A critique of ecosystem health concepts and indexes



Because people wish to preserve their health and do something equivalent for ecosystems, the metaphor of ecosystem health springs to mind. This paper presents the argument that it is a mistake for environmental scientists to treat this metaphor as reality. First, the metaphor fails because it misrepresents both ecology and health science. Ecosystems are not organisms, so they do not behave like organisms and do not have properties of organisms such as health. Also, health is not an operational concept for physicians or health risk assessors because they must predict, diagnose, and treat specific states called diseases or injuries; they do not calculate indexes of health. Second, attempts to operationally define ecosystem health result in the creation of indexes of heterogeneous variables. Such indexes have no meaning; they cannot be predicted, so they are not applicable to most regulatory problems; they have no diagnostic power; effects on one component are eclipsed by responses of other components; and the reason for a high or low index value is unknown. Their only virtue is that they reduce the complex array of ecosystem responses to various disturbances to one number with a reassuring name. A better alternative is to assess the real array of ecosystem responses so that causes can be diagnosed, future states can be predicted, and benefits of treatments can be compared.