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Floristic Quality Assessment


During the growing season, conduct a Floristic Quality Assessment (FQA) as defined by Wilhelm and Rericha and published in Flora of the Chicago Region. A Floristic and Ecological Synthesis, 2017.  


Generate a list of observed plant species in the wetland areas.  This FQA method assigns to plant species a rating that reflects the fundamental conservatism that the species exhibits for natural habitats.  A native species that exhibits specific adaptations to a narrow spectrum of the environment is given a high rating.  Conversely, an introduced, ubiquitous species that exhibits adaptation to a broad spectrum of environmental variables is given a low rating.  Utilizing this method, a Floristic Quality Index (FQI) and Native Mean C are derived for a given area.  The FQI is an indication of native vegetative quality for an area: generally 1-19 indicates low vegetative quality; 20-35 indicates high vegetative quality and above 35 indicates “Natural Area” quality.  Wetlands with a FQI of 20 or greater are considered high quality aquatic resources.  The Native Mean C is also an indication of native vegetative quality.  Wetlands with Native Mean C values over 3.5 are considered high quality aquatic resources.  To ensure accuracy using this method, it is important that this list of plant species be generated within the growing season.



Wilhelm, G. and L. Rerich. 2017. Flora of the Chicago Region. A Floristic and Ecological Synthesis. Indiana Academy of Science, Indianapolis. 1392 pp.  


Herman, B., Sliwinski, R. and S. Whitaker. 2017. Chicago Region FQA (Floristic Quality Assessment) Calculator. U.S. Army Corps of Engineers, Chicago, IL.


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Last updated: February 6, 2019