee species diversity and abundance. We employ quantitative remote sensing approaches with analysis of qualitative interview data to examine residential vegetation patterns and analyze the socio-cultural relationships between people and vegetation. Data analyses reveal both study sites have lower levels of vegetation composition and complexity, resulting in reduced habitat resources. We find neighborhood public-facing landscaping is shaped by various socio-cultural influences: aesthetics, norms, reference-group behavior, institutions, socioeconomics, and identity. Front yard land-use and decision-making practices are particularly meaning laden, as these spaces are often perceived as visible representations of longstanding neighborhood identity and contiguous common areas to be managed to a “perfect lawn” ideal. The quantitative and qualitative data are used to characterize the two study sites and inform future urban conservation and development efforts salient to citizen stakeholders.

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TL;DR: In this article, the authors examined the effects of different levels of catchment imperviousness, as a surrogate for the extent and intensity of urbanisation, on invasive weeds and soil physical and chemical attributes.
Abstract: The riparian zones of urban waterways are frequently degraded by weed invasions. This study examined the effects of different levels of catchment imperviousness, as a surrogate for the extent and intensity of urbanisation, on invasive weeds and soil physical and chemical attributes. The study was conducted adjacent to waterways in the partly urbanised Georges River catchment in south western Sydney. Vegetation and soil sampling was undertaken in the riparian zone of 10 freshwater streams in non-urban (low imperviousness), peri-urban (moderate imperviousness) and urban (high imperviousness) sub-catchments. Soil samples were tested for a suite of physical and chemical properties (moisture, bulk density, organic matter, pH, salinity, phosphorus, potassium and calcium). Increased levels of sub-catchment imperviousness and urbanisation were associated with higher weed coverage and elevated soil geochemical attributes. One of the most interesting findings in this study was that urban soil calcium concentrations were over 2000 times greater than soils collected from non-urban catchments. The BIOENV procedure identified soil pH, salinity, calcium, organic matter, moisture and catchment imperviousness to be important environmental factors associated with variation in riparian vegetation. The single factor of soil pH was most highly correlated with variations in riparian vegetation. Soil pH was approximately 1.5 units higher in urban compared to non-urban riparian soils. We speculate that there is a link between urban concrete materials, urban soil and water contaminants and riparian weed invasion. We also recommend further study into the contribution of urban concrete materials on the geochemical contamination of riparian soils.

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TL;DR: In this paper, the authors investigated alien plant species preferences for five urban land uses (densely built up areas, open built-up areas, industrial areas, broadleaved urban forests, and agricultural areas and small landscape elements).
Abstract: Since neophytes can become invasive in the future, untangling their ecological preferences is of paramount importance, especially in urban areas where they represent a substantial proportion of the local flora. Studies exploring alien species assemblages in urban environments are however scarce. This study aims to unravel alien plant species preferences for five urban land uses (densely built-up areas, open built-up areas, industrial areas, broadleaved urban forests, and agricultural areas and small landscape elements). We took the city of Brussels as a model, in which we recorded all vascular species growing spontaneously in grid cells of 1 km2. We tested two different ways of classifying the 1-km2 cells: (1) We simply associated each cell with its dominant land cover; (2) We used a fuzzy approach for which the degree of association of a given cell to a given land cover depended on the proportion of that land cover within the cell. For both classification methods, we calculated the indicator species of the resulting land cover types based on alien species only. The crisp and fuzzy classifications identified 33 and 49 species, respectively, with a clear preference for some urban land use types (from a total of 129 alien plant species analyzed). Results showed that urban land use types having apparently similar environmental conditions can actually harbor different neophyte assemblages. Fine-tuning the categorization of urban environments in future ecological studies is therefore important for understanding spatial patterns of alien species occurrence.

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TL;DR: In this article, the authors investigated the effect of different land-cover types on bird species richness and abundance in a densely built coastal Mediterranean city (Patras, Greece) during the breeding and wintering seasons.
Abstract: Urbanization causes rapid changes in the landscape and land use, exerting a significant pressure on bird communities. The effect of urbanization on bird diversity has been widely investigated in many cities worldwide; however, our knowledge on urban bird communities from the eastern Mediterranean region is very scarce. In this context, we aimed to investigate the effect of the different land-cover types on bird species richness and abundance in a densely built coastal Mediterranean city (Patras, Greece) during the breeding and wintering seasons. We sampled the bird community in 90 randomly selected sites along an urbanization gradient. Open green spaces proved to be the most significant factor favouring bird diversity in both seasons. In winter, woody vegetation and impervious surfaces had a positive effect on species richness as well. The local bird community consisted of a large number of species associated with open and semi-open unmanaged green areas, 12 of which are Species of European Conservation Concern (SPECs) showing a declining trend in Europe. On the other hand, in winter the number of forest-dwellers increased significantly. Species richness was significantly higher in winter indicating that the urban environment provides important wintering grounds. Thus, management actions in cities with similar characteristics in the Mediterranean region should focus on the maintenance of open green spaces and woody vegetation patches to enhance bird diversity.