Urban Ecology - Ecological Systems - page 276

Chandler Cowles, was working on the seemingly pristine plant communities of the
Indiana Dunes, distant from Chicago's immigrant-driven hurley burley. There was
conspicuously no empirical or theoretical collaboration between the pioneering
ecologists and social scientists at the University of Chicago in the early twentieth
century [ 20 ].
The tradition of treating city and nature as opposites was challenged by adven-
turesome scholars and practitioners in the closing decades of the twentieth century
[ 21 ]. This has led to a new conception of cities or urban areas as hybrid socio-
bioecological systems. In other words, urban places may be considered to be human
ecosystems. As such, they incorporate not only the traditionally recognized biotic
and physical components of ecosystems, but also the social structures and built
components so conspicuous in cities and towns [ 7 ].
The new conception of human ecosystems prompts researchers, planners, and
managers in urban systems to study and exploit the reciprocal feedbacks between
the social components in all their demographic, institutional, behavioral, and
economic complexity, and bioecological processes, whether conspicuous or not.
For example, the mitigation of urban heat extremes by trees is well known [ 22 ]. Put
simply, there is an ecosystem feedback between vegetation and human comfort or
risk of heat stress. However, because of the multifaceted nature of the human
ecosystem, the embedding of human values and culture, and the linkage of
vegetation cover with water demand, the causal link between the desire to mitigate
heat stress and the willingness to plant trees is complex. Included are citizen
concerns over private property access, commitments to tree maintenance and litter
removal on their property, fear of crime associated with vegetated hiding places,
risk of treefall, root fouling of infrastructure, and aesthetic judgments [ 23 ]. Other
examples of such processes are associated with later principles.
Two principles emerge from these considerations about human-natural system
coupling in urban contexts:
Principle 1 : Cities and urban areas are human ecosystems in which socioeconomic
and bioecological processes feed back to one another.
Principle 2 : Human values and perceptions are a key link mediating the feedbacks
between social and bioecological components of human ecosystems.
Principles Concerning Urban Form
One of the most remarkable features of urban areas is their spatial form. Architects
and urban planners have traditionally used figure-ground representations of urban
areas, which emphasize the built component of the human ecosystem. Pioneering
efforts by landscape architects have shown the need and power of going beyond
such classic representations to include both the hidden and the conspicuous
bioecological features of urban areas.