Urban Edge Research Articles

A categorization of gated eco-developments in South Africa

ABSTRACT Gated communities have evolved into providing unique residential offerings aimed at specific markets. Eco-estates and eco-friendly estates are examples of such niche estates which have witnessed increasing growth in their development throughout South Africa. This paper overviews the literature on the evolution of gated communities and provides a spatial articulation of the location of eco- and eco-friendly estates in South Africa towards creating a categorization of eco-developments. The study is positioned in the theoretical realms of eco-form and eco-urbanism which scaffold the global surge in eco-developments. A database of eco-developments in South Africa was created from several sources and surveys were conducted among developers and estate managers of such developments. The locational analysis shows most eco-developments being located in the Western Cape, Gauteng and KwaZulu-Natal, while more than half of the proposed developments were destined for the remaining provinces. Eco-estates and eco-friendly estates show a predilection for sites on the urban edge, along the coast or with mountain views. Criteria based on eco-practices were selected as standards for a five-category continuum of eco-estates. When applied the categorization confirms that eco-developments display differing levels of eco-ness. While eco-developments do have positive ecological impacts and they do enhance sustainable living, they do not add to social connectivity as they are exclusive ecological islands surrounded by walls.

An Unsupervised Urban Extent Extraction Method from NPP-VIIRS Nighttime Light Data

An accelerating trend of global urbanization accompanying various environmental and urban issues makes frequently urban mapping. Nighttime light data (NTL) has shown great advantages in urban mapping at regional and global scales over long time series because of its appropriate spatial and temporal resolution, free access, and global coverage. However, the existing urban extent extraction methods based on nighttime light data rely on auxiliary data and training samples, which require labor and time for data preparation, leading to the difficulty to extract urban extent at a large scale. This study seeks to develop an unsupervised method to extract urban extent from nighttime light data rapidly and accurately without ancillary data. The clustering algorithm is applied to segment urban areas from the background and multi-scale spatial context constraints are utilized to reduce errors arising from the low brightness areas and increase detail information in urban edge district. Firstly, the urban edge district is detected using spatial context constrained clustering, and the NTL image is divided into urban interior district, urban edge district and non-urban interior district. Secondly, the urban edge pixels are classified by an adaptive direction filtering clustering. Finally, the full urban extent is obtained by merging the urban inner pixels and the urban pixels in urban edge district. The proposed method was validated using the urban extents of 25 Chinese cities, obtained by Landsat8 images and compared with two common methods, the local-optimized threshold method (LOT) and the integrated night light, normalized vegetation index, and surface temperature support vector machine classification method (INNL-SVM). The Kappa coefficient ranged from 0.687 to 0.829 with an average of 0.7686 (1.80% higher than LOT and 4.88% higher than INNL-SVM). The results in this study show that the proposed method is a reliable and efficient method for extracting urban extent with high accuracy and simple operation. These imply the significant potential for urban mapping and urban expansion research at regional and global scales automatically and accurately.

An investigation of convective features and Z-R relationships for a local extreme precipitation event

Considerable rainfall presented as two precipitation centers (PCs) were created by two meso-β-scale convective systems occurred at the urban edge of the Pearl River Delta over South China on 7 May 2017. In this study, precipitation features of rainy storms, vertical structures and properties of convection for two PCs (PC-1, PC-2), and preliminary correlation between minute precipitation rate (MPR) and convective intensities are investigated based on detailed observation. Results show that most of the convection (~99%) over two PCs was active below the freezing level, indicating the extreme-rain-producing convection was dominated by warm-rain processes. Discrepancies of convective and precipitation features existed between two PCs. High precipitation rate had associated with those convection with lower echo centroids and more concentrated occurrence frequency in vertical structure, which presented obviously in PC-2. Percentile above 95th of the MPR over PC-2 was remarkably higher than those over PC-1 according to the classified statistics of MPR in their key precipitation stages. The intense-to-extreme MPR (≥ 1.6 mm min−1) had more related to those moderate-to-severe convection (≥ 46 dBZ) at 0.5 km above ground level in this extreme precipitation event, implying that large-size raindrops in warm-rain processes might play an important role in producing high-efficient MPR. In addition, relatively-large biases presented in three frequently-used Z-R relationships when estimating precipitation rate for the rainfall core of PC-2. More suitable Z-R relationship was surveyed for the rainfall core in this event, in which constant values a and b were calibrated and fell at the edge of the recommended range. This suggested that suitable Z-R relationship remained possible to be developed for such an extreme precipitation event in operational nowcasting over South China.

Analysis of Rare Plant Occurrence Data for Monitoring Prioritization

Efforts to conserve rare plant species can be limited by a lack of time and funding for monitoring. Understanding species occurrence and distribution patterns within existing protected habitat and throughout the entire species range can help stewards prioritize rare plant monitoring. We created a database of rare plant occurrences from public, private, and research sources to analyze the distribution of rare plant species throughout the existing protected area within the Nature Reserve of Orange County in California, USA. We analyzed species occurrence relative to the urban edge, roads, trails, and mean high tide line. We also determined the vegetation community with the highest number of rare plant species to help prioritize habitats for conservation and restoration. We found that some parts of protected areas have more rare plant species and we also found sampling biases on the location of occurrence data. We found that rare species occur close to roads and trails and the mean high tide line. Rare species were in all vegetation communities within the reserve, including degraded areas. Using patterns of distribution and considering the immediate threats to a rare species population can help land managers and stewards prioritize monitoring toward the most threatened species.

Sister Communities: Rejecting Labels of Informality and Peripherality in Vanuatu

AbstractSome labels have dire consequences. This article takes issue with the labels commonly used to describe the physical and social location of communities living on the edge of Port Vila, Vanuatu—labels that position communities for eviction by entrenching tropes of informality and peripherality into how they are seen and represented. Such terms include informal, settlement, informal settlement, squatter and peri‐urban. Based on interviews with around 100 people and two years of ethnographic engagement with urban communities in Port Vila, Vanuatu, I critique the language of policy against the lived experience of those at the urban edge. I use Bourdieu's articulation of power as an accumulation of symbolic capital that enables one to speak the world into being. I conclude that the language of policies and plans is reflective of a dominant discourse in urban studies and international aid, and non‐reflective of the experience and identities of people living at the urban edge. My interviewees and interlocutors maintain their identities as sister communities—as places grounded in the formality of customary tenure, and as part of the city rather than outside it.

Outdoor Recreation at the Wildland–Urban Interface: Examining Human Activity Patterns and Compliance with Dog Management Policies

Recreational use of public land is high and rising. Thus, it is critical to understand the dynamics of land use at the wildland–urban interface so managers can simultaneously meet varying human needs while mitigating environmental impacts caused by recreationists and their canine companions. Using motion-activated camera surveys along official trails near the urban edge of Boulder, Colorado, we quantified daily patterns and the relative frequency of human recreational activities, with particular focus on activities involving domestic dogs (Canis lupus familiaris) and human compliance with dog regulations. We also tested hypotheses regarding potential predictors of human activity as well as predictors of human accompaniment by dogs, both on-leash and off, and user compliance with leash laws. Pedestrians used the trail system most frequently, followed by dog-walkers, mountain bikers, and recreationists of other types, with activity peaking in the mornings and evenings. Use of open space lands was primarily, and positively, predicted by the presence of scenic vistas or trails on which users could be accompanied by their dogs. Compliance with dog regulations depended on the type of policy imposed, with stricter and more consistent restrictions resulting in fewer violations. This study suggests that to maximize compliance with leash laws, consistent policies may be more effective than temporally varying leash laws. Additionally, it may be beneficial to increase enforcement at peak times for all trails, and at all times on trails where violations are more likely, such as those with seasonal leash laws.Annie Kellner, Scott Carver, Ashley Gramza, Jesse S. Lewis, Sue VandeWoude, and Kevin R. Crooks. 2017. “Outdoor Recreation at the Wildland–Urban Interface: Examining Human Activity Patterns and Compliance with Dog Management Policies.” Natural Areas Journal 37(4):515-529.

Energetics at the urban edge: Environmental and individual predictors of urinary C-peptide levels in wild chacma baboons (Papio ursinus)

As human-modified landscapes encroach into natural habitats, wildlife face a reduction in natural food sources but also gain access to calorie-rich, human-derived foods. However, research into the energetics of wildlife living within and adjacent to urban and rural landscapes is lacking. C-peptide - a proxy for insulin production and a diagnostic tool for assessing pancreatic function in humans and domestic animals - can be quantified non-invasively from urine (uCP) and may provide a way to investigate the energetic correlates of living in human-altered landscapes. UCP is increasingly used in studies of primate energetics, and here we examine predictors of variation in uCP levels in n = 17 wild chacma baboons (Papio ursinus) living at the urban edge on the Cape Peninsula, South Africa. We find that uCP was positively associated with food provisioning and negatively with night fasting. UCP levels were comparable between winter and summer but significantly lower during spring, possibly driven by consumption of energy-rich seeds during summer and more human-derived foods during winter. UCP was elevated in pregnant females and similar for lactating and cycling females. We find no effect of dominance rank on uCP. Samples collected with synthetic Salivettes had significantly lower uCP levels than directly pipetted samples. Overall, our results indicate that uCP is a reliable, non-invasive measure of energy balance and intake in baboons, and suggest potential energetic benefits of living at the urban edge. More broadly, studies of uCP may offer unique insight into the environmental control of hormone-behaviour relationships in species crossing natural and urban environments.

Caught on camera: The impacts of urban domestic cats on wild prey in an African city and neighbouring protected areas

Domestic cats (Felis catus) have contributed to the extinction of indigenous species worldwide, but impacts in Africa are unstudied. We compare prey returned home from three questionnaire surveys (2009, 2010 and 2013/14) in Cape Town, South Africa, with footage from some of the same cats wearing animal-borne video cameras (KittyCams), to assess differences in actual predation vs. returns. Cape Town borders Table Mountain National Park (TMNP), so cats may prey on animals in a protected area. Urban edge (UE) and deep urban cats (DU) did not differ in predation rates, but the suite of species killed differed significantly. KittyCams revealed that most predation was nocturnal, and only 18% of prey recorded on video were returned home, thus cats kill 5.56 times more animals (averaged across all taxa) than returns data suggest. Reptiles constituted 50% of prey, but only 17% of returns; mammals constituted 24% of prey, but 54% of returns. Non-native species represented only 6% and 17% of animals killed by UE and DU cats, respectively, pointing to a high cost of cat predation for native fauna. Applying a correction factor of 5.56, the average domestic cat in Cape Town kills c. 90 (95% CI = 59, 123), animals.year−1. Thus, the approximately 300 000 domestic cats in Cape Town kill c. 27.5 million animals.year−1, and TMNP is likely to lose c. 203 500 animals to UE cats annually from within its boundaries. The scale of this predation necessitates conservation options to minimise impacts of cats on wildlife, particularly near protected areas.

Re-locating the identity of Amman’s city through the hybridization process

PurposeThe purpose of this paper is to define the identity, city identity and architectural identity; to review, analyze and synthesize different pieces from literature to explore and define the factors that shape the city identity; to define the strategies of hybridization process that can be used to re-locate (re-define) the city identity; to examine the most effective factors that shape the identity of Amman city from various perspectives, to examine the relationships/interrelationships between all the factors that shape any city identity from the designers’ perspective, finally, to apply the strategies of hybridization process to re-locate (re-define) Amman’s city identity.Design/methodology/approachThis research used two research methods to collect data as follows: literature review, content analysis and face-face questionnaire. Descriptive statistics were used to examine the most effective factors that shape the Amman’s identity from different perspectives. The Pearson product-moment correlation coefficient (Pearson r) was computed to assess the relationships between all factors that shape the identity of any city from the perspective of Jordanian designers and experts.FindingsThis research concluded that the factors that shape the city identity are cultural factors (socio-cultural, historical, economical and globalization factors), environmental factors (geographic, climate and building materials factors) and urban and architectural factors (spatial design organization, architectural style, open spaces and parks, urban structure factors). Additionally, the six urban development factors that responsible for the hybridization process in a city are new architectural typology and new special configuration, urban edges and hybrid textures, public hybridization open spaces, roads highway-scapes, urban redevelopment through super sites by star architects and downtown urban developments. This research found that there are different perspectives about the definition and factors that shape the identity of Amman’s city because of differences in cultures, experiences, knowledge, education level and personal preferences. The city identity is not a constant concept. It is changed according to time, place, people, culture, global trends, economic status and experience. Moreover, the correlation results revealed that the relationships/interrelationships between all the factors that shape the identity of any city have strong/very strong positive linear associations and significant relationships (r > 0.89).Practical implicationsGreater Amman Municipality (GAM) should provide a vision to redefine the identity of Amman city and control over the development pressure, built form and image of the city. This vision should be based on research, analysis and adoption of the most effective road map. GAM and all stakeholders should establish and enforce using specific architectural styles, urban design guidelines, building codes, policy tools and land use regulations to re-define the city identity. GAM should review, assess, approve and supervise all development projects through all design and construction phases especially in sensitive areas. GAM should focus on building capacity, empower its architects and planners, and re-organize (re-structure) their units and administrations especially planning and licensing departments to improve the city image and guide development. This research recommended that architects should design new, diverse and innovative architectural concepts, typologies and spatial configurations. Rapid development and new edges should be planned, designed and managed from the parts to the whole. The heterogeneous landscape and everyday activities will improve the vitality of urban and open public spaces and form of public culture. Architects and star architects ought not to make a clear and sharp separation between old and new development, architectural styles and typologies. Architects and urban designers ought to design hybrid physical urban environments, urban morphology, urban multi-functional activities, mix-use buildings, open spaces for social life, street patterns and furniture, squares, architectural style and typologies, spatial connectivity, green spaces and landscape entities. The designers and planners should consider how to create a city for living, working and recreation.Originality/valueThis research defined the identity, city identity, architectural identity and the factors that may shape the city identities. This research proposed and used the hybridization process as a tool to re-locate (re-define) the identity of Amman city and any city to be more obvious. Additionally, this research examined the relationships/interrelationships between the factors that shape the city identity.

Crop proximity index for monitoring of peri-urban land use in agro-industrial crop regions

The agro-industrial production of genetically modified organisms uses great amounts of pesticides, close to cities, which generates growing concern due to the numerous evidence of their negative effects on health and the environment. In a context of the lack, or inaccessibility, of official data on crop dynamics and pesticide use, environmental indicators using satellite data are needed for the proper monitoring of peri-urban areas. The objective of this research is to make a crop proximity index using satellite information to assess and monitor peri-urban agro-industrial activity. Twenty cities in Argentina and ten in the United States were selected. The CPI index is designed to evaluate a city and its peri-urban areas as a whole by taking account of the land uses and factors that can potentially influence the proximity to agro-industrial activity to the population living in those cities. Agriculture factor was weighted by proximity or remoteness using perimeter rings from the urban edge. All the necessary data for the calculation of the CPI index were obtained through the classification and processing of Sentinel 2 satellite images with software and the Google Earth Engine platform. The results show a worrying situation, 90% of cities in Argentina and 80% in the United States have a negative CPI. Most of the cities examined are extremely close to extensive areas of crops, that use a high amount of pesticides and which do not have the protection of trees or buffer zones.

Nonlethal management of baboons on the urban edge of a large metropole.

The transformation of natural land for agricultural and urban use has displaced baboons from large parts of their historical distribution. Abundant resources within transformed areas, however, continue to attract baboons back into these human-dominated areas resulting in chronic levels of conflict throughout much of Africa. In the city of Cape Town, chacma baboons (Papio ursinus) have been raiding human-derived foods for over 200 years. In the last 20 years, the management of this conflict has shifted from predominantly lethal to nonlethal methods. In this study, we assess the success of field rangers to deter baboons from urban areas and investigate whether such management affects the diet and activity patterns of baboons. We opportunistically sampled baboon behavior and movement when field rangers were temporarily absent from managed troops in 2008. We also compared the intensity of baboon management by comparing one troop on days when the field rangers aggressively herded the troop away from the urban edge versus passively monitored them in 2004/2005. Our results reveal that when field rangers were absent, the two troops spent 70% and 80% of their time within the urban edge compared to 3% and 19% when they were present. Both troops also consumed more human-derived foods when field rangers were absent. There was no significant change in the activity budget or daily distance traveled for either troop with and without field rangers. The intensity of herding did have an impact on baboon activity and high levels of herding significantly reduced time spent feeding and increased time spent traveling, socializing, and resting. Habitat use and dietary composition did not differ between high- and low-herding days. Our results suggest that field rangers are a successful nonlethal method for reducing spatial overlap between baboons and urban areas but that intensive, unsystematic herding of the troop does have measurable impacts on behavior and should be prevented.

Digital Visualisation as a New Driver of Urban Change in Africa

Cities in Sub-Saharan Africa are growing faster than in any other part of the world, driven by expanding informal settlement (usually on the urban periphery) and the real-estate sector aiming for up-market property development. The continent currently has the highest real-estate value growth potential in the world. Much up-market property development is currently taking the form of new ‘cities’—sometimes a redevelopment of an entire city (e.g., Kigali), sometimes a new city on an urban edge (e.g., Eko-Atlantic, Lagos) and sometimes a new satellite city (e.g., Tatu City, Nairobi). These projects are driven by international property development companies often in collaboration with governments and sometimes with local planning and property partners. All manifest as plans in a new way: as graphics on the websites of international consultants. Most involve no public participation and attempt to by-pass planning laws and processes. Producing these new plans (as computer generated images) are a new set of professionals: architects, planners, visualisers, advertising executives and project managers, working together in offices in global capitals of the world. Their aim is commercial. Planning in these projects is no longer shaped by the materiality of the city and attempts to achieve socio-spatial justice and sustainability. Rather planning is shaped by the circulation of graphics through a network of software programmes and marketing professionals. This article will situate Africa’s new cities in theorisation of urban development and the role of urban planning through digital visualization.

The Darker Side of Muddling Through: an Analysis of Spatial Planning Policy Decision-Making and Policy Termination in Cape Town, South Africa

Successes and failures in the use of urban edges or urban growth boundaries as policy instruments to contain or direct urban growth in order to protect non-urban areas and encourage the development of more compact, contiguous urban areas (Nelson and Dawkins 2004) have been widely documented. This is true particularly for cities in the more developed world where edges and boundaries have been in place for an adequate period of time to allow for evaluation of spatial outcomes. More recently cities in the global south have also embarked on such policy evaluation (Lerise 2000; Mubarak 2004; Msoffe et al. 2011; Du Plessis 2013; Inostroza et al. 2013). The City of Cape Town (CoCT), South Africa, has since the early 2000s employed an urban edge line as a growth management instrument in its spatial development framework (SDF) (CoCT 2009a). However, in the most recent Cape Town Spatial Development Framework (CTSDF) of 2017, an urban edge line is no longer applied as an instrument to contain horizontal urban spatial growth. Instead, the latest CTSDF champions development that will support transit-oriented development in the urban core and notes the city’s intention not to extend services towards the urban periphery in the short-term (CoCT (City of Cape Town Metropolitan Municipality) 2017a). This sees a considerable turn-around from the stated historic apprehension to persistent growth pressure to the northern and eastern urban extremities of the metropolitan area by using an urban edge (CoCT 2012a) and seems to suggest that the former urban edge policy was considered inappropriate or problematic to the CoCTs objectives for spatial development. While the spatial effect of the urban edge over the period of 16 years for which it was employed remains a valuable subject of research, this research is interested more in the reasons behind termination of the policy. The paper postulates that, despite a solid policy foundation, the effectiveness of its intent was gradually eroded by political decision-making counter to the policy.

La caminabilidad como estrategia proyectual para las redes peatonales del Borde Urbano

El barrio Sierra Morena se ubica en el borde urbano sur oriental de la ciudad de Bogotá y contiene huellas de un pasado y presente marcados en recorridos veredales que transforman un entorno natural, a causa de asentamientos de comunidades que encontraron en esta, cualidades estratégicas para subsistir. Este proyecto ofrece una nueva perspectiva respecto al papel de la arquitectura en función del espacio colectivo, como respuesta proyectual frente a situaciones de calidad de vida en los recorridos de sectores desestructurados, a partir de la aplicación de un marco investigativo desde la teoría del Nuevo Urbanismo, donde se valida en términos cualitativos de diseño la caminabilidad como estrategia que impacta en la construcción social del borde urbano. Se diseña un proyecto urbano integral, para la re significación del tejido urbano existente que articula los distintos sistemas funcionales y que aúne las prácticas urbanas rurales.

Molecular detection of tick-borne pathogens in caracals (Caracal caracal) living in human-modified landscapes of South Africa

BackgroundWild carnivores living alongside humans and domestic animals are vulnerable to changes in the infectious disease dynamics in their populations. The aims of this study were to determine the prevalence and diversity of selected tick-borne pathogens (TBPs) of veterinary and/or zoonotic concern in wild populations of caracals (Caracal caracal) occurring in human-modified landscapes in South Africa. Using molecular techniques, we screened 57 caracal blood samples for infection by rickettsial bacteria and piroplasms in three regions of South Africa: rangeland in the Central Karoo (n = 27) and Namaqualand (n = 14) as well as the urban edge of the Cape Peninsula (n = 16) of South Africa. To characterise pathogen identity, we sequenced the 18S rRNA and 16S rRNA genes from positive samples and analysed sequences within a phylogenetic framework. We also examine the diversity of potential tick vectors.ResultsAll individuals tested were infected with at least one tick-borne pathogen. Pathogens included Hepatozoon felis, Babesia felis, Babesia leo and a potentially novel Babesia species. An Anaplasma species previously described in South African domestic dogs was also found in 88% of urban edge caracals. Higher rates of co-infection characterised urban edge caracals (81% vs 15% and 0% in the two rangeland populations), as well as a greater incidence of mixed infections. Host attached tick species include Haemaphysalis elliptica, an important pathogen vector among carnivore hosts.ConclusionsThis study confirms the occurrence of previously undocumented tick-borne pathogens infecting free-ranging caracals in human-modified landscapes. We identify clear differences in the pathogen profiles among our study populations and discuss the likely health costs to caracals living adjacent to urban areas.

Peri-urban pesticide contamination risk index

• Most of the cities analysed have very high indices of exposure to pesticides. • Proximity of crops to cities and low peripheral tree cover increase the PUPCRI index. • PUPCRI allows an easy and quick assesment of the risk of exposure to pesticides in peri-urban area. The massive use of pesticides in the production of food and raw materials generates growing world concern due to the numerous evidences of their negative effects on health and the environment. In countries where detailed information of agricultural pesticide use near to urban areas is not available, it is necessary have a simple methodology that does not require data that are difficult to obtain in order to create an ecological indicator of the risk of pesticide contamination at the peri-urban level. The objective of this research is to generate a peri-urban pesticide contamination risk index using satellite information and accessible scientific pesticide data. The Peri-urban Pesticide Contamination Risk Index (PUPCRI) is composed of an indicator of the toxicity of the set of pesticides used in each crop, and two factors that quantify the surface occupied by agricultural activity and the tree surface in the urban periphery. The Environmental Risk Index has been used to calculate the toxicity of herbicides, insecticides and fungicides used in soybean, corn and wheat crops. Through the classification of Sentinel 2 satellite images, data was obtained of arable land, soybean, corn and wheat crops, and tree cover, in different peri-urban rings, with a maximum distance of two kilometers from the urban edge. The PUPCRI index was tested in 20 cities pertaining to the region with the highest agricultural productivity in Argentina. The results show that most of the cities have high to very high indices of exposure to pesticides, mainly due to the proximity of agricultural activity to the urban edge and the lack of tree cover. The PUPCRI index allows a quick and simple analysis of the potential risk of exposure to the use of crop pesticides in the urban periphery.

Extended urbanisation and the spatialities of infectious disease: Demographic change, infrastructure and governance

This paper argues that contemporary processes of extended urbanisation, which include suburbanisation, post-suburbanisation and peri-urbanisation, may result in increased vulnerability to infectious disease spread. Through a review of existing literature at the nexus of urbanisation and infectious disease, we consider how this (potential) increased vulnerability to infectious diseases in peri- or suburban areas is in fact dialectically related to socio-material transformations on the metropolitan edge. In particular, we highlight three key factors influencing the spread of infectious disease that have been identified in the literature: demographic change, infrastructure and governance. These have been chosen given both the prominence of these themes and their role in shaping the spread of disease on the urban edge. Further, we suggest how a landscape political ecology framework can be useful for examining the role of socio-ecological transformations in generating increased risk of infectious disease in peri- and suburban areas. To illustrate our arguments we will draw upon examples from various re-emerging infectious disease events and outbreaks around the world to reveal how extended urbanisation in the broadest sense has amplified the conditions necessary for the spread of infectious diseases. We thus call for future research on the spatialities of health and disease to pay attention to how variegated patterns of extended urbanisation may influence possible outbreaks and the mechanisms through which such risks can be alleviated.

Into the woods: Changes in mosquito community composition and presence of key vectors at increasing distances from the urban edge in urban forest parks in Manaus, Brazil

Mosquito-borne Zika virus (ZIKV) was recently introduced into the Americas and now has the potential to spill back into a sylvatic cycle in the region, likely involving non-human primates and Aedes, Haemagogus, and Sabethes species mosquitoes. We investigated potential routes of mosquito-borne virus exchange between urban and sylvatic transmission cycles by characterizing mosquito communities in three urban forest parks that receive heavy traffic from both humans and monkeys in Manaus, Brazil.Parks were stratified by both distance from the urban-forest edge (0, 50, 100, and 500 m) and relative Normalized Difference Vegetation Index (NDVI) (low, medium, or high), and mosquitoes were sampled at randomly selected sites within each stratum using BG-Sentinel traps. Additionally, temperature, relative humidity, and other environmental data were collected at each site.A total of 1,172 mosquitoes were collected from 184 sites sampled in 2018, of which 98 sites were resampled in 2019. Using park as the unit of replication (i.e. 3 replicates per sampling stratum), a two-way ANOVA showed no effect of distance or NDVI on the mean number of identified species (P > 0.05 for both comparisons) or on species diversity as measured by the Shannon-Wiener diversity index (P > 0.10 for both comparisons). However, the Morisita overlap index revealed that mosquito communities changed substantially with increasing distance from edge, with communities at 0 m and 500 m being quite distinct. Aedes albopictus and Ae. aegypti penetrated at least 100 m into the forest, while forest specialists including Haemagogus janthinomys, Sabethes glaucodaemon, and Sa. tridentatus were detected in low numbers within 100 m from the forest edge. Trichoprosopon digitatum and Psorophora amazonica were among the most abundant species collected, and both showed distributions extending from the forest edge to its interior.Our results show overlapping distributions of urban and forest mosquitoes at park edges, which highlights the risk of arbovirus exchange via multiple bridge vectors in Brazilian urban forest parks. These parks may also provide refugia for both Ae. albopictus and Ae. aegypti from mosquito control programs.

An integrated dietary assessment increases feeding event detection in an urban carnivore

Urbanisation radically changes habitats and alters available resources. Populations of large, highly mobile species are often extirpated at the urban-wildland interface, while species like mesocarnivores may thrive by capitalising on changes in prey abundance. We investigated the diet of the caracal (Caracal caracal), a medium-sized felid inhabiting patchy natural habitat isolated within the dense urban matrix of South Africa’s second largest city, Cape Town. We systematically integrated two classic dietary methods (scat and GPS clusters) by accounting for gut transit times. As part of a larger caracal ecology study, we GPS-collared 26 individuals over a two-year period (2014–2016) to generate coarse (3-hour) and fine-scale (20-minute) GPS movement data. Using the movement data, we investigated 677 GPS-clusters for prey remains. We collected 654 scats, half of which were found at GPS-clusters and were linked with the individual sampled. By systematically correcting for a range of gut transit times, we determined whether scat at cluster sites was from the same or an earlier feeding event, thereby increasing the overall detection of feeding events by > 50%. Avian prey dominated GPS cluster findings while micromammals were overwhelmingly represented in scat. Although > 40% of feeding events occurred within 200 meters of the urban edge, caracals largely preyed on native species. Our findings have implications for understanding the ability of some species to persist in the face of rapid environmental change, human-wildlife conflict, pathogen transmission, and bioaccumulation of pesticides. Further, this approach could be incorporated into studies that estimate foraging-explicit resource selection and habitat preference.

Abnormal shoot growth in Korean red pine as a response to microclimate changes due to urbanization in Korea.

Impacts of climate change (e.g., abnormal growth in plants, early flowering, and shifting vegetation zones) are being detected throughout the world. Urban land use and its resulting microclimates work in conjunction with the impacts of climate change. Among the principal environmental signals that modulate bud flush, only temperature has changed significantly in recent years. Throughout South Korea, abnormal shoots (usually known as lammas shoots) in Korean red pine (Pinus densiflora), which were once a rare phenomenon, have become notably more common in recent years. The phenomenon is prominent in urban site of each local area. These abnormal shoots appear at a higher frequency and grow to longer lengths in Seoul's hotter urban center than in suburban sites and showed a close positive correlation with urban density and a close negative correlation with vegetation cover expressed as NDVI. Differences in temperature among the urban center, urban edge, and suburban greenbelt were significantly correlated with land-use intensity. Korean red pines planted in urban parks at sites in urban centers showed a lower frequency of abnormal shoots, and the length of the shoots was shorter, compared with those at the other urban sites. Furthermore, the phenology of Korean red pines in an urban park with a fountain showed a spatial difference, depending upon the distance from the fountain: pine trees close to the fountain did not produce abnormal shoots, but abnormal shoot growth increased with the distance from the fountain. These results are noteworthy because they are related to the cooling effects of evapotranspiration from vegetated landscapes and evaporation from a water body. From the results of this study, we could confirm that microclimate change due to urbanization accelerates the impacts of climate change on plant phenology. Furthermore, we identified the possibility that judicious land-use planning could contribute to minimizing the adverse effects of climate change.