Ecological Heterogeneity in Urban Ecosystems: Reconceptualized Land Cover Models as a Bridge to Urban Design

Abstract

in the system, the amounts, and the con fi gurations of those elements. Of course, heterogeneity on a coarse scale can be made up of homogeneous elements, and design in fl uences that as well, as in the case of uniformity of a streetscape. Hence, urban design plays a large role in determining the spatial heterogeneity of urban systems, whether it be coarse or fi ne in scale, great or small in spatial extent. This chapter addresses heterogeneity as an empirical fact in urban systems that may reciprocally interact with ecological processes rather than as a design value or aesthetic (Ellin, Chap. 4 , this volume). A central goal of ecological science is to investigate the link between spatial hetero-geneity of systems and the ecological functioning of those systems. Studying urban systems through an ecological lens, however, is a relatively new pursuit (McDonnell 2011 ; Cadenasso and Pickett, Chap. 2 , this volume) and ecologists are only now discovering how to quantify and map urban heterogeneity so that they can test how het-erogeneity is linked to ecosystem function (Cadenasso et al. 2007). Such a link between structure and function suggests that a collaboration between ecologists and urban designers can fruitfully advance the understanding of urban areas as social-ecological systems and such a collaboration is imperative for designing resilient cities. This chapter re fl ects not only the fundamentals of heterogeneity from ecological science, but also key insights that have emerged from a 10 year collaboration between the ecologists, the architect, and the landscape architect who are its authors (e.g. McGrath et al. 2007). Therefore, this chapter aims to address the question: how can an understanding of spatial heterogeneity serve as a bridge connecting ecology and urban design? The heterogeneity of an urban system is often depicted using land use/land cover models. These models, however, are generally inadequate to capture the heteroge-neity in system structure that is relevant to ecological processes. Simply adding more classes to these models, or expressing these models at fi ner scales, will not overcome this limitation. As a consequence, the approach to depicting heterogene-ity needs to be reconceptualized using an ecological lens. We will present our recon-ceptualization of urban heterogeneity and demonstrate its utility through a new land cover model. In an effort to address a cross-disciplinary audience, we will begin with de fi ning the fundamental concept of spatial heterogeneity from an ecological perspective and provide a brief discussion of its development within the science. The factors and dynamics that create and maintain heterogeneity will also be discussed. We will build understanding of the motivations for developing a new land cover model and conclude with a presentation of the model as an example of a tool to bridge ecology with design. This bridge is still very much under construction and future opportunities for research and application will be suggested. We begin by using the patchwork quilt as a metaphor to aid in understanding the abstract concept of spatial heterogeneity. Each patch in the quilt is distinct from other patches and the distinctions exist because the entire quilt is constructed of