Urban Ecology - Ecological Systems - page 286

A useful guide to these integrative approaches is the human ecosystem frame-
work. Introduced originally by the social scientist William R. Burch, Jr., and his
colleagues [ 21 ], this framework has been modified to reflect more bioecological
content and thus to better support the integrative program of urban ecology [ 44 ].
The framework is not itself a model, but rather an organized roster of potential
causes, mechanisms, and interactions upon which specific models can draw.
The human ecosystem framework does take a human-centered perspective on
inhabited and managed systems and thus breaks the concept of human ecosystem
down into the social system as the primary focus and into the biophysical
foundations and sociocultural foundations of that social system ( Fig. 15.1 ). This
framework is an excellent abstract picture of any urban ecosystem. The components
contained in this causal framework will have specific instances and representations
in any urban area.
The biophysical foundations start metaphorically with the earth, air, fire (or
energy), and water perspectives that must comprise any environment [ 45 ].
However, to prevent neglecting important environmental features that ecologists
have come to appreciate in all systems they study, it goes on to include nutrients,
which at some concentration often become pollutants, toxic materials and
contaminants, soil structure and chemistry, vegetation composition and dynamics
through time, and the spatial mosaic that the biophysical and built components
jointly define in urban systems. Each of these categories has at least as much
component complexity, if not more, than appears in Fig. 15.1 . The sociocultural
foundations include the resources provided by culture in its material, mental, and
spiritual forms. Socioeconomic resources among the sociocultural foundation
include information, population, labor, and capital. Capital of course refers not
only to financial resources but also to the talents and skills of individual persons and
the social capital embodied in networks of human interaction. The social system is
the structure that enables and constrains the social interactions that all humans
depend upon for their immediate well-being. The social system is characterized by
the intuitions, in the broad sense, that humans construct to accomplish the tasks of
survival, interaction, health, and control. The social system also establishes order
among persons and does so in the form of social identity, formal and informal
norms of behavior, and the establishment of social rank hierarchies along several
dimensions ( Fig. 15.1 ). The framework identifies cycles as a way of recalling that
the components of the social system are not fixed in time or space, but can change
with the collective changes in individual and household life cycles, individual and
group psychological changes, organizational age as expressed in capacity and
flexibility, and the degree of persistence of the various institutional structures in
a society. The current intensification of globalization suggests that in many cases
local or regional dynamics will be affected by biophysical, economic, and social
changes that originate at a distance. For example, the massive migrations from
countryside to cities, or from countries in which unemployment is high to different
countries where people know or perceive there to be greater opportunities, or the
displacements by war and disaster, all suggest looking beyond immediate
boundaries for causes of change in city-suburban-exurban systems.