Approaches to the study of urban ecosystems: The case of Central Arizona—Phoenix

CAP LTER focuses on an arid-land ecosystem profoundly influenced, even defined, by the presence and activities of humans and is one of only two LTER sites that specifically studies the ecology of an urban system. In this large-scale project, biological, physical, and social scientists are working together to study the structure and function of the urban ecosystem, to assess the effects of urban development on surrounding agricultural and desert lands, and to study the relationship and feedbacks between human decisions and ecological processes.Our interdisciplinary investigations into the relationship between land-use decisions and ecological consequences in the rapidly growing urban environment of Phoenix are of broad relevance for the study of social ecological systems and cites in particular. Refinements in our conceptual model of social ecological systems focuses our attention on recognizing the scales and periodicities of ecological and human phenomena, understanding the means and impacts of human control of variability in space and time, and finally an evaluation of the resilience of various aspects of socio-ecological systems especially their vulnerabilities and their potential for adaptive learning.     

Vegetation structure along urban ephemeral streams in southeastern Arizona

Riparian areas in Arizona are being encroached upon by urban developments. This study investigated the impacts of different urban housing densities on riparian vegetation structure along ephemeral streams. Nine sites representing three levels of housing density were selected within the town of Marana, located in southeast Arizona. The housing densities were categorized as high (7–8 houses ha^?1), moderate (2.5–4.5 houses ha^?1), and low (< 1.5 houses ha^?1). Each treatment had three replications. The urban developments were relatively young (less than 15 years). No significant differences were found among the treatments for the tree variables (density, height, mean canopy volume and total canopy volume) or the herbaceous vegetation variables (species richness, percentage of introduced species and percentage of ground cover). However, the shrub variables (mean density, mean height, mean canopy volume, total canopy volume and species richness) showed some significant differences. Shrub density and species richness was significantly greater adjacent to ephemeral channels than just three meters upland. In addition, whitethorn acacia shrubs were significantly taller and larger adjacent to the stream channels in the high and moderate housing density sites than in the low housing density sites. Creosote shrubs showed the opposite trend. Increased runoff in the more heavily urbanized streams may have promoted the growth of the facultative riparian species (whitethorn acacia) but not the non-riparian species (creosote). Overall, in these young developments, vegetation was resilient across the levels of urbanization explored in the study.     

The Persistence of the slave market in seventeenth-century Central Mexico

This study, based on an extensive notarial database, demonstrates the significance of slavery in Central Mexico during the seventeenth century. Thousands of bills of sale from Mexico City and Puebla – the largest and most lucrative slave markets in the region – show that the slave trade did not collapse with the end of the Portuguese asiento in 1640. A growing population of American-born creoles sustained the market during the subsequent decades, along with a modest number of new African arrivals. In 1700, slavery remained integral to Central Mexico's economy.     

Frugivory and habitat use by thrushes (Turdus spp.) in a suburban area in south Brazil

Thrushes (Turdus spp., Turdidae) are among the most common frugivorous birds in urban areas around the world, where they disperse the seeds of a variety of plant species. We studied the abundance, habitat use, foraging behavior and diet of four thrush species (Turdus rufiventris, T. amaurochalinus, T. leucomelas, and T. albicollis) in a suburban area in south Brazil. Abundance, habitat use and foraging behavior were based on birds surveyed along a 3,240 m transect crossing open (formed by lawns, streets, and buildings) and forested areas. Diet was based on fecal samples collected from mist-netted birds. Turdus rufiventris was the most abundant species, followed by T. amaurochalinus, T. leucomelas, and T. albicollis. All species used forest fragments more frequently than expected by chance. A total of 91.8% (n = 147) of the fecal samples contained fruit remains, while 42.2% contained only animal matter. Most of the foraging records were on the ground, where birds got mainly invertebrates. Fruits and invertebrates were eaten more frequently in open than in forested areas. A total of 25 seed morfospecies were found in the droppings, including five exotic plant species. Thrushes overlapped widely in the fruit composition of their diets. The high abundance and degree of frugivory, coupled with the frequent use of forest patches, indicate that thrushes are among the great bird contributors to the seed dispersal occurring in urban forest patches, potentially influencing the vegetation dynamics of such habitats so important for the maintenance of the biodiversity in urban areas.     

Small mammal assemblages in fragmented shrublands of urban areas of Central Chile

Mediterranean-type ecosystems are one of the most affected environments by habitat loss and fragmentation due to urban development, however only few studies have evaluated the effects of urbanization on the biodiversity of remnant fragments in these ecosystems. This study aims to evaluate the effects of urban development over small mammal assemblages inhabiting isolated forest fragments of an urban area of Chilean Mediterranean zone. We compared abundance and richness of small mammal assemblages of six remnant fragments within an urban matrix, and six fragments similar in area and habitat characteristics with those of urban area, but surrounded by a rural matrix. We found that small mammal assemblages differ considerably among fragments types (urban vs rural), with lack of endemic species from urban fragments and with high proportion of introduced rodents in urban fragments. Furthermore abundance of small mammals was higher in rural than in urban fragments. In urban areas small mammal abundance and richness were not correlated with any of the explanatory variables assessed (woody cover, flora heterogeneity, fragment area, perimeter/area ratio). However in rural fragments small mammal richness was negatively correlated with flora heterogeneity and the abundance of small mammals was positively correlated with perimeter/area ratio. These results reveal important differences within the effects of fragmentation over small mammal assemblages among the two types of fragments assessed. Our findings suggest that in forest fragments isolated by urbanization, larger areas with good quality habitats are not sufficient to maintain native small mammal population.     

The origin and development of the urban flora of Central Europe

The florae of Central European cities and towns differ largely from the flora of the hinterland. Characteristics of the urban flora (in comparison to that of the hinterland) are: a remarkable decrease in the percentage of indigenous and archeophytic species, in particular of those that have a narrow ecological amplitude and/or are strictly bound to oligotrophic habitats; an increase in the population of a small group of indigenous species resulting from a change from natural to synanthropic habitats (apophytisation, synanthropisation); an immigration of alien species (neophytes), in particular to disturbed habitats; and the development of new ecotypes. The origin and development of the typical features of the Central European urban flora can be divided into four distinctive periods: the time up until the end of the 15th century, the time from the 16th century to the beginning of the industrial age, the industrial age, the post-industrial age.     

Effect of habitat characteristics on mesocarnivore occurrence in urban environment in the Central Europe

Although urbanization is generally considered a major threat to local and global biodiversity, some recent studies have shown that urban environments provide suitable habitat for some wildlife species, including carnivores, yet little is known about the factors that determinate their occurrence and habitat preferences. The main aim of this study was to examine the relative importance of habitat characteristics in relation to carnivore occurrence along an urban–rural gradient in the Central Europe. Carnivore occurrence was monitored using scent stations (summer period) and snow tracking (winter period) in the regional city which was divided into the network of 154 quadrates (25 ha/quadrate) for the purposes of this study. From a total of six recorded native carnivore species, the stone marten Martes foina and the least weasel Mustela nivalis were the most dominant and widespread species in both study periods. PCA analysis revealed the existence of two informative axes corresponding to (A) urban vs. non-urban habitat and (B) residential vs. industrial areas. Surprisingly, the only species exhibiting marked habitat selectivity and avoidance of highly urbanized areas was the red fox (i.e. negative correlation with the first PCA axis). The stone marten tends to avoid industrial areas and prefers residential areas; however its presence/absence was not associated with the first PCA axis. On the other hand, the ermine stoat and the least weasel were relatively unselective according to our results. In conclusion, our results demonstrate high adaptability of various species of carnivore mesopredators to urban environment; however their response to the level of urbanization and habitat characteristics exhibits interspecific variation.     

Outcharming crime in (D)urban space

This paper is an inquiry into the uses of space and emotions in the governance of urban dangers. Cities have always been affective assemblages, yet the role of both space and affect in the control of urban crime has dramatically changed over the century. What defines spatial urban management today, in Africa and elsewhere, are not the prohibitive, moralising or forcefully exclusionary techniques of the past; instead, the powers of seduction and atmosphere have gained pride of place and given rise to a regime of spatial management through flirty surfaces. Crime, according to security strategists and city makers in the South African city of Durban, can be literally charmed out from particular bubbles of governance. Urban practitioners do not search for the root causes of violent crime somewhere deep in the history of society, but rather in space itself, right at the city's surface. While part of a worldwide trend, this recent fascination with the charming aspects of space has a particularly strong South African dramatic. Governing through handsome space in South Africa is not simply a creation of beautiful illusions against the reality of pervasive violence, but a constant endeavour to re‐draw a troubled spatial history.     

Effects of urban matrix on reproductive performance of Great Tit (Parus major) in urban woodlands

In urban areas the density of breeding tits (Paridae) is generally higher and reproductive performance lower compared to rural areas. To explain these landscape differences several hypotheses have been proposed, e.g. differences in habitat quality, inter- and intra-specific competition, predation and food abundance. How breeding performance of birds within remnants of natural vegetation in urban areas is affected by adjacent matrix has been less studied. We performed an experimental study in four urban woodlands surrounded by three types of habitat matrix: residential, high-rise building and grassland/golf course. We placed 300 nest boxes for tits (great tit Parus major and blue tit Cyanistes caeruleus) in 15 transects that were 200 m long, extending from the adjacent matrix 150 m into urban woodland. Density of breeding great tit pairs was highest in residential areas and hatch date was earlier in the residential habitat compared to the other two habitats, however, nestling condition was lower in residential areas. Hatching date was earlier but hatching spread (heaviest nestling/lightest nestling) higher in the three types of urban matrix than inside the urban woodlands. In contrast to previous large-scale comparisons of urban and rural matrix, we almost exclusively found differences in qualitative measures (nestling condition and hatchling spread) at the small scale in which this study was conducted. Adjacent matrix affect great tits breeding in remnant urban woodlands, thus we suggest that management of the surrounding matrix should be included in conservation plans for urban woodlands.     

Basking habitat use and response of freshwater turtles to human presence in an urban canal of Central New Jersey

Pressures of rapid development continue to increase, and recreational activities are becoming a prominent driving force in many urban wildlife communities. Freshwater turtles live in many urban environments, yet little attention has been given to the impact of human recreation upon these communities. We examined the response of basking turtles to observer presence along the towpath of a recreational canal in central New Jersey. All species, except for turtles of the family Kinosternidae, were more frequently observed basking on substrate with less than 50 % canopy cover, log substrate was most preferred, and turtles on the towpath side basked an average of 3 m from the towpath. Turtles were vigilant and over 75 % of C. picta, T.S. elegans, and P. rubriventris responded to observer presence by retreating (swimming away). The distance from the towpath turtles were first seen basking by the observer (approach distance) was significantly correlated with the flight-initiation distance (distance of first respond to observer). Nearly 80 % of the variability in flight initiation distance for Kinosternidae was accounted for by the percent canopy cover, percent cloud cover, and height basking above the water. Researchers aiming to quantify and manage human recreational impact on turtles should examine flight-initiation distances. We encourage wildlife managers of urban parks to construct towpaths or recreational areas at a minimum of 7 m from the water’s edge, maintain moderate vegetation in basking areas, and construct additional basking platforms opposite from towpaths or at great distances from human recreational areas.     

The role of dispersal and local environment in urban land snail assemblages: an example of three cities in Central Italy

Ecologists increasingly appreciate the central role that urban biodiversity plays in ecosystems, however much urban biodiversity is neglected, especially some very diverse groups of invertebrates. For the first time in southern Europe, land snail communities are analysed in four urban habitats along a geographical gradient of three cities, using quantitative methods and assessing the relative roles of local environmental conditions (“distance from sea”, “distance from city centre”, “vegetation cover”) and spatial effects by principal coordinate analysis of neighbour matrices, redundancy analysis and variation partitioning. A total of 53 species was recorded, a richness similar to that of natural areas. At habitat level, species richness did not show a clear increasing trend from more to less urbanized habitats, but rather a homogeneous pattern. At city level, study areas hosted rather heterogeneous species assemblages and biotic homogenization did not seem to have any impact; indeed, only three species could be considered alien. Variation partitioning showed that land snail communities were mostly structured by environmental factors, even when spatial structures independent of measured environmental variables were included: “vegetation cover” and “distance from city centre” were the environmental variables that explained most of the variation in species composition. The lack of strong spatial structure also unexpectedly suggested that transport by humans aids dispersal of organisms with low mobility, which are usually limited by spatial constraints in natural environments. These results provide ecological and conservation implications for other invertebrate groups, suggesting to set priorities in management strategies that include habitat conservation at local scale.     

Dawisha,K., Parrott,B. (eds.): Conflict,Cleavage, and Change in Central Asia and the Caucasus

RJB Review of Journals and Books

Dawisha, K., Parrott, B. (eds.): Conflict, Cleavage, and Change in Central Asia and the Caucasus     

Exploring structural habitat heterogeneity in sustainable urban drainage systems (SUDS) for urban biodiversity support

Implementation of sustainable urban drainage systems (SUDS) as part of cities’ transition towards climate resilience encompasses unique opportunities to enhance urban nature qualities. SUDS include individual elements integrated in the urban landscape, e.g. rain gardens or wet basins, which are usually constructed with low structural heterogeneity. Structural heterogeneity of habitats is, however, associated with a high degree of biodiversity. This study explored potentials of habitat heterogeneity enhancement in SUDS using structural heterogeneity as a proxy for biodiversity potential. In an interdisciplinary workshop, landscape architects and urban ecologists designed individual SUDS elements with enhanced structural habitat heterogeneity, hereafter bio-SUDS. The redesigned SUDS elements were infiltration trench, curb extension, rain garden, swale, wet basin, and dry basin. To evaluate the bio-SUDS designs, we developed an index of habitat heterogeneity in SUDS based on registration of 45 structurally important components. The conversion from standard SUDS to bio-SUDS entailed substantial increases in structural heterogeneity ranging from 4 to 18 additional components within elements. Larger bio-SUDS elements returned higher index scores, but the relative score increases were substantial for all bio-SUDS and in the range of a factor of 2–5.5. Increased terrain differences, meandering edges, stones, gravel, boulders, deadwood, and brown roof-like vegetation were the components most often employed in the bio-SUDS designs. In conclusion, implementation of bio-SUDS has potential to increase structural habitat heterogeneity thereby providing habitat for biodiversity in urban green areas. The developed bio-SUDS index can assist in future assessments of ecological qualities in designs and real-world SUDS elements.     

Urbanization and warming of Phoenix (Arizona,USA): Impacts,feedbacks and mitigation

This paper examines the impacts, feedbacks, and mitigation of the urban heat island in Phoenix, Arizona (USA). At Sky Harbor Airport, urbanization has increased the nighttime minimum temperature by 5°C and the average daily temperatures by 3.1°C. Urban warming has increased the number of misery hours per day for humans, which may have important social consequences. Other impacts include (1) increased energy consumption for heating and cooling of buildings, (2) increased heat stress (but decreased cold stress) for plants, (3) reduced quality of cotton fiber and reduced dairy production on the urban fringe, and (4) a broadening of the seasonal thermal window for arthropods. Climate feedback loops associated with evapotranspiration, energy production and consumption associated with increased air conditioning demand, and land conversion are discussed. Urban planning and design policy could be redesigned to mitigate urban warming, and several cities in the region are incorporating concerns regarding urban warming into planning codes and practices. The issue is timely and important, because most of the world's human population growth over the next 30 years will occur in cities in warm climates.     

Analysis of the spread of Rhynchophorus ferrugineus in an urban area,using GIS techniques: a study case in Central Italy

Urban Ecosystems - The spread of the red palm weevil is now a very severe problem on a global scale. In this paper, we investigate its spread during the 2007–2013 period in a coastal urban...     

The Persistence of Workplace Gender Segregation in the US

Occupational gender segregation remains one of the defining elements of gender inequality in modern societies. Recent trends for the United States show that occupational segregation remains high and did not substantially decline in the decade of the 2000s for the first time since 1960. Men and women work in different occupations because of a combination of forces, including culturally defined choices by workers themselves, discrimination by employers, and differences in skill levels and qualities. Research has shown that occupational segregation is an important aspect of gender inequality in earnings and contributes to other forms of inequality as well. The prospects for reducing gender segregation in the short term appear slim, based on the weak effects of educational attainment, cultural attitudes, and state intervention in the current period.     

The synanthropic flora in the Mendoza (Argentina) urban area

The synanthropic flora in the Mendoza urban area was studied in terms of its three most relevant sub-environments: house and school gardens, parks and borders of narrow ditches used to irrigate the whole city. The current synanthropic flora comprises 487 species, 8 native and 479 alien species. Neophytes include 282 genera and 104 families, with the dominant families being Fabaceae, comprising 41 species, Myrthaceae (38 spp), Rosaceae and Oleaceae (24 spp), all of which together represent 26% of the total richness recorded. Ephemerophytes, non-naturalized plants, represent 25.4% of the urban flora. Xenoergasiophytes and ergasiophytes are dominant in gardens and parks, whereas xenophytes grow in irrigation ditches across the city. Considering life forms, nanophaerophytes are prevalent in all three sub-environments, but succulents and therophytes are absent from ditches. The number of non-native plant species is increasing in the urban area of Mendoza, especially in the suburbs, and many of them at times become invasive.     

Home gardening practice in Pune (India), the role of communities,urban environment and the contribution to urban sustainability

Urban Ecosystems - Urban agriculture (UA) is regarded as an emerging tool and strategy for sustainable urban development as it addresses a wide array of environmental, economic and social...