Urban Ecosystems最新文献

Urban areas form a complex, heterogeneous, fragmented mosaic of habitats, including ecosystems in different degrees of alteration. Nevertheless, some species of birds of prey can thrive in cities. But, there is a knowledge gap regarding the species of birds of prey that who inhabit the cities in Chile, especially those that reproduce in it. Hence, we work in Valdivia, a city that preserves an important natural matrix. The object of this study was to characterize the diversity, abundance, and nest sites of diurnal and nocturnal raptors in the urban area of a city in southern Chile. Twelve species of raptor were recorded, seven diurnal and five nocturnal, 63.1% of the species expected for neighboring rural areas. Twenty-seven nesting sites were recorded two of diurnal raptors and four nocturnal raptors. The availability of nesting sites close to feeding sites, distance to houses, and grassland-shrub cover are essential factors for the success of raptor populations. Cities like Valdivia could offer suitable nesting sites for reproduction, helping to restore habitats for birds of prey.

Urban growth negatively impacts biodiversity through species loss and biotic homogenization. However, cities continue to grow and there are species with certain functional traits that bypass the urban environmental filters persisting in different urban niches. Our objective was to describe taxonomic and functional groups of amphibians and analyze alpha and beta diversity, relating them to environmental variables that characterize fourteen urban green sites with different types and degrees of urbanization, in the metropolitan area of Santa Fe city, Province of Santa Fe, Argentina. We registered 26 species that belong to 13 genera grouped in 5 families: Microhylidae (1), Odontophrynidae (1), Bufonidae (2), Leptodactylidae (10), Hylidae (12). The fourteen surveyed sites were grouped into five categories with similar urbanistic characteristics. Species richness varied from 4 to 15 species per site and between 12 and 19 species per urban green space category. Species corresponded to 10 functional groups and each urban green spaces categories harbor between 7 and 9 functional groups. Beyond the moderate to low beta diversity values, we found that the different urban green spaces categories are complementary as reservoirs of amphibians, since some categories harbor exclusive species or functional groups, while other urban green spaces categories, without exclusive species or functional groups, shelter numerous populations of some species or functional groups.

Increasing in human population causes expansion of urban areas, which threatens forest lands and the biodiversity they harbor. Greenspaces act a critical role maintaining bird diversity within urban areas. Here, we evaluated the effect of spatial characteristics of urban greenspaces on bird species richness to identify the role of greenspace design on bird diversity in Mexico City’s Metropolitan Area. We collected data on bird species richness residing in 44 greenspaces and quantified abiotic, biotic and dispersal attributes of each site. These attributes include size, degree of urbanization within and around the greenspace, vegetation cover, distance between sampled greenspaces, distance to nearby greenspace, distance to the closest natural vegetation patch, distance to city center and distance to periphery of the city. We used Generalized Linear Models to determine the effect of spatial characteristics of urban greenspaces on bird species richness. We then built matrices of beta diversity between greenspaces and assessed bird taxonomic dissimilarity via multivariate Bray-Curtis cluster analysis. Our results showed that bird species richness varies between greenspaces. However, species richness was not correlated with spatial characteristics or biotic attributes (P > 0.05), and we only found marginal correlations between built cover within the greenspace and richness of resident species (P = 0.065) and waterbird species (P = 0.070). Taxonomic similarity between greenspaces was correlated with distance between sampled greenspaces (P < 0.05), however, some dispersal attributes showed no significant effect, such as distance to periphery of the city and distance to the closest natural vegetation patch. Our resultssuggest that distances from areas with greater natural vegetation cover to the innermost parts of the city were too short to function as constraints on the ability of birds to disperse to and colonize urban greenspaces. Our study provides further support for the importance of greenspaces as refuges for conservation of bird diversity in urban areas and shows how urban greenspaces are being used by different bird species within a constantly growing urban landscape.

Human population growth is associated with increased disturbance to wildlife. This effect is particularly acute in urban and periurban areas, where the area of effective disturbance extends beyond that of human presence by the roaming behaviour of pet dogs. Dogs are globally the dominant companion animal, with a population of ~ 12 million in the UK. As urban areas extend, dogs are exercised in green space close to housing. In southeast and southern England these areas include lowland heath, a habitat of high conservation value. To quantify disturbance caused by dog walkers and their dogs, we used GPS units to track the movement of people and their dogs across four lowland heath sites, used a questionnaire to ask about dog walking habits, and mapped potential areas of disturbance caused by dog walkers. Questionnaires were completed by 798 dog walkers and the walks of 162 owners and their 185 dogs were recorded. Mean (± SE) walk time was 56 ± 23 min, walk distance 3.75 ± 1.68 km and dogs were a median distance of 20 m from the owner during walks. Dogs were walked once (44%) or twice (56%) a day. Most (always: 85%; always or occasionally: 95%) dogs were walked off the lead even when signs were present requesting that dogs were kept on a lead. This resulted in up to a 21% increase in reserve area disturbed. In one reserve (Snelsmore Common), > 90% of the area was disturbed by dogs, greatly eroding its conservation value. This work highlights the importance of considering how dog ownership can exacerbate levels of disturbance in sensitive periurban habitats when housing developments are planned.

Abstract

Urban environments are vulnerable to the introduction of non-native species and sometimes contribute to their invasion success. Knowing how urban landscape features affect the population dynamics of exotic species is therefore essential to understand and manage these species. The spotted-wing drosophila, Drosophila suzukii, is a highly polyphagous fruit fly that has become a very problematic invasive species over the last decade. Because of its important damage on fruit production, D. suzukii populations have mainly been studied in agricultural areas, while their dynamics in urban landscape remain poorly explored. The objective of this study was to investigate the role of urban environment in the invasion success of D. suzukii by identifying local and landscape factors driving the abundance of the fly along seasons and urbanization gradients. To achieve this, 526 insect traps were randomly set in four different habitats (urban forest, park, riverside and town centre) along an urbanization gradient in the city of Amiens (France), between September 2018 and August 2019. The influence of landscape and local environmental variables on Drosophilidae species diversity and composition was examined using GLM and multivariate analyses. We found that Drosophilidae species richness and abundance were negatively impacted by urbanization. The Drosophilidae community was dominated by D. subobscura and D. suzukii, but their relative abundance varied with seasons. Drosophila suzukii used urban forest during winter and also during heat waves in summer. The fly was still active in this habitat in winter when the ground was covered with snow. The cover of brambles, shrubs, soil litter and dead wood debris were identified as valuable ecological indicators of the presence of D. suzukii. We highlight the role of the different components of urban environment in the ecology of D. suzukii, particularly with regard to its winter survival. These results could serve for designing management strategies in urban habitats in order to reduce the invasion success of D. suzukii.

Graphical Abstract

Monitoring changes in biodiversity resulting from urban sprawl is an important topic for conservation. Automated biodiversity monitoring methods can quickly collect and process large datasets at minimal cost facilitating effective biodiversity monitoring. Despite being promising, the efficacy of acoustic monitoring in urban areas has not been established. Herein, our aim was to assess the effectiveness of acoustic indices in monitoring urban biodiversity. Thus, we acoustically sampled birds from a large neotropical city (Brasília, Brazil) across a gradient of urbanization. Human identification of recorded species revealed a clear reduction in bird richness in areas of greater urbanization. However, none of the six automated acoustic indices we tested [Normalized Difference Soundscape Index (NDSI), Acoustic entropy (H), Bioacoustic Index (BI), Acoustic Evenness (AEI), Acoustic Diversity Index (ADI), and Acoustic Complexity Index (ACI)], correlate with the degree of urbanization, indicating that these indices may not be a suitable tool for monitoring biodiversity in urban environments. In urban areas, it seems more appropriate to use traditional metrics, that make it possible to accurately identify the heard species. We recommend the need to ground truth the indices and explore alternative acoustic signal’s ability to monitor biodiversity in the complex soundscape of urban environments.

In the debate on the impact of urbanisation on biodiversity, two characteristics of urbanisation have been identified that mainly determine the extent of the impact, namely the level of urbanisation and the landscape context. More recently, it has been theorised that urban sprawl in an intensive agricultural landscape has a positive influence on pollinators by increasing habitat and resource availability. Using the eastern Po Plain (north-eastern Italy) as a model system, we investigated the relationship between attributes of landscape composition and configuration, pollinator richness and visits in 39 randomly selected permanent plots. Contrary to expectations, we found no relationship between urban sprawl and pollinator species richness. Conversely, descriptors of urban sprawl such as landscape heterogeneity and the proportion of urban green spaces had a positive influence on the number of pollinator visits. This suggests that urban sprawl, when occurring in an intensive agricultural land, has a positive effect on the abundance of local pollinator populations, while it may not promote pollinator richness due to limited immigration opportunities in the matrix of intensive agricultural land. Our results emphasise the importance of urban green spaces in supporting pollinator communities, but also the need to improve the heterogeneity and permeability of the landscape matrix for biodiversity to enhance pollinator conservation in human-modified landscapes.

Increasing urbanisation reduces available habitat and increases human-wildlife interactions, presenting social and ecological challenges for many species; however, flexible generalist species, such as the vervet monkey, Chlorocebus pygerythrus, thrive under these pressures. In the urban mosaic, human-food sources represent clumped, monopolisable food that can increase contest competition. Social network analysis (SNA) is a powerful tool to monitor changes in social structure, yet it has rarely been used to study urban wildlife. Using SNA, we investigated the effect of anthropogenic food and human-wildlife interactions on social cohesion in five vervet monkey groups in urban KwaZulu-Natal, South Africa. Over six months, we conducted group scan samples every 30-min on each group and recorded all humans-vervet monkey interactions during dawn to dusk follows. We analysed the effect of foraging on natural and human-related food sources and human-vervet monkey interactions on social network metrics for grooming and aggression at group (density, clustering coefficient and distance) and individual (eigenvector centrality and degree) levels, using linear mixed models. Anthropogenic food influenced almost all social metrics. At the group level, foraging on anthropogenic food was related to increased density and cohesion in both grooming and aggression networks. At the individual level, increasing anthropogenic food affected high-ranking monkeys most: eigenvector centrality and outdegree in aggression networks increased with rank. Social network analysis can be a useful tool to document urban effects on wildlife groups, and aids our understanding of wildlife behavioural flexibility, a key tool in developing educated and effective management strategies.

A variety of stormwater infrastructure such as constructed wetlands, rain gardens, vegetated drainage channels and retention ponds are primarily used for managing water runoff, but these environments can also foster biodiversity. Despite extensive literature about certain taxa (e.g., amphibians, aquatic macroinvertebrates, etc.) found in these human-made environments, the terrestrial plants and invertebrates present there remain understudied. Here, we compared alpha and beta diversity of plant and terrestrial invertebrate communities and assessed the influence of landscape characteristics on their composition in different types of urban stormwater basins and ponds. Plants and terrestrial invertebrates were identified in the main body (excluding the aquatic section) and on the banks of 54 basins and ponds (dry basins, wet basins with and without a water channel and retention ponds) in Quebec City and Trois-Rivières, in Eastern Canada. Results showed poor and homogenous plant and invertebrate communities in dry basins. Wet basins had the highest plant alpha diversity, with more facultative wetland species than the two other types. Wet basins with and without a water channel had similar plant and invertebrate composition, and wet basins and retention ponds were the most heterogeneous. Retention ponds (with permanent water) had distinct communities with fewer plant species than wet basins. The presence of natural areas around the infrastructure significantly influenced communities within a 2000 m and 500 m radius for plant and invertebrate communities, respectively. Wetland plant species were generally found in infrastructure close to natural areas, whereas tolerant and opportunist species were associated with disturbed environments. Our results suggest that enhancing diversity of the stormwater basins and ponds at the regional and local (microhabitat) scales has the potential to maximize diversity of plants and terrestrial invertebrates.

Urbanisation results in the loss and alteration of natural wetlands and ponds. However, garden ponds in cities and towns can potentially act as rich reservoirs of aquatic biodiversity and stepping stones for dispersal. Homeowners with a range of different motivations, including biodiversity values, install garden ponds. Here, our main aim was to study whether the design and management choices of garden pond owners depended on the location of ponds (capital city vs. countryside), when ponds were installed (pond age), or whether fish were introduced. We surveyed 834 garden pond owners across Hungary using a citizen science questionnaire, asking questions on pond size, location, construction date and materials, vegetation structure, introduction of fish and management practices. From 753 validated responses, we found that the introduction of fish into ponds and high urbanisation were strongly associated with local features and management practices, especially large ponds with a water circulation feature, irrespective of pond age. A typical garden pond in Hungary is ~ 20 m², < 10 years old, made of rubber lining, contains fish, aquatic vegetation and circulating water, and is actively managed. There was a spatial separation of ponds based on local features between ponds in the capital city (Budapest) and elsewhere. These findings suggest that garden pond owners in the city were more likely to make different choices in pond design and management compared to owners in regional areas. Our results also suggest that pond owners may primarily select management practices to improve habitat quality for ornamental fish. Our findings have important implications for maintaining aquatic biodiversity in urban areas, where garden ponds may be the only aquatic habitat available.