Oregon Marketplace: Habitat Assessment Tool for Multi-credit Banks

The basic premise of this tool is that regulators, by virtue of the way regulatory systems are structured, calculate improvements (or damage) to a site through a single resource lens. At the same time, however, there has been a need to be able to calculate the full suite of resources on a site. This accounting tool tries to do both; it collectively calculates "ecological uplift" from restoration actions, while also providing a calculation for each individual resource.

The Oregon Department of Transportation invested in the development of this accounting tool because the agency is required to mitigate its impacts from road development and enhancement. The department contracted with Parametrix (an engineering, planning and environmental services firm) to develop a tool to assess multiple types of ecosystem functions associated with habitat features. These values could generate credits to meet the department's mitigation requirements. Although the agency ran into implementation issues and decided not to complete development of the tool, Parametrix has continued to refine it with the assistance and encouragement of other parties. In order to determine the value of an ecosystem function, the tool involves these steps:

Step 1: Identify the ecosystem functions that are relevant to the ecosystem features of concern.

This step identifies the primary ecological functions being impacted by development.  For instance, the current method used in wetland mitigation banking measures the ability of wetlands to perform nine functions, such as habitat value or nitrogen uptake. This same logic applies to the Parametrix tool.

Step 2: Identify the habitat elements and structures that are most pertinent to performing the function(s) identified in step 1.

The intent of this step is not to identify all relevant habitat structures or elements, but only the most significant contributors. In most instances, the list can be limited to the top 3 to 5 factors that contribute to the ecological function. For example, the density of the tree canopy would be a significant factor in achieving cooling water temperatures.

Step 3: For each of the habitat elements or structures identified in step 2, determine how each can be measured.

This step looks beyond whether a habitat element or structure is present or not to determine its value. It evaluates how a habitat element or structure exists within the landscape. For example, how does the existing amount of tree density at a bank site contribute to the function of cooling water?

Step 4: Once the habitat element or structure is measured within the specific bank site, determine how adding or subtracting the element or structure will positively or negatively affect the function.

This can be visualized in a graph that is based on existing studies, published literature or best professional judgment in the field.  For example, a graph looking at the amount of tree density in relation to cooling water could look like this:


The graph represents that tree density at 40-60% produces the best results for reducing water temperature.   

This is a basic explanation of the tool, but does demonstrate how different types of ecosystem functions can be incorporated into the method.  For further explanation or information, please contact:  Kevin Halsey, Parametrix.