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.

BES Annual Report 2017: Part 1 - What Have We Been Up To?

Major Goals of BES

The Baltimore Ecosystem Study (BES) conducts research on metropolitan Baltimore as an ecological system. Focus on urban systems is important for several reasons. First, they are a novel ecosystem type which has been neglected during most of the history of ecology in the United States. As such, they contain 1) a variety of constructed and highly managed components and substrates; 2) altered climates, environmental resources, stresses, and signals, 3) unprecedented mixtures of species including exotic invasives and; 4) human intention and perception, individual and institutional decision making, and built and social legacies.

Second, the novel combinations of factors, and their changing relationships over time, can expose new mechanisms controlling ecosystem function. From a pure science perspective, the novel conditions allow ecologists to evaluate the understanding of ecosystem structure and function generated from study of non-urban systems. There is still much to discover at the interface of the ecological and the urban.

Finally, urban systems are an increasingly important ecosystem type at continental and global scales. In the United States some 84% of the population resides in officially designated urban areas, and globally more than 50% reside in such places. These percentages are increasing, and the area affected by urban cover, economy, social values, and byproducts is increasing disproportionately (Buijs et al. 2010, Merrifield 2014). 

Thus, BES contributes to 1) the fundamental understanding of a novel ecosystem type, 2) exposing how different mechanisms control the structure and function of the ecosystem through experiments, opportunistic environmental disturbances, and social interventions over time, and 3) generating knowledge that is increasingly relevant as urbanization continues to spread and intensity over time. 

Urban LTER Core Areas

BES generates data using long-term comparative and experimental approaches, and pursues synthesis via conceptual frameworks, quantitative simulation, and statistical prediction. BES research addresses the five original core areas of the Long-Term Ecological Research Network as articulated in 1980 (, in addition to the three specific kinds of human effects and human-environment interactions called for in by the 1997 urban LTER request for proposals:
  1. Primary Production 
  2. Population Studies 
  3. Movement of Organic Matter 
  4. Movement of Inorganic Matter
  5. Disturbance Patterns 
  6. Human impact on land use and land-cover change;
  7. Land use and land-cover effects on ecosystem dynamics;
  8. Integrated approaches to human-environment interactions.
The specifically urban core areas, appearing in items six through eight above, are extracted from the 1997 RFP, quoted here:

"In addition to the traditional LTER core areas, an Urban LTER will:
·        examine the human impact on land use and land-cover change in urban systems and relate these effects to ecosystem dynamics,
·        monitor the effects of human-environmental interactions in urban systems, develop appropriate tools (such as GIS) for data collection and analysis of socio-economic and ecosystem data, and develop integrated approaches to linking human and natural systems in an urban ecosystem environment, and
·        integrate research with local K-12 educational systems."

The first two of the additional core areas actually identify several, more specific research mandates. We have broken the first new item into two, because it suggests complementary causal models involving land cover: change versus effect. The requirement for examining human-environment interaction also embodies specific concerns with new data sources and analytic tools, and a focus on integrating the human and natural components of urban ecosystems. 

To satisfy these requirements, the urban LTERs necessarily have additional and compound core research areas, beyond the five traditional ones that the LTER program has required since 1980. The final item requires a specific channel for engaging with the local community and institutions. 

The mandate of the urban LTERs, encompassing eight core research areas, demands a social-ecological approach rather than a strictly ecological approach (Grove and Burch 1997, Collins et al. 2000, Redman et al. 2004). A biological ecosystem exists in a specified area or volume of the Earth, and consists of a biotic component, a physical component, and the interactions between those two components. The concept also recognizes that some fluxes can move across the ecosystem boundary. 

To apply the ecosystem concept to urban systems, that is those that occupy extensive combinations of cities, suburbs, and exurbs, a component consisting of human and social processes and structures must be added (Naveh 2000, Pickett and Grove 2009). Perhaps the most cogent way to accomplish this addition is to focus on the decisions that people and institutions make about where to locate and build, and how to manage the constructed and biological features of an urban ecosystem or landscape. 

Three Major Research Foci

The larger goals, the conceptual frameworks they require, and the empirical complexity of urban ecosystems have prompted BES research to adopt three major, linked foci: 
1) the flux of materials and energy; 
2) the organization of biotic communities; and 
3) the locational and management decisions by people and institutions. 

The eight core areas for urban LTERs are distributed across these three foci. The foci are one tool by which data gathering is integrated in habitat-based research or shared, cross disciplinary sampling regimes. In addition, integration is accomplished by eco-hydrological modeling, agent based social and economic modeling, and Bayesian network analysis. 

In the next post, we will present some of the key activities undertaken over the past year that serve the goals of the project.