Urban ecology: advancing science and society

www.frontiersinecology.org © The Ecological Society of America I proposing the ecosystem as an organizational framework, Tansley (1935) explicitly included the effects of humans. When asking, “Is man part of ‘nature’ or not?”, Tansley concluded that “human activity finds its proper place in ecology”. Nowhere is the human–nature interface more unmistakable than in urban ecosystems, and urban ecology has quickly become established within the discipline of ecology (Grimm et al. 2013). This rapid development was fueled by a need for multidisciplinary approaches when studying the extraordinary rate of urbanization and the complex connections among sociological and environmental factors (Brennan 1999; Young 2009). Now, for the first time in recorded history, the majority of people live in cities; moreover, with the characteristics of cities foreshadowing those of the planet, urban ecology is playing an increasingly important role within ecology (Grimm et al. 2008a). Furthermore, urban ecosystems will be on the “front lines” of environmental and sociological change, providing urban ecologists with new and exciting possibilities that combine research with implementing urban design and planning, as well as advocating policy. Across the biological sciences, efforts to understand the mechanisms that underlie patterns have found both inspiration and a worthy challenge in the city (Grimm et al. 2008b). Human amplification of ecological processes in urban areas tightens the links among these processes at different biological, temporal, and spatial scales. For example, disease spread through co-occurring populations of wild animals and household pets depends on the behavior, evolution, and immunological responses of both the wild and the domesticated animals; local regulations; pet owner behavior; and the habitat configuration, nutrient availability, and climate of the broader ecosystem (Adler and Tanner 2013). Ecologists have developed principles to help understand such processes, but considering them within an urban framework demands a more integrative way of thinking (Grimm et al. 2000; Forman 2008a). Pickett et al. (2008) characterized the challenges urban ecologists face: “urban ecosystems are complex, dynamic biological–physical–social entities, in which spatial heterogeneity and spatially localized feedbacks play a large role”. Addressing such challenges requires interdisciplinary thinking and, depending on the goals of a project, CONCEPTS AND QUESTIONS