Dynamic heterogeneity: a framework to promote ecological integration and hypothesis generation in urban systems

Abstract

Urban areas are understood to be extraordinarily spatially heterogeneous. Spatial heterogeneity, and its causes, consequences, and changes, are central to ecological science. The social sciences and urban design and planning professions also include spatial heterogeneity as a key concern. However, urban ecology, as a pursuit that integrates across these disciplines, lacks a theoretical framework that synthesizes the diverse and important aspects of heterogeneity. This paper presents the concept of dynamic heterogeneity as a tool to explore how social and ecological heterogeneities interact and how they together act as both an outcome of past interactions and a driver future heterogeneity and system functions. To accomplish this goal, we relate heterogeneity to the fundamental concept of the human ecosystem. The human ecosystem concept identifies key processes that require operationalized models of dynamic heterogeneity in three process realms: the flow of materials, the assembly of urban ecosystem biota, and the locational choices humans make concerning land. We exemplify a specific dynamic model of heterogeneity in each of these realms, and indicate a range of complementary statistical approaches to integrate the drivers and outcomes of dynamic heterogeneity across the three realms. We synthesize a hierarchical framework for a theory of dynamic urban heterogeneity, noting its complementarity to other major urban theories and general model approaches. We hypothesize that human actions and structures amplify the dynamics of heterogeneity in urban systems.

Global urban signatures of phenotypic change in animal and plant populations

“…At the community level, cities directly and indirectly affect phenotypic change by altering spatial and temporal habitat heterogeneity. Increasing evidence supports the hypothesis that urban regions amplify heterogeneity by the intensity and speed of human-biophysical and social interactions (26). Cities worldwide retain native species, but loss of functional heterogeneity driven by Significance levels: ***P < 0.001, **P < 0.01, *P < 0.05, · P < 0.1.…”

Human and biophysical legacies shape contemporary urban forests: A literature synthesis

“…Urban Forestry & Urban Greening 31 (2018) 157-168 ecological interactions (Cadenasso and Pickett, 2008;Vogt et al, 2015), with time as a central element (Pickett et al, 2016). In this paper, we examine how legacy effects -the impacts that previous events, processes, and phenomena have on current properties or processes (Monger et al, 2015) -have shaped contemporary urban forests.…”

“…These conceptual and philosophical discussions about space-time from the social sciences share much in common with ecological discourse on why history matters (Szabó, 2010), as well as dynamic heterogeneity and historical contingencies in landscape patterns (Cadenasso et al, 2006;Pickett et al, 2016), in that all recognize human history and temporal processes as central pillars explaining space and place. Our examination of legacies in the urban forest context builds upon these multiple disciplinary traditions of understanding spatio-temporal dynamics.…”

A roadmap for urban evolutionary ecology

“…Although cities often share environmental features when averaged across an urban area, they can exhibit considerable spatial and temporal heterogeneity at a finer scale (Niemelä, 2011;Pickett et al, 2017). Environmental differences among cities can also affect genetic and phenotypic divergence between urban and nonurban populations (Reid et al, 2016;Thompson et al, 2016;Winchell et al, 2016;Yakub & Tiffin, 2017).…”