Environmental Engineering Reference
In-Depth Information
FIGURE 17.2
Development of the ecosystem concept.
(a) Until the early twentieth century, the world was con-
ceptually viewed as a group of organisms being influ-
enced (note arrow direction) by the environment.
(b) In the mid-1900s scientists introduced the term eco-
system, and suggested the importance of feedbacks (bidi-
rectional effects, see arrows) between different
components of the system. This new model recognized
flows of energy and matter through ecological communi-
ties, and among the different abiotic and biotic compo-
nents but did not have a human component.
(a)
Abiotic
factors
Organisms
(b)
Air
(c) In
1950
2000, many models incorporated the effects of
humans as forces influencing ecosystems from the out-
side. (d) Currently, ecosystem models have begun to
include humans (including society and human institu-
tions) as parts of the ecosystem, and acknowledge the
mutual influences that occur among all components in
the model.
Organisms
Water
Soil
(c)
Air
Humans
Organisms
Water
Soil
(d)
Air
Organisms
Society
Water
Soil
nonexistent. The human-in-ecosystems concept is fundamental to many growing interdis-
ciplinary fields that are related to ecosystem science, such as sustainability science, urban
ecology, and adaptive resource management.
These new human-in-ecosystems models will have to account for social and built
components of ecosystems and their interactions with the biotic and physical components
of ecosystems (
Figure 17.2
d). In addition, models that integrate humans into ecosystems
should incorporate information in addition to matter and energy flows. The wide variety
of information relevant for modeling humans as part of complex systems will have to be
obtained from interaction with a host of other disciplines such as traditional ecological
knowledge, political science, and anthropology (see the following section on the changing
