Urban Ecosystems

Oladimeji, Akinwale; Woodgate, Zoë; O’Riain, M. Justin

2024 Urban Ecosystems

doi: 10.1007/s11252-024-01606-1

Urbanisation is rapidly transforming and fragmenting natural habitats, disrupting ecosystems and negatively impacting biodiversity. The City of Cape Town (CoCT) is situated in a global biodiversity hotspot, but sustained anthropogenic activities have resulted in the local extirpation of most medium and large mammals. A recent survey of mammals within urban protected areas of CoCT revealed that a few, mostly medium-sized generalist species, persist. It is uncertain which native mammal species, if any, inhabit the unprotected green belts and parks in suburban and urban areas of the city. A total of 37 camera trap sites were established along four transects for a period of four months between 31 January and 31 May 2022. A total of 12 terrestrial mammal species were detected, nine of which were wild native mammals and three domestic species. Most detections were in natural habitat followed by suburban, with urban areas having the lowest detection rate of wildlife. Single season hierarchical multi-species occupancy models revealed that tree cover had a significant positive effect on both community and individual species occupancy. Contrary to our predictions, neither human population density nor the extent of the impervious surface at sites significantly affected occupancy. Cape grysbok (Raphicerus melanotis) were significantly more likely to occur at sites with a higher proportion of impervious surfaces supporting other recent research, which showed this species together with water mongoose (Atilax paludinosus) and Cape porcupine (Hystrix africaeaustralis) are one of only a few native mammals that appear to persist and may even thrive in human-modified landscapes. Our findings underscore the complexity of urban biodiversity conservation and the species-specific responses to environmental factors, emphasising the importance of tree cover in urban wildlife management.

Dutta, Aditi; Samajpati, Indranil; Basu, Parthiba

2024 Urban Ecosystems

doi: 10.1007/s11252-024-01609-y

Urbanization in tropical landscapes is a complex phenomenon that can lead to community shifts rather than simple species extinction in response to multiple stressors in peri-urban and urban settings. We have investigated the impacts of different stressors along a tropical urban-peri-urban gradient on the bee community, the health of which is a global conservation concern. Several stressors such as increased built-up area, pesticide application and air pollution may effectively regulate bee community composition and corresponding functional diversity along urban-peri urban gradients. We investigated the changes in bee community structure in response to associated stressors in 20 locations including parks and gardens along an urban-peri-urban gradient surrounding the megacity of Kolkata. Bee community structure differed significantly between urban and peri-urban sites with urban sites showing lower value of nestedness. Network analysis also revealed that Apis florea and Lasioglosssum sp. 1 were the most important species in the urban and peri-urban areas respectively, as they had the highest values in bee-site network parameters. Functional diversity increased with urbanization and decreased with pesticide toxicity. Functional redundancy decreased with urbanization. Individual stressors impacted the bee assemblage differentially along the urbanization gradient. SO2 and pesticide toxicity negatively influenced bee abundance and diversity. Urban sites sustained more specialized species and therefore are more vulnerable to shocks while peri-urban sites had a more functionally redundant community making it comparatively more resilient.

Eydoux, Louise; Jay Robert, Pierre; Kaufmann, Bernard; Hedde, Mickael; Vergnes, Alan

2024 Urban Ecosystems

doi: 10.1007/s11252-024-01608-z

Soil unsealing, the process of removing the impermeable top layer of soil, is increasingly advocated by urban planning policies. The role of unsealed areas in biodiversity conservation, particularly soil biodiversity, remains strongly understudied and especially in understanding the recolonization dynamics of soil biodiversity in these new habitats. Besides, the various types of soil cover resulting from soil unsealing could potentially influence the recolonization kinetics. This study focused on 79 unsealed plots located in 14 schoolyards along the French Mediterranean coast, investigating ant communities through the placement of 485 baits on unsealed plots. Two variables were considered: the duration since soil unsealing (1 or 2 years) and the type of soil cover (wood chips, plantations mulched with wood chips or lawns). Remarkably, these unsealed areas act as habitats for ants from their very first years of creation: a rich number of ant species (21 species; a fifth of the regional pool and 10% of the metropolitan French species) has been observed. Additionally, notable changes in ant communities were evident within a single year: plots unsealed for 2 years exhibited significantly higher indices of ant abundance and species richness compared to those unsealed for 1 year. However, the construction of these spaces influences the present communities, with wood chip-covered areas significantly less rich and abundant in ants compared to other ground cover types. These findings represent a promising starting point and offer insights into the potential of such projects for soil biodiversity conservation.

Cabon, Valentin; Amiar, Dylan; Georges, Romain; Dubreuil, Vincent; Pétillon, Julien; Quénol, Hervé; Bergerot, Benjamin

2024 Urban Ecosystems

doi: 10.1007/s11252-024-01591-5

Urbanisation is an ongoing process associated with multiple environmental changes affecting ecosystems worldwide. Temperature and habitat are main drivers of animal communities within cities, but quantifying their relative weights remains a challenge, as urban heat islands (UHI) often co-vary with land-cover. This study aims to disentangle the effects and relevant scale of temperature and habitat on ground-dwelling spider communities. Based on an original sampling design, we collected 20,761 spider individuals belonging to 137 species at 36 sampling sites in the city of Rennes (northwest France). We characterised communities by assessing the number of trapped individuals at each site, as well as calculating several metrics to estimate taxonomic and functional diversities. Temperature metrics were obtained from two sensor networks monitoring UHI (100-m resolution) and near-ground temperature (1-m resolution) independently. Land-cover and isolation were used to describe landscapes, and vegetation structure to describe local habitats. We used generalized linear mixed models to disentangle the effects of temperature from those of habitat at the landscape and local scales, and identified relationships between community descriptors and predictors. We show that temperature-related metrics are important predictors of spider communities, and that the landscape and local scales have independent effects. Near-ground temperature alone explained 24% of the number of trapped individuals, whereas UHI explained 20% of taxonomic diversity. Local vegetation height and cover were significant predictors of functional diversity, and explained 22% and 25% of variance, respectively. We conclude that locally applied planning measures could mitigate the loss of taxonomic diversity induced by the atmospheric UHI and promote the establishment of more diverse communities.

Flaminio, Silvia; Salomon Cavin, Joëlle; Guex, Guillaume; Moretti, Marco

2024 Urban Ecosystems

doi: 10.1007/s11252-024-01603-4

Many authors have described ‘urban ecology’ as a subfield of ecology that emerged in the 1990s and has expanded exponentially. We propose to take a step further and analyse the expansion of the ‘urban’ in ecology with a novel quantitative approach, with the aim to better understand the relationship between ecology and the urban. Previous quantitative assessments of the urban in ecology have focused on short to medium time spans (5 to 40 years) and on research coined as ‘urban ecology’, and have rarely considered the content of publications (e.g., vocabulary and topics) using quantitative methods. In this paper, we conduct a bibliometric assessment and an in-depth quantitative textual data analysis of a corpus of 960 articles published from 1922 to 2018 in 10 leading English-language journals in ecology and conservation biology. We address the following questions: (1) When and how have urban environments been integrated into ecological research during the past century? (2) What urban research topics have been investigated in ecology during the same period? (3) How have these research topics changed through time? Our results show that the urban was never entirely absent from publications in ecology. The quantitative analyses highlight three turning points (1970s, 1990s and 2000s) in the relationship between ecology and the urban. Moreover, they help visualize the shift from particularly scattered publications at the beginning of the period to publications characterized by a more homogeneous vocabulary, reflecting the stabilization of a research field focused on the urban in ecology.

Shishira, D.; Uthappa, A. R.; Chavan, S. B.; Kuberappa, G. C.; Jinger, Dinesh; Sringeswara, A. N.

2024 Urban Ecosystems

doi: 10.1007/s11252-024-01607-0

Understanding the diversity of nectar sources in urban honey samples is crucial for effectively managing honey bee (Apis cerana indica Fabricius, 1978.) colonies and promoting pollinator health. This study analysed honey samples from various urban locations in Bangalore to assess pollen diversity, foraging behaviour, and the significance of urban flora in supporting beekeeping practices. A total of 39 pollen types were identified, with 62.50% of samples being unifloral, predominantly from Eucalyptus sp., followed by Casuarina equisetifolia, Areca catechu, Citrus sp., Mallotus philippensis, Cocos nucifera, and Ocimum sp. Multifloral samples (37.50%) highlighted the diverse diet available to urban bees, promoting biodiversity within urban landscapes. Major plant families contributing to pollen content included Myrtaceae, Arecaceae and Fabaceae. Seasonal variation in pollen composition reflected shifts in dominant nectar sources, with the monsoon season characterized by Casuarina equisetifolia, Areca catechu, Citrus sp., Mallotus philippensis, and Cocos nucifera, while winter saw Eucalyptus sp. and Ocimum sp. as predominant sources, and summer featured Pongamia pinnata. Cluster analysis found high similarity in pollen composition in honey samples from Bagalur, Yelahanka and M S Palya but distinct pollen in GKVK, suggesting unique conditions and emphasizing the importance of considering spatial variations in beekeeping practices and conservation strategies. This research underscores the importance of floral diversity in sustaining urban bee populations and provides guidance for urban planning and policy decisions to promote pollinator health and urban sustainability.