A critique of ecosystem health concepts and indexes

Abstract

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.

Restoring ecosystem health to improve human health and well-being: physicians and restoration ecologists unite in a common cause

“…Ecosystem health: "An ecological system is healthy and free from 'distress syndrome' if it is... active and maintains its organization and autonomy over time and is resilient to stress" Haskell et al (1992:9, see also Ford et al 2015) Some regard the concept of ecosystem health as problematic given that it is difficult to measure and can only be meaningfully assessed over long periods of time (Suter 1993, Rapport et al 1998. Certainly characterization and measurement of both terms require subjective as well as objective human judgements.…”

Valuing Wildlands

“…Furthermore, indicators developed at one spatial scale may be not be useful to a decision that targets a different spatial scale (Efroymson et al 2008a(Efroymson et al , 2008b. Some of Suter's (1993) criticisms of ecosystem health indices also apply to the aggregation of variables into a multimetric index of environmental benefit. Several of his arguments against the use of indices include:…”

Applying a Large, Statewide Database to the Assessment, Stressor Diagnosis, and Restoration of Stream Fish Communities

“…The original IBI was developed for mid-western stream fish assemblages, but has since been successfully modified to be applicable in a large number of geographic areas and water body types (Karr and Chu, 2000) and has been shown to reflect the condition of aquatic resources across the gradient of human influences in many studies (Miller et al, 1988;Simon, 1999;Simon and Lyons, 1995). However, the IBI has been criticized, by Suter (1993), because it is difficult to diagnose causes of biological impairment using additive indexes. Yoder and Rankin (1995) were the first to use IBI metrics to diagnose stressors affecting biological communities (biological response signatures).…”

“…Since then, the biological response signature concept has been applied widely in conjunction with multi-metric community assessments (Simon, 2003). However, since each species can have a unique response to changes in its physical and chemical environment, the relationship of each individual species to environmental variables can potentially be used to identify many specific physical and chemical causes for ecosystem changes (Suter, 1993). The responses of key species to stressors have been useful in establishing restoration and ecological recovery endpoints for select stressors .…”