Symposium: Effects of Human Choices on Characteristics of Urban Ecosystems

Most urban ecology in cities remains an “ecology in cities” rather than an “ecology of cities.” Accomplishing the latter requires the inclusion of humans within the concept of “ecosystem,” both how humans alter the properties of urban ecosystems and how these alterations in turn influence human well-being. These influences are both direct (e.g., physiological and psychological influences on the human organism) and indirect, by influencing ecosystem sustainability. For the 2007 ESA meeting, Larry Baker, Loren Byrne, Jason Walker, and Alex Felson organized a symposium to address the relationships among human choices and urban ecosystems. In the introductory talk of this symposium, these authors discussed how the cumulative effect of individual household choices can have major effects on the properties of urban ecosystems. For example, direct resource consumption by households accounts for 40% of U.S. energy use; in the Twin Cities of Minnesota, households account for 75–80% of total N and P inputs. Households also have a major impact on vegetation biodiversity in cities. Drawing from the social science literature, this first talk introduced the variety of conceptual models that have been put forth to understand how humans make choices. Economists use classic supply–demand models to understand consumption of market goods (such as energy) and other tools to understand the value of nonmarket goods. Environmental psychologists have often used the Theory of Planned Behavior and related models to explain barriers to adopting specific environmental practices. Political scientists focusing on group processes stress the process by which choices are made and the distributive effects of decisions. Although ecologists often focus on how human behaviors are environmentally destructive, there are also many examples of how collective choices have had very positive environmental outcomes. These include large declines in soil erosion and smaller declines in fertilizer P use by farmers in the United States, widespread adoption of household recycling, greatly reduced household water consumption in some water conservation programs, and rapid increases in the sales of the Prius hybrid automobile in recent years. Programs leading to these positive environmental choices generally include a mix of several of the following: a persistent, meaningful message; dissemination of accurate, trusted knowledge; early adoption by trusted individuals; financial incentives or disincentives; targeting of high-consumption individuals; direct regulations; personal economic benefit and feedback. Three presenters examined factors regarding choices of managing the vegetation in urbanized landscapes. Morgan Grove from the Baltimore Ecosystem Study (BES-LTER) discussed an “ecology of prestige” in which consumption and expenditure on environmentally relevant goods and services are motivated by group identity and perceptions of social status associated with different lifestyles, and have used this theory to examine landscaping patterns. Grove and his colleagues combined high-resolution social and ecological spatial and temporal data such as property parcels and land cover (\u3e1 m) with composite measures of population, social stratification, and lifestyle for this presentation. Fig. 1 shows the relationship between percentage tree canopy cover (height of bars) with PRIZM lifestyle classifications. Of particular interest in a long-term context is the relationship between cause and effect: the possibility that some social groups are attracted to and conserve existing, desirable landscapes at a neighborhood scale, while others move to and rehabilitate their landscapes

An In-Class Role-Playing Activity to Foster Discussion and Deeper Understanding of Biodiversity and Ecological Webs

In a general sense, biodiversity is an intuitively simple concept, referring to the variety of Earth’s organisms. Ecologists, however, conceptualize biodiversity in a more nuanced, multidimensional way to reflect the enormous diversity of species, niches, and interspecific interactions that generate spatiotemporal complexity in communities. Students may not fully comprehend or appreciate this deeper meaning if they fail to recognize the full range of species in a community (e.g., the often-ignored microbes and small invertebrates) and how their varied interactions (e.g., mutualism, parasitism) and activities (e.g., ecosystem engineering) affect an ecosystem’s emergent structure (e.g., food webs) and function (e.g., decomposition). To help students learn about biodiversity and complex ecological webs, a role-playing activity was developed in which students “become” a different species (or resource) that they investigated for homework. In class, students work in small groups to “meet” other species in their community and, as appropriate for their roles, “consume” or “interact” with each other. As they make intraspecific connections, students collectively create an ecological web diagram to reveal the structure of their community’s relationships. This diagram is used for further exploration and discussion about, e.g., trophic cascades, non-trophic interactions, ecosystem engineering, and species’ effects on the movement of energy and nutrients. This inquiry-based activity has been observed to sustain student engagement and yield productive discussions and positive responses. Further, qualitative assessment indicates that students’ knowledge about biodiversity and ecological interactions improves after the activity and discussions, suggesting that students benefit from acting in and constructing their own ecological webs

Scale Model of a Soil Aggregate and Associated Organisms: A Teaching Tool for Soil Ecology

Soil is a complex habitat for diverse biota. A significant challenge in teaching soil ecology is our inability to observe organisms as they live and interact in the soil. The objective of this article is to describe an interactive class project to help students visualize the sizes of different groups of soil organisms and to relate these to soil structural components. This project was carried out by students in an upper-level undergraduate soil ecology class. It involved the design and construction of a 4000× scale model of a soil aggregate and its associated organisms. The body of the model was made from inexpensive, lightweight materials and had a diameter of approximately 1 m to depict a 0.25-mm aggregate. Students identified and discussed appropriate size ranges and construction materials for the model’s bacteria, fungi, nematodes, mites, springtails, and other components. Instructor-guided questions addressed size and arrangement of sand, silt, and clay particles; pores; and organic matter in a typical soil aggregate. The model is a useful tool for conveying physical and ecological relationships among soil organisms and is adaptable for use at diverse educational levels

Scratching the Surface and Digging Deeper: Exploring Ecological Theories in Urban Soils

Humans have altered the Earth more extensively during the past 50 years than at any other time in history (Millennium Assessment 2003). A significant part of this global change is the conversion of land covers from native ecosystems to those dominated by human activities (Kareiva et al. 2007; Ellis and Ramankutty 2008). Although agricultural needs have historicall

The essence of soil biodiversity

Soil ecologists and conservationists should focus on raising people’s awareness of the essence of soil biodiversity: its complex ecologicalwebs and emergent ecosystemservices that support aboveground life and human well-being. Conservation and communication efforts regarding soil biodiversity must consider local-scale ecological contexts and different audiences. Engaging educational and outreach materials and methods should be prioritized to advance preservation of soil systems and their biodiversity