Urban Ecosystems最新文献

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.

The ecosystem services concept has been studied in rural contexts but not as much in urban landscapes, particularly for aquatic ecosystems in Africa. There is little knowledge of how people perceive ecosystem services (ES) supplied by rivers in urban centres and the factors influencing their perceptions. To fill this gap, the research presented here addresses two objectives: 1) to assess local communities’ perception and knowledge of different types of ecosystem services of an urban river in South Africa, 2) to assess the influence of particular demographic characteristics (age and gender), socio-economic characteristics (education, housing type, income, and years of residence), and prior knowledge of the ecosystem services concept on people’s perception of the ecosystem services provided by the Swartkops River in the Eastern Cape of South Africa. To address these objectives, a team of ten trained field staff collected 181 surveys between May–June 2021 in communities within the river catchment. We used multinomial logit models to analyse the relationships between demographic and socio-economic variables, and people’s perception of ecosystem services. For the majority of the ecosystem services, there was almost an equal split between the perception “sometimes” and “never” that the river provides a particular ecosystem service, and people were less likely to say that the river always provide a particular service. Prior knowledge of the ecosystem services concept, years of residence, age, income and housing type significantly influence people’s perception of ecosystem services. Prior knowledge, was important for the intangible services, whereas years of residence was more important for tangible services with direct use value. Level of formal education was not a significant variable. An important implication of this study is that ecological interventions can be designed through an understanding of factors influencing people’s perceptions of ecosystem services.

Monitoring species distribution and abundance accurately and efficiently are vital for conservation efforts. Next-generation sequencing and DNA metabarcoding using environmental DNA (eDNA) allow for the simultaneous identification of multiple species in one sample, enabling swift biodiversity assessment in complex ecosystems. However, most eDNA studies focus on aquatic organisms and ecosystems.This study’s main objective was to use eDNA metabarcoding to monitor mammal and bird species in an urban ecological park. The chosen study site was Gildong Ecological Park, Seoul, South Korea, with a total area of 80,000 m² divided into three marsh area, a forested mountain area, and a rural experience learning center. Water sampling occurred five times from August to September, yielding 65 samples from three park sections. We employed MiMammal and MiBird primers targeting mitochondrial 12 S to investigate mammals and birds, serving as pivotal biological indicators within urban ecosystems.Metabarcoding revealed the presence of 73% (11/15) and 67% (represented 67% of the total 6268 individual) of the dominant mammalian and avian species, respectively, known to inhabit the park, compared to the results of traditional surveys. The mountain samples (1.51) and marsh samples (2.32) had significantly different median read counts when including all species; however, the same comparison within each taxonomic group yielded no statistically significant differences. Though we detected species differences using eDNA across summer, autumn, and winter monitoring, no statistically significant differences were found among seasons within the park. However, the park’s area is relatively small for detecting variations in eDNA. This might be because there is a lot of animal activity throughout the study site and/or a limited influence of microhabitats. These results could provide valuable insights for using eDNA to monitor animals in urban ecological parks.