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"Cadenasso, Mary L."
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Trees Grow on Money: Urban Tree Canopy Cover and Environmental Justice
This study examines the distributional equity of urban tree canopy (UTC) cover for Baltimore, MD, Los Angeles, CA, New York, NY, Philadelphia, PA, Raleigh, NC, Sacramento, CA, and Washington, D.C. using high spatial resolution land cover data and census data. Data are analyzed at the Census Block Group levels using Spearman's correlation, ordinary least squares regression (OLS), and a spatial autoregressive model (SAR). Across all cities there is a strong positive correlation between UTC cover and median household income. Negative correlations between race and UTC cover exist in bivariate models for some cities, but they are generally not observed using multivariate regressions that include additional variables on income, education, and housing age. SAR models result in higher r-square values compared to the OLS models across all cities, suggesting that spatial autocorrelation is an important feature of our data. Similarities among cities can be found based on shared characteristics of climate, race/ethnicity, and size. Our findings suggest that a suite of variables, including income, contribute to the distribution of UTC cover. These findings can help target simultaneous strategies for UTC goals and environmental justice concerns.
Journal Article
Evolution and future of urban ecological science: ecology in, of, and for the city
The contrast between ecology in cities and ecology of cities has emphasized the increasing scope of urban ecosystem research. Ecology in focuses on terrestrial and aquatic patches within cities, suburbs, and exurbs as analogs of non-urban habitats. Urban fabric outside analog patches is considered to be inhospitable matrix. Ecology of the city differs from ecology in by treating entire urban mosaics as social-ecological systems. Ecology of urban ecosystems incorporates biological, social, and built components. Originally posed as a metaphor to visualize disciplinary evolution, this paper suggests that the contrast has conceptual, empirical, and methodological contents. That is, the contrast constitutes a disciplinary or \"local\" paradigm shift. The paradigm change between ecology in and ecology of represents increased complexity, moving from focus on biotic communities to holistic social-ecological systems. A third paradigm, ecology for the city, has emerged due to concern for urban sustainability. While ecology for includes the knowledge generated by both ecology in and ecology of, it considers researchers as a part of the system, and acknowledges that they may help envision and advance the social goals of urban sustainability. Using urban heterogeneity as a key urban feature, the three paradigms are shown to contrast in five important ways: disciplinary focus, the relevant theory of spatial heterogeneity, the technology for representing spatial structure, the resulting classification of urban mosaics, and the nature of application to sustainability. Ecology for the city encourages ecologists to engage with other specialists and urban dwellers to shape a more sustainable urban future.
Journal Article
Quantifying Spatial Heterogeneity in Urban Landscapes: Integrating Visual Interpretation and Object-Based Classification
Describing and quantifying the spatial heterogeneity of land cover in urban systems is crucial for developing an ecological understanding of cities. This paper presents a new approach to quantifying the fine-scale heterogeneity in urban landscapes that capitalizes on the strengths of two commonly used approaches—visual interpretation and object-based image analysis. This new approach integrates the ability of humans to detect pattern with an object-based image analysis that accurately and efficiently quantifies the components that give rise to that pattern. Patches that contain a mix of built and natural land cover features were first delineated through visual interpretation. These patches served as pre-defined boundaries for finer-scale segmentation and classification of within-patch land cover features which were classified using object-based image analysis. Patches were then classified based on the within-patch proportion cover of features. We applied this approach to the Gwynns Falls watershed in Baltimore, Maryland, USA. The object-based classification approach proved to be effective for classifying within-patch land cover features. The overall accuracy of the classification maps of 1999 and 2004 were 92.3% and 93.7%, respectively. This exercise demonstrates that by integrating visual interpretation with object-based classification, the fine-scale spatial heterogeneity in urban landscapes and land cover change can be described and quantified in a more efficient and ecologically meaningful way than either purely automated or visual methods alone. This new approach provides a tool that allows us to quantify the structure of the urban landscape including both built and non-built components that will better accommodate ecological research linking system structure to ecological processes.
Journal Article
The Effect of Nitrogen Deposition on Plant Performance and Community Structure: Is It Life Stage Specific?
Nitrogen (N) deposition is a key global change factor that is increasing and affecting the structure and function of many ecosystems. To determine the influence of N deposition on specific systems, however, it is crucial to understand the temporal and spatial patterns of deposition as well as the response to that deposition. Response of the receiving plant communities may depend on the life stage-specific performance of individual species. We focus on the California oak savanna because N deposition to this system is complex-characterized by hotspots on the landscape and seasonal pulses. In a greenhouse experiment, we investigated the relative influence of N deposition on plant performance during early growth, peak biomass, and senescent life stages across different soil types, light, and community compositions. To represent the community we used three grass species-a native, naturalized exotic, and invasive exotic. At early growth and peak biomass stages performance was measured as height, and shoot and root biomass, and at the senescent stage as seed production. Simulated N deposition 1) increased shoot biomass and height of the native and, even more so, the naturalized exotic during early growth, 2) positively affected root biomass in all species during peak biomass, and 3) had no influence on seed production at the senescent stage. Alone, N deposition was not a strong driver of plant performance; however, small differences in performance among species in response to N deposition could affect community composition in future years. In particular, if there is a pulse of N deposition during the early growth stage, the naturalized exotic may have a competitive advantage that could result in its spread. Including spatial and temporal heterogeneity in a complex, manipulative experiment provides a clearer picture of not only where N management efforts should be targeted on the landscape, but also when.
Journal Article
Does the ecological concept of disturbance have utility in urban social-ecological-technological systems?
The ecological concept of disturbance has scarcely been applied in urban systems except in the erroneous but commonplace assumption that urbanization itself is a disturbance and cities are therefore perennially disturbed systems. We evaluate the usefulness of the concept in urban ecology by exploring how a recent conceptual framework for disturbance (Peters et al.
2011
, Ecosphere, 2, art 81) applies to these social-ecological-technological systems (). Case studies, especially from the Long-Term Ecological Research sites of Baltimore and Phoenix, are presented to show the applicability of the framework for disturbances to different elements of these systems at different scales. We find that the framework is easily adapted to urban and that incorporating social and technological drivers and responders can contribute additional insights to disturbance research beyond urban systems.
Journal Article
Stormwater utility fees and household affordability of urban water services
Stormwater utility fees provide dedicated revenues for managing stormwater. In setting fees, household-level affordability should be considered. Existing research does not address methods to evaluate the affordability of stormwater utility fees, especially alongside other household water costs. This paper aims to fill that gap. We present a scenario-based approach to evaluate household affordability of stormwater utility fees in a municipality, which considers other essential household water service charges. We estimate the relative contribution of stormwater utility fees to total household water costs and evaluate affordability across income brackets by integrating data for socioeconomic status, land use, water utility charges, and impervious surface cover. Using data for a case study region, results indicate that stormwater utility fees are small contributors to overall household urban water costs and comprise no more than 2% of the median household income across nearly all income quintiles. For low-income households, stormwater charges only exceed 1% of the household income for the lowest-income brackets (<$20,000) and still represent a small portion of household water costs. The analysis demonstrates a generalizable approach that can be applied everywhere when evaluating a stormwater utility fee as a funding strategy.
Journal Article
Patch Atlas
A new tool for mapping urban land cover that integrates design principles and ecological knowledge for understanding cities as complex, patchy and dynamic systems Using a new, hybrid approach to urban land cover classification as an impetus to bring ecologists and urban designers together, this atlas is a unique conceptual tool to describe and analyze cities as complex systems. It brings together over a decade of shared knowledge from the Baltimore Ecosystem Study to inspire ecologically motivated design practice. The atlas displays maps and tables depicting land cover classes and the relationships between them; information on how the specific cover arrangements evolved over time; and speculations on how they might change through design, disturbance, or succession. Rather than separating human-constructed spaces from predominantly biological and geological ones, this book integrates social and ecological structures and shows how this can contribute to the scholarship of ecology and the practice of design. Interdisciplinary and strikingly illustrated, the atlas is a new way to study, measure, and view cities with a more effective interaction of scientific understanding and design practice.
eBook
Predicting Opportunities for Greening and Patterns of Vegetation on Private Urban Lands
This paper examines predictors of vegetative cover on private lands in Baltimore, Maryland. Using high-resolution spatial data, we generated two measures: “possible stewardship,” which is the proportion of private land that does not have built structures on it and hence has the possibility of supporting vegetation, and “realized stewardship,” which is the proportion of possible stewardship land upon which vegetation is growing. These measures were calculated at the parcel level and averaged by US Census block group. Realized stewardship was further defined by proportion of tree canopy and grass. Expenditures on yard supplies and services, available by block group, were used to help understand where vegetation condition appears to be the result of current activity, past legacies, or abandonment. PRIZM[trade mark sign] market segmentation data were tested as categorical predictors of possible and realized stewardship and yard expenditures. PRIZM[trade mark sign] segmentations are hierarchically clustered into 5, 15, and 62 categories, which correspond to population density, social stratification (income and education), and lifestyle clusters, respectively. We found that PRIZM 15 best predicted variation in possible stewardship and PRIZM 62 best predicted variation in realized stewardship. These results were further analyzed by regressing each dependent variable against a set of continuous variables reflective of each of the three PRIZM groupings. Housing age, vacancy, and population density were found to be critical determinants of both stewardship metrics. A number of lifestyle factors, such as average family size, marriage rates, and percentage of single-family detached homes, were strongly related to realized stewardship. The percentage of African Americans by block group was positively related to realized stewardship but negatively related to yard expenditures.
Journal Article
Shifting concepts of urban spatial heterogeneity and their implications for sustainability
Context
Spatial heterogeneity has myriad influences on ecosystem processes, ecosystem services, and thus the sustainability of urban areas. It acts as a medium for urban design, planning, and management to determine how processes affecting sustainability can operate and interact. Therefore, how spatial heterogeneity is conceptualized and measured in cities is crucial for enhancing sustainability.
Objectives
We show that the two most commonly used, but contrasting paradigms of urban ecology, ecology IN versus ecology OF the city, determine how spatial heterogeneity is thought of and used in different ways. We identify the key implications of these theoretical contrasts for the practice and assessment of sustainability in urban areas.
Methods
We review and compare the different ways in which ecology IN versus ecology OF the city affect how to conceptualize, model and map urban spatial heterogeneity. We present a new framework to guide the comparison of spatial heterogeneity under the two paradigms.
Results and conclusion
The integrative nature of this new framework becomes apparent under the ecology OF the city paradigm, because it recognizes the hybrid social and bioecological nature of heterogeneity in urban ecosystems. The hybrid approach to patchiness resonates with the three pillars of sustainability—environment, society, and economy. We exemplify how the more comprehensive and integrated framework of spatial heterogeneity under the ecology OF the city paradigm (1) supports more effective measurement and integration of the three components of sustainability, (2) improves management of heterogeneous urban ecosystems, and (3) satisfies calls for improved ecological tools to support urban ecosystem design.
Journal Article