Urban Fragments Research Articles

Forms and patterns of mixticity in compact cities. Mixed-use synergies in the Sagrada Familia neighbourhood of Barcelona

ABSTRACT This article explores empirical and objective approaches to combinations of non-residential activities in contemporary urban settings. The research measures the mix of uses in compact cities through the analysis of an urban fragment of Barcelona with high population density that is strolled around daily by thousands of tourists and intensified by a unique combination of daily services, commercial uses and productive activities. The resulting cartography offers a parametric interpretation at the scale of plots, blocks and streets, and establishes some tools to better understand the spatial relations of urban functional mix and proximity.

Experience in Design-Plastic Modelling of the Light Environment: Part 2. Space and Light as Fragment of the Urban Environment

The article presents a technique for creating a plastic and design-plastic light-spatial model based on the layout of the urban environment fragment. It also describes how this model corresponds to electrical lighting parameters. The paper formulates the tasks and potential of plastic and design-plastic light modelling and their role in the concept-based search and educational design of lighting solutions. In terms of this article, the plastic model is understood as a layout that exaggeratedly or generically reveals the spatial characteristics of an urban fragment. The design-plastic model is more detailed; it reveals the features of functioning of the latter both in daylight and in electrical lighting. The final stage of educational light modelling is the creation of a computer model of electrical lighting of an environmental situation. The authors of this paper studied the tools of electrical lighting and their role in identifying the device of the environmental fragment, in light routes creation and in scenario of the visual form of urban space. Conclusions are given on the further development of the methodology in the field of lighting design, including the assessment of the emotional perception of the architectural environment objects under electrical lighting. The results of this research were then applied as the basis for the practical project work of students who won the competition “Russian Lighting Design” in 2018.

Urban Industries and the Production of Urban Form

The proposed paper aspires to provide a typomorphological analysis of patrimony of industrial activity in the urban fabric of a productive hotspot of the Brussels Capital Region. The research fits within a larger PhD-track on the sustainable retrofit of such productive activities in this region.
 Due to zoning policies and increasing real estate pressure on urban land, a major part of the space-extensive productive activities has disappeared from Brussels’ urban areas, taking jobs and artisanal knowledge towards monotonous enclaves in the outskirts. Whereas European cities were rich in productive activities, they now mostly host consumption. This is problematic. Urbanists, architects and policy makers plead for the inversion of this process by reintegrating industrial enterprises in the urban fabric.
 Despite the observed shrinkage in the amount of active urban industries, a GIS informed hotspot analysis revealed a concentration in the Jette-Koekelberg area. The presented work therefore provides a typomorphological study of the patrimony of these remaining structures. In this light, the analysis is performed at different scales in order to bridge between the urban form and the architectural type. The studied area is therefore decomposed into the analysis of its urban fragments, building blocks and parcels.
 Informed by the logical classification of these productive urban artefacts at different scales, this paper aspires to obtain insights on their typomorphological setup. Deploying this approach which is mainly focused on the residential use, to a mixed-use area, unveils strongholds and alterations on basic types in the urban fabric. In doing so, this investigation attempts to inform the ongoing planning debate on productive cities and mixed-use development by looking specifically at the existing built environment: urban form and building types. Despite the large interest in productive cities, this has not yet been treated systematically.

Strong relationships between urbanization, landscape structure, and ecosystem service multifunctionality in urban forest fragments

Urban forest fragments are highly multifunctional and provide many ecosystem services to people. However, the expansion and densification of cities is threatening this particular type of urban forest, resulting in further fragmentation, degradation and a change in forest function. Understanding how urbanization affects urban forests fragments and the multiple ecosystem services they provide is important for the creation of livable cities. We used an urban-to-rural gradient in Maple Ridge, Canada, to explore relationships between urban forest structure, urbanization, surrounding landscape structure, and the supply of eight different ecosystem services, including merchantable timber, carbon storage, flood control, food (berries), non-native shrub control, cultural use, and habitat provision. We found that the supply of multiple ecosystem services was higher at the rural end of our gradient and that forest fragments spaced closer together showed strong negative associations with most services. Crucially, forest fragment size had very weak effects on most services, emphasizing the importance of conserving small urban forest fragments with large trees. We also identified key tree genera, including Picea and Thuja, that could be retained or planted in urban forests to maximize individual services and multifunctionality. Our results highlight the potential for strategically managing urban landscapes to maintain forest fragments and enhance their ability to provide ecosystem services and multifunctionality. Our findings are relevant to inform urban conservation and greening strategies in cities around the world that are currently expanding into surrounding forests or losing greenspace through densification.

Sampling techniques and environmental variables influence the distribution of pseudoscorpions in urban forest fragments in the central Amazon

ABSTRACT The growth of urban landscapes has genarally reduced biodiversity worldwide. Invertebrates have explored different environments, and it usually takes different sampling techniques to get a representative sample of the species assemblage in a given location. Some studies have sought to determine the minimum necessary number of sampling techniques, including ecological relationships or costs to guide the sampling protocol. In the Amazon, the effect of soil characteristics on invertebrate distribution is well known. We evaluated if sampling techniques have a complementary effect on the detection of pseudoscorpion assemblages and tested whether environmental variables affect the distribution of pseudoscorpion species. The study sites were two urban forest fragments in the city of Manaus, in the central Amazon. In each fragment, we sampled 20 palm trees using the beating technique, and installed transects with 12 sampling points for collection of soil and litter samples for extraction of arthropods in a Berlese funnel and a Winkler extractor, respectively. We collected 267 individuals of 11 species of pseudoscorpions. Most records were obtained through the Winkler extraction in both fragments. The assemblage from the palm trees was different from that in the edaphic samples. Pseudoscorpion species composition also differed significantly between soil and litter, and was influenced by potassium concentration. The number of species in the fragments and the environmental effect on the distribution of pseudoscorpions was similar to that recorded in environmental protection areas, evidencing that urban forest fragments can serve as an efficient repository of Amazonian pseudoscorpion biodiversity.

Filtros ambientais urbanos na movimentação de aves e morcegos em uma cidade média do Sul do Brasil

Urbanization causes drastic changes in the diversity and distribution of many species in Brazil, there are insufficient data on the accessibility and quality of urban forest fragments for wildlife. Thus, we estimated the proportion of bird and bat species barred from entering the intra-urban area of Ponta Grossa (PR) through a multiscale study of landscape and vegetation quality in the core area and the avian and chiropteran fauna present. Phytosociological analyses were carried out by means of tree and shrub vegetation plots in three urban parks. Bird surveys were carried out in a non-systematic manner over 12 months at dawn and dusk at potential birding sites in the urban area. Data on bats were obtained from the literature on local sampling in the urban area. Finally, landscape fragmentation metrics were calculated to assess the resistance of urban areas to the transit of the target species. A total of 142 shrub and tree taxa were surveyed in forested urban remnants, with diversity H' ranging from 3.68 to 3.87. This vegetation supported 62 species of birds and 8 bats, exceeding the literature estimative. The urban space is frequented by 37% of the regional avifauna and 50% of the regional chiropterofauna. The forest fragments have significant areas with a good supply of resources, close enough to connect these populations. However, the species observed are mostly generalists due to the poverty of the transition area corridors, which causes those peri-urban source areas could strongly select species adapted to environments subjected to edge effects. An integrated analysis of the vegetation cover of riparian areas, street trees, and backyard vegetation could point out the bottlenecks that urban planning should focus on to increase the environmental quality of the urban area.

Urban forest fragments vs residential neighborhoods: Urban habitat preference of migratory birds

Both residential areas and urban forest fragments can provide stopover habitat for migrating birds. However, it is not clear which migrant species use urban forest fragments versus residential areas. Objectives for this study were to determine: (1) which species primarily use urban forest fragments versus adjacent residential areas during migration; (2) whether birds in different vertical strata guilds (canopy and under canopy) are associated with urban forest fragments versus residential areas, and which vegetation characteristics are important for certain species that preferentially utilize one habitat over the other. Conducted in Gainesville, Florida, 39 random point counts were situated in urban forest fragments, adjacent residential areas, and forest-residential edges during spring and fall migration. We recorded 44 migrant species across all point counts. Ten (38%) under-canopy birds significantly preferred urban forest fragments compared to residential neighborhoods. Canopy birds typically used forest fragments and residential areas more equally, with only one species showing significant preference for the residential habitat. Residential neighborhoods that retain vertical vegetation structure were more likely to have more species of birds. These results show the importance of conserving and restoring certain vegetative characteristics in urban ecosystems: preserving large trees in residential neighborhoods, retaining small forest remnant patches throughout the urban matrix, and increasing vertical vegetation structure in yards. These practices will help provide avian habitat during migration, increasing avian diversity in urban areas.

Novel Ehrlichia and Hepatozoon genotypes in white-eared opossums (Didelphis albiventris) and associated ticks from Brazil

White-eared opossums (Didelphis albiventris) are well adapted to anthropized areas. The increased contact with domestic animals and humans mediates the transmission of arthropod-borne pathogens. Despite the worldwide occurrence of tick-borne Anaplasmataceae and Hepatozoidae species in a variety of vertebrates, few studies reported serological evidence or molecular detection of theses agentes in marsupials. Up to now, while Ehrlichia/Anaplasma spp. have only been detected in marsupials from Brazil, Hepatozoon spp. have been reported in marsupials from Chile, Australia and Brazil. The present work aimed to investigate, using molecular techniques and blood smear analysis, the presence of Ehrlichia spp., Anaplasma spp., and Hepatozoon sp. in the blood and ticks collected from D. albiventris in urban forest fragments from midwestern Brazil. Between May and December 2017, 43 D. albiventris (27 males and 16 females) were captured for blood and tick collection in the city of Campo Grande, state of Mato Grosso do Sul, midwestern Brazil. Ticks (46 Amblyomma dubitatum nymphs and 24 Amblyomma spp. larvae) were collected from 14 out 43 (32.5%) of the white-eared opossums. Panoptic-stained blood smears were performed using peripheral blood (tail tip) of the captured opossums. DNA extracted from blood and tick samples were subjected to PCR/qPCR assays for Anaplasmataceae agents (rrs, gltA, groEL, sodB, and dsb genes, and 23S-5S intergenic region) and Hepatozoon spp. (18S rRNA gene), followed by Sanger sequencing, BLASTn and phylogenetic analyses. An inclusion resembling Ehrlichia morulae was found in a white-eared opossum's monocyte from a blood smear stained with Panoptic. Five (11.63% [5/43]) white-eared opossums’ blood samples and 7 (25% [7/28]) tick samples (2 pools of Amblyomma spp. larvae and 5 pools of A. dubitatum nymphs) were positive for Anaplasmataceae via a PCR assay targeting the conserved rrs gene. Phylogenetic analysis based on the rrs gene positioned three sequences obtained from opossums and ticks together as a subclade within the Ehrlichia canis clade. However, all samples were negative in a qPCR assay specific for E. canis based on the dsb gene. Phylogenetic analyses positioned the gltA and 23S-5S ITS sequences obtained from opossums’ blood samples in a separate clade from the other validated Ehrlichia species. One (2.3% [1/43]) opossum blood sample was positive for the 18S rRNA gene of Hepatozoon sp. The phylogenetic analysis positioned the Hepatozoon sp. sequence obtained from a D. albiventris specimen in a clade with a sequence previously detected in a black storm petrel (Oceanodroma melania) from Mexico. All the other sequences of Hepatozoon sp. previously detected in marsupials from Brazil were positioned in a separated clade. The present work showed the occurrence of putative novel genotypes of Ehrlichia sp. and Hepatozoon sp. in white-eared opossums and associated A. dubitatum ticks from midwestern Brazil.

Influence of urban noise in call traits of the Atlantic Forest treefrog Bokermannohyla hylax

Anurans commonly use sound signals as the main form of communication. This system is diverse in both structure and social functions, and can be used from mate recognition until evaluation of conspecifics. Consequently, when in noisy environments, the main constraint is to correctly identify acoustic signals. Thus, this study aims to evaluate the influence of traffic noise in call parameters of Bokermannohyla hylax. We recorded individuals in collecting sites closer and further from the boulevard, inside the area of Parque Estadual das Fontes do Ipiranga, an urban Atlantic Forest fragment at municipality of São Paulo, Brazil. We evaluated if noisy or silent collecting sites influence temporal and spectral variables and signal-to-noise ratio. As expected, we observed influence of collecting site on temporal variables and on signal-to-noise ratio, but not on spectral variables. Spectral traits, unlike temporal ones, are more related to intrinsic aspects of individuals, and consequently they tend to present limited or no modification in face of anthropogenic noise. We also observed an influence of traffic noise on signal-to-noise ratio, which means that if the traffic noise is more intense, individuals increased calling power amplitude. This increase has several implications in different aspects of the life of individuals, even influencing the spent of energy in other anuran life story traits. Consequently, traffic noise can impact the long-term permanence of the species in highly noisy environments.

How can forest fragments support protected areas connectivity in an urban landscape in Brazil?

Cities continue to grow worldwide, and the highly modified urban landscape becomes an inhospitable environment for many species because the natural vegetation cover is commonly fragmented, and the remnants are often isolated. Protected Areas (PAs) located surrounding or within urban areas may not achieve their goal of protecting local or regional biodiversity. Thus, an urban ecological network is essential to support their PAs. Thus, this study aimed at assessing the PAs connectivity in an urban landscape in Brazil and understanding whether urban forest fragments can support an urban ecological network. Besides spatial models based on functional connectivity and graph theory, we used participatory techniques to design the resistance surface and the least-cost paths (LCPs) for Atlantic Forest birds. The results showed critical paths (LCPs), important areas for restoration programs for improving PAs connectivity, and essential forest fragments for conservation and restoration. Although the landscape has a forest structure with 1873 forest fragments and 516 links through which the LCPs were structured, most forest fragments and LCPs cannot provide the necessary support for the PAs connectivity. The current ecological network is dependent on forest fragments neighboring (outside PAs) and the flux dispersions occurred mainly in the peri-urban areas. Riparian zones and anthropic grasslands also showed importance for the PAs connectivity. We identified only 28 forest fragments spatially connected, presenting several sizes, and located near large forest areas, relevant PAs, and riparian zones. Six of these forest fragments, smaller than ten hectares and strategically located in the urban matrix, were indicated for restoration actions. The current low connectivity among PAs brings the importance of native vegetation restoration in the riparian zone and anthropic grassland and the importance of the periurban areas to promote biodiversity connectivity in the urban landscape.

Remarkable Resilience of Forest Structure and Biodiversity Following Fire in the Peri-Urban Bushland of Sydney, Australia

In rapidly urbanizing areas, natural vegetation becomes fragmented, making conservation planning challenging, particularly as climate change accelerates fire risk. We studied urban forest fragments in two threatened eucalypt-dominated (scribbly gum woodland, SGW, and ironbark forest, IF) communities across ~2000 ha near Sydney, Australia, to evaluate effects of fire frequency (0–4 in last 25 years) and time since fire (0.5 to >25 years) on canopy structure, habitat quality and biodiversity (e.g., species richness). Airborne lidar was used to assess canopy height and density, and ground-based surveys of 148 (400 m2) plots measured leaf area index (LAI), plant species composition and habitat metrics such as litter cover and hollow-bearing trees. LAI, canopy density, litter, and microbiotic soil crust increased with time since fire in both communities, while tree and mistletoe cover increased in IF. Unexpectedly, plant species richness increased with fire frequency, owing to increased shrub richness which offset decreased tree richness in both communities. These findings indicate biodiversity and canopy structure are generally resilient to a range of times since fire and fire frequencies across this study area. Nevertheless, reduced arboreal habitat quality and subtle shifts in community composition of resprouters and obligate seeders signal early concern for a scenario of increasing fire frequency under climate change. Ongoing assessment of fire responses is needed to ensure that biodiversity, canopy structure and ecosystem function are maintained in the remaining fragments of urban forests under future climate change which will likely drive hotter and more frequent fires.

Seed rain in two areas with different relief types in a tropical rainforest

Seed rain participates in species enrichment during the natural regeneration of terrestrial ecosystems, as this ecological process promotes gene flow and the maintenance of forest biodiversity. However, few studies assessed variations in seed rain related to environmental heterogeneity inside forests. We studied the influence of relief (flat or slope areas) on the seasonal and monthly variation in density, floristic composition, and richness of the seed rain in an urban fragment of Atlantic Forest. We carried out the present study in Rain Tropical Forest, Northeastern Brazil. We selected two areas within the fragment: one with flat relief and the other on a slope. In each relief type we set up 20 0.25-m2 seed collectors, in a total of 40 units, to quantify seed rain. After ten months of study, we counted 9,474 seeds: 8,061 in the flat area and 1,413 in the slope area. There were significant differences in dispersal syndromes and plants habit between relief types. The seed density in the flat area differed between seasons and the species richness varied seasonally in both areas. There were variations in floristic composition between seasons in the flat and slope areas. Seed density was higher in December and January in the flat area. Differences in seed rain suggest that it is influenced by spatial heterogeneity and climate seasonality, and that the areas with different kinds of relief are important for the biodiversity conservation.

Time budget and foraging strategies of two provisioned groups of tufted capuchin monkeys, Sapajus libidinosus, in a small, seasonal urban forest fragment.

Studies of urban monkeys provide important insights into the behavioral flexibility of primate species. We studied two provisioned groups of capuchin monkeys that inhabit a small forest fragment in the city of Goiânia, Brazil. One of the groups was dominant and had priority of access to both native and provisioned resources. Anthropic resources were available in two relatively small areas within this forest, but varied in their quality. We hypothesized that intergroup dominance and the seasonality of native resources would have different impacts on the foraging strategies and use of space by the two study groups. Data on the location of the members of the two groups, their behavior, and consumption of different food items were collected during five dry season and five rainy season months. The members of the dominant group spent more time in the provisioned area where anthropic food was less costly to obtain and consumed more provisioned fruit and vegetables than the members of the subordinate group. The differences between groups were exacerbated during the dry season, when sources of native fruit were less abundant. The results of the present study illustrate how capuchins may respond to the variation in proximate factors, such as intergroup dominance and seasonality. These factors were determinants to the variation in the diet and the use of space observed between the two study groups.

Urine washing in urban robust capuchin monkeys (Sapajus sp.): The relation with visitors.

In primates, urine washing (UW) is a behavior in which individuals intentionally deposit urine on their bodies. Social and nonsocial hypotheses have been proposed to explain the adaptive function of this behavior. For capuchins, different functions have been assigned for UW, suggesting it as a flexible behavior, but studies have been mainly in captivity. However, no investigations have been performed in urban environments, where these animals can modify their behavior. Our goal was to study UW in a semi-provisioned group of an introduced unknown robust capuchin species (Sapajus sp.) living in a tiny urban fragment in Foz do Iguaçu, Brazil, where they have contact with humans. We assessed the influence of social (sexual, agonistic, and anointing behaviors) and environmental (temperature, relative air humidity, height of the monkeys in the trees, number of people present in the fragment, and human-monkey interactions) variables, the influence of behavior before and after UW, and the influence of sex-age classes, on the frequency of UW. We observed 75 records of UW in 300 h of observations, where urine was mostly deposited on hands and passed on to feet (95%). There were no significant differences in the frequency of the behavior between sex-age classes nor in the behaviors before and after UW. Around 50% of UW took place in the late morning and we found no correlation between UW and temperature, relative air humidity, nor the heights of the monkeys in the trees. However, we found a significant association between UW and the daily number of people in the fragment, but not between UW and human-monkey interactions, anointing, agonisms, and sexual behavior. Our study increases the scope of UW flexibility by identifying the presence of visitors affecting the occurrence of this behavior. We discussed different possibilities through which people could influence the capuchins to display UW.

The role of urban savannah fragments and their characteristics for the conservation of ants (Hymenoptera: Formicidae) in central Brazil

The role of urban savannah fragments and their characteristics for the conservation of ants (Hymenoptera: Formicidae) in central Brazil

Birds in the ‘Burbs’: Do migratory birds prefer urban forest fragments or residential yards?

During migration, birds travel from their northern breeding grounds to their southern wintering grounds and vice versa. To understand which urban habitats are valuable for specific migratory species, we compared the diversity of migratory bird species that used urban forest fragments vs residential areas with tree canopy in Gainesville, Florida. Study results summarized in this fact sheet can help inform urban planners, developers, and homeowners about vegetation migratory birds use. Conservation of large, forested areas is important, but fragmented landscapes are not useless, and conserving urban forest fragments and trees in residential areas is also important for bird conservation.

Urbanization increases floral specialization of pollinators.

Understanding how urbanization alters functional interactions among pollinators and plants is critically important given increasing anthropogenic land use and declines in pollinator populations. Pollinators often exhibit short‐term specialization and visit plants of the same species during one foraging trip. This facilitates plant receipt of conspecific pollen—pollen on a pollinator that is the same species as the plant on which the pollinator was foraging. Conspecific pollen receipt facilitates plant reproductive success and is thus important to plant and pollinator persistence. We investigated how urbanization affects short‐term specialization of insect pollinators by examining pollen loads on insects’ bodies and identifying the number and species of pollen grains on insects caught in urban habitat fragments and natural areas. We assessed possible drivers of differences between urban and natural areas, including frequency dependence in foraging, species richness and diversity of the plant and pollinator communities, floral abundance, and the presence of invasive plant species. Pollinators were more specialized in urban fragments than in natural areas, despite no differences in the species richness of plant communities across site types. These differences were likely driven by higher specialization of common pollinators, which were more abundant in urban sites. In addition, pollinators preferred to forage on invasive plants at urban sites and native plants at natural sites. Our findings reveal indirect effects of urbanization on pollinator fidelity to individual plant species and have implications for the maintenance of plant species diversity in small habitat fragments. Higher preference of pollinators for invasive plants at urban sites suggests that native species may receive fewer visits by pollinators. Therefore, native plant species diversity may decline in urban sites without continued augmentation of urban flora or removal of invasive species.

The probability of occurrence of disperser and pollinator birds in urban riparian forests

Riparian forests are important for their ecological function and provision of services regarding the maintenance of water resources and wild fauna. Paradoxically, it is one of the ecosystems that suffer most from anthropization, especially urbanization. Thus, our objective was to compare the probability of occurrence of pollinating and dispersing species in two areas of riparian forest, where the periurban fragment is inserted in an area with patches of forest remnants and the urban fragment, an area of forest remnant located in a heavily constructed region. From the results obtained, we note that the riparian forest area considered preserved had the highest occurrence of dispersers, while the area inserted in the urban matrix had the highest occurrence of pollinators. In this way, it was possible to observe that the most preserved area showed greater equality between the groups, with a greater number of dispersers. Still, riparian forest isolated by strong urbanization showed that dispersers had a low frequency of occurrence, an essential function in the renewal and continuity of riparian forest in the future.

Predator-Prey Dynamics Are Decoupled in the Raptor Community in a Large Urban Forest

Predator-prey dynamics are fundamental in shaping and regulating wildlife communities; however, these relationships are often altered by urbanization. An urban predation paradox, where predation rates are lower in urban areas despite an increase in predator abundance, has been observed in some predator communities. We looked for evidence of an urban predation paradox in a raptor community in a large urban forest fragment in north Texas, USA. From May–August 2019, we conducted weekly raptor surveys and deployed prey mimics along an urban-to-rural gradient within the forest fragment. We examined relationships between predation rates on mimics, predator abundance, and urbanization intensity using a variety of statistical tests. We detected 161 raptors representing eight species and found that raptor activity was significantly higher in our low urbanization sites. Of the 732 prey mimics deployed, 61 were attacked, and we found no relationship between predation rates and urbanization. Furthermore, we found no relationship between raptor activity and depredation events. Although we failed to find evidence for an urban predation paradox, our results showed a decoupling of the relationship between the abundance of predators and prey in this urban setting. The use of prey mimics is a useful tool for assessing predator-prey dynamics, and more research is necessary to fully understand the impacts of urbanization on this important ecological process.

Ecological Networks in Urban Forest Fragments Reveal Species Associations between Native and Invasive Plant Communities.

Forest fragments are characteristic features of many megacities that have survived the urbanisation process and are often represented by unique assemblages of flora and fauna. Such woodlands are representations of nature in the city—often dominated by non-native and invasive species that coexist with resilient native congeners and purposefully introduced flora. These forest fragments also provide significant ecosystem services to urban society and therefore, understanding their compositional patterns is of considerable importance for conservation and management. In this work, we use a complex network approach to investigate species assemblages across six distinct urban forest fragments in the South Delhi Ridge area of the National Capital Territory, India. We generate bipartite ecological networks using conventional vegetation sampling datasets, followed by network partitioning to identify multiple cliques across the six forest fragments. Our results show that urban woodlands primarily form invasive–native associations, and that major invasive species, such as Prosopis juliflora and Lantana camara exclude each other while forming cliques. Our findings have implications for the conservation of these urban forests and highlight the importance of using network approaches in vegetation analysis.