Urban Ecosystems最新文献

Ecosystem services (ESs) valuation is important for advancing biodiversity objectives and investing in green infrastructure (GI) establishment. Little is known about the potential of health clinic gardens (HCGs) to provide ESs and their potential values. This study sought to determine the plant and bird species composition and potential value of ESs provided by 32 HCGs in two South African district municipalities. HCG sizes range from 513.0m² to 13531.0m² and each had at least one micro-garden. Among the 312 plant species observed across all HCGs, 60% were exotic. The small HCGs had 31 ± 3.6 different plant species per garden, compared to the medium-sized (32 ± 3.7) and large ones (49 ± 5.2). Provisioning ESs from the observed species were prominent with 17.4 ± 1.16 species potentially used for general well-being, 13.66 ± 1.08 as potential food plants, and 11.91 ± 0.93 potentially raw materials. Trees in HCGs were estimated to sequester up to 163481.87 kg of carbon from trees covering an area of up to 9620.80m². Approximately 1390.70 ± 427.50m² of HCG space had the potential to provide a habitat for plants and birds, and 11 bird species were observed across all HCGs. Sixty-three bird nests encountered in 18 HCGs are believed to belong to the Passer domesticus. HCGs resemble other types of gardens like home and domestic gardens, and their rich plant biodiversity positions them as ideal ecosystems to benefit even the most vulnerable members of society. They provide an opportune platform for knowledge upscaling in the cultivation and use of plant species as a supplement of primary healthcare and food security issues in the summer months to the rural, urban, and peri-urban poor in the Global South.

The issue of environmental injustice has received critical attention in sustainable development. Whereas, there is still a lack of research on exploring the complexity of environmental injustice related to the spatial mismatch of ecosystem services (ES) supply–demand. Hence, we firstly built a framework consisting of 10 types of ES supply and 3 types of ES demand to evaluate the ES supply–demand ratio (ESDR) at county scale in three mega cities in China. Then we adopted spatial autocorrelation analysis and MGWR model to explore the spatial heterogeneity and driving mechanisms of the environmental injustice on ESDR. Results showed that most counties in mega cities were suffering from ES shortages clustered in the city centers. Natural and socio-economic factors including temperature, precipitation, NDVI, housing price and vulnerable group were significantly correlated with the spatial heterogeneity of ESDR. Finally, we discuss the possible intervention policies for discision-makers to mitigate server environmental injustice caused by the spatial imbalance of ESDR.

Urban bird species represent a subset of the regional species pool, consisting of species that have been able to survive in, or colonise, urban areas. Urban birds are typically resident non-forest species with a broad diet and nesting high in trees or in cavities, and some studies have also claimed that they are large-brained. However, little is known about how urban bird communities change over time. Does the urban environment impose specific selective pressures favouring particular species or ecological groups, or do birds in urban areas simply have population changes reflecting population trends at larger scales? We assessed population changes of 45 breeding land bird species in Oslo, the capital of Norway, based on surveys conducted ca. 15 years apart. Population changes within Oslo most closely matched changes occurring at the regional level (national population trends from Norway and Sweden). Thus, species increasing in Oslo were those that also increased at the regional level. We found no evidence that relative brain size, diet or habitat preferences influenced population trends. However, controlling for regional population trends, there were additional residual effects of nest site and migration: species nesting on the ground or low in bushes had more positive changes than species nesting high in trees or in cavities, and resident species did better than long- or short-distance migrants. These results indicate that urban environments are not isolated islands only influenced by own selection pressures, but are connected with regional population dynamics, most likely through immigration.

Civic transition experiments targeting sustainable food production increasingly engage with edible cities aiming at providing free food on public urban spaces. To deepen the understanding regarding how transition experiments can build urban transformative capacities, this paper presents a transdisciplinary case study on two civic edible city initiatives and their measures to cooperatively initiate, innovate, and accelerate edible cities in Dresden (Germany). We identified the two key action areas “civic participation” and “cooperative area activation” covering ten key transition activities to illustrate the variety and content of a transformation towards an edible city. Based on expert interviews and document analyses, we evaluated their process progression by linking research from urban ecology with transformation science. By visualizing its quantitative results, common and distinct patterns of the edible city initiatives could be made visible. Overall, we found that the level of activity is highest in the key action area of “citizen participation”. In this context, both transition experiments had different but specific foci in terms of their key transition activities (i.e. education, activation of stakeholders), whereby activities related to civic empowerment and social cohesion were lacking in both cases. To re-shape narratives pertaining to land access, food production, and participation under the principles of justice, we suggest that transition experiments related to “civic participation” and “cooperative area activation” must be approached together. Our systematic assessment can then enable civic transition teams to strategically identify common goals that need to be prioritized for initiating, innovating, and accelerating urban edible commons.

To enhance the establishment of container-grown trees, nursery and urban forest practitioners use root pruning to improve plant root structure. However, some methods of root pruning may cause stress to the plant and reduce shoot growth. One potential approach to mitigating tree stress is the application of biostimulants. This study aimed to determine the impact root shaving, a type of root pruning, has on the growth of urban plant species, and whether biostimulant application mitigates this impact. To address these aims, we applied root shaving (not shaved, shaved) and biostimulant (control, humic substance, protein hydrolysate, seaweed extract) treatments to six tree species that are commonly planted in the Sydney metropolitan area, Australia in a factorial design. The study consisted of a glasshouse and field experiment to simulate nursery production and urban field conditions, respectively. We found that the assimilation rate of the plants was not affected by root shaving but four of the species still experienced reductions in shoot growth in the short-term. This reduction was a result of the plants allocating resources to root growth to compensate for the root loss. However, in the long-term, the plants were able to compensate for this reduction in shoot growth. We found that biostimulant application did not mitigate the short-term impacts of root shaving on plant growth. We can conclude that root shaving and biostimulant application do not affect plant establishment in the long-term.

Implementation of nature into urban areas provides resting, breeding, watering, feeding and movement opportunities for urban wildlife, whose knowledge of spatial ecology is still incomplete. This article focuses on space use by urban wild boar Sus scrofa in the central part of the Bordeaux Metropolis (France). We used species distribution modelling to assess urban ecological niche of wild boars and to identify landscape features that they select or avoid. We created a database based on field surveys carried out on a sample of grid cells where evidence of boar presence was recorded. We used logistic regression models to predict wild boar presence in the study area. Our results showed that the probability of boar presence was driven by access to resources and modulated by avoidance of densely built-up areas. In contrast, urban boars appeared to be indifferent to habitat fragmentation and secondary roads. Finally, a large part of the urbanistic urban green frame of Bordeaux was likely to support wild boar. These results provide a first picture of the situation, but must be considered as a first stage of investigations on the spatial ecology of urban boars. They also need to be placed in a broader socio-ecological context. From a life science perspective, urban wild boars provide an excellent example of urban wildlife adaptation. However, human-wildlife coexistence also raises planning, management, socio-cultural and ethical issues. We argue that objectifying wildlife use of urban space is a prerequisite to implement meaningful management measures. With this in mind, we proposed and discussed a simple protocol that could be adapted to other species whose urban ranges are poorly known.

Tropical cities provide challenging conditions for resident wild species to undertake critical activities such as roosting and breeding. Tree-nesting waterbirds are widespread urban inhabitants but how they choose sites for these critical activities in urban areas, and whether requirements vary by species, are poorly understood. We assessed whether waterbirds chose roosting and nesting sites using similar cues in a rapidly urbanising small Indian city, Udaipur. Roost sites (N = 78, 17 species especially Ardeola grayii, Bubulcus ibis, Pseudibis papillosa) were located mostly beside roads and wetlands. Nest sites (N = 130, 12 species especially B. ibis, P. papillosa and Anastomus oscitans) were different from roost sites and were located mostly in built-up areas and wetlands. Waterbirds used 23 of 39 available tree species for roosting and nesting, strongly preferring snags and the largest trees of introduced (Azadirachta indica), native (Ficus spp., Vachellia nilotica) and exotic (Eucalyptus sp.) species. Site locations for both activities were associated negatively with built-up areas at the smallest spatial scale. At larger spatial scales they were associated positively with wetlands and built-up areas, with waterbirds entirely avoiding the Aravalli mountains. Individual waterbird species displayed idiosyncrasies in choice of tree species but used similar cues to locate roost and nest sites. Retaining large trees and wetlands across Udaipur city is essential to allow space for waterbirds’ critical activities. The scale and diversity of waterbirds roosting and nesting in Udaipur city is unprecedented suggesting that the ability of small tropical cities to aid urban biodiversity conservation has been overlooked.

Urban areas often have low soil water availability due to their impervious surfaces reducing rainfall infiltration. These water-limited conditions may be exacerbated by the projected increases in drought events caused by climate change. As a result, plants that grow in urban areas are vulnerable to drought stress. There are a range of practices that can be used to help mitigate drought stress, including the use of biostimulants. This study aimed to determine whether biostimulant application (1) improves plant performance and (2) mitigates the drought stress on urban plant species. To address these aims, we selected six woody and three graminoid plant species that are commonly planted in Australian urban areas and exposed them to different watering (drought-stressed, well-watered) and biostimulant (control, humic acid, protein hydrolysate, seaweed extract) treatments. We then measured their assimilation rate, growth metrics and biomass allocation. We found that drought stress reduced the assimilation rates and shoot growth of the study species. However, this did not translate into a biomass reduction because the drought-stressed plants reallocated resources towards root biomass. We found no evidence to suggest biostimulant application mitigated the impacts of drought stress on plant performance. Further, the only effect biostimulant application had on plant performance irrespective of the watering treatment was that the seaweed biostimulant increased the plant height growth of the woody species. These results show that the biostimulants used in this study will have a limited effect on the performance of plant species commonly planted in Australian urban areas.

Abstract

Cali is the third most prominent, and one of the most crowed, Colombian cities. It still harbours some tropical dry forest patches that can mitigate the impacts of the urban transformation; however, there is an almost total absence of information on the biological importance of these sites and their potential for future ecological restoration processes. To assess if they serve as important refuges for insect bioindicator species, we sampled five urban patches of tropical dry forest in the city, plus one nearby rural patch, using specific trapping procedures for ants and carabid beetles. Patch areas were variable, from 1 to 50 ha. We found that the smallest patch presented the highest ant richness, with a tendency towards generalists and a few unique species. Meanwhile, some specialist species were found in the rural patch. A total of 109 ant and 13 carabid species were recorded, including four new records of ants for Colombia. Results suggest that environmental variables favour the presence of generalist and opportunistic ants. Despite this, the high ant richness demonstrates that. Urban forest patches are important refuges for biodiversity. The low richness observed for carabids could be a sign of the challenges that urban forests face considering the ecological importance of beetles. The possible dangers of intensive internal use of these forests is discussed to prevent local extinctions, since the biggest forests are not necessarily conserving a higher richness. This work represents an important contribution to urban ecology in the region, with possibilities of further restoration in urban environments.

Abstract

Night-flying pollinators, such as hawkmoths, are particularly vulnerable to the global spread of urban artificial lighting which is changing nighttime environments worldwide, impacting organisms and their interactions. Incident light quality can alter flower and leaf color perception by insects, depending on the emission spectra of light sources and the spectral sensitivity of insects. We asked, using Manduca sexta visual models, whether color contrast against natural backgrounds is altered by artificial lights for flowers and leaves of 16 plant species with an estimated long history of coevolution with hawkmoth pollinators. Specifically, we compared the perception of flowers and leaves by hawkmoths under artificial lights, including light-emitting diodes (5000 K LED), mercury vapor (MV), and high-pressure sodium (HPS) artificial lights, with the perception under natural illuminations. The models we implemented estimate that LED and HPS lighting change hawkmoth perception of flowers and leaves, with color loci appearing nearer to each other in hawkmoths perceptual space than they would be under natural nighttime conditions. Receptor Noise Limited models show that under the different lighting conditions hawkmoths would still discriminate flowers from their leaves in most but not all species. Consequently, artificial lights likely alter perception by hawkmoths of floral and leaf signals possibly affecting interactions and fitness of plants and pollinators. Our results emphasize the intricate and insidious ways in which human-made environments impact species interactions. Further studies should confirm whether light pollution represents a novel selective force to nocturnal interacting partners as emerging evidence suggests. Addressing the effects of artificial lighting is crucial for designing infrastructure development strategies that minimize these far-reaching effects on ecosystem functioning.