Online tool helps landowners assess the quality of their wetlands

Friday, November 22, 2013 - 9:36am

Across the Mid-Atlantic region, state agencies, environmental groups, developers, and private landowners have struggled to assess the quality of their wetlands in a consistent and actionable way. Sarah Chamberlain, a senior research assistant with Riparia, hopes a tool she’s been researching and developing for more than a decade, the Floristic Quality Assessment (FQA) method, will be able to help them do these kinds of assessments better and faster.



Special excerpt from the fall 2013 GEOGRAPHY newsletter commemorating 20 years of Riparia


Developing the calculator
The Floristic Quality Assessment (FQA) method was developed by Floyd Swink and Gerould Wilhelm in the 1970s to assess prairie habitats in the Chicago region. The method was used to estimate nativity, or how well present-day habitats matched those of pre-colonial times using plant community composition as an indicator. Their goal was to identify habitats with high nativity, that were more likely to contain remnant prairie plants, and that could then be singled-out for protection.

The original FQA dropped out of use until the 1990s when it was rediscovered as a way to measure condition of habitats, Chamberlain explains. When the average coefficient of conservatism (represented by “C”) is multiplied by the square root of native species richness (represented by “N”), the result is the Floristic Quality Index (FQI), a score for the habitat. As with C values for plants, high-quality habitats typically have high FQI scores, while low-quality habitats have low scores.

The C value indicates the degree to which each plant can tolerate disturbance or has an affinity to a pristine ecological condition. “So, if a plant will only grow in a wetland of high ecological integrity, it gets a high score.  If a plant will grow just about anywhere, it gets a low score,” Chamberlain says, adding, “For example,  Red maple (Acer rubrum) is a generalist and gets a lower score than Pitcher plant (Sarracenia purpurea), a conservative species that is restricted to  bogs and other low-nutrient wetlands. There are many species in the middle.”

“What we found is that the original FQI score is very sensitive to overall species richness,” Chamberlain says. “For example, in Laurel Run, one of our reference sites in Rothrock State Forest, species richness is low, with only twelve species identified throughout the entire wetland. Although it is one of our most pristine sites, we observed that it was scoring lower than less pristine sites with a greater number of  species. To account for this, we developed an adjusted FQI that basically calculates the index as a percentage of the total possible score and, unlike Swink and Wilhelm’s version, takes into account nonnative species. Now, sites with a lot of nonnative species score lower.”

“Because C values need to be assigned for all the plants in an area before you can calculate FQI, we decided that the most effective way to facilitate the use of FQA in the Mid-Atlantic would be to assign those values to the entire region. So, in 2009 we convened thirteen botanists to assign scores to the entire flora. To facilitate the process, we calculated the mean and median scores based on existing lists from around the region or in adjacent regions and final values were assigned based on consensus,” Chamberlain says, adding that despite the large geographic area and varied knowledge brought to the table, committee members worked together well and ranked over 2000 species within a three and one-half day meeting.  The values have been used to create the FQI calculator which is available for the public to use.  This research has been funded primarily by the U.S. Environmental Protection Agency.

Using the calculator

To conduct an assessment, the first thing you’ll need is a list of all the plants you observe in your site, explains Chamberlain.  The calculator is available here:

Since rankings are assigned by eco-region, you will then select the eco-region for your site from a drop- down menu. Next, enter your list of observed species by typing in or pasting your list from an Excel file.  A built-in search function allows you to find plants based on scientific names.  “We use scientific names because they are consistent,” Chamberlain observes. “Common names vary from region to region.”

Chamberlain suggests using sources like the USDA’s plants database ( or Wikipedia to find the scientific names for plants.
Once complete, submit your list, and then the calculator automatically matches the entered names against the database, returning any errors. The corrected list is used to calculate the score. Other metrics generated by the calculator include the mean coefficient value and percentage of native plants.  For all native plants, the calculator will show the family and C-value.  For nonnative plants, the calculator will show the family, but nonnatives do not have a C-value.





Top, an example of the results for a superior quality wetland with an adjusted FQI score of 54.2.

Bottom, an example of the results for a limited quality wetland with an adjusted FQI score of 17.7.





























Calculating the future
Down the road, Chamberlain hopes to create a rapid assessment tool that does not require as many plant names and also to incorporate the FQI score into the Department of Environmental Protection (DEP) wetland monitoring program.

Under the federal Clean Water Act, DEP has an ongoing program to assess the quality of waters in Pennsylvania and to identify wetlands and other bodies of water that are impaired. One way to do this is using a Biological Condition Gradient (BCG) that defines six condition categories and helps in setting restoration goals. Although Chamberlain needs to do more testing, so far it looks like FQA metrics are useful in defining BCG category breakpoints for wetlands in Pennsylvania.


The table below shows Biological Condition Gradient categories based on FQI scores.  Category 1 wetlands are considered reference standard wetlands, the highest condition category, while Category 6 wetlands represent wetlands that are severely degraded.


So what can you do to restore a wetland that is assessed as Condition Category 3 based on an FQI score of 27?  Because most wetlands occur on private property, regulators envision restoration to occur on a watershed basis.  Best Management Practices that could be used to increase a wetland’s quality include removal of invasive species and planting or protecting buffers.

Chamberlain is currently investigating developing a rapid version of the index.  “We know that FQA is a great method for condition assessment, but it’s time-consuming and requires some knowledge of plant identification.  Most state agencies don’t have the resources to conduct this kind of detailed assessment on a routine basis,” Chamberlain says.

A rapid version of the FQI tool would make it easier for natural resource managers, environmental groups and developers to quickly assess the quality—not just the quantity (in acres)—of their wetlands.  “This information could aid in deciding appropriate mitigation for wetlands or be used to pinpoint high quality wetlands for protection,” Chamberlain says, adding,  “I’d like to see the FQI tool combined with Level 1 (landscape assessment) and 2 (rapid assessment on site stressors and buffer characteristics) tools to make it a one-stop shop for wetland assessment.”