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Urban Ecosystems (urban + ecosystem)
Selected AbstractsAdvancing urban ecological studies: Frameworks, concepts, and results from the Baltimore Ecosystem StudyAUSTRAL ECOLOGY, Issue 2 2006S. T. A. PICKETT Abstract Urban ecological studies have had a long history, but they have not been a component of mainstream ecology until recently. The growing interest of ecologists in urban systems provides an opportunity to articulate integrative frameworks, and identify research tools and approaches that can help achieve a broader ecological understanding of urban systems. Based on our experience in the Baltimore Ecosystem Study (BES), Long-term Ecological Research project, located in metropolitan Baltimore, Maryland, USA, we identify several frameworks that may be useful in comparative urban studies, and may be worthy of consideration in other integrative urban ecosystem studies: (i) spatial patch dynamics of biophysical and social factors; (ii) the watershed as an integrative tool; and (iii) the human ecosystem framework. These frameworks build on empirical research investigating urban biota, nutrient and energy budgets, ecological footprints of cities, as well as biotic classifications aimed at urban planning. These frameworks bring together perspectives, measurements, and models from biophysical and social sciences. We illustrate their application in the BES, which is designed to investigate (i) the structure and change of the urban ecosystem; (ii) the fluxes of matter, energy, capital, and population in the metropolis; and (iii) how ecological information affects the quality of the local and regional environments. Exemplary results concerning urban stream nutrient flux, the ability of riparian zones to process nitrate pollution, and the lags in the relationships between vegetation structure and socio-economic factors in specific neighbourhoods are presented. The current advances in urban ecological studies have profited greatly from the variety of integrative frameworks and tools that have been tested and applied in urban areas over the last decade. The field is poised to make significant progress as a result of ongoing conceptual and empirical consolidation. [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] Urban pattern and land cover variation in the greater Toronto areaTHE CANADIAN GEOGRAPHER/LE GEOGRAPHE CANADIEN, Issue 1 2007TENLEY CONWAY Recent epistemological shifts in environmental geography have created a space to consider the interactions between ecological and urban systems more seriously. While openness to thinking about urban ecosystems has increased in recent years, there remain fundamental gaps in our knowledge. For example, recent research has examined the impact of urban,rural gradients on ecological conditions, but major voids exist regarding the relationship between urban development patterns and land cover heterogeneity, particularly for new forms of urbanization. This article attempts to address some of these gaps by examining the relationship between urban pattern and land cover in the greater Toronto area (GTA). In particular, measures of urban pattern that reflect aspects of development density, grain and function, as well as socio-economic characteristics, are systematically analyzed in relation to land cover heterogeneity. The regression analysis shows that multiple components of urban development pattern and socio-economic conditions are correlated with vegetated land covers, while urban density variables are not related. These results indicate more detailed representations of urban pattern should be incorporated into future human,environmental interaction studies in cities. Les changements épistémologiques récents en géographie environnementale ont créé un espace dans lequel les interactions entre les systèmes écologiques et urbains sont considérées plus sérieusement. Par contre, bien qu'il existe depuis quelques temps plus de possibilités pour réfléchir aux écosystèmes urbains, des questions fondamentales subsistent. Par exemple, des recherches récentes se sont penchées sur l'impact des gradients urbain-ruraux sur les conditions écologiques. Toutefois, des lacunes importantes demeurent en ce qui concerne les liens entre les modèles de développement urbain et l'hétérogénéité de la couverture des sols, notamment en ce qui a trait aux nouvelles formes d'urbanisation. Cet article aborde certaines de ces lacunes en examinant les liens entre le modèle urbain et la couverture des sols dans la région du Grand Toronto (RGT). En particulier, des mesures du modèle urbain reflétant des aspects de la densité de développement, la texture et la fonction, ainsi que les caractéristiques socio-économiques sont systématiquement analysées par rapport à l'hétérogénéité de la couverture des sols. L'analyse de régression montre une corrélation entre plusieurs composantes du modèle de développement urbain et des conditions socio-économiques, d'une part, et le type de couverture végétale des sols, d'autre part. Les variables utilisées pour la densité urbaine ne sont pas reliées. Ces résultats font ressortir que des représentations plus détaillées du modèle urbain devraient être intégrées aux études ultérieures consacrées aux interactions humain-environnement en milieu urbain. [source] Harbour swimming nets: a novel habitat for seahorsesAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 5 2008B. G. Clynick Abstract 1.Artificial structures are becoming increasingly important in conserving biodiversity in urban ecosystems, by providing habitat for endangered or rare species. Their role in providing habitat for such species has, however, been largely unexplored. 2.In Sydney Harbour, Australia, seahorses were observed among the netting used to keep sharks out of swimming enclosures. Over a 2-year period, the relative densities of two species of seahorses observed on netting was measured at swimming enclosures with permanent netting and at swimming areas that were only enclosed with netting during the summer months. 3.The rate of colonization by seahorses to new netting was also examined over a period of 10 months. 4.Numbers of seahorses on permanent swimming enclosures were 10 to 100 times greater than numbers present on swimming enclosures that were only set up during the summer months. 5.This large difference may have been attributed to the slow rate of colonization of seahorses to new habitat. Seahorses were not observed at experimental nets that were deployed in two areas in the harbour until at least 4 months after the netting was deployed. 6.Swimming pool nets are a habitat for species of seahorses in Sydney Harbour and, consequently, the removal or disturbance of swimming nets may impact the survival of these fish. Management of these artificial habitats may therefore best be focused on providing a permanent habitat that may help to compensate for the loss of netting during winter months. Copyright © 2007 John Wiley & Sons, Ltd. [source] Introduced birds in urban remnant vegetation: Does remnant size really matter?AUSTRAL ECOLOGY, Issue 2 2006MARK J. ANTOS Abstract Introduced birds are a pervasive and dominant element of urban ecosystems. We examined the richness and relative abundance of introduced bird species in small (1,5 ha) medium (6,15 ha) and large (>15 ha) remnants of native vegetation within an urban matrix. Transects were surveyed during breeding and non-breeding seasons. There was a significant relationship between introduced species richness and remnant size with larger remnants supporting more introduced species. There was no significant difference in relative abundance of introduced species in remnants of different sizes. Introduced species, as a proportion of the relative abundance of the total avifauna (native and introduced species), did not vary significantly between remnants of differing sizes. There were significant differences in the composition of introduced bird species between the different remnant sizes, with large remnants supporting significantly different assemblages than medium and small remnants. Other variables also have substantial effects on the abundance of introduced bird species. The lack of significant differences in abundance between remnant sizes suggests they were all equally susceptible to invasion. No patches in the urban matrix are likely to be unaffected by introduced species. The effective long-term control of introduced bird species is difficult and resources may be better spent managing habitat in a way which renders it less suitable for introduced species (e.g. reducing areas of disturbed ground and weed dominated areas). [source] | ||||||||||