Developing Coefficients of Conservatism to Facilitate Floristic Quality Assessment of Wetlands in the Southeastern United States

Project Summary

Floristic quality assessment is a recognized technique for assessing habitat quality using plant species as the indicator. The Floristic Quality Index (FQI), the most widely used metric in floristic quality assessment for wetland and terrestrial ecosystems, employs a measure of conservatism (Coefficient of Conservatism, or C value) along with species richness of a plant community (N) to estimate habitat quality. The index was developed by Swink and Wilhelm in the 1970s as a method of determining habitat degradation. The FQI can be utilized in a variety of ways, including:

  • Identifying quality natural areas;
  • Comparing sites, regardless of community type;
  • Monitoring natural area or restoration site quality through time;
  • Comparing mitigation sites to reference sites; and
  • Assisting in habitat restoration and informing mitigation policy.

Coefficients of Conservatism values (C values) range from 0 to 10, and rate an individual plant species based on its ability (or lack thereof) to tolerate human-caused disturbance to its habitat. Plant taxa that are obligate to high quality natural areas are given high C-values (9 or 10), whereas taxa typically found in a wide variety of habitats and that are tolerant of unnatural disturbance are assigned low C-values. Non-native taxa receive a C-value of zero.

Before this project was undertaken, C values had not been developed for much of the Southeast. To create this database, we assembled 15 expert botanists from across the Southeast to generate C-values for wetland plant taxa. The resulting database includes C-values for 2,523 wetland taxa, across five separate ecoregions, totaling over 7,100 C-values available for floristic quality assessment. A large portion (51%) of native wetland taxa are intolerant of disturbance (C-value >7), while tolerant taxa (C-value <3) comprise only 9% of native wetland taxa of the Southeast. This carries implications for wetland conservation and restoration in the Southeast.

Online FQI Calculator:

C value databases developed for this project were also uploaded by ecoregion to the Universal FQA Calculator website (Freyman et al. 2016). The full database from the project is downloadable here.

 Distribution of C-values for wetland plants in the Southern Coastal Plain ecoregion, with information on proportions of species listed as threatened, endangered, or species of special concern. Native wetland plants in the Southeast tend to have high C values.

Distribution of C-values for wetland plants in the Southern Coastal Plain ecoregion, with information on proportions of species listed as threatened, endangered, or species of special concern. Native wetland plants in the Southeast tend to have high C values.

References:

Freyman, W.A., L.A. Masters, and S. Packard. 2016. The Universal Floristic Quality Assessment (FQA) Calculator: an online tool for ecological assessment and monitoring. Methods in Ecology and Evolution 7(3): 380–383

Swink, F. and G. Wilhelm. 1979. Plants of the Chicago Region, 2nd Ed. Morton Arboretum, Lisle, IL. 922pp.