Ecological Integrity Assessment: Willamette Valley Upland Prairie and Savanna

This document is part of a collection of Ecological Integrity Assessments addressing 67 of Washington’s 99 Ecological Systems. EIA’s are also available for: Wet Prairie, Oak Woodland, Herbaceous Bald and Bluff, and Hypermaritime Shrub and Herbaceous Headland.

Ecological integrity can be defined as “the structure, composition, and function of an ecosystem operating within the bounds of natural or historic range of variation.” An Ecological Integrity Assessment (EIA) rates the current ecological integrity of an occurrence of a plant association or ecological system.  NatureServe and the Natural Heritage Network have developed the EIAas an index of ecological integrity based on metrics of biotic and abiotic condition, size, and landscape context. Each metric is rated by comparing measured values with the expected values under relatively unimpaired conditions (i.e., operating within the natural range of variation). The ratings are aggregated into a total score or a scorecard matrix. A rating or score for individual metrics, as well as an overall index of ecological integrity, are communicated with the scorecard.

The EIA can be applied to multiple spatial scales (e.g., landscape or site-scale) and with a variety of data types (e.g., GIS or field-based). EIAs are developed for individual ecological systems using a three level approach to identify a suite of metrics, including Level 1 (remote sensing), Level 2 (rapid ground-based), and Level 3 (intensive ground-based) metrics.

In summary, the EIA framework provides a standardized currency of ecosystem integrity across all terrestrial ecosystem types. This information can then be used for setting conservation priorities, identifying restoration strategies, and monitoring the effectiveness of conservation actions.