Environmental Engineering Reference
In-Depth Information
ecosystems. Because modern ideas about material cycles had been around since the mid-
nineteenth century (
Gorham 1991
), much of the essential conceptual foundation for ecosys-
tem science and its two major branches, material cycling and energy flow, was thus in
place by 1942. However, it would take a few more decades before ecosystem studies
formed a large part of ecology.
What remained was for the concept of ecosystems to be publicized and widely accepted
by ecologists, and for scientists to find suitable tools for studying these newly defined
“ecosystems.” Of course, many scientists and techniques made important contributions to
advance and shape what is now ecosystem science, but a few key contributions are worth
special mention. Readers who are interested in more information about the development
of the ecosystem concept and its use may want to read the detailed histories published by
Hagen (1992)
,
Golley (1993)
, and
Kingsland (2005)
.
A key advance in the adoption of the ecosystem concept and approach by working ecol-
ogists was the appearance of a popular textbook by Eugene
Odum (1953
and subsequent
editions through 2004). Odum's textbook was organized around the ecosystem concept,
and was enormously influential in introducing ecosystem science to generations of ecolo-
gists. This text showed with enthusiasm and clarity the possibility and value of quantita-
tive, large-scale studies, how the ecosystem approach could be applied to both aquatic and
terrestrial habitats, and the application of this approach for understanding complicated
interactions and linkages at large scales (
Likens 1992, 2001
). Odum and his brother
Howard T. Odum also conducted pioneering field studies showing how the ecosystem
concept could be insightfully applied in nature (e.g.,
Odum and Odum 1955; Odum 1957
).
Odum's textbook was closely followed by a high-profile article in Science by Francis
Evans
(1956
) that recommended the ecosystem as “the basic unit in ecology.”
The first Big Science initiative in ecology, the International Biological Program of
1964
1974, was organized around systems ecology and exposed hundreds of ecologists
around the world to measurements of productivity, nutrient cycling, and decomposition,
and the development of ecosystem models, despite controversy and criticism about the
program (
Committee to Evaluate the IBP 1975; Mitchell et al. 1976; Aronova et al. 2010
).
Thus, by the late 1960s, the basic ideas of ecosystem science were familiar to most
ecologists.
Among all the tools that developed with the science, we highlight two important
advances here. First, radioisotopes were widely used in the 1940s through 1960s to
trace movement of materials within and between ecosystems (see the earlier section
“Tracers”). In the wake of the development of atomic weapons, agencies such as the
United States Atomic Energy Commission (AEC) and equivalent agencies in other coun-
tries were looking for peaceful uses of radioactive materials. The timing of their interest
coincided with the rise of ecosystem science, and led the AEC and similar agencies to
provide radioisotopes and funding for many of the early studies on the movement of
materials through ecosystems (
Golley 1993
).
Second, and more significantly, ecosystem scientists began to conduct large-scale
experiments on entire ecosystems. As the essentially reductionist approach of the IBP
showed, it is very difficult to understand or predict the behavior of entire complex ecosys-
tems from the bottom up by measuring all of their many pieces and trying to model how
the whole system will behave. Instead, a direct experimental approach can be used to cut
