Urban Gradient Research Articles

Intersectional approach of everyday geography

Hour-by-hour variations in spatial distribution of gender, age and social class within cities remain poorly explored and combined in the segregation literature mainly centred on home places from a single social dimension. Taking advantage of 49 mobility surveys compiled together (385,000 respondents and 1,711,000 trips) and covering 60% of France’s population, we consider variations in hourly populations of 2572 districts after disaggregating population across gender, age and education level. We first isolate five district hourly profiles (two ‘daytime attractive’, two ‘nighttime attractive’ and one more ‘stable’) with very unequal distributions according to urban gradient but also to social groups. We then explore the intersectional forms of these everyday geographies. Taking as reference the dominant groups (men, middle-age and high educated people) known as concentrating hegemonic power and capital, we analyze specifically whether district hourly profiles of dominant groups diverge from those of the others groups. It is especially in the areas exhibiting strong increase or strong decrease of ambient population during the day that district hourly profiles not only combine the largest dissimilarities all together across gender, age and education level but are also widely more synchronous between dominant groups than between non-dominant groups (women, elderly and low-educated people). These intersectional patterns shed new light on areas where peers are synchronously located over the 24-hour period and thus potentially in better position to interact and to defend their common interests.

High losses of farmland birds and potential biocontrol along an urbanization gradient in a tropical megacity

Worldwide, urban areas are spreading at massive rates. Simultaneously, urban agriculture is growing in importance. However, urbanization effects on functional biodiversity on farmland remain poorly studied, especially in urbanization hotspots of the global south. Here, we sampled birds on 36 farms across three seasons (one full year) and along two urbanization gradients in the Indian megacity Bangalore, using a paired site design to separate local and landscape effects of urbanization. At various spatial scales, including local and multiple landscape scales, we observed a consistent reduction in bird diversity as a result of urbanization. An increase of landscape-wide impervious surface area from 0% to 80%, lead to an average reduction of 50% of bird species and individuals, with open woodland species being the biggest losers. Invertebrate-feeding birds already experienced 60% losses with only 40% of impervious surface, particularly during the monsoon, i.e. the main cropping season, suggesting a great potential decrease in biocontrol services for farmland in urban areas. In conclusion, we documented high losses of farmland birds in an Indian megacity due to intense and rapid urbanization, which is generally little studied but can be currently observed in many other tropical countries.

CO-OCCURRENCE OF MOSQUITO COMMUNITIES IN DISTURBED ENVIRONMENTS USING MARKOV RANDOM FIELDS (MRFs) IN ST. JOHNS COUNTY, FLORIDA

The distribution of mosquito communities is predicted by complex micro- and macrohabitat systems. While macrohabitat variables are significant in modeling the distribution of individual mosquito species, the distribution of mosquito communities in disturbed urban and semi-urban environmental gradients was overlooked in most of the previous models. In our study, we used conditional Markov Random Fields (CRF) to evaluate spatial co-occurrence patterns between mosquito vectors of eastern equine encephalitis (EEEV) and west Nile virus (WNV) in a disturbed urban environment in Saint John’s County, Florida. We aimed to 1) quantify the strength and direction of spatial unconditional and conditional correlations between mosquito assemblages in disturbed environments, and 2) evaluate whether the strength of correlations between mosquito assemblages is conditional on landscape or climate variables. We leveraged the longitudinal surveillance effort using Biogents sentinel traps (BGS) conducted by Anastasia Mosquito Control Districts in disturbed urban environments during 2017-2020. The distribution of high mosquito abundance, especially Aedes albopictus, Ae. aegypti, Ae. vexans, Ae. taeniorhynchus, Culex nigripalpus, Cx. salinarius, and Cx. quinquefasciatus, were conditionally correlated with other EEEV and WNV vector species in reduced woody and herbaceous wetlands and evergreen forests (-54.44%), and in urban developed landscapes (3.44%) during 2019 and 2020. Moreover, conditional correlations between mosquito species pairs were positively associated with increased total precipitation and in areas with high average minimum and maximum temperatures. Our results show that the micro- and macrohabitat characteristics demonstrated spatial effects on distribution and correlations between species pairs of EEEV and WNV mosquito vectors across disturbed environments. Our findings could be used to better understand the joint effects of drivers on mosquito diversity at a specific locality, interspecific interactions among mosquito assemblages, and how this diversity changes across environmental gradients.

Keep your cool: Overwintering physiology in response to urbanization in the acorn ant, Temnothorax curvispinosus

Winter presents a challenge for survival, yet temperate ectotherms have remarkable physiological adaptations to cope with low-temperature conditions. Under recent climate change, rather than strictly relaxing pressure on overwintering survival, warmer winters can instead disrupt these low-temperature trait-environment associations, with negative consequences for populations. While there is increasing evidence of physiological adaptation to contemporary warming during the growing season, the effects of winter warming on physiological traits are less clear. To address this knowledge gap, we performed a common garden experiment using relatively warm-adapted versus cold-adapted populations of the acorn ant, Temnothorax curvispinosus, sampled across an urban heat island gradient, to explore the effects of winter conditions on plasticity and evolution of physiological traits. We found no evidence of evolutionary divergence in chill coma recovery nor in metabolic rate at either of two test temperatures (4 and 10 °C). Although we found the expected plastic response of increased metabolic rate under the 10 °C acute test temperature as compared with the 4 °C test temperature, this plastic response, (i.e., the acute thermal sensitivity of metabolic rate), was not different across populations. Surprisingly, we found that winter-acclimated urban ant populations exhibited higher heat tolerance compared with rural ant populations, and that the magnitude of divergence was comparable to that observed among growing-season acclimated ants. Finally, we found no evidence of differences between populations with respect to changes in colony size from the beginning to the end of the overwintering experiment. Together, these findings indicate that despite the evolution of higher heat tolerance that is often accompanied by losses in low-temperature tolerance, urban acorn ants have retained several components of low-temperature physiological performance when assessed under ecologically relevant overwintering conditions. Our study suggests the importance of measuring physiological traits under seasonally-relevant conditions to understand the causes and consequences of evolutionary responses to contemporary warming.

Microplastic burden in invasive signal crayfish (Pacifastacus leniusculus) increases along a stream urbanization gradient.

Microplastics are a globally pervasive pollutant with the potential to directly impact species and accumulate in ecosystems. However, there remains a relative paucity of research addressing their accumulation in freshwater ecosystems and a near absence of work in crayfish, despite their high ecological and economic importance. This study investigated the presence of microplastics in the invasive signal crayfish Pacifastacus leniusculus along a stream urbanization gradient. The results demonstrate a ubiquitous presence of microplastics in crayfish digestive tracts at all sites and provide the first evidence of microplastic accumulation in tail tissue. Evidence of a positive linear trend was demonstrated between microplastic concentration in crayfish and upstream urban area size in generalized linear models. Evidence for a positive effect of the upstream urban area and a negative effect of crayfish length on microplastic concentrations in crayfish was demonstrated in multiple generalized linear regression models. Our results extend the current understanding of microplastics presence in freshwater ecosystems and demonstrate their presence in crayfish in the wild for the first time.

Increasing Antimicrobial Resistance and Potential Human Bacterial Pathogens in an Invasive Land Snail Driven by Urbanization

Our understanding of the role urbanization has in augmenting invasive species that carry human bacterial pathogens and antimicrobial resistance (AMR) remains poorly understood. Here, we investigated the gut bacterial communities, antibiotic resistance genes (ARGs) and potential antibiotic-resistant pathogens in giant African snails (Achatina fulica) collected across an urbanization gradient in Xiamen, China (n = 108). There was a lack of correlation between the microbial profiles of giant African snails and the soils of their habitats, and the resistome and human-associated bacteria were significantly higher than those of native snails as well as soils. We observed high diversity (601 ARG subtypes) and abundance (1.5 copies per 16S rRNA gene) of giant African snail gut resistome. Moreover, giant African snails in more urban areas had greater diversity and abundance of high-risk ARGs and potential human bacterial pathogens (e.g., ESKAPE pathogens). We highlight that urbanization significantly impacted the gut microbiomes and resistomes of these invasive snails, indicating that they harbor greater biological contaminants such as ARGs and potential human bacterial pathogens than native snails and soils. This study advances our understanding of the effect of urbanization on human bacterial pathogens and AMR in a problematic invasive snail and should help combat risks associated with invasive species under the One Health framework.

Land use-based characterization and source apportionment of microplastics in urban storm runoffs in a tropical region

Urban stormwater runoff has been suggested as one important land-based pathway of microplastics (MPs) entering the oceans, in which the abundance and characteristics of MPs may be influenced by urban land use types. However, little information has been reported regarding this, especially in the tropical monsoon region. This study first reports the MPs in urban stormwater runoffs in a tropical monsoon region that were collected from four typical urban land use types, including industrial, highways, commercial, and residential areas. The average MP particle count and mass concentration were measured as 4.7 ± 3.5 particles/L and 3.8 ± 2.9 mg/L, respectively. MP abundances showed clear urban land use gradients following the order of industrial > transportation > commercial > residential area. In terms of the seasonal variation in MP abundances, a slightly increasing particle count in the dry season was noted for the residential site. Source apportionment of MPs in stormwater runoffs was demonstrated based on the land use type, particle morphology, and chemical compositions. With the simple apportionment approach, approximately 85% of the MP sources were able to be identified in the industrial, transportation, and residential sites. However, the commercial site showed high variability in terms of the morphology and polymer type of MPs. Furthermore, significantly positive correlations between MP abundance and runoff turbidity, TSS, COD, and rainfall intensity were identified, while, no significant correlation was found between MP characteristics and selected water quality/meteorological parameters.

The effect of grassland type and proximity to the city center on urban soil and vegetation coverage

Urban soils with associated vegetation are important components of urban ecosystems, providing multiple regulating and supporting ecosystem services. This study aimed to analyze the differences in the soil chemistry and vegetation of urban grasslands considering urbanization gradient and urban grassland type (UGT). We hypothesized that the chemical properties of soil, such as metal content, as well as vegetation traits, differ according to grassland type (lawns, grasslands in parks, grasslands on river embankments, and roadsides) and the location of grassland patches (city center versus peripheries). Our samples included 94 UGT patches which each patch represented by four square sampling plots sized 1 m2. The results showed high differentiation of measured traits unrelated to UGT and location. The exception was K content, with a relatively high concentration in lawns, and some metals (Cd, Cu, Pb, Zn), with higher concentrations in the city center than in the peripheries. We found two grassland patches located in the city center where the concentrations of Pb, Zn, and Cu exceeded the level authorized by Polish standards. In the case of vegetation traits, the variability was not structured considering the UGT and location of the patches, except for bare soil cover, which was higher in lawns in the city center compared to embankments in the peripheries. We observed correlations between vegetation traits and soil chemical properties. The vascular plant species richness decreased when N, P, and C content, along with an increase in grass cover and a decrease in herbs.

Structure of breeding bird assemblages in the city of Windhoek, Namibia

The line transect method was employed to count birds in four urbanized habitats in the city of Windhoek, Namibia. Most counts were conducted during July-October, in 2012-2014. Twelve transects with a total length of c. 86 km were located in places representing major urban habitats: residential areas (city centre, suburbs in lowland, suburbs in highland, and city periphery), sport fields, and a modern industry area. In total, 80 bird species (excluding Palearctic visitors) were recorded. For all species, we calculated linear population densities and dominance. Six species were classified as dominant: house sparrow, red-eyed bulbul, Southern masked weaver, laughing dove, wattled starling and white-backed mousebird. Their cumulative numerical abundance comprised 54.2 % of all the breeding species. The group of dominant species varied markedly among transects. Granivores were the most important feeding guild, comprising more than half of all birds in Windhoek. Frugivores (26 %) were more numerous than insectivores (19 %). Birds nesting in trees and/or in shrubs comprised two thirds of all birds. Surprisingly, few differences in the structure of feeding and nesting guilds were recorded among the four urban habitats. Windhoek avifauna is similar in dominance structure to avifauna in other southern African cities and towns, where sparrows, doves/pigeons, bulbuls and mousebirds dominate, and with granivores being the main feeding guild. Species richness declines and bird abundance increases along urban gradient (towards the city centre).

Responses of hover fly diversity and abundance to urbanisation and local attributes of urban greenspaces

Urban greenspaces are vital refugia for insect biodiversity, but seasonal fluctuation responses of insect taxa to urbanisation and local attributes of urban greenspaces are not well known. Regions with mild temperate climates and winter-flowering plants have active winter pollinators that are often neglected. A thorough knowledge of the seasonally fluctuating ecological needs of insects is essential for adequate insect-friendly greenspace management. Hover flies are cosmopolitan inhabitants of urban greenspaces where they provide multiple critical ecosystem services such as pollination and pest control. Our study uses a multi-scale approach to determine the seasonal effects of urbanisation on hover fly richness, abundance, and assemblages in urban greenspaces. We selected 30 sites along an urbanisation gradient (as measured by human population density) in Sydney, Australia, and sampled each site over a year across seasons. We found that hover fly species richness was higher in winter and spring than in summer, while abundance was highest in winter and lowest in summer. Our results also show that a combination urbanisation and local attributes of urban greenspaces (flower richness, flower abundance, human population density, and proportion of native flowers) combined to affect hover fly species richness and abundance in seasonally dependant ways. Hover flies are especially abundant and diverse during winter- a time of the year when other native floral visitors are less active. Thus, hover flies may be important pollinators of the large community of winter-flowering plants in Australia. Urban greenspaces can be made more hospitable to hover flies by implementing simple management initiatives, such as complementing native floral resources with non-native flowers in periods of scarcity.

Plant Traits of Tilia tomentosa Moench, Fraxinus excelsior L., and Pinus nigra J.F.Arnold as a Proxy of Urbanization

Linden, ash, and pine are ubiquitous ornamental trees due to their ability to adapt to the urban environment. They have been key species in urban green infrastructure from more than hundreds of years and play an active role in maintaining ecosystem services. The urbanization rate in recent decades, combined with global climate change, has led to dynamic changes in the environmental factors which pose new challenges to urban vegetation. Hence, the aims of this study were as follows: (i) to track changes in the content of some elements in plant leaves after transplanting them into an urban environment; (ii) to investigate the relationship between urbanization intensity with plant traits (leaf injuries, photosynthetic activity, transpiration, stomatal conductance, and molecular changes); and (iii) to provide recommendations for improving the management and ecological functions of urban trees. To address these aims, data on urbanization intensity (according to the percentage of built-up area and traffic volume), plant performance, and intraspecific variations of silver linden (Tilia tomentosa), European ash (Fraxinus excelsior), and European black pine (Pinus nigra) were collected at four experimental plots in the city of Plovdiv (Bulgaria) during 2015–2020. The initial concentrations of some potentially toxic elements (As, Cd, Cr, Cu, Mn, Pb, V, and Zn) in the tree leaves at the beginning (prior to planting into the urban environment) and at the end of the experiment were also measured. We illustrate that the growth of urbanization intensity increased the concentrations of potentially toxic elements in tree leaves, caused leaf injuries, and enhanced the maximum photosynthetic rate but decreased the transpiration rate and stomatal conductance. At the molecular level, the percentage of polymorphic bands was also found to depend on urbanization intensity. High similarity was observed between the trees in the first three experimental plots (subjected to urbanization load), with the lowest similarity in the control plot. These findings are of high practical value for urban planners regarding how to build a new green infrastructure and how to preserve plant diversity in urban areas across urbanization gradients.

Co-occurrence patterns and assembly processes of abundant and rare bacterioplankton in plain river network areas of eastern China

In the context of anthropogenic impacts on riverine ecosystems globally, understanding the response of bacterioplankton to anthropogenic stress is important for human and environmental health. Bacterioplankton communities are critical for maintaining ecosystem stability, but little is known about their co-occurrence networks and assembly processes in intense human-impacted plains river networks. By applying cooccurrence networks, variance partitioning, and null model analysis, we investigated the mechanisms of interaction and assembly of abundant (>1% relative abundance) and rare (<0.01%) taxa at 32 sites in river networks along an urbanization gradient (urban, suburban, and agricultural areas). Our results show that interactions between the bacterioplankton communities were more complex in urban areas than in other areas, and that environmental factors (primarily fluoride, nitrate nitrogen, and dissolved organic carbon) as well as spatial factors (i.e., Moran’s Eigenvector Maps) explained most of the variation in bacterioplankton communities. Abundant taxa showed stronger spatial turnover than rare taxa, indicating that spatial factors played a greater role in the assemblage of abundant taxa. Land use types, especially impervious surfaces, had a unique influence on rare taxa, but contributed less to community change than other factors. In addition, rare taxa were mainly influenced by deterministic processes, whereas abundant taxa were more influenced by stochastic processes, especially in agricultural areas. These findings suggest that the shares of abundant and rare taxa mediate disturbances in local environmental conditions in anthropogenic river network areas, while deterministic processes play a greater role in shaping bacterioplankton communities. Overall, our study provides important insights for environmental monitoring and management in areas of intense human activity, emphasizing the need to consider both abundant and rare taxa when assessing the impact of human activities on riverine ecosystems.

Home ranges of box turtles in a rural woodland and an urban park in Saint Louis, MO; implications for turtle conservation

The negative consequences of fragmentation, infrastructure development, and urbanization on biodiversity are well known. However, careful urban planning can provide viable habitat for some species and communities. Generally, r-selected species are more likely to persist in urbanizing landscapes, while long lived, mobile species, such as turtles, are likely to decline toward extinction. Understanding species responses across urban gradients is important for developing mitigation planning. We used VHF telemetry to quantify ranging behavior of three-toed box turtles in fragmented urban forest patches and a semi-contiguous large rural forest in Saint Louis, Missouri. We then simulated movement trajectories based on empirical data from the two turtles with the largest and smallest home ranges, overlaid on forest cover and road network maps of Missouri, to quantify the state-wide probability of turtles encountering roads. Home range (HR) size varied from 1–250Ha. The mean home range estimate of rural turtles was > 9 times larger than that of urban turtles. Simulations indicated that the least mobile turtle (HR 1Ha) would have a 22% likelihood of encountering a road if placed randomly in suitable habitat anywhere in the state. The likelihood increased to 90% for the most mobile turtle (HR 250Ha), with 10 road crossings per year. High turtle mortality, range restriction and population fragmentation are likely even in rural areas. In urban cityscapes, large, roadless forest patches offer the highest conservation potential for this species.

The changing dynamics of ant-tree cholla mutualisms along a desert urbanization gradient.

Urbanization, among the most widespread and multifaceted anthropogenic change drivers, exerts strong influences on a diversity of ecological communities worldwide. We have begun to understand how urbanization affects species diversity, yet we still have limited knowledge about the ways that species interactions are altered by urbanization. We have an especially poor understanding of how urbanization influences stress-buffering mutualisms, despite the high levels of multivariate stress that urban organisms must overcome and the importance of these interactions to the fitness of many organisms. In this study, we investigated the effects of urbanization on a mutualism between tree cholla cacti (Cylindropuntia imbricata) and visiting ants. We first examined how plant size, ant species composition, and ant activity varied on C. imbricata across an urbanization gradient (urban, suburban, wild) in and around Albuquerque, NM. Ant species composition and activity varied significantly across the urbanization gradient, with ant communities from wildlands having the highest activity and the most dissimilar species composition compared to both suburban and urban sites. In contrast, plant size remained constant regardless of site type. We then experimentally assessed how nectar levels influenced ant aggressive encounters with proxy prey (Drosophila melanogaster larvae) on C. imbricata across urban and wild sites. Ants were more likely to discover, attack, and remove proxy prey in wild sites compared to urban sites; they also performed these behaviors more quickly in wild sites. Nectar supplementation had weaker effects on ant aggression than urbanization, but consistently increased the speed at which aggressive behaviors occurred. Future studies that examine nectar quality and herbivorous arthropod abundance may help explain why this strong difference in ant composition and aggression was not associated with lower plant fitness proxies (i.e. size traits). Nevertheless, this study provides unique insight into the growing body of work demonstrating that mutualisms vary significantly across urbanization gradients.

Negative effects of urbanization on plants: A global meta-analysis.

Understanding the response of plant diversity to urbanization is essential for conserving urban biodiversity. In this paper, a meta-analysis of 34 articles and 163 observations regarding the impact of urbanization on plant diversity was conducted. The results revealed that urbanization had marked negative effects on plants. Urbanization had positive effects on introduced species and negative effects on native species. In the subgroup analysis, we found that trees responded better to the effect of urbanization than herbs and shrubs. There was no evidence that urban size, population density, nighttime light, and GDP per capita had moderating effects on plant richness. Based on meta-regression analyses, native species in urban areas were less affected by urbanization at lower latitudes. Overall, urbanization had a marginally negative effect on plant abundance. The effects of urbanization on plant diversity during different stages of urban development were inconsistent. Our research shows that the suburbs play a crucial role in the urbanization gradient; there, plants survive with high species richness.

Heavy Metal Pollution of Soil in Vienna, Austria

Along an urbanization gradient, we explored the soil metal pollution in Vienna, Austria. We analyzed the physical and chemical parameters of topsoil from urban, suburban, and rural areas. The following elements were quantified using ICP-OES technique: Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, S, Sr, and Zn. For heavy metals, PI (pollution index) values were used to assess the level of pollution. We found that the concentration of Cu, Pb, Sr, and Zn was higher in the urban and suburban area than in the rural area. The PI values indicated a moderate level of pollution by Cd (1 ≤ PI ≤ 2) along the urbanization gradient. We found a low level of pollution for Cr, Cu, Ni, Pb, and Zn (PI ≤ 1) in studied areas. Our findings demonstrated the presence of anthropogenic contamination, and it is likely that traffic emission may be the major source of metal pollution in Vienna. Our findings also demonstrated that the elemental analysis of soil and the values of PI are adequate indicators of the level of pollution based on soil sample analysis in urban ecosystems.

Adaptive slope and CPSO-based energy management strategy of hybrid energy storage system for electric logistics vehicles

Energy management strategy play a crucial role in the optimal control of energy in pure electric logistics vehicles with hybrid energy storage system (HESS). Aiming at the problem that the energy management strategy of HESS cannot be reasonably allocated according to different slope conditions, this paper adds the road slope coefficient to the input of fuzzy control and designs a fuzzy controller that automatically adjusts the output power of ultracapacitor based on different road slope coefficients. Then, a chaotic particle swarm optimization (CPSO) method is used to optimize the designed fuzzy controller. Finally, the simulation test is carried out under urban dynamometer driving schedule (UDDS) urban road driving cycle by using Matlab/Simulink. The results show that the improved control strategy can increase the energy utilization by 3.63\% and reduce the battery power consumption by 3.97%. Furthermore, the proposed strategy can improve 30.66% energy utilization and 18.70% ultracapacitor power storage at the downhill situation, and can reduce the energy consumption of the whole vehicle by 5.23%, the average current by 6.19%, and the lithium-ion battery power consumption by 2.20% under the actual urban road gradient.

Assessing Effects of Multi-Scale Landscape Pattern and Habitats Attributes on Taxonomic and Functional Diversity of Urban River Birds

Several studies have revealed that urban rivers with relatively complete habitat structures can support a high level of biodiversity in urban areas. However, few studies have analyzed the impact of the plan, design, and management of multi-scale urban riverside green space on bird communities by assessing several aspects of diversity (e.g., taxonomic and functional). In this study, we explored bird community variation (taxonomic and functional) among three rivers (28 sampling sites) with different levels of human disturbance along the urban development gradient in Kunming, Yunnan Province, China, during an annual cycle. This study related bird species richness and functional diversity to environmental variables at three spatial scales: landscape metrics at two different landscape scales (500 and 100 m radius) and vegetation structure at patch scales (20 m radius). Using partial least squares regression (PLSR) and multiple linear regression, we found that bird species richness and functional diversity were strongly related to various landscape- and patch-level variables. Multiple linear regression models revealed that, compared with the richness influenced by explanatory variables on three spatial scales (500, 100, and 20 m), the functional diversity was significantly influenced by explanatory variables on the 100 and 20 m scales. Tree cover at the 20 m scale had significantly positive impacts on bird species richness and functional diversity. Forest land in the 100 m scale had a significantly positive effect on bird species richness and functional diversity, while construction land in the two landscape scales (the 500- and 100 m scales) had a significantly negative effect on species richness. Accordingly, we suggest that urban riverside green space should be planned and managed at multiple scales.

Effects of light and noise pollution on avian communities of European cities are correlated with the species’ diet

Urbanization affects avian community composition in European cities, increasing biotic homogenization. Anthropic pollution (such as light at night and noise) is among the most important drivers shaping bird use in urban areas, where bird species are mainly attracted by urban greenery. In this study, we collected data on 127 breeding bird species at 1349 point counts distributed along a gradient of urbanization in fourteen different European cities. The main aim was to explore the effects of anthropic pollution and city characteristics, on shaping the avian communities, regarding species’ diet composition. The green cover of urban areas increased the number of insectivorous and omnivorous bird species, while slightly decreasing the overall diet heterogeneity of the avian communities. The green heterogeneity—a measure of evenness considering the relative coverage of grass, shrubs and trees—was positively correlated with the richness of granivorous, insectivorous, and omnivorous species, increasing the level of diet heterogeneity in the assemblages. Additionally, the effects of light pollution on avian communities were associated with the species' diet. Overall, light pollution negatively affected insectivorous and omnivorous bird species while not affecting granivorous species. The noise pollution, in contrast, was not significantly associated with changes in species assemblages. Our results offer some tips to urban planners, managers, and ecologists, in the challenge of producing more eco-friendly cities for the future.

Urbanization and abundance of floral resources affect bee communities in medium‐sized neotropical cities

AbstractBees are important pollinators that have been negatively impacted by anthropogenic environmental changes, such as urbanization. In addition, urban development can reduce and degrade the natural habitat of bees by increasing the proportion of impervious surfaces, decreasing green areas and increasing the number of exotic ornamental plants. However, cities can provide refuge for bees because they provide an environment with a wide variety of nesting and foraging resources. The objective of our study was to evaluate the richness and abundance of bees, their respective functional groups, and community composition along with an urbanization gradient in 21 locations distributed among six medium‐sized Brazilian cities (with populations between 80 000 and 170 000 inhabitants). We also evaluated the effect of richness, number of plants and proportion of native plants. We collected a total of 132 species of bees. Total bee richness decreased with increasing impervious cover and increased with landscape heterogeneity, which also had a positive effect on the richness of above‐ground nesting bees and generalist bees. Regarding abundance data, solitary bees and belowground‐nesting bees were positively influenced by the increase in grass cover. The total number of native and exotic plants collected positively influenced the total abundance of bees, as well as the abundances of eusocial bees, which nest above‐ and belowground, and generalists. The proportion of native plants positively influenced the total richness and abundance of specialist bees. Our results indicate that medium‐sized urban areas may be home to a wide diversity of bee species, but species that nest in the soil and specialist species may be more sensitive to urbanization and the decrease in the supply of floral resources.