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The method of developing city centers is the responsibility of local authorities, which must reconcile the interests of investors applying for valuable land with the utility needs and expectations of residents regarding, inter alia, free squares and green enclaves. This study was conducted in Warsaw (Poland). In the study area, for 20 years there has been a discussion about how the area should be developed. So far, the area is used as lawns. During the monitoring period, 72 plant taxa were found. It is possible to state that an urban lawn is an ecosystem with relatively stable conditions, which is, however influenced by human disturbance and specific stress in the city. A city lawn is an oasis of greenery that is easy to set up and maintain, in the case of modernization, it does not generate large costs related to its restoration, unlike gardens. Maintaining an intensive lawn requires not only the selection of appropriate grass species resistant to the influences of the urban environment, but also the optimal way to us it. This research can be used to choose the optimal method for managing and maintaining greenery, considering the conditions of spatial development and environmental factors. [ABSTRACT FROM AUTHOR]

Animals in urban areas can be exposed to human-mediated land use change and radiant heat (called urban heat island effect). Few studies have empirically evaluated the effects of urban heat on wild vertebrates. We live-trapped desert wild rodents from a large metropolitan area in the Sonoran Desert, USA, across seven field sites spanning three strata of land surface temperatures. During the summers of 2019 and 2020, we captured 116 adult pocket mice (Chaetodipus spp. and Perognathus spp.) and Merriam's kangaroo rats (Dipodomys merriami) in mountainous urban parks and open spaces. We measured body condition, proxy for health, using percent body fat (i.e., fat mass divided by body mass). For mammals, this parameter estimates the storage of energy-rich fat, which is important for growth, survival, and reproduction. We measured body condition using a noninvasive quantitative magnetic resonance instrument. Site-level surface temperatures were measured using data loggers and long-term climate data. Results supported the prediction that body condition was greatest in cooler temperature strata compared to the hottest areas. To relate body condition to resource availability, we evaluated vegetation cover and degree of urbanization. Body fat of adult pocket mice was greater in areas with more vegetation cover and where nighttime temperatures and surface temperatures were lower and urbanization was greater. Kangaroo rats had more fat in areas with the lowest strata of surface temperature. These results demonstrate that extreme heat negatively covaries with small mammal body condition, which indicates that urbanization and climate change have the potential to reduce rodent fitness. [ABSTRACT FROM AUTHOR]

The lines between natural areas and human habitats have blurred as urbanization continues, creating a need for the study of ecosystems at all levels of development. This need is particularly acute for exurban environments, which have low population density but are rapidly changing and have a dynamic mix of natural and human-dominated features. We examined long-term (1998–2018) trends in nitrate and chloride concentrations and fluxes in forested and exurban streams in Baltimore County, Md USA. Concentrations and fluxes of nitrate and chloride were an order of magnitude higher in the exurban stream than the forested stream and were increasing even though snowfall and road salt use did not increase over the study period. In the forested stream, concentrations and fluxes of chloride increased from 1998 to 2008, but decreased from 2008 to 2018 due to unquantified factors. Concentrations of nitrate decreased in the forested stream, likely due to decreases in atmospheric deposition. These decreases in atmospheric deposition, and efforts to reduce fertilizer use by county governments, do not appear to have affected nitrate concentrations and fluxes in the exurban watershed. Any efforts to reduce the concentrations and fluxes of chloride and nitrate in exurban streams will likely benefit substantially from further understanding of the mechanisms underlying the temporal patterns. [ABSTRACT FROM AUTHOR]

Land-use and land-cover change strongly affect biodiversity patterns and are assumed to be growing threats in the future. Particularly increasing urbanisation may affect species turnover and functional composition of biological communities. This study aimed to assess the characteristics of land-cover change in a medium-sized urban municipality from 2011 to 2018, and the effects of urbanisation on avian species- and functional diversity. The study was performed in Trondheim (Norway), using local land-cover maps and GBIF bird species occurrence records. GLMMs were used to model species turnover as a function of urbanisation, and the probability of species appearance and disappearance based on urbanisation and species traits. The extent of bird species turnover within a municipality-wide 500 × 500m2 grid was not predicted by a changes in developed area, but the probability of disappearance and appearance of bird species varied with urbanisation and bird functional traits. Species associated with urban- or open areas showed a decreasing probability of disappearing and an increasing probability of appearing with increasing amount of developed area within grid cells. Similarly, granivorous species showed a decreasing probability of disappearing. Species feeding above ground-level showed positive responses to changes in land-cover. The probability of both appearance and disappearance, thus species turnover, increased with increasing longevity. Most functional groups respond negatively to increasing urbanisation, indicating a potential impoverishment of local avifauna with future land-cover modifications. Considering planned future land-cover changes within the municipality, the local avian communities are in danger of homogenisation. The recommendations for local management are to minimise conversion of vulnerable habitats, such as wetlands and woodlands, in particular if these are converted to developed area. [ABSTRACT FROM AUTHOR]

Urban litterfall that is deposited on impervious surface leaches nutrients into stormwater, contributing to downstream eutrophication. Previous studies have focused on the leaching potential of deciduous leaf litter, while other smaller-volume litterfall types—such as blossoms and fruit—may leach significant amounts of nitrogen, phosphorus, and carbon. These additional litterfall types represent an unaccounted-for source of nutrients to urban stormwater. We explored variation in leaching potential of dissolved nutrients and organic carbon across litter types and species by collecting litterfall (blossoms, fruit, leaves) from ten common urban tree species. After 24 h of leaching, we measured total phosphorus (TP), total dissolved nitrogen (TDN), and dissolved organic carbon (DOC) contributions and compared differences across litter types and species. Litter basket estimates then allowed us to quantify annual litterfall inputs. We found that blossoms leached 3–20 times more TDN and 1.5–7 times more TP than leaves of the same species. Furthermore, considering litterfall mass, several species had greater springtime nutrient-leaching potential compared to fall due to high leaching potential in blossoms and lower potential in leaves. We found mixed effects of leaf crushing and leachate solution (stormwater, salinity) on leaching rates. This study highlights the need to consider all litterfall types as well as variation in urban forest communities and conditions when seeking to budget, control, and maintain for potential nutrient sources from the urban forest. [ABSTRACT FROM AUTHOR]

Stormwater wet detention ponds (hereafter "detention ponds") are implemented to mitigate impacts of urban stormwater runoff on downstream waterbodies. We evaluated the effectiveness of detention ponds in providing this protection by quantifying hydrological, chemical, and biological responses in urban depressional wetlands with and without detention ponds draining into them and comparing these responses to non-urban reference depressional wetlands. We predicted if detention ponds protect waterbodies, then the hydrology, water and soil chemistry, and plant communities of urban depressional wetlands receiving detention pond drainage should be more similar to non-urban depressional wetlands than urban depressional wetlands not receiving detention pond drainage. We found wetlands receiving detention pond drainage had post-storm water level recession rates that were slower than wetlands not receiving detention pond drainage, but faster than non-urban wetlands. We also found wetlands with and without detention ponds draining into them (i.e., urban wetlands) to be more similar to each other regarding water and soil chemistry and vegetation than to non-urban wetlands. Compared to non-urban wetlands, both urban wetland types had elevated pH, inorganic nitrogen, and total phosphorus in their soils and waters, and greater coverage and species richness of disturbance-adapted native and nonnative plant species of lower conservation value. Differences in plant communities were related to changes in hydrology and water and soil chemistry, suggesting detention ponds need to better mitigate the effects of urbanization on these factors. Our findings reveal the need to improve detention pond efficiency and/or identify alternative strategies for protecting waterbodies from the effects of urbanization. [ABSTRACT FROM AUTHOR]

Stream restoration is a popular approach for managing nitrogen (N) in degraded, flashy urban streams. Here, we investigated the long-term effects of stream restoration involving floodplain reconnection on riparian and in-stream N transport and transformation in an urban stream in the Chesapeake Bay watershed. We examined relationships between hydrology, chemistry, and biology using a Before/After-Control/Impact (BACI) study design to determine how hydrologic flashiness, nitrate (NO3−) concentrations (mg/L), and N flux, both NO3− and total N (kg/yr), changed after the restoration and floodplain hydrologic reconnection to its stream channel. We examined two independent surface water and groundwater data sets (EPA and USGS) collected from 2002–2012 at our study sites in the Minebank Run watershed. Restoration was completed during 2004 and 2005. Afterward, the monthly hydrologic flashiness index, based on mean monthly discharge, decreased over time from 2002 and 2008. However, from 2008–2012 hydrologic flashiness returned to pre-restoration levels. Based on the EPA data set, NO3− concentration in groundwater and surface water was significantly less after restoration while the control site showed no change. DOC and NO3− were negatively related before and after restoration suggesting C limitation of N transformations. Long-term trends in surface water NO3− concentrations based on USGS surface water data showed downward trends after restoration at both the restored and control sites, whereas specific conductance showed no trend. Comparisons of NO3− concentrations with Cl− concentrations and specific conductance in both ground and surface waters suggested that NO3− reduction after restoration was not due to dilution or load reductions from the watershed. Modeled NO3− flux decreased post restoration over time but the rate of decrease was reduced likely due to failure of restoration features that facilitated N transformations. Groundwater NO3− concentrations varied among stream features suggesting that some engineered features may be functionally better at creating optimal conditions for N retention. However, some engineered features eroded and failed post restoration thereby reducing efficacy of the stream restoration to reduce flashiness and NO3− flux. N management via stream restoration will be most effective where flashiness can be reduced and DOC made available for denitrifiers. Stream restoration may be an important component of holistic watershed management including stormwater management and nutrient source control if stream restoration and floodplain reconnection can be done in a manner to resist the erosive effects of large storm events that can degrade streams to pre-restoration conditions. Long-term evolution of water quality functions in response to degradation of restored stream channels and floodplains from urban stressors and storms over time warrants further study, however. [ABSTRACT FROM AUTHOR]

Federal regulations for municipal separate storm sewer systems (MS4s) in the United States have been in place since 1990 as part of the Nation Pollutant Discharge Elimination System (NPDES), aiming to reduce sediment and pollutant loads originating from urban areas. However, small-municipality (Phase II) MS4s frequently grapple with several challenges, resulting in a lack of stakeholder buy-in and actionable stormwater management plans. We identify five common challenges concerning MS4 requirements based on literature review, professional experience, and feedback solicited from stakeholders, municipal managers, and fellow professionals and offer real-world examples of efficient, effective MS4 frameworks and/or solutions. The five challenges are summarized as beliefs that: (1) agricultural land use is the largest pollutant contributor and the root cause of pollution problems; (2) stormwater management only benefits downstream communities; (3) large, expensive projects are required to comply with regulations; (4) maintenance, monitoring, and inspection of best management practices (BMPs) is overwhelmingly complex and expensive; and (5) a lack of direct funding makes complying with regulations an impossible task. These challenges are universal in nature for Phase II MS4 permittees and can create real barriers for effective stormwater management. However, we found many examples of methods or techniques to effectively address these five specific challenges, making them well-suited and important for discussion. BMPs can create tangible improvements for surrounding communities (e.g., reduced streambank erosion and flooding), and improved understanding of the structure and options within the MS4 program will help small municipalities make informed choices about management plans. [ABSTRACT FROM AUTHOR]

Residential yardscapes are at the forefront of human interaction with nature for those living in urban areas across Europe and North America. In recent years a significant amount of research has investigated urban green spaces using the ecosystem services framework (ES) along with ecosystem disservices (ED) and how such spaces deliver urban ecosystem services (UES). However, a gap exists in understanding how ES and ED manifest themselves in the more specific context of residential yardscapes. Specifically, do homeowners conceptualize ES and ED when talking about their yards without specific prompts to reflect services and disservices? The current work presents a case study of homeowners in the Minneapolis-St. Paul metropolitan area in Minnesota, United States. We used two associated surveys to elicit responses related to homeowners' yards. Without prompting, homeowner conceptualizations of their yardscapes reflected all ES categories with cultural (CES) (e.g., family recreation) and provisioning (PES) (e.g., vegetable cultivation) services cited most often. Homeowners also mentioned ED associated with their own or a neighbor's yard (e.g., attraction of nuisance wildlife). Their plans for yardscapes indicated largely incremental changes (e.g., putting in a new planting bed) vs. drastic shifts (e.g., complete replacement of turfgrass with alternative vegetation). This case study illustrates that the homeowners' conceptualizations of their yards do indeed reflect current ES & ED frameworks without specific prompting. The ES framework, combined with the identified leverage points, can be a fruitful approach for enhancing UES and minimizing ED within residential yardscapes. [ABSTRACT FROM AUTHOR]

Trait-based approaches have been successfully used to demonstrate how the modified ecological conditions within urban areas filter plant species within plant communities. However, there is growing evidence that trait measurement in situ may improve knowledge of the ecological mechanisms underlying such filtering processes. This study aimed to determine the relative contribution of inter- and intraspecific trait variation in explaining the influence of urban-rural gradients on grassland plant communities. Twenty-one stations were sampled along an urban-rural gradient in two French cities. Three functional traits (specific leaf area, maximum height and phenology), chosen to represent general adaptive strategies of plants, were measured on the 26 most abundant grassland plant species. By decomposing the community-level variance of these traits into species turnover, intraspecific trait variability and covariation, we showed how important it may be to take field measurements into account when studying trait distributions in urban ecology. High intraspecific variability may reinforce trait selection effects, for example by favoring both taller species and populations of taller individuals in urban areas in comparison with rural contexts. Advanced phenology at community-level was influenced by early flowering for almost all urban populations of each species while Specific Leaf Area responses were inconsistent. Because trait distributions and ecosystem functions are closely linked, we suggest that it is now important to develop trait-based approaches at community-level, including both intra- and inter-specific trait variability, in order to improve our knowledge of ecological processes operating in urban areas. [ABSTRACT FROM AUTHOR]

Urban green spaces have been recognized as an important source of ecosystem services, whose quantification requires the determination of quantities related to energy, water, carbon and soil nutrient content. In this paper we propose a stochastic ecohydrological model that couples two existing models for water and nutrients in urban soil at the single street-tree scale. The model input are rainfall and irrigation, for water, and deposition and fertilization, for nitrogen, while the output are evapotranspiration, runoff and deep percolation, for water, and plant uptake and leaching, for nitrogen. The various terms are related to the amount of paved and impervious surfaces that surround the tree trunk and regulate the water and nutrient fluxes in and out the soil. Particular attention is paid to the effects of seasonal variations on plant water and nutrients through a temporal variation of the hydrologic variables (i.e., temperature and rainfall intensity and frequencies). The average model outputs are preliminarily compared with the scant existing literature data, supporting the model application to cities with different climatic conditions. The model results are used to estimate the potential for ecosystem services like tree cooling effects, soil carbon sequestration or storm-water management. Because of the minimal structure of the proposed model, it requires a very low amount of data, while accounting for the stochastic input of rainfall. In the context of climate change and increasing urbanization, the model may offer useful indications to urban planners to enhance ecosystem services while minimizing irrigation, fertilization and their related costs. [ABSTRACT FROM AUTHOR]

Urbanization substantially increases nitrogen (N) inputs and hydrologic losses relative to wildland ecosystems, although the fate of N additions to lawns and remnant grasslands remains contested. In montane semi-arid ecosystems, N cycling is often closely coupled to snowmelt (the dominant period of infiltration) and snow cover, which impact soil temperature and moisture. Here, we compared soil N dynamics between a fertilized and irrigated urban lawn and nearby riparian meadow in Salt Lake City, Utah during a snow manipulation experiment. Snow removal increased freeze/thaw events but did not affect N pools, microbial biomass, denitrification potential, or soil oxygen (O). Mineral N was similar between sites despite lawn fertilization, but dissolved organic N (DON) was four-fold greater (2.1 ± 0.1 mg N l) in lawn soil water. Infiltration was lower in the lawn subsoil, and leaching losses (modeled with Hydrus) were small at both sites (< 2 kg N ha y) despite substantial lawn fertilization. Lawn soil O fluctuated between 20.9 and 1.6 % following snowmelt and irrigation, but remained near 20 % in the meadow; the lawn had more reducing microsites as indicated by iron speciation. Post-snowmelt potential denitrification was six-fold greater in the lawn than the meadow. Lawns can potentially provide hotspots of denitrification in a semi-arid landscape that exceed some natural riparian ecosystems, whereas DON may represent an increasingly important form of N loss from lawns. [ABSTRACT FROM AUTHOR]

Urbanization is becoming increasingly important in terms of climate change and ecosystem functionality worldwide. We are only beginning to understand how the processes of urbanization influence ecosystem dynamics and how peri-urban environments contribute to climate change. Brisbane in South East Queensland (SEQ) currently has the most extensive urban sprawl of all Australian cities. This leads to substantial land use changes in urban and peri-urban environments and the subsequent gaseous emissions from soils are to date neglected for IPCC climate change estimations. This research examines how land use change effects methane (CH) and nitrous oxide (NO) fluxes from peri-urban soils and consequently influences the Global Warming Potential (GWP) of rural ecosystems in agricultural use undergoing urbanization. Therefore, manual and fully automated static chamber measurements determined soil gas fluxes over a full year and an intensive sampling campaign of 80 days after land use change. Turf grass, as the major peri-urban land cover, increased the GWP by 415 kg CO-e ha over the first 80 days after conversion from a well-established pasture. This results principally from increased daily average NO emissions of 0.5 g NO ha d from the pasture to 18.3 g NO ha d from the turf grass due to fertilizer application during conversion. Compared to the native dry sclerophyll eucalypt forest, turf grass establishment increases the GWP by another 30 kg CO-e ha. The results presented in this study clearly indicate the substantial impact of urbanization on soil-atmosphere gas exchange in form of non-CO greenhouse gas emissions particularly after turf grass establishment. [ABSTRACT FROM AUTHOR]

To improve understanding of human impacts on headwater stream condition, we quantified relationships between human, terrestrial landscape, and stream system variables in 29 central Iowa watersheds. Across study watersheds, between 0 and 100 % of total land area was characterized as 'urban' (developed and barren land), whereas cultivated land constituted between 0 and 71 % of watershed area. Several variables were measured for each stream and associated watershed. Strengths of correlative relationships were used to select variables for path analysis, which we used to gain insight into factors affecting stream condition by evaluating direct and indirect effects of human system variables, terrestrial landscape variables, and physical stream variables on stream invertebrates. Results indicated that in predominantly urban watersheds, contaminant inputs to streams (measured by streamwater conductivity) negatively affected invertebrates, including EPT taxa (Ephemeroptera, Plecoptera, Trichoptera), and streamwater contaminant concentrations increased with impervious surface and human population density in the watershed. In rural watersheds, high streamwater nitrogen concentrations associated with cultivated land were related to declines in invertebrate taxon richness. Independent of land use, invertebrate abundance and taxonomic diversity were positively related to coarse substrate abundance on the streambed. Additionally, stream flow (discharge) increased with watershed area, which in turn increased invertebrate taxonomic diversity. Apparently, mechanisms responsible for human impacts on stream condition in central Iowa depend on dominant land use in the watershed. Additionally, stream ecosystems with high quality benthic habitat, and those located in large watersheds with greater flow, appear to be more resilient to land use effects. [ABSTRACT FROM AUTHOR]

Urban ecosystems' demands for energy and materials are rapidly growing, as is the burden of wastes produced in utilizing these resources. Current consumption patterns are considered unsustainable, as they degrade resource stocks and ecosystem services that support human populations. While an urban metabolism approach is useful in analyzing resource flow dynamics that affect sustainability, challenges regarding data resolution and temporal and spatial consistency have been persistent issues in both time-series and comparative cross-sectional analyses. We envisioned that addressing these issues would allow a deeper examination of changes in metabolic trends and more robust comparison between urban ecosystems. To minimize inconsistencies, we conducted a time-series and cross-sectional metabolism analysis of three proximate urban ecosystems over a common time period. Our study compared the metabolism of Durham, Orange, and Wake Counties in North Carolina, USA using the highest available data resolution from 1985 to 2005. We found that high resolution temporal data made it possible to identify specific metabolic trends and suggest connections to changes in infrastructure, policy, and weather patterns using additional data resources. Analyzing proximate urban ecosystems over a common time period allowed us to identify the metabolic effects of policy, weather patterns, infrastructure, and waste management programs. In evaluating these outcomes, we demonstrate how urban metabolism analyses could be a valuable tool for management and planning related to resource and energy flows. [ABSTRACT FROM AUTHOR]

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Prompted by recent sustainability trends, some institutions and municipalities have begun quantifying their local impact on the nitrogen (N) cycle. To better understand the N budget at Auburn University (AU), we measured N inputs and outputs in four subsystems (near surface atmosphere, human metabolism, animal metabolism, and landscape) utilizing methods established by Savanick et al. () for the University of Minnesota-Twin Cities (UM). The total AU input of 245.7 Mg N yr and total output 217.5 Mg N yr was made up of the balance of subsystem inputs and outputs (near surface atmosphere 174 Mg N yr input, 174 Mg N yr output; human metabolism 22.8 Mg N yr input, 20.5 Mg N yr output; animal metabolism 39.2 Mg N yr input, 20.9 Mg N yr output; landscape 9.7 Mg N yr input, 2.1 Mg N yr output). We compared these results with N balances for UM and the University of Virginia (UVA) (Leach et al. ) and found that larger campus area was associated with higher commuter emissions, colder average temperatures were associated with more on-campus energy emissions, presence of agriculture and veterinary schools were associated with larger animal metabolism N flux, and campuses greater urban density or crop presence tended to have greater landscape N flux. We found that overall N flux for each campus was similar when normalized per capita (7-11 kg N cap yr). This study provides insight towards reaching sustainability goals at AU and other institutions and can inform decisions regarding pollution reduction plans. [ABSTRACT FROM AUTHOR]

A global warming of 2 °C is predicted to drive almost half the world's lizard populations to extinction. Urban heat island (UHI) effects may further exacerbate the impacts of climate change on organisms that are sensitive to small changes in temperature. Currently, the Phoenix metropolitan region in Arizona, USA, is an average of 3 °C warmer than the surrounding desert. With continuing urbanization and climate change, thermal stress will become an increasingly important facet of urban ecology in coming decades. The main objective of our study was to investigate which landscaping styles and microhabitat variables can most effectively reduce the surface temperatures experienced by lizards. Using a bare lot as a control, we placed copper lizard models with data loggers in several vegetation and irrigation treatments that represent the dominant backyard landscaping styles in Phoenix (grassy mesic with mist irrigation, drip irrigated xeric, unirrigated native, and a hybrid style known as oasis). Our lizard models recorded 6915 estimates of potential body temperatures. We show that lizard activity time in summer was restricted to a few hours in un-irrigated native desert landscaping, while heavily irrigated grass and shade trees allowed for continual activity during even the hottest days. Shade, humidity, and sky view factor explained the majority of variation in temperature at a sub-meter scale. We suggest that maintaining the existing diversity of landscaping styles (as part of an ongoing UHI mitigation strategy targeted at humans) will be beneficial for lizards. [ABSTRACT FROM AUTHOR]

Humans are greatly modifying biogeochemical cycles, in part, by increasing the abundance of many trace elements in heavily developed environments. As a means to study the biogeochemical cycling of trace elements in the urban landscape, we examined their accumulation in the sediments of ponds located in residential developments. To do so, we measured the content of trace elements (Ti, V, Cr, Co, Ni, Cu, Zn, Mo, Ag, Cd, Ba, Tl, Pb) and minerals (Na, Mg, Al, K, Ca, Mn, Fe) in the sediments of stormwater management ponds located in residential catchments of southern Ontario, Canada. Trace elements and associated mineral composition of the sediments primarily clustered in three groups. In one group, several trace elements (e.g., Co and V) were correlated to soil-related minerals (Al and Fe), which indicate a predominant role of soil erosion in their movement across the urban landscape. Elements in the second group (Cd, Pb, Cu, Zn, and Mo) were positively correlated with sediment organic carbon content suggesting an importance of internal pond processing such as adsorption to organic matter. In the third group, Ca and Ag negatively correlated with most other elements likely because, at least for Ca, importation of carbonates in coarse particulate material (i.e., sand) dilutes the concentration of other trace elements. Variability in trace elements among ponds and between municipalities suggests that these elements are deposited and move differently among catchments in a relatively homogenous urban landscape. Our results demonstrate a trace element biogeochemistry in urban environments that is connected to human sources, physical disturbance of the landscape, biological processing, and underlying geological composition of the catchment. [ABSTRACT FROM AUTHOR]

As urbanization can involve multiple alterations to the soil environment, it is uncertain how urbanization effects soil nitrogen cycling. We established 22-0.04 ha plots in six different land cover types-rural slash pine ( Pinus elliottii) plantations ( n = 3), rural natural pine forests ( n = 3), rural natural oak forests ( n = 4), urban pine forests ( n = 3), urban oak forests ( n = 4) and urban lawns ( n = 5) to investigate how net soil nitrogen mineralization rates and soil microbial biomass differed between urban forests and rural forests and between urban forests and urban lawns in the Florida panhandle. Urban forest sites have 2.5 times as much net total nitrogen mineralized than rural forest sites based on the mean daily rates averaged over the 2 years study (2010-2012). Urbanization may increase soil microbial biomass and activity (potential carbon mineralization rates) and this may be influencing the soil nitrogen mineralization rates in the forest sites. To include an urban lawn (turfgrass) component in the study, one time measurements of soils from the aforementioned forest sites and from urban lawn sites (no fertilization, no irrigation) were collected in 2012. Urban forest sites and urban lawns sites do not differ in their potential carbon mineralization rates, potential net total nitrogen mineralization rates or microbial biomass carbon and nitrogen contents. However, lawns have a higher potential net nitrification rate compared to urban forests. [ABSTRACT FROM AUTHOR]

The residential yard is an integral part of the urban ecosystem. Individual preferences and social expectations influence homeowners' yard care choices, which in turn affect urban ecology. However, little is known about residents' conceptions of their yards as part of the urban ecosystem. We asked how homeowners conceive of their yard as part of the urban ecosystem by examining urban ecosystem concepts embedded within homeowners' descriptions and stories of their yards. Our study sites included an urban and suburban area in the Saint Paul-Minneapolis metropolitan area of Minnesota, USA. We found that people's understandings of their yards as urban ecosystems are complex but have prominent gaps. Salient concepts included biotic and abiotic interactions within the yard, linkages of human inputs and weeds across yards and watersheds, and yards as social space. Stories described managing dynamic ecological processes within yards to maintain a steady state and limiting linkages of human inputs beyond the yard. Prominent gaps included ecological cycles, biodiversity, and ecosystem services within yards and ecological linkages across yards. In general, people conceived of their yards in terms of inputs rather than cycles and in terms of creating barriers between their yards and surrounding areas rather than fostering ecological interconnections across them. We provide recommendations for resident outreach programs based on our findings. Finally, our study presents a challenge to urban ecosystem research to unravel where there are gaps in understandings of urban ecosystems versus where there is resistance to incorporating certain ecological interactions within the residential yard. [ABSTRACT FROM AUTHOR]

On-going human population growth and changing patterns of resource consumption are increasing global demand for ecosystem services, many of which are provided by soils. Some of these ecosystem services are linearly related to the surface area of pervious soil, whereas others show non-linear relationships, making ecosystem service optimization a complex task. As limited land availability creates conflicting demands among various types of land use, a central challenge is how to weigh these conflicting interests and how to achieve the best solutions possible from a perspective of sustainable societal development. These conflicting interests become most apparent in soils that are the most heavily used by humans for specific purposes: urban soils used for green spaces, housing, and other infrastructure and agricultural soils for producing food, fibres and biofuels. We argue that, despite their seemingly divergent uses of land, agricultural and urban soils share common features with regards to interactions between ecosystem services, and that the trade-offs associated with decision-making, while scale- and context-dependent, can be surprisingly similar between the two systems. We propose that the trade-offs within land use types and their soil-related ecosystems services are often disproportional, and quantifying these will enable ecologists and soil scientists to help policy makers optimizing management decisions when confronted with demands for multiple services under limited land availability. [ABSTRACT FROM AUTHOR]

Urban runoff has become an increasingly important environmental concern in recent years. With increasing urbanization, turfgrass area has substantially expanded in North America, and these lawns are often established on subsoil stripped of topsoil. In this study, 24 turfgrass-type tall fescue ( Festuca arundinacea) plots were established on subsoil or topsoil, and managed with inorganic fertilizer (Scott's Turf Builder®), organic fertilizer (Nature's Touch® with enzymes), or no fertilizer (control). A one-hour simulated rainfall at 8.9 cm/hour was applied to the plots, and the time to runoff initiation and total runoff volume were measured. Runoff water samples were analyzed to quantify the amounts of sediment, N (NH-N), P, K, and S losses. The results indicated that runoff initiation time was almost half in subsoil lawns (12.5 min) than in topsoil lawns (23 min). The total runoff volume and sediment loss were significantly larger in subsoil lawns (11,900 ml and 3,700 mg, respectively) than in topsoil lawns (2,200 ml and 900 mg, respectively). Although the N, P, K, and S losses in runoff were low, they were significantly higher from the subsoil-based than topsoil-based lawns, and were higher from inorganic fertilizer treated lawns than those treated with organic fertilizer. These results highlight the significance of topsoil preservation in city planning and urban development with respect to urban run-off and water quality and show distinct benefits of organic lawn management practices over the conventional inorganic practices for maintaining urban water quality. [ABSTRACT FROM AUTHOR]

In this era of rapidly urbanising human populations, urban practitioners are under increasing pressure to create resilient and sustainable cities and towns. Urban ecologists currently have a unique opportunity to apply solid, evidence-based research to help create biodiversity-rich and sustainable cities and towns for the future. Unfortunately, there is currently a mismatch between the questions planners, designers and decision-makers are asking urban ecologists that would allow them to improve the biodiversity outcomes in urban areas, and the questions urban ecologists must ask to contribute to the development and application of the science of urban ecology. For a number of reasons, urban ecologists over the past 25 years have primarily focused on describing the patterns of biodiversity in cities and towns using broad, aggregate predictor variables (e.g., distance to city center, land-use, percent cover of impermeable surfaces and vegetation, etc.). We refer to these results as 'low-hanging fruit'. If the discipline of urban ecology is going to provide the necessary information to inform actions to preserve and enhance urban biodiversity, we need to move beyond place-based research, and work towards the development of confirmed generalizations regarding the relationship between the structure and function of urban ecosystems and biodiversity. We propose three essential strategies for achieving this refined understanding: 1) defining the study window to place the study into a broader global context, 2) collecting and using more explicit question-driven measures of the urban condition in order to improve our understanding of urban ecological drivers, as well as recording more detailed ecological responses to provide insights into the ecological mechanisms underlying an observed response, and 3) expanding studies to include multiple cities, regions and countries. These strategies will help to expedite the ability of urban ecology to contribute to the creation of biodiversity-rich, healthy, resilient cities and towns. [ABSTRACT FROM AUTHOR]

Trees provide important ecological services in cities, yet the vulnerability of the urban forest to massive tree losses from pest outbreaks could threaten those services, with unknown environmental consequences. The outbreak of emerald ash borer is an imminent threat to the ash population in North America. In the Minneapolis-Saint Paul, Minnesota, metropolitan area, ash trees are present in 50 % of residential landscapes in Ramsey and Anoka Counties. We used a large survey of household activities, a tree inventory, a Household Flux Calculator accounting tool, and a set of annual evapotranspiration measurements, to quantify the current carbon, nitrogen, and phosphorus storage in ash trees, the cycling of these elements, and the total evapotranspiration from ash trees in residential areas in the metropolitan region. Ash represented 6 % of the trees in residential areas and the removal of the entire ash population would correspondingly reduce net primary production and carbon sequestration by only a few percent and would have negligible effects on losses of nitrogen and phosphorus from residential landscapes. Similarly, the effects of ash loss on the hydrologic cycle would be minimal and would depend largely on management choices for the ground currently underneath ash tree canopies. Overall, the percentage change in biogeochemical and hydrological fluxes corresponded closely with the percent of the total urban tree population that was represented by ash, suggesting that areas with higher densities of ash would experience correspondingly larger effects. A hypothetical tree replacement scenario with similar broadleaf species was determined to be likely to re-establish the original biogeochemical and hydrological conditions once the replacement trees reach maturity. [ABSTRACT FROM AUTHOR]

A Multi-sectoral Systems Analysis (MSA) methodology is presented as a tool for identifying the level of importance of flows of energy and materials (water, nitrogen, phosphorus, and carbon) as they pass through an anthropogenically manipulated system. That system comprises a web of processes, across a total of five industrial sectors: water, forestry, food, energy and waste management. Given the heterogeneous nature and quality of data sources, the propagation of data uncertainty is considered through a Regionalized Sensitivity Analysis (RSA) procedure, based on the Monte Carlo simulation approach. The MSA reveals the advantages of studying different material cycles simultaneously, in addition to interpreting them individually, while gaining insight into the magnitude of the associated flows. The proposed framework is illustrated for a case study of the Upper Chattahoochee Watershed, in which parts of Metro Atlanta are located. Results show that natural flows are predominant in the water and energy cycles. Direct human manipulations of water, i.e., withdrawals for public supply and power generation, are less than 25% of the amount received as precipitation. Solar input is 200 times the total demand for electricity. Apart from sun-light, gasoline for transportation is the flow with the largest content of energy; it is responsible for providing 71% of the total demand of fuels for uses other than power generation. In contrast, cycles of nutrients such as N and C are strongly related to the flows of fuels, mainly coal and natural gas. In a second tier, fertilizer use and the poultry industry in the region are significant for the use of nitrogen. Phosphorus fluxes are similarly dominated by the food sector and, as a consequence, to a lesser extent by the water sector, because of water's role as a waste-conveyance medium. [ABSTRACT FROM AUTHOR]

Urban ecosystems are constantly evolving, and they are expected to change in both space and time with active management or degradation. An urban watershed continuum framework recognizes a continuum of engineered and natural hydrologic flowpaths that expands hydrologic networks in ways that are seldom considered. It recognizes that the nature of hydrologic connectivity influences downstream fluxes and transformations of carbon, contaminants, energy, and nutrients across 4 space and time dimensions. Specifically, it proposes that (1) first order streams are largely replaced by urban infrastructure (e.g. storm drains, ditches, gutters, pipes) longitudinally and laterally within watersheds, (2) there is extensive longitudinal and lateral modification of organic carbon and nutrient retention in engineered headwaters (3) there are longitudinal downstream pulses in material and energy exports that are amplified by interactive land-use and hydrologic variability, (4) there are vertical interactions between leaky pipes and ground water that influence stream solute transport, (5) the urban watershed continuum is a transformer and transporter of materials and energy based on hydrologic residence times, and (6) temporally, there is an evolution of biogeochemical cycles and ecosystem functions as land use and urban infrastructure change over time. We provide examples from the Baltimore Ecosystem Study Long-Term Ecological (LTER) site along 4 spatiotemporal dimensions. Long-term monitoring indicates that engineered headwaters increase downstream subsidies of nitrate, phosphate, sulfate, carbon, and metals compared with undeveloped headwaters. There are increased longitudinal transformations of carbon and nitrogen from suburban headwaters to more urbanized receiving waters. Hydrologic connectivity along the vertical dimension between ground water and leaky pipes from Baltimore's aging infrastructure elevates stream solute concentrations. Across time, there has been increased headwater stream burial, evolving stormwater management, and long-term salinization of Baltimore's drinking water supply. Overall, an urban watershed continuum framework proposes testable hypotheses of how transport/transformation of materials and energy vary along a continuum of engineered and natural hydrologic flowpaths in space and time. Given interest in transitioning from sanitary to sustainable cities, it is necessary to recognize the evolving relationship between infrastructure and ecosystem function along the urban watershed continuum. [ABSTRACT FROM AUTHOR]

We assessed biogeochemical cycling of elements through residential household landscapes to evaluate the importance of annual to decadal household-level decisions for element fluxes that contribute to urban and regional pollution. We combined a mailed survey, vegetation measurements, and allometric and biogeochemical models to estimate fluxes and accumulation of carbon (C), nitrogen (N), and phosphorus (P) in landscapes of 360 single-family homes in the Minneapolis-Saint Paul, Minnesota metropolitan area. Carbon inputs and accumulation were strongly influenced by the presence of trees on the property. Nitrogen inputs to the landscape exceeded estimated ecosystem demand for N on average by 51% and were dominated by N fertilizer application. Because Minnesota state law restricts the use of P fertilizer, pet waste was responsible for 84% of P inputs to the landscape. The results have implications for understanding sources of urban pollution and the potential flexibility (i.e., the potential for change) in household behaviors such as tree planting, fertilization, and pet waste management that contribute to such pollution. [ABSTRACT FROM AUTHOR]

Residential landscapes are a common setting of human-environment interactions. These ubiquitous ecosystems provide social and ecological services, and yard maintenance leads to intended and unintended ecological outcomes. The ecological characteristics of residential landscapes and the human drivers of landscape management have been the focus of disciplinary studies, often at a single scale of analysis. However, an interdisciplinary examination of residential landscapes is needed to understand the feedbacks and tradeoffs of these complex adaptive social-ecological systems as a whole. Our aim is to synthesize the diversity of perspectives, scales of analysis, and findings from the literature in order to 1) contribute to an interdisciplinary understanding of residential landscapes and 2) identify research needs while providing a robust conceptual approach for future studies. We synthesize 256 studies from the literature and develop an interdisciplinary, multi-scalar framework on residential landscape dynamics. Complex human drivers (attitudinal, structural, and institutional factors) at multiple scales influence management practices and the feedbacks with biophysical characteristics of residential landscapes. However, gaps exist in our interdisciplinary understanding of residential landscapes within four key but understudied areas: 1) the link between social drivers and ecological outcomes of management decisions, 2) the ecosystem services provided by these landscapes to residents, 3) the interactions of social drivers and ecological characteristics across scales, and 4) generalizations of patterns and processes across cities. Our systems perspective will help to guide future interdisciplinary collaborations to integrate theories and research methods across geographic locations and spatial scales. [ABSTRACT FROM AUTHOR]

There are numerous examples of small-scale hydrogeomorphic manipulations within urban ecosystems. These modifications are motivated both by a need to handle storm drainage and by a human desire for aquatic ecosystems as places for recreation and aesthetics. In the Phoenix Arizona metropolitan area, two examples of these local modifications are artificial lakes and stormwater retention basins. Although lakes are not a natural feature of Sonoran Desert ecosystems, numerous artificial lakes are evident in the region. Retention basins are a common landscaping practice for preventing damage from rare but potentially large storm events. Here we attempt to quantify the heretofore unknown number and extent of these designed aquatic ecosystems and consider their potential impact on hydrologic landscape connectivity and regional nitrogen (N) removal. For lakes, we found that official GIS layers from local and state agencies had significant misclassifications and omissions. We used two published GIS datasets and state impoundment-permit information to determine the number, areal extent, and water source for artificial lakes. We discovered that there are 908-1,390 lakes in the Phoenix area, with the number varying according to level of aggregation. There are no existing GIS data on retention basins, so we employed drywell-permit data to estimate that there may be 10,000 retention basins in the region. Basic data on N stocks in these ecosystems are discussed within the context of the regional N budget. Accurate data on the extent and distribution of these designed ecosystems will be vital for water-resources planning and stormwater management. [ABSTRACT FROM AUTHOR]

Researchers have identified the importance of social characteristics for understanding ecological patterns in cities but the use of these characteristics in urban stream research has yet to be fully explored. Urban development is currently the second-largest cause of stream impairment in North America due in part to nutrient loading. However, research into factors that influence nutrient concentrations in urban streams is lacking. We sampled seven streams on the island of Montréal daily to measure phosphorus (P) concentration and P flux in each stream. We then compared stream P concentration and flux to several watershed characteristics commonly used to predict stream nutrients (e.g., watershed imperviousness, land use, existence of a riparian buffer) as well as several socio-economic characteristics of the watersheds (e.g., average home value, median household income). Overall, impervious surface cover and measures of land use were most effective at explaining the variation in P concentration and P flux in streams on the island of Montréal, while the riparian buffer and socio-economic variables were less effective. However, dollars spent on fertilizer per hectare of residential land and percent residential land use became important predictors of stream P concentration when impervious surface cover was removed from the regression model. This suggests that after accounting for the impact of physical watershed characteristics, social factors may be important predictors of urban stream P concentration. The results of our study suggest that more research is needed to determine the role that socio-economic variables play with respect to urban stream P. [ABSTRACT FROM AUTHOR]

Urbanization in the southeastern U.S. has progressed rapidly due to economic development and population growth. This is particularly the case in the Piedmont physiographic region of Georgia where an interdisciplinary group of researchers conducted a series of studies, collectively known as the West Georgia Project, to evaluate the causes and consequences of urbanization associated with a mid-size city (<200,000 pop). Although the results of this project have been presented as individual facets, in this manuscript, we will provide a comprehensive picture of the drivers and effects of urbanization across that landscape. First, socio-economic drivers of land use change in Georgia were identified. The feedback of urbanization influences on cultural responses, namely environmental knowledge, was studied in urban vs. rural watersheds. Additionally, an urban-rural gradient of selected watersheds was used to examine the effects of urban development on terrestrial and aquatic ecosystem structure and function. We hypothesized that negative feedbacks would occur as a result of environmental impacts that could alter the rate of development or its spatial distribution. These studies suggested that urbanization has greatly altered many environmental indices. However, environmental awareness seemed to decline as populations became more urbanized and, consequently, there was little indication that the previously mentioned negative feedbacks occurred. With continued conversion of forests to urban land expected through the foreseeable future, greater emphasis on outreach must occur in order to enhance environmental knowledge of rural and urban residents alike and to make urbanizing populations aware of any degradation of environmental quality. [ABSTRACT FROM AUTHOR]

Urban green spaces provide important ecosystem services, such as amenity, biodiversity, productivity, climate amelioration, hydrological and biogeochemical cycling. Intensively managed urban gardens can sequester carbon through vegetation growth and soil C increase, but may experience nitrous oxide (N2O) emissions and reduced soil methane (CH4) uptake from irrigation and fertiliser use. Soil atmosphere exchange of N2O, CH4 and carbon dioxide (CO2) was measured in lawn and wood chip mulched garden areas in Melbourne, Australia in winter, spring and summer under various water and fertiliser regimes. Gas exchange before and after lawn fertiliser application was measured continuously for three weeks using an automated chamber system. Applying fertiliser led to a peak N2O emission of >60 μg N m−2 h−1, but overall only weekly irrigation (10 mm) significantly increased mean soil N2O emissions above that in other treatments. Under mulch, mean soil N2O emissions (14.0 μg N m−2 h−1) were significantly smaller than from irrigated lawn (27.9 μg N m−2 h−1), whereas mean soil CH4 uptake under mulch (−30.7 μg C m−2 h−1) was significantly greater ( p < 0.01) than in any lawn treatment. Lawns were either a weak CH4 sink or source. Soil C density (0–25 cm) under mulch (12.5 kg C m−2) was greater that under lawn (8.0 kg C m−2). On a carbon dioxide equivalent (CO2-e) basis, soil N2O emissions offset the benefits of soil CH4 uptake. Mulched garden areas provide greatest C sequestration potential in soil and vegetation and the smallest non-CO2 emissions, as soil CH4 uptake offsets a large fraction of soil N2O emissions. Results of this study suggest that reducing the irrigation and fertiliser application to lawns can help mitigate GHG emissions from urban garden systems, and increasing the area of mulched perennial garden beds can also provide net GHG benefits; however, this needs to be tested in other garden systems with different soil types and environmental conditions. [ABSTRACT FROM AUTHOR]

Desert landscaping has become a dominant land cover type in arid US cities and often includes native plant species. Does replacement of native plant distribution in urban areas also reestablish ecological functioning characteristic of natural deserts? We compared ecological processes in three landscape types that are common to the metropolitan area of Phoenix, Arizona (USA): residential desert yards created from former lawns, Sonoran Desert preserves within the city, and Sonoran Desert preserves outside the city boundaries. Canopy cover, abundance of herbivorous insects, and soil properties (concentration of inorganic nitrogen (N), soil moisture and organic matter content, and water-holding capacity) were higher in residential desert yards than in native desert sites located both within and outside of the city. Furthermore, soil resources in desert yards were not organized around plant canopies, departing from the predictable resource island pattern that is characteristic of natural deserts. Intentional human manipulation and land use history accounts for these differences, while the urban environment contributes only subtly to soil N concentrations beneath plant canopies. While the use of desert landscaping may have important water conservation benefits, it does not help to mitigate the well-documented excess of reactive N within the Phoenix metropolitan area. [ABSTRACT FROM AUTHOR]

Urbanization is increasing in arid and semi-arid regions of the world and impacting native ecosystems through disturbance, climatic modification, and pollution deposition. Arid ecosystems often exhibit a mosaic of shrub/tree canopy covered and noncanopy covered patches that differ in elemental pools and processes. We measured belowground ecosystem attributes and processes in native Larrea tridentata {(D.C.) Cov} dominated communities along an urban-rural gradient in Phoenix, Arizona. Organic carbon (C), total nitrogen (N), and nitrate levels were significantly greater in the urban locations, but soil respiration rates (Rs) were higher at the rural sites. Urban sites exhibited no difference in Rs and N between the canopy and interplant patches while both the rural and suburban sites had significantly greater N and higher Rs under the canopy than in the interplant spaces. Soil respiration rates at the urban locations were not correlated with either soil moisture or temperature individually. These data suggest that urbanization has caused a disconnect of ecological pattern and processes in L. tridentata ecosystems within the urban setting such that water and N limitations no longer explain expected spatial Rs patterns, or elemental pools. [ABSTRACT FROM AUTHOR]

Urban biodiversity conservation needs a firm scientific foundation, one that draws upon active and regionally calibrated research programs. Until recently this foundation has not existed. In this paper we examine the way in which the emerging discipline of restoration ecology in an urban context can learn from the experiences of ongoing restoration projects and in turn how novel insights from research of urban soils can help these projects define and reach their goals. Limitations on collaboration between academic researchers and practitioners continues be problematic. We discuss a model whereby this impediment may be removed. A case study of Rhamnus cathartica, an invader of Midwestern woodlands which modifies some important soil ecosystem properties will be used to illustrate the potential for engagement between research and practice. [ABSTRACT FROM AUTHOR]

A central principle in urban ecological theory implies that in urbanized landscapes anthropogenic drivers will dominate natural drivers in the control of soil organic carbon storage (SOC). To assess the effect of urban land-use change on the storage of SOC, we compared SOC stocks of turf grass and native cover types of two metropolitan areas (Baltimore, MD, and Denver, CO) representing climatologically distinct regions in the United States. We hypothesized that introducing turf grass and management will lead to higher SOC densities in the arid Denver area and lower densities in the mesic Baltimore area relative to native cover types. Moreover, differences between turf grass soils will be less than differences between the native soils of each metropolitan region. Within Baltimore, turf grass had almost a 2-fold higher SOC density at 0- to 1-m and 0- to 20-cm depths than in rural forest soils, whereas there were no differences with soils of urban forest remnants. Moreover, urban forest remnants had more than 70% higher SOC densities than rural forest soils. Within Denver, turf grass (>25 years of age) had more than 2-fold higher SOC densities than in shortgrass steppe soils, while having similar densities to Baltimore turf grass soils. By contrast, the native soils of Baltimore were almost 2-fold higher than the native steppe grass soils of Denver using SOC densities of remnant forests as representative of native soils in the Baltimore region. These results supported our hypothesis that turf grass systems will be similar in SOC densities across regional variations in climate, parent material, and topography. These similarities are apparently due to greater management efforts in the Denver region to offset the constraint of climate, i.e., anthropogenic factors (management supplements) overwhelmed native environmental factors that control SOC storage. [ABSTRACT FROM AUTHOR]

We propose a framework of key concepts useful in understanding how urban soils can contribute to general ecological theory. The major factors that can cause urban soils to be different from soils in non-urban ecosystems are identified and related to the familiar state factor approach. We evaluate directly altered resource availability, and the role of stress in mediating resource availability in urban ecosystems. Modified groundwater and stream flow, and atmospheric deposition of nitrogen and base cations are particularly important resource fluxes to soils in urban ecosystems. Disturbance can be conceptualized in the same way in urban as in non-urban ecosystems. However, in addition to biophysical disturbances familiar to ecologists studying wild lands, demographically and socially mediated changes in ecosystem structure must also be considered. These changes include human migration and population structure, institutional shifts, and the effects of human health. Finally, spatial heterogeneity, including fragmentation and differential connectivity, integrates the effects of resources and disturbance, and has an effect on subsequent resource availability and susceptibility to disturbance. Layers of heterogeneity include not only the geomorphic template, but urban climate, biotic composition, buildings and infrastructure, and demographic-social patterns. The complex layering of natural and social factors that constitute urban heterogeneity permit the continuation of important ecological processes, as well as modify ecological fluxes involving soils. We present a modification of the state factor approach as an expanded framework for the study of urban soils. The understanding of urban soils can contribute to general ecological theory by testing the generality of important ecosystem drivers and their linkage with social processes in an under investigated ecosystem type that is increasing in extent and impact worldwide. [ABSTRACT FROM AUTHOR]

Information about the topic discussed at the 2004 annual meeting of the Ecological Society of America in the U.S. It mentions that the focus of the symposium was in reviewing and discussing contemporary understandings of urban soils with particularly on how studying urban soils can contribute to the development and testing of ecological theory. Moreover, the study of urban soil ecology and its relevance to general theory and applied knowledge was also discussed.

We conducted an urban "metabolic" study of inputs and outputs of food, water, energy, and pollutants from Los Angeles County, USA. This region has been the subject of recent debate about the nature of population density and distribution as it relates to urban form and associated environmental impacts. We found that with the exception of food imports and wastewater outputs, inputs of resources and outputs of pollutants generally declined on a per capita basis from 1990 to 2000. Reductions likely reflected a combination of changes in public policy, improvements in technology and public infrastructure, and impacts of increases in population density. However, in comparison to other municipalities and urban regions, resource consumption per capita was still relatively high in some categories, particularly inputs of water and transportation energy. Per capita greenhouse gas emissions were lower in Los Angeles County than for the average of the USA as a whole but higher than previous analyses of urban areas internationally, largely due to comparatively high emissions from the transportation sector. Wastewater discharge accounted for less than 40% of water inputs excluding precipitation; however the partitioning of water outputs through other potential losses, specifically evapotranspiration, runoff, and groundwater recharge, remains highly uncertain. We suggest that more detailed information about water losses will greatly improve future mass and energy accounting for analyses of urban environmental sustainability in this semi-arid region. [ABSTRACT FROM AUTHOR]

High levels of endemism, the sensitivity of species that have evolved without humans, and the invasion of exotic species have all contributed to severe depletion of indigenous biodiversity in New Zealand. We considered the contribution that urban restoration can make to maximising biodiversity by analysing landcover patterns from two national databases along an urban-rural gradient. Thirteen of 20 land environments in New Zealand are represented in cities, and nearly three-quarters of all acutely threatened land environments are represented within 20 km of city cores nationally. Despite this, remaining indigenous landcover is low within urban cores, with less than 2% on average, but increasing to more than 10% on average in the periurban zone. Threatened lowland environments are most commonly represented within cities, and least represented within protected natural areas. Restoration of existing urban habitat is insufficient to halt biodiversity loss. Ecosystem reconstruction is required to achieve a target of 10% indigenous cover within cities. A co-ordinated national urban biodiversity plan to address issues beyond a local and regional focus is needed. Analysis of national patterns of urban land environments, indigenous cover and remnant ecosystems will support action at a regional and local level while enhancing national and global biodiversity goals. [ABSTRACT FROM AUTHOR]

Habitat structure is defined as the composition and arrangement of physical matter at a location. Although habitat structure is the physical template underlying ecological patterns and processes, the concept is relatively unappreciated and underdeveloped in ecology. However, it provides a fundamental concept for urban ecology because human activities in urban ecosystems are often targeted toward management of habitat structure. In addition, the concept emphasizes the fine-scale, on-the-ground perspective needed in the study of urban soil ecology. To illustrate this, urban soil ecology research is summarized from the perspective of habitat structure effects. Among the key conclusions emerging from the literature review are: (1) habitat structure provides a unifying theme for multivariate research about urban soil ecology; (2) heterogeneous urban habitat structures influence soil ecological variables in different ways; (3) more research is needed to understand relationships among sociological variables, habitat structure patterns and urban soil ecology. To stimulate urban soil ecology research, a conceptual framework is presented to show the direct and indirect relationships among habitat structure and ecological variables. Because habitat structure serves as a physical link between sociocultural and ecological systems, it can be used as a focus for interdisciplinary and applied research (e.g., pest management) about the multiple, interactive effects of urbanization on the ecology of soils. [ABSTRACT FROM AUTHOR]

Using a spatially extensive urban database constructed from the Maryland Biological Stream Survey (MBSS), we describe the relationships of nutrients in small-order streams to eight defined categories of percent catchment urbanization, correlations between chloride and conductivity in urban streams, and relationships between nutrients and chloride with two Maryland-specific indices of biotic integrity for benthic macroinvertebrates and fish assemblages. Stream nutrients become elevated with increasing percent catchment urbanization, followed by increases in all four measured nitrogen species and total phosphorus at catchment urbanization levels greater than 10%. There was a strong collinear relationship (r²=0.90) between chloride and conductivity (trimeans) across all eight urbanization classes, where Cl (mg/L)=-0.397+0.188*conductivity (μS/cm). Critical values for all water quality parameters with the two Maryland biological indices were derived using quantile regression, with significant regressions developed for 11 of 16 water quality parameters and the two biotic indices. For nitrate (NO3-N), the critical thresholds between fair and poor stream quality for the two Maryland biological indices were 0.83 mg/L (benthic macroinvertebrate assemblages) and 0.86 mg/L (fish assemblages). Increasing stream nutrient and chloride levels, associated with widespread catchment urbanization intensity, now affect many small streams in Maryland, with implications for decreasing water quality in major tributaries and the Chesapeake Bay. [ABSTRACT FROM AUTHOR]

This paper reviews the main bodies of contemporary urban sustainability theory. From this analysis, two underpinning paradigms of urban sustainability are identified: (1) The ‘Human Exemptionalism Paradigm’ (HEP), which emphasizes the ability of humans to overcome environmental problems—see Urban Sociology, Urban Ecology, Urban Geography, Urban Psychology and Political Economy; and (2) The ‘New Ecological Paradigm’ (NEP), which emphasizes the criticality of ecological limits to human progress—see Urban Metabolism, Energy/Emergy Analysis and Ecological Footprinting. Each of these approaches is critically reviewed, highlighting their main assumptions, theoretical and practical foci. It is argued in the paper that if the related issues of urban sustainability and development are to be progressed, there needs to be: (1) a greater maturation of the NEP approaches, which are ‘relative newcomers’ to the area of urban theory; and (2) greater integration and dialogue between the HEP and NEP approaches to urban sustainability than has hitherto been the case. [ABSTRACT FROM AUTHOR]

Households are an important scale of analysis for human ecosystems because they are a major source of pollutants and could thus be a new focus for pollution management, particularly for education-based source reduction strategies. The household is also a meaningful unit for analysis of human ecosystems, being common to all human cultures. This study develops a Household Flux Calculator (HFC) to compute C, N, and P fluxes for scenarios intended to represent three levels of household consumption: low, typical, and high. All three scenarios were developed for suburban households with two adults and two children in the Minneapolis-St. Paul (Twin Cities) metropolitan area, Minnesota. Calculated ratios of fluxes between high and low consumption households were 3.5:1 for C, 2.7:1 for N and 1.4:1 for P. Results suggest a high level of discretionary consumption that could be reduced without a substantial reduction in standard of living. Thus, modest changes in behavior in high consumption households would greatly reduce fluxes of C, N, and P without major changes in lifestyle. [ABSTRACT FROM AUTHOR]

Studies of flowering and leafing phenology have dramatically increased during the last few decades because changes in plant phenology can be indicative of possible effects of climate change at multiple scales. This article reviews the available literature focusing on the effects of urbanization on flowering phenology. The literature of flowering phenology in urban environments suggests that spring-blooming plants in a variety of ecosystems in North America, Europe, and China tend to bloom earlier in the city than in the surrounding un-urbanized habitat. Moreover, ephemerals, early spring bloomers, and insect-pollinated plants in these environments tend to be more sensitive than perennials, mid- or late-spring bloomers, and wind-pollinated plants. Researchers attribute advanced flowering in urban environments to the Heat Island Effect. The potential ecological consequences of changes in flowering phenology in urbanized areas are not well understood or explicitly studied. However, studies in global biology have suggested that climate change may result in a series of important ecological consequences as well as human-related problems such as earlier and extended allergy seasons. More field-based studies are needed to elucidate this issue. [ABSTRACT FROM AUTHOR]