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Urban Ecology (urban + ecology)
Selected AbstractsStudies in Urban Ecology: the First Wave of Biological Invasion by Pistacia chinensis in Armidale, New South Wales, AustraliaGEOGRAPHICAL RESEARCH, Issue 3 2000J. M. B. Smith Biological invasions by deliberately introduced organisms seriously compromise the integrity of ecosystems, but their early stages have seldom been documented, especially in urban contexts. Since the 1940s, the small Asian tree Pistacia chinensis has been widely planted in streets and gardens in Armidale, New South Wales, Australia, where it makes a major contribution to the autumn colours that are exploited to promote the city. Numerous wild plants are now becoming established in and near Armidale. This ongoing biological invasion may have been accelerated by the large size of the initial (planted) population, and by the presence of efficient avian seed dispersers. It is now at the stage of the first wild generation reaching reproductive maturity. While it is probably still possible to halt the invasion, various human factors appear to make this an unlikely prospect. [source] Children's work, earnings, and nutrition in urban Mexican shantytownsAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2010Alexandra Brewis For many children living in conditions of urban poverty, earning money can provide additional resources to them and their families, and this raises interesting questions about the potential biological consequences (costs and benefits) of children's work in ,modern' settings. This study uses time allocation, ethnographic, dietary, and anthropometric data collected with 96 urban Mexican shantytown children (aged 8,12 years) and their older and younger siblings (aged 1,18 years) to test hypotheses related to the effects of children's cash earning and cash contributions to their households for their own and their sibs' nutritional status. Regression models show that children's contributions to household income and the time they allocate to working outside the home makes no difference to their own or their younger siblings' nutritional status assessed anthropometrically. Dietary quality, based on food recalls, is worse in working than non-working children, even taking household income into account. Children's allocation of time to work and their cash contributions to the household do however significantly improve the weight of their older siblings, especially sisters. This suggests children's work in urban ecologies might have different constraints and opportunities for their own and siblings' growth and nutrition than typically observed in subsistence settings. Am. J. Hum. Biol. 2010. © 2009 Wiley-Liss, Inc. [source] Climatology at Urban Long-Term Ecological Research Sites: Baltimore Ecosystem Study and Central Arizona,PhoenixGEOGRAPHY COMPASS (ELECTRONIC), Issue 1 2009Anthony J. Brazel The Baltimore Ecosystem Study (BES) and Central Arizona,Phoenix (CAP) Long-Term Ecological Research (LTER) programs, established in 1997, are part of an international National Science Foundation long-term ecology monitoring and research network. The study sites are excellent laboratories to integrate ideas on climate of urban areas and how climate change and local variability of climate relate to social, political, economic, and ecological processes over a long time period. A large variety of research data are available online from individual LTER Web sites and a combined database called CLIMDB/HYDRODB is available for climate and ecology researchers and others, to investigate climate and hydrology in LTER study regions including those of BES and CAP. The basic program, climate aspects of these two areas, selected past research, and current ongoing work is briefly reviewed. A large benefit of this National Science Foundation program is the maintenance of support over a very long period of time. With the advent of a National Ecological Observatory Network, continuing collection of climate and environmental information over the coming decades at the local and regional scales, and maintenance of protocols of measurement, it is hoped that a more meaningfully integrated urban climatology with urban ecology will emerge. This will better prepare scientists to gage the impending rapid global warming expected not only of natural environments, but also of burgeoning urban places around the world. [source] Habitat influences on urban avian assemblagesIBIS, Issue 1 2009KARL L. EVANS Urbanization is increasing across the globe and there is growing interest in urban ecology and a recognition that developed areas may be important for conservation. We review the factors influencing urban avian assemblages, focusing on habitat type and anthropogenic resource provision, and analyse data from a common bird monitoring scheme to assess some of these issues. The review suggests that (1) local factors are more important than regional ones in determining the species richness of urban avian assemblages, raising the potential for the management of urban sites to deliver conservation; (2) habitat fragmentation frequently influences urban avian assemblages, with the effects of patch size being greater than those of isolation, and (3) urban bird assemblages appear to respond positively to increasing the structural complexity, species richness of woody vegetation and supplementary feeding, and negatively to human disturbance. Data from Britain's Breeding Bird Survey, combined with habitat data obtained from aerial photographs, were used to assess a number of these issues at the resolution of 1-km squares. Green-space constituted 45% of these squares, and domestic gardens contributed 50% of this green-space, though their contribution to large continuous patches of green-space was negligible. There was no significant positive correlation between the densities of individual species in urban areas and surrounding rural areas. Rural species richness declined with increasing latitude, but urban species richness was not correlated with latitude. This contrast contributes to slightly higher avian species richness in rural squares in Southern England than urban ones. Occupancy and abundance were strongly positively correlated in urban avian assemblages, and some indicator species of conservation concern occurred in few urban areas and at low densities. Such species will require conservation action to be precisely targeted within urban areas. Of the urban indicators of conservation concern, only the House Sparrow Passer domesticus and Common Starling Sturnus vulgaris were more abundant in urban than rural areas. Moreover, the densities of these two species were strongly and positively correlated, indicating that they may be limited by shared resources, such as nest-sites or supplementary food. There was little evidence that high densities of nest-predating corvids were associated with reduced densities of their prey species. Species richness and the densities of individual species frequently declined with an increasing number of buildings. Current trends for the densification of many British urban areas are thus likely to be detrimental for many bird species. [source] The establishment of an urban bird populationJOURNAL OF ANIMAL ECOLOGY, Issue 5 2008Christian Rutz Summary 1Despite the accelerating global spread of urbanized habitats and its associated implications for wildlife and humans, surprisingly little is known about the biology of urban ecosystems. 2Using data from a 60-year study period, this paper provides a detailed description of how the northern goshawk Accipiter gentilis L. , generally considered a shy forest species , colonized the city of Hamburg, Germany. Six non-mutually exclusive hypotheses are investigated regarding the environmental factors that may have triggered this invasion. 3The spatio-temporal analysis of 2556 goshawk chance observations (extracted from a total data set of 1 174 493 bird observations; 1946,2003) showed that hawks regularly visited the city centre decades before the first successful breeding attempts were recorded. Many observations were made in parts of the city where territories were established in later years, demonstrating that these early visitors had encountered, but not used, potential nest sites. 4Pioneer settlement coincided with: (i) an increase in (legal) hunting pressure on goshawks in nearby rural areas; (ii) an increase in avian prey abundance in the city; and (iii) a succession of severe winters in the Greater Hamburg area. On the other hand, there was no evidence to suggest that the early stages of the invasion were due to: (i) decreasing food availability in rural areas; (ii) major habitat changes in the city; or (iii) rural intraguild dynamics forcing hawks into urban refugia. While breeding numbers of a potential rural source population were at a long-term low when the city was colonized, prior to first settlement there was a sharp increase of goshawk chance observations in the city and its rural periphery. 5The urban population expanded rapidly, and pair numbers began to stabilize after about 10 years. Ringing data (219 ringed nestlings from 70 urban broods; 1996,2000) demonstrated that most urban recruits had fledged in the city, but also confirmed considerable gene flow between urban and rural habitats. Analysis of chance observations (as raw data or as detrended time series) suggested a tight coupling of population dynamics inside and outside the city. 6City-colonizations such as the one described here provide a valuable opportunity to study some fundamental aspects of population ecology on a scale at which detailed monitoring is logistically feasible. Furthermore, a good understanding of urban ecology has become essential for efficient wildlife conservation in modern, human-altered environments. [source] Review of the ecology of Australian urban fauna: A focus on spatially explicit processesAUSTRAL ECOLOGY, Issue 2 2006JENNI GARDEN Abstract Cities have a major impact on Australian landscapes, especially in coastal regions, to the detriment of native biodiversity. Areas suitable for urban development often coincide with those areas that support high levels of species diversity and endemism. However, there is a paucity of reliable information available to guide urban conservation planning and management, especially regarding the trade-off between investing in protecting and restoring habitat at the landscape level, and investing in programmes to maintain the condition of remnant vegetation at the local (site) level. We review the literature on Australian urban ecology, focusing on urban terrestrial and aquatic vertebrate and invertebrate fauna. We identify four main factors limiting our knowledge of urban fauna: (i) a lack of studies focusing at multiple ecological levels; (ii) a lack of multispecies studies; (iii) an almost total absence of long-term (temporal) studies; and (iv) a need for stronger integration of research outcomes into urban conservation planning and management. We present a set of key principles for the development of a spatially explicit, long-term approach to urban fauna research. This requires an understanding of the importance of local-level habitat quality and condition relative to the composition, configuration and connectivity of habitats within the larger urban landscape. These principles will ultimately strengthen urban fauna management and conservation planning by enabling us to prioritize and allocate limited financial resources to maximize the conservation return. [source] A conceptual framework for the colonisation of urban areas: the blackbird Turdus merula as a case studyBIOLOGICAL REVIEWS, Issue 3 2010Karl L. Evans Despite increasing interest in urban ecology the factors limiting the colonisation of towns and cities by species from rural areas are poorly understood. This is largely due to the lack of a detailed conceptual framework for this urbanisation process, and of sufficient case studies. Here, we develop such a framework. This draws upon a wide range of ecological and evolutionary theory and the increasing number of studies of how the markedly divergent conditions in urban and rural areas influence the traits of urban populations and the structure of urban assemblages. We illustrate the importance of this framework by compiling a detailed case study of spatial and temporal variation in the urbanisation of the blackbird Turdus merula. Our framework identifies three separate stages in the urbanisation process: (i) arrival, (ii) adjustment, and (iii) spread. The rate of progress through each stage is influenced by environmental factors, especially human attitudes and socio-economic factors that determine the history of urban development and the quality of urban habitats, and by species' ecological and life-history traits. Some traits can positively influence progression through one stage, but delay progression through another. Rigorous assessment of the factors influencing urbanisation should thus ideally pay attention to the different stages. Urbanisation has some similarities to invasion of exotic species, but the two clearly differ. Invasion concerns geographic range expansion that is external to the species' original geographic range, whilst urbanisation typically relates to filling gaps within a species' original range. This process is exemplified by the blackbird which is now one of the commonest urban bird species throughout its Western Palearctic range. This is in stark contrast to the situation 150 years ago when the species was principally confined to forest. Blackbird urbanisation was first recorded in Germany in 1820, yet some European cities still lack urban blackbirds. This is especially so in the east, where urbanisation has spread more slowly than in the west. The timing of blackbird urbanisation exhibits a marked spatial pattern, with latitude and longitude explaining 76% of the variation. This strong spatial pattern contrasts with the weaker spatial pattern in timing of urbanisation exhibited by the woodpigeon Columba palumbus (with location explaining 39% of the variation), and with the very weak spatial pattern in timing of black-billed magpie Pica pica urbanisation (in which location explains 12% of the variation). Strong spatial patterns in timing of urbanisation are more compatible with the leap-frog urbanisation model, in which urban adapted or imprinted birds colonise other towns and cities, than with the independent urbanisation model, in which urban colonisation events occur independently of each other. Spatial patterns in isolation do not, however, confirm one particular model. Factors relating to the arrival and adjustment stages appear particularly likely to have influenced the timing of blackbird urbanisation. Spatial variation in the occurrence of urban populations and the timing of their establishment creates opportunities to assess the factors regulating urbanisation rates, and how the composition of urban assemblages develops as a result. These are major issues for urban ecology. [source] | |||||||||||||