Urban Fragments Research Articles

Changing Bird Migration Patterns Have Potential to Enhance Dispersal of Alien Plants From Urban Centres

ABSTRACTThere is increasing recognition that alien species may be ‘sleepers’, becoming invasive with favourable changes in conditions, yet these changes remain difficult to predict. As populations of frugivorous birds shift with urbanisation and climate change, they could provide dispersal services for introduced fruiting plants that have previously been considered benign. This is likely to be especially problematic at higher latitudes where bird migration phenologies are altering rapidly. However, any consequences for fruit dispersal have not yet been explored. Here, we use Helsinki, Finland, to investigate whether (i) streetscapes provide birds with a fruit resource that differs from urban forest fragments and (ii) the chances for dispersal of alien species (i.e., preferential consumption of native fruits). While there were both more fruits and birds in streetscapes (replicated across multiple years), fruits were not consumed preferentially according to origin. Additionally, seed analysis from faecal samples of blackbird Turdus merula L., a previously migratory but increasingly resident species, suggested that alien and native plants are equally likely to be dispersed. These results indicate that birds could be dispersing alien species more frequently than previously thought and highlight the complex effects of changing climates on potentially invasive species.

Differential predation pressure on island pit vipers shape their niches and defensive behavior

Abstract Animals are naturally exposed to several predators, and, given that a single encounter with a predator may cause prey’s death, natural selection will strongly act upon its defensiveness. Therefore, defensive behavior is strongly shaped by predation pressure. Predation rate in islands tends to be relaxed due to lower abundance of predators. The aim of this study was to test the hypothesis that predation rates upon the two island pit vipers Bothrops alcatraz and B. insularis would be lower than correlated mainland B. jararaca. Additionally, we evaluated the defensive behavior of these island snakes in the field to compare with the mainland B. jararaca. Predation pressure upon the insular species was assessed utilizing plasticine replicas, and we evaluated their defensive behavior to approach. These data were compared to those previously reported for B. jararaca. We found a lower predation pressure on B. insularis (from the smaller area) than on B. alcatraz and B. jararaca from the urban mainland forest fragment (areas with intermediate size), and all of them showed lower predation pressure than B. jararaca from the continuous mainland forested area. In the field, island snakes show narrower defensive repertoire than B. jararaca, since most B. insularis fled, and B. alcatraz either fled or remained immobile on approach. Apparently, the predation pressure to which these island pit vipers are exposed shapes their defensive behavior, as well as the niches exploited by them.

Urbanization drives partner switching and loss of mutualism in an ant-plant symbiosis.

Mutualistic interactions between species underpin biodiversity and ecosystem function, but may be lost when partners respond differently to abiotic conditions. Except for a few prominent examples, effects of global anthropogenic change on mutualisms are poorly understood. Here we assess the effects of urbanization on a symbiosis in which the plant Cordia nodosa house ants in hollow structures (domatia) in exchange for defense against herbivores. We expected to find that mutualist ants would be replaced in the city by heat-tolerant opportunists, leaving urban plants vulnerable to herbivory. In five protected forest sites and five urban forest fragments in southeast Perú, we recorded the identity and heat tolerance (CTmax) of ant residents of C. nodosa. We also assayed their plant-defensive behaviors and their effects on herbivory. We characterized the urban heat-island effect in ambient temperatures and within domatia. Forest plants housed a consistent ant community dominated by three specialized plant ants, whereas urban plants housed a suite of 10 opportunistic taxa that were, collectively, about 13 times less likely than forest ants to respond defensively to plant disturbance. In the forest, ant exclusion had the expected effect of increasing herbivory, but in urban sites, exclusion reduced herbivory. Despite poor ant defense in urban sites, we detected no difference in total standing herbivory, perhaps because herbivores themselves also declined in the city. Urban sites were warmer than forest sites (daily maxima in urban domatia averaged 1.6°C hotter), and the urban ant community as a whole was slightly more heat tolerant. These results illustrate a case of mutualism loss associated with anthropogenic disturbance. If urbanization is representative of increasing anthropogenic stressors more broadly, we might expect to see destabilization of myrmecophytic mutualisms in forest ecosystems in the future.

Domestic chicken predation and prey sharing by urban capuchin monkeys (Sapajussp.).

Capuchin monkeys are omnivorous platyrrhines with a high frequency of faunivory and can survive in urban forest fragments. Predation of wild vertebrates (high-quality foods) by capuchin monkeys has been frequently reported in many species of Cebus and Sapajus. However, predation of domestic animals is unknown. We describe a rare episode of predation, consumption, and sharing of an adult domestic chicken (Gallus gallus domesticus) by individuals from a social group of robust capuchin monkeys (Sapajus sp.) living in a small urban park in the city of Foz do Iguaçu, southern Brazil. This relatively large prey is freely farmed at the study site. The capture, slaughter, preparation (removal of feathers from the body), and consumption of the prey by the capuchins lasted 22min. The dominant adult male ate the chicken's head and tolerated the approach of two juveniles. The juveniles shared the remainder of the prey after the adult abandoned it. These juveniles scared other group members that approached the carcass. We recorded an opportunistic hunt for easily accessible domestic prey, a case of human resource use by urban primates that shared passively the atypical and valuable food. Though a rare event, the predation on a domestic animal indicates a potential source of conflict with humans that can have negative impacts on urban primates.

Visualizing everydayness, questioning interstitiality

This visual essay explores the possibility of everyday spaces to be theorized as interstices, i.e. in-between or temporary spaces. The images are black-and-white video snapshots of urban spaces in several cities in the German state of Thuringia showing the everyday movement of people and cars, and in some cases, spaces that are used by a limited number of inhabitants. Through these images, the author questions the normal nature of everyday spaces by exploring Rodrigo Vidal’s notion of interfragmentary space, which refers to urban fragments contained within any open space in the city. This article highlights the interplay between everydayness and interstitiality, which can redefine people’s perception of their environment.

Urban conservation and tree diversity: a case study in Parque Xokleng, Nova Veneza, Southern Santa Catarina

Urban forests can be defined as sets comprising vegetation fragments and isolated or grouped trees inserted in urban or peri-urban areas. Within this mosaic, urban fragments are important for biodiversity conservation. The aim of this study is to contribute to the knowledge about the structure of vegetation in an urban forest in the town of Nova Veneza, Santa Catarina, Brazil. The study was conducted in the Parque Natural Municipal Xokleng (PNMX). A phytosociological survey was conducted in the forest, using the plot method, in which 30 continuous plots of 10 m x 10 m were established. We considered a tree every individual that had a diameter at breast height greater than or equal to 5 cm. In this study, 497 individuals belonging to 75 species and 32 families were sampled, along with 14 dead individuals, three individuals identified only at genus level, and one unidentified individual. The species with the highest importance values were Tetrorchidium rubrivenium, Machaerium stipitatum, Ficus adhatodifolia, Cabralea canjerana, Mollinedia triflora. The vegetation structure is similar to the structure observed in other secondary forest fragments in the southern region of Santa Catarina. The presence of secondary species in the canopy and with high dominance values reflects the regeneration process the forest is undergoing.

PHYTOSOCIOLOGICAL CHARACTERIZATION OF AN URBAN FRAGMENT OF INTERIOR ATLANTIC FOREST - PARANÁ, BRAZIL

The Parque Natural Municipal Paulo Gorski, located in western Paraná, comprises an urban remnant of Mixed Ombrophilous Forest. This study aimed to identify tree species and conduct the phytosociological characterization of this fragment of the Atlantic Forest. Monthly visits were made in ten plots (20 x 5 m) to collect fertile samples. A rarefaction curve was generated, and phytosociological parameters, diversity, and the distribution of individuals in diameter classes were calculated. A total of 158 tree individuals were sampled, distributed across 23 families and 47 species (including six exotic ones). Among the species found, 74.4% exhibited zoochoric dispersion syndrome, 19.1% anemochoric, and 6.5% autocoric. Concerning successional category, 63.8% were early successional species. Alchornea triplinervia (Spreng.) Müll.Arg. and Prunus myrtifolia (L.) Urb. had the highest importance values due to their high number of individuals, greater frequency, and basal area. Araucaria angustifolia (Bertol.) Kuntz, an endangered species, also had a high importance value. The Shannon diversity index was 3.43, and evenness was 0.89. Approximately 70% of the individuals were distributed in smaller diameter classes (< 15 cm), forming an inverted J-shape, an expected pattern indicating a regenerative capacity and structure of preserved forest remnants, despite being in an urban area and facing significant human pressures. This urban forest fragment should be preserved, as it contains native and endangered tree species from the region, serving as an ecological corridor, and maintains important ecological and social functions for the region.

The structure of plant-herbivore interactions in urban savanna fragments reveals an unexpected high specialization and dependency on plant and insect attributes

The structure of plant-herbivore interactions in urban savanna fragments reveals an unexpected high specialization and dependency on plant and insect attributes

City configurations to optimise pedestrian level ventilation and wind comfort

Mediterranean coastal cities encounter two conflicting urban environmental challenges. First, strong winds that pose a risk of pedestrian wind discomfort on coastal streets, and second, weak winds that lead to inadequate outdoor ventilation in inner urban fragments. This study aims to optimise pedestrian level ventilation and wind comfort in Izmir, a compact coastal city in the Mediterranean climate. Three hypothetical city configurations were created based on four morphological parameters: street layout, urban street canyon form, tower layout, and tower height variation. Computational fluid dynamics simulations of the city configurations were performed and validated by wind tunnel experiments. The weak, comfortable, and strong winds were determined and mapped at the pedestrian level to assess each city configuration's performance. The results show that using the strategy of a shifted coastal street layout with adding towers on second-row blocks results in a 20 % reduction of the maximum wind velocity ratio on coastal streets compared to a grid street layout without towers. Moreover, positioning step-up towers on step-up city blocks and shifted towers on step-down city blocks can increase pedestrian-level ventilation efficiency by up to 73 %. The research methodology and findings can be transferred to other climates and urban environments and guide urban designers.

Ecology of the Arboreal Vegetation of the Cerrado in Urban Area, Palmas – Tocantins

Objective: To investigate the floristic diversity in three remaining urban forest fragments in Palmas, Tocantins, aiming to understand the structure and floristic composition and their importance for urban biodiversity conservation. Theoretical Framework: Based on concepts of phytosociology and biodiversity conservation, highlighting the importance of urban fragments for the preservation of native flora and the challenges posed by increasing urbanization. Method: Setup of 10 plots, each measuring 20x50 meters in the three studied fragments. All individuals with a circumference at breast height (CBH) equal to or greater than 10 cm were sampled. The phytosociological data were collected and analyzed using FITOPAC software. Results and Discussion: A total of 1,346 individuals belonging to 67 species and 44 families were found. The observed phytophysiognomies were cerrado sensu stricto and cerradão. The species Connarus suberosus, Caryocar brasiliense, and Qualea parviflora showed higher occurrence and wider distribution. These results reflect the richness and diversity that can be found in remaining fragments of the Cerrado. Research Implications: The practical and theoretical implications of this research are discussed, providing results that influence conservation practices and sustainable management in urban areas. Originality: Universidade Federal do Tocantins, Palmas, Tocantins, Brasil. Value: This study contributes to the literature by providing a detailed analysis of the floristic composition of urban fragments of the Cerrado, highlighting their importance for biodiversity conservation in urban areas. The relevance of this research is evidenced by the proposed strategies for the preservation of native species in Palmas' urbanization plan.

Effect of urbanisation on feces deposited across natural urban forest fragments

Effect of urbanisation on feces deposited across natural urban forest fragments

Urban Green Infrastructure Connectivity: The Role of Private Semi-Natural Areas

Green spaces and blue spaces in cities provide a wealth of benefits to the urban social–ecological system. Unfortunately, urban development fragments natural habitats, reducing connectivity and biodiversity. Urban green–blue infrastructure (UGI) networks can mitigate these effects by providing ecological corridors that enhance habitat connectivity. This study examined UGI connectivity for two indicator species in a rapidly developing city in the southern United States. We mapped and analyzed UGI at a high resolution (0.6 m) across the entire city, with a focus on semi-natural areas in private land and residential neighborhoods. Integrating graph theory and a gravity model, we assessed structural UGI networks and ranked them based on their ability to support functional connectivity. Most of the potential habitat corridors we mapped in this project traversed private lands, including 58% of the priority habitat for the Golden-cheeked Warbler and 69% of the priority habitat for the Rio Grande Wild Turkey. Riparian zones and other areas with dense tree cover were critical linkages in these habitat corridors. Our findings illustrate the important role that private semi-natural areas play in UGI, habitat connectivity, and essential ecosystem services.

Local factors influence the wild bee functional community at the urban-forest interface

IntroductionUrban forests provide necessary habitat for many forest-associated bee species amidst development and fragmentation. These forest fragments provide a variety of important floral and non-floral resources for bees that encompass a diversity of functional guilds characterized by size, diet breadth, nesting, sociality, origin, and seasonality. The relative importance of forest edge vs. interior habitats to these organisms is not well understood.MethodsHere, we compare bee communities between forest edge and interior locations at eight locations in Athens, GA, USA. We also explore the effects of stand structure, tree composition, ground cover type, and the presence of snags and downed wood on these organisms.ResultsWe found bee abundance and richness to be higher at the forest edge than interior with distinct community compositions at both locations. Canopy cover, invasive shrub cover, ground cover, and tree diversity influenced the observed community composition. We also determined that the most impactful functional traits influencing bee community structure in urban forest fragments were nesting substrate, origin (native or exotic to North America), sociality, and diet breadth.DiscussionOur findings will help establish the effects of local forest characteristics on the community composition, diversity, and abundance of wild bees and further our knowledge of the conservation value of urban forests for preserving wild bee communities.

Variation in the timing and duration of autumn leaf phenology among temperate deciduous trees, native shrubs and non-native shrubs.

The timing and duration of autumn leaf phenology marks important transitions in temperate deciduous forests, such as, start of senescence, declining productivity and changing nutrient cycling. Phenological research on temperate deciduous forests typically focuses on upper canopy trees, overlooking the contribution of other plant functional groups like shrubs. Yet shrubs tend to remain green longer than trees, while non-native shrubs, in particular, tend to exhibit an extended growing season that confers a competitive advantage over native shrubs. We monitored leaf senescence and leaf fall (2017-2020) of trees and shrubs (native and non-native) in an urban woodland fragment in Wisconsin, USA. Our findings revealed that, the start of leaf senescence did not differ significantly between vegetation groups, but leaf fall started (DOY 273) two weeks later in shrubs. Non-native shrubs exhibited a considerably delayed start (DOY 262) and end of leaf senescence (DOY 300), with leaf-fall ending (DOY 315) nearly four weeks later than native shrubs and trees. Overall, the duration of the autumn phenological season was longer for non-native shrubs than either native shrubs or trees. Comparison of the timing of spring phenophases with the start and end of leaf senescence revealed that when spring phenology in trees starts later in the season senescence also starts later and ends earlier. The opposite pattern was observed in native shrubs. In conclusion, understanding the contributions of plant functional groups to overall forest phenology requires future investigation to ensure accurate predictions of future ecosystem productivity and help address discrepancies with remote sensing phenometrics.

Urban Heritage, and the Theory of Fragmentation: The Development of Archaeology in the City of Turku, Finland

ABSTRACT Despite the shift from object- to landscape-based approaches in urban heritage management, the analysis of heritage as objects is still viable, as the current archaeological theories of material culture do not see objects in the same manner as the object-based approach. To reveal the broader significance of urban archaeology for the cityscape, the relationship between the discipline and urban space is analyzed in the framework of fragmentation theory. The theory is based on prehistoric archaeology but modified to describe urban archaeology and its effects in the contemporary city. It is argued that fragments, regardless of their connection with the past and their central role in heritage work, also have autonomous potential to distract and act as agents disconnected from their original objects. The creative character of urban fragments should be explored further by archaeologists and heritage management. These ideas are scrutinized using the development of urban archaeology and heritage in the city of Turku in Finland as an example.

Urban fragments or fractals of resilience? A systematic review of empirical cases of gated communities in Accra, Ghana

The development of gated communities within the urban realm in Ghana has become a major concern for urban planning and governance. As an aspect of the broader urban system, gated communities have a preponderant effect on the urban fabric and the achievement of urban resilience. Under the framework of the Sustainable Development Goals (SDGs) particularly Goal 11, resilience has become the preoccupation of urban planning and governance. Also, there is the realization that resilient communities are building blocks of a resilient and sustainable city. The paper argues that despite the increase in scholarship on gated communities in Ghana, no attempt has been made to relate the development of gated communities to urban resilience in spatial and temporal scales. Therefore, using systematic review methodology, the paper assessed the gated communities and urban resilience nexus in the rapidly urbanizing city of Accra, Ghana. The results revealed a dichotomous stance which portrays gated communities as both drawbacks (fragments) and promoters (fractals) of urban resilience. The paper further proffers policy recommendations and highlights empirical gaps pertaining to the gated community and urban resilience discourse in Ghana.

Biotransformation of monoterpenes using Streptomyces strains from the rhizosphere of Inga edulis Martius from in an Amazonian urban forest fragment

To investigate the biocatalytic potential of Amazonian actinomycetes for monoterpenes biotransformation. To carry out the present study, eleven actinomycetes of the genus Streptomyces isolated from inga-cipó (Inga edulis Mart.) rhizospheres were tested for their ability to bioconvert the substrates R-(+)-limonene, S-(-)-limonene, 1S-(-)-α-pinene, and (-)–β–pinene as sole carbon and energy source. According to gas chromatography-mass spectrometry analysis, three strains, LabMicra B270, LaBMicrA B310, and LaBMicrA B314, were able to biotransform 1S-(-)-α-pinene after 96 h of growth. However, Streptomyces LaBMicrA B270 was the most promising since it converted after only 72 h all the 1S-(-)-α-pinene mainly into cis-verbenol (74.9±1.24%) and verbenone (18.2±1.20%), compounds that have important biological activities and great industrial interest as additives in foods and cosmetics. These findings can stimulate the development of natural aromas using naturally abundant monoterpenes, ratify the potential of microorganisms from almost unexplored niches such as the Amazonian rhizosphere, and reinforce the importance of preserving those niches.

Carbon and nitrogen stock in soils of subtropical urban forests: Isotopic δ13C and δ15N indicators for nature-based solutions in a megacity

Urban forest soils play a pivotal role in enhancing the environmental sustainability of cities, contributing to various natural processes, including plant–microbe interactions, microbial activity, and the decomposition of organic matter. Consequently, urban forest soils emerge as effective NBS, underscoring their potential to mitigate environmental challenges and foster sustainable urban ecosystems. In these sense, this manuscript aimed at evaluating how soil attributes of the urban forests of São Paulo, Brazil, with different adjacent land uses, influence the capacity to store the excess of C and N from anthropogenic emissions, making this ecosystem an important reservoir of urban anthropogenic emissions. Three hundred urban forest soil samples were collected from the surface to a depth of 50 cm. All samples were analyzed for C and N content (and their stable isotopes). In addition, granulometric tests were also carried out to classify the soils. It was found that the most central forest fragment has the highest C and N contents at all analyzed depths, probably due to the association with physical aspects of soil texture. For all layers, the most central fragment soil sample, the only one with a clay soil, presented approximately twice as many elements when compared to the soil samples of the other sites. In general, C and N stocks (and their stable isotopes, δ13C and δ15N, respectively) varied significantly in forests located in the center-periphery direction (%N - F = 24.58, p < 0.05; %C - F = 22.48, p < 0.05; δ15N - F = 4.27, p < 0.05; δ13C - F = 19.8, p < 0.05; C/N - F = 14.56, p < 0.05). This more central forest fragment with higher vehicle emissions showed greater potential to store these atmospheric elements and with greater neutralizing efficiency than the other forest fragments. δ13C and δ15N contents together with the C:N ratio indicated the efficiency of biogeochemical cycling, through decomposition, in different urban forest fragments. More peripheral fragments showed high efficiency in C and N cycling along the analyzed soil profiles, while in the most superficial layer, the most central fragment was highly efficient. These shed light results how integrating NbS principles into strategic urban planning and city-level climate policies can bolster the effectiveness of urban green areas. The integration not only promotes carbon sequestration and efficient nutrient cycling in the soil but also fosters sustainable practices, contributing to a more resilient urban landscape.

Characterizing spring phenology in a temperate deciduous urban woodland fragment: trees and shrubs.

Phenological research in temperate-deciduous forests typically focuses on upper canopy trees, due to their overwhelming influence on ecosystem productivity and function. However, considering that shrubs leaf out earlier and remain green longer than trees, they play a pivotal role in ecosystem productivity, particularly at growing season extremes. Furthermore, an extended growing season of non-native shrubs provides a competitive advantage over natives. Here, we report spring phenology, budburst, leaf-out, and full-leaf unfolded (2017-2021) of a range of co-occurring species of tree (ash, American basswood, red oak, white oak, and boxelder) and shrub (native species: chokecherry, pagoda dogwood, nannyberry, American wild currant and Eastern wahoo, and non-native species: buckthorn, honeysuckle, European privet, and European highbush cranberry) in an urban woodland fragment in Wisconsin, USA, to determine how phenology differed between plant groups. Our findings show that all three spring phenophases of shrubs were 3weeks earlier (p < 0.05) than trees. However, differences between shrubs groups were only significant for the later phenophase; full-leaf unfolded, which was 6days earlier (p < 0.05) for native shrubs. The duration of the spring phenological season was 2weeks longer (p < 0.05) for shrubs than trees. These preliminary findings demonstrate that native shrubs, at this site, start full-leaf development earlier than non-native species suggesting that species composition must be considered when generalizing whether phenologies differ between vegetation groups. A longer time series would be necessary to determine future implications on ecosystem phenology and productivity and how this might impact forests in the future, in terms of species composition, carbon sequestration, and overall ecosystem dynamics.

Correction to: Reptile responses to outdoor recreation in urban habitat fragments

Correction to: Reptile responses to outdoor recreation in urban habitat fragments