Ecological Integrity Assessments provide a standard “biophysical exam” that assesses how well an ecosystem is doing, including its component vegetation, soil and hydrology, as well as its size and interactions with the surrounding landscape. We use a three-level approach to assess ecological integrity, from remote sensing imagery, to rapid field assessments and detailed quantitative assessments.
Ecological Integrity Assessment models provide land managers, conservationists, and agencies with critical information on factors that may be degrading, maintaining or helping to restore an ecosystem. The models also guide assessment of element occurrences for Heritage Methodology.
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Determining the integrity of a particular occurrence of a ecosystem is a critical aspect of targeting conservation of ecosystems, ensuring that the best remaining examples are identified, and setting thresholds by which ecosystem collapse can be judged. NatureServe and its member Natural Heritage Programs have developed a rigorous and consistent method for evaluating ecological integrity, especially for wetlands.
Many ecosystem monitoring and assessment programs are expanding their focus to address changes in ecosystem condition, in addition to changes in acreage. Our multi-metric assessment method can be effectively used in the field and with remote sensing imagery to measure condition using an index of ecological integrity, in a practical, repeatable manner.
Features & Benefits
We developed our ecosystem condition assessment for all terrestrial ecosystems using the concept of ecological integrity. Building on the related concepts of biological integrity and ecological health, ecological integrity can be defined as “an assessment of the structure, composition, and function of an ecosystem as compared to reference ecosystems operating within the bounds of natural or historic disturbance regimes.” This broad definition can serve as a guide to developing ecological integrity assessment methods that are distinct from related assessment methods for ecological functions or ecosystem services.
Our multi-metric approach for our Ecological Integrity Assessment (EIA) method is similar to the Index of Biotic Integrity (IBI) for aquatic systems. Our method builds on the work of other rapid assessment methods (especially the Ohio Rapid Assessment Method and California Rapid Assessment Method), and our previous work on standardized methods for assessing ecosystem condition for the Natural Heritage Network, along with setting performance standards for wetland mitigation.
Critical to our effort was the use of conceptual models that highlight ecological factors and attributes for which metrics (or specific indicators) of integrity are most needed. We defined metrics as values derived from specific measures (e.g., basal area, stand structural class, species diversity) that inform us about the status of an ecological factor or attribute of integrity.
For our model, the primary rank factors and major ecological factors are landscape context (landscape, buffer), size, and condition (vegetation, soils, and hydrology). We then select key metrics that are most responsive, practical, cost-effective and well-tested in measuring the condition of the ecosystem. The conceptual model also provides a structure in which to identify known stressors, or agents of change, that affect these major ecological factors. Together they can help guide management decisions to maintain or restore ecological integrity.
The method has great value for the Natural Heritage Network, contributing to a consistent evaluation of reference sites and the potential for establishing a network of reference standard (minimally disturbed) sites within and across jurisdictions. It can be a component of inventory and ambient monitoring of ecosystem condition, and it helps set ecological performance standards to assess site-specific and watershed-scale mitigation and restoration projects. The approach is also used by the National Park Service to provide service-wide products that improve management of biological resources in national parks, and maintain a broad ecosystem-based framework for park management.