Ecological engineering is a new field with its roots in the science of ecology. It can be viewed as designing or restoring ecosystems according to ecological principles learned over the past century (Figure 1). Ecology, as a field often designated as a discipline within the biological sciences, has had a strong history of development over the past century, dating back to the coining of the term ecology by the German biologist Ernst Haeckel (1866). The principles of the field have been developed by scientists such as Cowles, Shelford, Clements, Gleason, Lotka, Elton, Thienemann, Forel, Lindeman, Likens, Hutchinson, the Odum brothers, and others. As with any science, much discussion centers on which theories are correct, particularly with ecological energetics and concepts such as succession, but a strong science has developed at the population, community, and ecosystem levels.
Applied ecology, as an extension of these ecological theories, has become popular since the 1960s, particularly in light of public concern for environmental matters. But it has usually been limited to monitoring and assessing environmental impacts or managing natural resources; that is, it has principally remained descriptive. Good examples of recent applied fields in ecology are ecotoxicology and landscape ecology, both of which are descriptive of humanity's effects on the environment. But description alone is not sufficient to deal with many of today's environmental issues. The solution to some of these seemingly unsolvable problems requires a prescriptive discipline (Odum, 1989a), that is, one that depends on the environmental problems being defined and then prescribes a solution to those problems. One recently proposed prescriptive discipline is called ecological engineering (Mitsch and Jørgensen, 1989a; Mitsch, 1993).
Both basic and applied ecology provide fundamental concepts to ecological engineering but do not define it completely. Ecological engineering should have its roots in the science of ecology, just as chemical engineering is close to chemistry and biochemical engineering is close to biochemistry. It logically should be considered a branch of ecology as well as a new field of engineering.
At a May 1993 workshop on ecological engineering sponsored by the National Research Council (see New Discipline, 1993), in a slight variation of the definition given in the Mitsch and Jørgensen (1989b), ecological engineering was defined as
the design of sustainable ecosystems that integrate human society with its natural environment for the benefit of both.