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Washington Floristic Quality Assessment

What is a Floristic Quality Assessment?

The Washington Natural Heritage Program (WANHP) received funding from the U.S. Environmental Protection Agency, Region 10 to update wetland conservation priorities for Washington State. In order to prioritize which wetlands are of conservation significance, rarity and relative ecological integrity of a particular site are considered. One of the tools that can be used to determine ecological integrity is the Floristic Quality Assessment (FQA).

The Floristic Quality Assessment (FQA) method uses the proportion of conservative plant species in a plant community to assess the degree of "naturalness" of an area. Conservative species are defined as being restricted to intact ecosystems where ecological processes, functions, composition, and structure have not been (or minimally so) degraded/modified by human stressors. Non-conservative or generalist species are those which have a broader ecological niche and thus don’t show fidelity to a specific set of environmental parameters. FQA refers to multiple indices many of which share a common variable—the coefficient of conservatism value (C-value) of native species—and are used to assess the quality of a particular habitat or site (see below). C values reflect the relative conservatism of a given species by assigning it a value between 0-10 (10 being the most conservative). WANHP convened a group of experts to assign C-values for all native plant species occurring in Washington. Since both upland and wetland species are assigned, FQA can be used in all ecosystem types, not just wetlands.

FQA provides a unique approach to ecological monitoring and assessment which moves beyond simple measures of species richness and abundance and provides an estimate of the quality of native plants at a site. FQA-based indices have been rigorously tested in other regions of the United States and have been shown to be very sensitive indicators of ecological condition.

What is FQA used for?

FQA integrates the overall conservatism of a site’s flora into an indicator of ecological integrity that can be utilized for numerous objectives including monitoring, conservation prioritization, and setting restoration benchmarks.

Species lists are compiled for a given area (defined by project objectives) and the C-values associated with those species are then used to calculate an index value. Many different conservatism-based indices have been constructed. The most basic is the average C value of native species occurring in a given area. The Floristic Quality Index (FQI) is another commonly used index that incorporates species richness into the calculation. Numerous variations of both these indices have been employed. Determining which index to use is a function of project objectives and index performance in a given ecosystem type.

Below are some examples of the type of projects that FQA-based indices could be applied toward:

  • Identifying conservation priorities
  • Identifying reference conditions for specific ecosystem types
  • Monitoring and evaluating the short- and long-term performance of ecosystem restoration and enhancement projects;
  • Monitoring and evaluating the long term effectiveness of ecosystem protection projects;
  • Monitoring and evaluating the effectiveness of ecosystem management practices (i.e. water management, weed control, buffers, etc.);
  • Method for prioritizing ecosystem restoration and protection projects;
  • Regulatory programs such as wetland mitigation, Section 404 permitting, critical areas ordinances, etc.

FQA Report

The following report provides a detailed description of FQA as well as the methods and results of assigning coefficients of conservatism for the western and eastern Washington flora.

        Floristic Quality Assessment for Washington   (Jan. 2013 version)

FQA Calculators

WANHP has also developed Microsoft Excel-based calculators which include the final FQA databases for western and eastern Washington. The calculator will automatically compute index values for a given dataset. Many different indices are calculated including conservatism-based indices as well as more commonly used metrics such as % non-natives, % annuals, etc. Instructions are included within the calculator and report.

      Western Washington Floristic Quality Assessment Index Calculator   (June 2013 version)

Because wetland indicator values differ between arid land and mountainous portions of eastern Washington, there are two calculators for eastern Washington:

      Eastern Washington Floristic Quality Assessment Index Calculator - Columbia Basin   (Jan. 2014 version) - Sites within the Columbia Bain (i.e. arid lands below lower treeline)

      Eastern Washington Floristic Quality Assessment Index Calculator - Mountains  (Jan. 2014 version) - Sites above lower treeline in the East Cascades, Okanogan Highlands, Northern Rocky Mountains, and Blue Mountains

An alternative option is to use the Universal Floristic Quality Assessment (FQA) Calculator ( which is an open source project developed by Openlands, a conservation organization based in the Midwest.  The Universal FQA calculator is free for any user, although registration is required. The user can enter data into either a site inventory/releve plot or transect calculator.  Assessment results can be downloaded and saved for private or public viewing on the Universal FQA website.   

Note: Please email Joe Rocchio if you find or suspect any errors in the calculator.  Also, please check this website regularly for updates to the calculator.

For more information, contact:

Joe Rocchio
Natural Heritage Ecologist
Forest Resources and Conservation Division
Washington Department of Natural Resources
Olympia, WA
Office: 360.902.1041

Washington Natural Heritage Program -
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Washington Dept. of Natural Resources, PO Box 47014, Olympia, WA 98504-7014