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Urban Landscape Heterogeneity Influences the Relationship Between Tree Canopy and Land Surface Temperature

Jung, Meen Chel; Dyson, Karen; Alberti, Marina. (2021). Urban Landscape Heterogeneity Influences the Relationship Between Tree Canopy and Land Surface Temperature. Urban Forestry & Urban Greening, 57.

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Abstract

Urban trees play a key role in alleviating elevated summertime land surface temperatures in cities. However, urban landscape influences the capacity of urban trees to mitigate higher temperatures. We propose that both developed land characteristics and tree cover should be considered to accurately estimate the mitigation effects of canopy cover. We subclassified original land cover based on the canopy cover ratio to capture the within-land cover heterogeneity. We selected two coastal cities with different summertime climatic conditions: Seattle, Washington, USA, and Baltimore, Maryland, USA. We used Landsat-based grid cells (30 m x 30 m) as our spatial analytical unit, with corresponding land surface temperature, canopy area, canopy compactness, population size, and National Land Cover Database (NLCD)-based land cover group. We first used grouped boxplots, Kruskal-Wallis H tests, and post-hoc multiple comparison tests to detect the distribution of land surface temperatures by the land cover group. We then introduced statistical models to test the group effects on the relationship between land surface temperatures and canopy cover variables. We found: (1) land surface temperature increases with level of development, (2) land surface temperature decreases with canopy cover level, (3) the magnitude of the mitigation effects from canopy area differs based on development level and current canopy cover, (4) the differing efficacies of canopy area in decreasing land surface temperature follows a nonlinear threshold relationship, and (5) compactness of canopy cover was not significant in reducing the land surface temperature. These findings suggest the importance of considering heterogeneous canopy cover within developed land cover classes in urban heat island research. Tree planting strategies need to consider the nonlinear relationships between tree canopy cover and land surface temperature alongside environmental equity concerns.

Keywords

Extreme Heat Events; Climate-change; Cover Data; Island; Pattern; Cities; Vegetation; Mortality; Phoenix; Impact; Canopy Cover; Environmental Equity; Land Cover; Land Surface Temperature; Mitigation Effect; Area; Canopy; Cells; Climatic Factors; Databases; Heat Island; Landscapes; Multiple Comparison Test; Planting; Population Size; Research; Statistical Models; Summer; Surface Temperature; Testing; Trees; Urban Forestry; Maryland

Integrating Solutions to Adapt Cities for Climate Change

Lin, Brenda B.; Ossola, Alessandro; Alberti, Marina; Andersson, Erik; Bai, Xuemei; Dobbs, Cynnamon; Elmqvist, Thomas; Evans, Karl L.; Frantzeskaki, Niki; Fuller, Richard A.; Gaston, Kevin J.; Haase, Dagmar; Jim, Chi Yung; Konijnendijk, Cecil; Nagendra, Harini; Niemela, Jari; Mcphearson, Timon; Moomaw, William R.; Parnell, Susan; Pataki, Diane; Ripple, William J.; Tan, Puay Yok. (2021). Integrating Solutions to Adapt Cities for Climate Change. Lancet Planetary Health, 5(7), E479 – E486.

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Abstract

Record climate extremes are reducing urban liveability, compounding inequality, and threatening infrastructure. Adaptation measures that integrate technological, nature-based, and social solutions can provide multiple co-benefits to address complex socioecological issues in cities while increasing resilience to potential impacts. However, there remain many challenges to developing and implementing integrated solutions. In this Viewpoint, we consider the value of integrating across the three solution sets, the challenges and potential enablers for integrating solution sets, and present examples of challenges and adopted solutions in three cities with different urban contexts and climates (Freiburg, Germany; Durban, South Africa; and Singapore). We conclude with a discussion of research directions and provide a road map to identify the actions that enable successful implementation of integrated climate solutions. We highlight the need for more systematic research that targets enabling environments for integration; achieving integrated solutions in different contexts to avoid maladaptation; simultaneously improving liveability, sustainability, and equality; and replicating via transfer and scale-up of local solutions. Cities in systematically disadvantaged countries (sometimes referred to as the Global South) are central to future urban development and must be prioritised. Helping decision makers and communities understand the potential opportunities associated with integrated solutions for climate change will encourage urgent and deliberate strides towards adapting cities to the dynamic climate reality.

Keywords

Urban; Resilience; Energy; Water; Transformations; Sustainability; Opportunities; Challenges; Mitigation; Knowledge

Effects of Mid-Twenty-first Century Climate and Land Cover Change on the Hydrology Of the Puget Sound Basin, Washington

Cuo, Lan; Beyene, Tazebe K.; Voisin, Nathalie; Su, Fengge; Lettenmaier, Dennis P.; Alberti, Marina; Richey, Jeffrey E. (2011). Effects of Mid-Twenty-first Century Climate and Land Cover Change on the Hydrology Of the Puget Sound Basin, Washington. Hydrological Processes, 25(11), 1729 – 1753.

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Abstract

The distributed hydrology-soil-vegetation model (DHSVM) was used to study the potential impacts of projected future land cover and climate change on the hydrology of the Puget Sound basin, Washington, in the mid-twenty-first century. A 60-year climate model output, archived for the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4), was statistically downscaled and used as input to DHSVM. From the DHSVM output, we extracted multi-decadal averages of seasonal streamflow, annual maximum flow, snow water equivalent (SWE), and evapotranspiration centred around 2030 and 2050. Future land cover was represented by a 2027 projection, which was extended to 2050, and DHSVM was run (with current climate) for these future land cover projections. In general, the climate change signal alone on sub-basin streamflow was evidenced primarily through changes in the timing of winter and spring runoff, and slight increases in the annual runoff. Runoff changes in the uplands were attributable both to climate (increased winter precipitation, less snow) and land cover change (mostly reduced vegetation maturity). The most climatically sensitive parts of the uplands were in areas where the current winter precipitation is in the rain-snow transition zone. Changes in land cover were generally more important than climate change in the lowlands, where a substantial change to more urbanized land use and increased runoff was predicted. Both the annual total and seasonal distribution of freshwater flux to Puget Sound are more sensitive to climate change impacts than to land cover change, primarily because most of the runoff originates in the uplands. Both climate and land cover change slightly increase the annual freshwater flux to Puget Sound. Changes in the seasonal distribution of freshwater flux are mostly related to climate change, and consist of double-digit increases in winter flows and decreases in summer and fall flows. Copyright (C) 2010 John Wiley & Sons, Ltd.

Keywords

Joaquin River-basin; Water-resources; Change Impacts; Model; Sensitivity; Temperature; Prediction; Streamflow; Forecasts; Humidity; Hydrologic Prediction; Climate Change Impacts; Land Cover Change Impacts

The Benefits and Limits of Urban Tree Planting for Environmental and Human Health

Pataki, Diane E.; Alberti, Marina; Cadenasso, Mary L.; Felson, Alexander J.; McDonnell, Mark J.; Pincetl, Stephanie; Pouyat, Richard V.; Setala, Heikki; Whitlow, Thomas H. (2021). The Benefits and Limits of Urban Tree Planting for Environmental and Human Health. Frontiers In Ecology And Evolution, 9.

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Abstract

Many of the world's major cities have implemented tree planting programs based on assumed environmental and social benefits of urban forests. Recent studies have increasingly tested these assumptions and provide empirical evidence for the contributions of tree planting programs, as well as their feasibility and limits, for solving or mitigating urban environmental and social issues. We propose that current evidence supports local cooling, stormwater absorption, and health benefits of urban trees for local residents. However, the potential for urban trees to appreciably mitigate greenhouse gas emissions and air pollution over a wide array of sites and environmental conditions is limited. Consequently, urban trees appear to be more promising for climate and pollution adaptation strategies than mitigation strategies. In large part, this is due to space constraints limiting the extent of urban tree canopies relative to the current magnitude of emissions. The most promising environmental and health impacts of urban trees are those that can be realized with well-stewarded tree planting and localized design interventions at site to municipal scales. Tree planting at these scales has documented benefits on local climate and health, which can be maximized through targeted site design followed by monitoring, adaptive management, and studies of long-term eco-evolutionary dynamics.

Keywords

Outdoor Thermal Comfort; Improved Public-health; Carbon Storage; Ecosystem Services; Air-quality; Rainfall Interception; Vegetation; Cover; Design; Impact; Urban Ecology; Forestry; Sustainability; Policy; Climate Mitigation; Climate Adaptation; Ecosystem Disservices

PhD in the Built Environment

The College of Built Environments consists of five departments that together provide one of the country’s few comprehensive built environment programs within one academic unit: Architecture, Construction Management, Landscape Architecture, Real Estate, and Urban Design and Planning. Together, this combination of departments enable faculty and students to engage almost the entire development process, from economic and environmental planning, real estate, regulatory processes, siting and design, through actual financing and construction, to facility management and adaptive reuse in subsequent stages. Thus, the college is inherently multi-disciplinary, not only in terms of the dimensions of reality that it treats, but also in regard to the specialized disciplines, methods, and practices that it employs: history, theory, cultural criticism, engineering, design, planning, urban design, energy sciences, acoustics, lighting, environmental psychology, ecology, real estate analysis, statistics, management, horticulture, soil science, law, public policy, and ethics. In addition, because of the College’s focus on comprehensive analysis and practice concerning the built environment and its interrelation with society, it is substantially engaged in interdisciplinary work with other units on campus and outside of the campus, including mechanical, civil, and electrical engineering; with public policy and the health sciences; with art and art history; with textual interpretation in the humanities; with many of the computing and digitization activities that range from digital arts to the information school and technical communications; with education and social studies and services; with sustainability and ecological programs, including urban ecology, geography, the College of Forest Resources (especially urban horticulture and urban forestry), and Ocean Science and Fisheries; with environmental and land use law.

The College’s interdisciplinary character is a good fit with the emerging trends in today’s complex world, where only a pluralistic and collaborative approach will generate the necessary learning and teaching, research, and service. If we are to provide, in the end, both disciplinary and professional means to promote environmental well-being, the diverse environmental specializations must be fully integrated. Thus, working outside traditional disciplinary and departmental categories, the College’s faculty will advance solutions to problems that demand interdisciplinary perspectives and expertise. Other UW units bring much to bear on the built environment and students are wholeheartedly encouraged to explore possible cross-campus connections both in obvious and seemingly unlikely places. The Technology and Project Design/Delivery specialization especially connects with Psychology, the Information School, Technical Communication, Computer Science and Engineering, and Industrial Engineering; the Sustainable Systems and Prototypes field with Civil Engineering, Electrical Engineering, Industrial Engineering, Mechanical Engineering, the Information School, Technical Communication, the College of Forest Resources (especially Eco-System Science and Conservation, Urban Horticulture and Urban Forestry), the Evans School of Public Affairs, Geography, Public Health, Ocean Science and Fisheries, and Social Work, Urban Ecology, and perhaps Advanced Materials and Manufacturing Processes and Nanotechnology; the area of History, Theory, and Representation with Textual Studies, Art History, Interdisciplinary Arts & Sciences at Tacoma, and Comparative History of Ideas.

Urban Design & Planning Interdisciplinary PhD

The Urban Design & Planning Interdisciplinary Ph.D. at the University of Washington is one of 39 Ph.D. programs in urban and regional planning in North America, and one of the oldest, founded in 1967.

This program brings together faculty from disciplines ranging from Architecture to Sociology to focus on the interdisciplinary study of urban problems and interventions. Covering scales from neighborhoods to metropolitan areas, the program addresses interrelationships between the physical environment, the built environment, and the social, economic, and political institutions and processes that shape urban areas. The breadth of this program permits students to pursue doctoral studies in the various aspects of urban design and planning as well as in a number of related social science, natural resource, and engineering areas.

The Program seeks to prepare scholars who can advance the state of research, practice, and education related to the built environment and its relationship to society and nature in metropolitan regions throughout the world. The program provides a strong interdisciplinary educational experience that draws on the resources of the entire University, and on the laboratory provided by the Seattle metropolitan region and the Pacific Northwest. The program emphasizes the educational values of interdisciplinarity, intellectual leadership and integrity, and the social values of equity, democracy and sustainability. It seeks to promote deeper understanding of the ways in which public decisions shape and are shaped by the urban physical, social, economic, and natural environment. The program envisions its graduates becoming leaders in the international community of researchers, practitioners and educators who focus on improving the quality of life and environment in metropolitan regions.

Urban Ecology Research Lab

The Urban Ecology Research Laboratory (UERL) is an interdisciplinary team of University of Washington researchers and Ph.D. students studying cities as urban ecosystems. The lab studies urban landscapes as hybrid phenomena that emerge from the interactions between human and ecological processes, and the interactions between urban development and ecosystem dynamics. 

As part of the University of Washington’s innovative leadership in urban ecology research and education, the UERL transcends traditional disciplinary boundaries to address some of society’s most challenging problems. UERL research interests include: complexity and resilience in coupled natural and human systems, urban landscape patterns and ecosystem function, urban ecosystem management, modeling land cover change, adaptation and scenario planning. The UERL assists planners, decision makers and non-governmental organizations in making informed decisions about urban development in a rapidly changing environment.

The Urban Ecology Research Laboratory is directed by Professor Marina Alberti, and includes interdisciplinary PhD students, post-doctoral research associates, research scientists, and affiliate faculty from diverse disciplines who collaborate to study coupled natural and human systems.

Northwest Center for Livable Communities

The Northwest Center’s mission is to enhance the livability of communities in the Pacific Northwest through applied research and outreach in the areas of land use planning, policy, and design; healthy communities; food security; and public participation and democracy.

The Center is a research and policy center focused on issues of environmental and economic sustainability, quality of life, and responsible governance using Washington as a model. Recognizing that the term “livability” has many different definitions and interpretations, the Center’s programs are focused on how the fields of urban planning and design, landscape architecture, and architecture work within this broader context to address livability factors.

The Center operates from the belief that the university should, in cooperation with state agencies, local governments, and community leaders, seek to improve existing social and environmental conditions through research and innovative policy development. It advocates development strategies that focus on smart and efficient land use, strong communities, high-wage, low waste jobs and economic development and public participation and accountability in government.

Marina Alberti

Marina Alberti is Professor of Urban and Environmental Planning in the Department of Urban Design and Planning at the University of Washington. She directs the Urban Ecology Research Laboratory and lead the International Research Network on Urban Eco-Evolutionary Dynamics. She teaches courses in Urban Science, Urban Ecology, Environmental Planning, Research Design, Geographic Information Systems, and Group Dynamic and Conflict resolution. Alberti’s research interests are in urban ecology and evolution. Her studies focus on the interactions between urban patterns and ecosystem function, urban signatures of evolutionary change, and the properties of cities that enhance their resilience and transformative capacity. She also leads research on urban ecological modeling, scenario planning, and urban ecological metrics to monitor progress and inform policy-making and planning. In her book Cities That Think like Planets (UW Press 2016), Alberti advances a science of cities that work on a planetary scale and link unpredictable dynamics to the potential for socio-ecological innovation.