Environmental Engineering Reference
In-Depth Information
SECTIONV
CASE STUDIES
Ecosystems,
Tansley's (1935)
“units of nature,” are the fundamental ecological units
supporting life on our planet. The complexity of ecosystems represents a strength for
biotic survival and a challenge for human understanding. Case studies may be one of the
best ways to illustrate the complexity of ecosystems, as well as to show the importance
and relevance of the ecosystem approach. We present here five case studies, representing
a spectrum of systems and approaches.
The initial case study by Pamela Matson presents an excellent example of how the com-
plex biotic functions of ecosystems are intimately intertwined with the abiotic, and thereby
drive the biogeochemistry of nitrogen. The agricultural ecosystems in the Yaqui Valley of
Mexico are the focus of these studies. Nitrogen is a vital plant nutrient for these ecosys-
tems, but when heavily fertilized for agriculture, they can become so enriched that they
give off large amounts of nitrous oxide, an important “greenhouse” gas in the global atmo-
sphere. Understanding these complicated relationships gives the fundamental information
to describe this environmental problem and the guidance to regulate this unwanted flux
of nitrogen.
Richard Ostfeld provides a clear example in the second essay of how the complexity of
ecosystems needs to be understood to gain insight into the numerous, critical relationships
among humans and the populations of plants and animals that they interact with daily.
Although human disease is traditionally viewed as a medical problem, Ostfeld shows how
the ecology and behavior of organisms and their relationships within an ecosystem are a
primary determinant in the ecology of disease. Ostfeld uses Lyme disease, a common and
serious tick-borne disease, as his example.
In the third essay, Emily Stanley presents an impressive story about the ecosystem
effects that occur when flowing waters are dammed, a practice that has been done by
humans for millennia. The removal of these dams, both experimentally and as a manage-
ment intervention, provides a powerful opportunity to gain ecological insight into how
streams and rivers function within a landscape.
The need for an ecosystem understanding of a major environmental problem to pro-
pose intelligent management
interventions,
including federal regulation of pollutant
