Thursday, April 20, 2017

Asphalt: Evolving Urban Boundary Object

Asphalt.  What could be more pedestrian, literally underfoot?  Or ignored as a dull gray ribbon somewhere beneath the floorboards as one navigates along city streets, concentrating on one's destination?  Or still more invisibly, as the cladding along the ditches keeping parking lots and pavement from flooding during rainstorms.

In reality, asphalt is a complex "boundary object" that points out how cities, suburbs, and exurbs are intricate social and ecological systems.  Asphalt as a boundary object links the consideration of social processes and ecological phenomena across the three-dimensional spatial mosaics of urban systems.  Furthermore, as those systems change, the role of asphalt as a boundary object can change through time as well.  

A recent paper by BES colleagues Geoff Buckley, Chris Boone, and Morgan Grove (2016) provides an excellent example of the changing role a boundary object may play, and it does so by elevating the virtually ubiquitous and nearly invisible substance of asphalt to our full attention. I recommend this paper not only for its scholarly rigor, but for the poetic imagery and narrative power it employs in bringing the roles and dynamics of asphalt to our attention.  This post is a teaser for that paper.

Contemporary urban residents would hardly recognize the streets of cities in the late 19th and early 20th centuries.  There was a time when city streets were paved with bricks, cobblestones, and even wood blocks if they were paved at all.  The expense and unstable footing for horses were points contributing to contentious civic discussion about these paving materials.  Buckley and colleagues show in detail how asphalt rose to primacy among a welter of available materials, economic considerations, and networks of political influence.  Asphalt achieved its familiar roles only after it had been argued for by automobile drivers, bicyclists, and those concerned with provision of mud-free school playgrounds.  

Franklin Square school yard, asphalt partially removed.
But as a multifaceted boundary object, the perceptions and actions focusing on asphalt have proven to be anything but permanent.  For example, as cities have shifted from the engineered "sanitary" focus of the last 150 or so years (Melosi 2000) to an emerging sustainability focus by looking toward a future that is jointly motivated by ecological, social, and economic integrity (Grove et al. 2016), so has the role of asphalt shifted.  Now, city policy makers and activists promote the removal of asphalt from school yards in an effort to reduce stormwater runoff and lessen the heat island effects around schools.  So too is asphalt reduced by replacement with pervious pavement, or by piercing the streetside with bioswales or rain gardens.  Over the century of the sanitary city and moving into the desired sustainable city century, asphalt has illustrated an integrative, but changing role in the social-ecological functioning of urban areas.

As a boundary object, asphalt focuses urban social-ecological researchers on the shifting networks of concern and changing understanding of what constitutes an amenity or disamenity among urban ecosystem structures.  The very factors of imperviousness and availability that led to the widespread adoption of asphalt ultimately contributed to its disavowal by environmentally conscious policy makers and by communities and agencies sensitive to social equity.  Have a look at Buckley et al's (2016) paper to understand this compelling history and its ecological implications more fully.

Steward Pickett, Director Emeritus

Literature Cited

Buckley, G. L., C. G. Boone, and J. Morgan Grove. 2016. The Greening of Baltimore’s Asphalt Schoolyards. Geographical Review:n/a-n/a. DOI: 10.1111/j.1931-0846.2016.12213.x

Grove, J. M., D. L. Childers, M. Galvin, S. Hines, T. Muñoz-Erickson, and E. S. Svendsen. 2016. Linking science and decision making to promote an ecology for the city: practices and opportunities. Ecosystem Health and Sustainability 2:n/a-n/a. DOI: 10.1002/ehs2.1239

Melosi, M. V. 2000. The Sanitary City: Environmental Services in Urban America from Colonial Times to the Present. University of Pittsburgh Press, Pittsburgh.

Tuesday, March 7, 2017

Renewal and Diversity

Dear BES Community,

As we begin 2017, we are grateful for the opportunity to clarify our research outlook. We are hard at work developing a new conceptual model, research questions, hypothesis and experimental plan for the 2018 Renewal Proposal. At the January Quarterly meeting, we had some great input from our Hydrology, Biodiversity and Social Science Breakout Groups. Since then, our ideas have been reviewed and insightfully critiqued by an independent Ad Hoc Advisory Committee and the iterative process continues. We look forward to sharing the new conceptual model once it is finalized.

Long-term Climate data was also discussed at the January meeting with a focus on what is needed for Baltimore disaster and all-hazards planning. Thanks go to Kristin Baja, who presented at our meeting and provided information about the status of the All Hazards Management Plan (AHMP).  This plan is updated every five years and looks at historical hazards. We also looked at Regional Climate Trends – John Dillow and Bob Shedlock, Climate Trends Analysis in BES – Ellen Woytowitz, Climate data sources – Bernice Rosenzweig, and NEXRAD rainfall data for spatial and temporal patterns and links to models (Jim Smith, presented by Peter Groffman).

In February we welcomed a new co-Investigator, Colin Studds, Ph.D., from the Department of Geography and Environmental Systems at UMBC. Colin has plans for investigating mammals and further research on birds in BES to complement our ongoing research on bird dynamics led by Dr. Charles Nilon.

Looking ahead to our April 26th Quarterly Meeting, we will be exploring ways of increasing diversity in BES.  Alan Berkowitz and Bess Caplan have provided the following goals for discussion at our upcoming meeting:
1.      Raise awareness within BES community of the importance and challenges of increasing diversity within our community.
2.      Help BES make progress towards crafting a visionary and feasible Diversity Plan.
3.      Evoke a shared understanding of the roles of diversity in science, and the current landscape of diversity in environmental careers and interventions.
4.      Build bridges for collaboration and contribution within BES and between BES and others in the region.
5.      Make concrete plans for the future of diversity in BES.
6.      Consider producing a short paper about diversity in, of and for BES and the urban social-ecological “workforce.”
We are anticipating a very productive meeting and hope to see you there!

Finally, we are restructuring our social media strategy and want to share the latest details. We hope that these changes will better serve the BES Community and help to raise the profile of the quality research that our project does every day and year after year. We will be archiving the existing Facebook Group and the Education page (BPESL) at the end of March 2017. There will be one BES Facebook page with more varied content appealing to investigators, educators, and artists alike: Baltimore Ecosystem Study - BES. In addition, you can follow us on Twitter @BESlter. Follow us, like our page, comment and discuss! We want to hear your thoughts on what’s happening.

Thank you,

Friday, January 13, 2017

BES Annual Report 2017: Part 3 - Key Activities for the Year

Major Activities.

There are a large number of contributors to BES, including senior scientists, post-doctoral researchers, undergraduates, and even high school students. Their activities are presented below, divided into the Core Areas for urban LTER research, and ending with the Core Activity of engagement, especially through education. Some of the published papers explaining the methods and approaches, and recent results are cited.  These can be found in the publication list of the BES website here:

This post is complementary to two earlier ones, focusing on the goals of BES (, and the theory motivating our research (

  1. Primary Production- BES measures parameters that support understanding the growth of dominant plants in terrestrial and stream environments. Woody plant biomass and change over time are assessed via extensive and intensive sampling. The i-Tree-Eco model is used to quantify woody plant production every five years based on 195 randomly located plots (Nowak et al. 2013). Eight intensively measured permanent plots combine assessment of vegetation and soil biogeochemistry (Groffman et al. 2006). The RHESSys model simulates coupled ecosystem primary production, hydrology, and nutrient cycling (Band et al. 2001; Tague and Band 2004). The primary production by stream biofilms and the effects of pharmaceutical contaminants on that production is investigated (Rosi-Marshall et al. 2013).

  1. Population Studies- Population studies and biodiversity assessments are a component of BES research. The organisms were chosen to satisfy specific criteria: sentinels for human health (mosquitoes), invasion of exotics (trees and herbaceous plants, mosquitoes, aquatic invertebrates), impact of pollutants and contaminants (aquatic biofilms); transformers of organic matter in soil nutrient cycles (earthworms); landscape integrators (birds); and predominant structuring elements (trees). Therefore, populations of birds (Rega et al. 2015), soil invertebrates, such as earthworms and isopods, are measured in both long-term and short term studies (Szlavecz et al. 2006, 2011, Pickett et al. 2011, Parker and Nilon 2012, Parker et al. 2014). Aquatic invertebrates are quantified in streams and in constructed stormwater detention ponds (Sokol et al. 2015). Plant populations are assessed in the 195 randomly located i-Tree permanent plots, which are sampled in all land uses (Nowak 2012). Plant population studies include experiments in vacant lots and measurements in residential lawns (Johnson et al. 2015), and assessments of alpha versus beta diversity along gradients of management intensity (Swan et al. 2015). The populations of introduced disease vectors are measured relative to their habitat and food web relationships along the urban-rural gradient and in neighborhoods of contrasting social-demographic characteristics (LaDeau et al. 2013).

  1. Movement of Organic Matter- Soil organic matter is assessed in Baltimore soils, including forests and lawns. Organic matter dynamics are also included in the studies of streams ecosystems (Kaushal et al. 2014), including assessment of stream burial which alters metabolism (Beaulieu et al. 2014). The input and dynamics of organic matter in streams is examined (Martinez et al. 2014). The effects of dissolved organic carbon on stream water quality has been examined (Duan 2014). Intercity comparisons of decomposition include work in Baltimore (Yesilonis et al. 2014). Several of the focal groups in the biotic population studies are important in decomposition of organic matter in soil (Szlavecz et al. 2011).

  1. Movement of Inorganic Matter- Inorganic nutrients and nutrient pollutants are routinely measured in BES watershed and stream research. Nitrate, phosphate, and particulates are key pollutants in metropolitan streams, and in the receiving waters of the Chesapeake Bay (Groffman et al. 2004; Kaushal et al. 2011). Nitrate and chloride are also drinking water pollutants. Nutrient processing data are collected in the permanent plots, in streams, and in riparian zones. Decades of road salt application have been assessed by historical analysis and now are complemented by on-going measurements of chloride concentration in Baltimore region streams, including those draining into the region’s reservoirs (Kaushal et al. 2005). Heavy metal contamination of soils is measured because those elements have implications for both public health and soil nutrient processing (Yesilonis et al. 2008; Schwarz et al. 2012). A flux tower on a suburban edge of the city measures a variety of inorganic compounds and physical conditions connecting soils and atmosphere (Chun et al. 2014).

  1. Disturbance Patterns- Disturbances, detected as pulsed structural alterations in ecosystems and landscapes of the Baltimore region, appear in long-term data on the geomorphology of stream channels, the alteration of forest cover, and the mortality of trees in permanent plots and coarse-scale vegetation surveys. Extreme climatic events are exposed as disturbances in long-term data sets on stream flow and nutrient loading. More subtle press disturbances include invasion of novel exotic species, and differential alteration of forest regeneration along urban-rural contrasts. Disturbances also take the form of social presses and pulses, such as shifting economic investment and disinvestment, migration of racial groups and social classes, and policy interventions such as the court-ordered retrofitting of Baltimore's sanitary sewers. An integrated urban research program such as BES must account for both biophysical and social disturbance (Grimm et al., forthcoming 2017).

  1. Land Use/Land Cover Change- The National Land Cover Database is now available to provide coarse scale (30-m resolution; 16 categories) land cover information for Baltimore allowing the project to explore land cover/land use changes over time and to compare with other regions in the United States. However, the high degree of heterogeneity characteristic in cities, older suburbs, and in any urban area that has experienced parcel-level vegetation change, changes in occupancy and density, and shifts in use of industrial and commercial lands, requires more detailed characterization. A first step has been developing a sub-meter land cover mapping suitable for parcel analysis and as input for the patch-based HERCULES classification, which combines biophysically and socially generated cover elements to differentiate patches (Cadenasso et al. 2007). This results in a highly refined set of classes, currently being used to quantify "signatures" of urban cover in Baltimore to allow for temporal and inter-city comparisons. Forest patch change continues to be analyzed based on new remote imagery (Zhou et al. 2011). Fine scale assessments of land cover are being used to clarify the nature of shading both to improve patch discrimination and to provide data on insolation and shading of surfaces and buildings. Land use/cover change is being quantified at the level of suburban subdivision, using data on transacted price of home sales, as well as size and density of subdivisions (Irwin et al. 2014, Zhang et al. 2016). These are compared to distance from urban core, the different regulatory contexts of various counties in metropolitan Baltimore, and the nature of adjacent stormwater infrastructure. Lifestyle information is being extracted and mapped based on market segmentation data (Grove et al. 2015).

  1. Land Use/Land Cover Effects- The ecological effects of land use/land cover are being explored as a driver of Urban Heat Island effects by measuring land surface temperature relative to the census block geography of Baltimore (Zhou et al. 2011, Huang et al. 2011). Additional work focuses on the relationship of "hotspots" of land surface temperature to impervious and built land covers to assess the role of spatially explicit configuration of trees and buildings on UHI heterogeneity. Land cover heterogeneity is being explored relative to stream flow and chemistry, biodiversity in yards and vacant lots, and biogeochemical processes in urban forest fragments and lawns.

  1. Human-Natural Feedback- Feedbacks are best assessed through temporal changes following design and management interventions, policy shifts, and external disturbances. Activities to assess the fedbacks between social and ecological patterns and processes employ both extensive and intensive sampling frameworks that can be applied at multiple scales. The long term field-based sampling represents diverse urban landuses (e.g., i-Tree; stream gages). The high-resolution landcover mapping is being analyzed relative to the biogeochemical processes and social features including both demographic and lifestyle or consuption-based models. The 3000-household telephone survey, referenced by address and latitude/longitude, assesses environmental knowledge, attitudes, activities, and social involvement with the resident's neighborhood in order to facilitate integration with biophysical measurements and social and economic census data. The role of environmentally active institutions is assessed via inventory and network analysis of stewardship organizations. A new theoretical structure for following human-natural causality through temporal sequences of intervention and response in a heterogeneous matrix is being explored.

The final requirement, to engage with local school systems, is exemplified by research on ecological teaching and learning. Through participation in the Pathways to Environmental Science Literacy project, BES continued to explore patterns in student thinking and learning about key concepts in environmental science. Work this year focused on data from biodiversity assessments, learning progression framework, and patterns of student accounts based on this framework.

BES educators are collaborating with three other LTERs to explore factors shaping how ecology is taught in middle and high school classes. Work during the reporting period continued on a case study that included four BES teachers looking in depth at supports and constraints on learning progression-based teaching. Researcf specific to Baltimore focused on teachers’ responses to the BES professional development program.

BES Annual Report 2017: Part 2 - What Is Our Theoretical Foundation?

A Role for Theory

The goals of BES are supported by three major kinds of theories. Theories are unifying frameworks that embrace many models and identify the fundamental postulates and relationships of a broad area of research. Each of the three empirical foci of BES has at least one overarching theory that justifies its use in urban ecology, and serves to relate the understanding of urban ecosystems to habitats beyond the urban realm.

Focus 1: Ecosystem Flux of Matter and Energy

The major foundations of ecosystem ecology include principles of thermodynamics, conservation of matter and energy, the law of the minimum, and chemical stoichiometry. A major prediction of ecosystem ecology is that limiting nutrients will be retained by intact ecosystems. A guiding question for ecosystem research in BES is to test the prediction of ecosystem retention in urban areas. Because urban systems are driven by human goals and structures for using and transporting water, materials, and energy, the assumptions that nutrient limitation drives retention may not hold. This assumption is tested by Focus 1 of BES.

The watershed approach is a powerful tool for facilitating this test, and for understanding the mechanisms of nutrient retention or loss from ecosystems. Furthermore, following the variable source area concept from hydrology, the watershed approach suggests that identifying sources, sinks, and flow paths of materials can be used to examine whether an ecosystem at the watershed scale is in fact retentive or leaky. Consequently, this theory provides a framework for addressing the mechanisms that may underlie an urban exception to limitation as a driver by identifying sources and sinks of nutrients and contaminants, and discovering their long-term relationships in space.

Focus 2: Biotic Community Organization and Change

The biota  ̶  plants, animals, and microbes  ̶  are the metabolic engines for ecosystem fluxes. Therefore, the second Focus of BES is on the patterns and mechanisms of assembly of the biological communities of the urban ecosystem. Biological community theory is founded on familiar theories of competition, niche partitioning, top-down versus bottom up control, disturbance, and succession, all operating in the three dimensional spaces of heterogeneous watershed landscapes. This focal research area rests on the theory of the metacommunity, cast in terms of regional versus local sources of species over space. The guiding question is whether or how does metacommunity theory apply in the fragmented, constructed, and highly managed mosaics of urban systems. The data collected in service to this theory also can be used to test relationships of biodiversity to ecosystem functioning in key habitat types in the metropolitan area.

Focus 3: Locational Decisions and Land Management

The theory of "urban land rents" or "bid rents" is a classic set of economic propositions to explain the distribution of various land uses with distance from urban cores. Bid rent theory is based on assumptions that land use decisions are driven by price, and that markets identify the relevant quality of land in different locations in the metropolitan area. Furthermore, competition among bidders recognizes these differences in quality, which may include such location-specific factors as transportation costs, materials, inputs for production, and infrastructure. Land rent theory assumes that amenities such as climate and soils are uniformly distributed across the territory.

Over its long history, land rent theory has been modified by many factors, such as labor, speculative behavior in periurban agricultural areas, and so on. BES extends the testing and refinement of bid rent theory by taking explicit account of heterogeneous ecological structures and processes throughout a metropolitan area. In addition to identifying environmental features that act as amenities and disamenities, the application of this theory in BES examines the unintended negative effects of environmentally motivated regulation of subdivision size and density, of county-wide zoning regulations, and spillover effects of amenities and regulations. Finally, the prediction of land use decisions in the urban core, where de-industrialization and population loss have made use of classic transaction-based modeling of housing markets impossible, new models are being developed to extend and modify the theory. Because "shrinking cities" exist in many industrialized regions and countries, this theoretical refinement is widely relevant.

An Integrative Frontier for Theory

The three theoretical areas are linked by shared processes. For example, the natural and constructed features of watersheds influence transacted housing prices, with nearby stormwater detention basins decreasing housing prices, and stream restoration enhancing value. These same features influence the degree of watershed nutrient retention, and also serve as habitat for native and exotic aquatic organisms. The failed housing market in some neighborhoods in the residential core of Baltimore results in abandoned buildings that, as ruins, provide habitat for exotic mosquitoes that vector human and bird diseases, and stimulate demolition with consequent fine scale heterogeneity and management opportunities. Vacant lots, although they contribute to social disamenities and biophysical hazards, provide stepping stones that can facilitate vegetation metacommunity dynamics, and support generalist native bird species. Policy and management options can be evaluated based on the plusses and minuses of those habitats. Other examples of the interactions of conditions predicted by the three theoretical realms exist, but the key point here is that the three areas areas motivate data that bridge among them, and address interacting human-natural drivers of urban ecosystem change over the long term.