Summary

A key to successful restoration, mitigation, and conservation is having an objective way to measure the biological condition of sites and to compare those sites to an objectively defined benchmark condition. Multimetric biological indexes provide a tool for doing so and, at the same time, allow society to set specific biological goals for restoration programs. Moreover, because their development has incorporated ecological knowledge that has emerged in recent decades, biological indicators like IBI have fundamentally changed water resource management in many regions. Continuing work in terrestrial systems

Table 1 Benthic invertebrate index of biological integrity (B-IBI) as applied in US Pacific Northwest streams

Score

Regulatory rubric

Biological condition

50-46

Healthy

Ecologically intact, supporting the most sensitive life forms

44-36

Compromised

Showing signs of degradation: impacts expected to one or more salmon life stages; loss of some

intolerant, long-lived, or other taxa (e.g., stoneflies)

34-28

Impaired

Ecosystem parts and processes demonstrably impaired; cannot support self-sustaining salmon

populations

26-18

Highly impaired

Highly inhospitable to many native fishes and invertebrates

16-10

Critically impaired

Cannot support a large proportion of native life forms; only the most tolerant taxa present

The index is partitioned into five scoring levels designed to associate regulatory language with specific biological conditions. Developed In consultation with Streamkeepers of Clallam County, Washington, USA.

The index is partitioned into five scoring levels designed to associate regulatory language with specific biological conditions. Developed In consultation with Streamkeepers of Clallam County, Washington, USA.

UD Physical Dump Ag Disturbance category

Figure 2 The effect of disturbance type (UD, minimally disturbed; Physical, physical/chemical disturbance; Dump, sites where chemicals or debris were buried; and Ag, agricultural disturbance) on the average biological condition of shrub-steppe communities in eastern Washington, as indicated by a nine-metric IBI based on terrestrial invertebrates. Reproduced from Kimberling DN, Karr JR, and Fore LS (2001) Measuring human disturbance using terrestrial invertebrates in the shrub-steppe of eastern Washington (USA). Ecological Indicators 1: 63-81, with permission from Elsevier.

on organisms as diverse as plants, invertebrates, and birds is changing the indicator framework in terrestrial ecology as well.

See also: Biomass, Gross Production, and Net Production; Connectance and Connectivity.

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