kane county stormwater technical guidance manual - Kane County, IL

For all on-site wetlands with buffers less than fifty feet, FQI must be
calculated. The procedure can be found in “plants of the Chicago Region”, 4 th
ED. by Floyd Swink and Gerald Wilhelm or by using the Floristic Quality
Assessment and Computer Applications V.1.O. The FQI program is available
from:
Conservation Design Forum
324 N. York Rd.
Elmhurst, IL 60126
(630) 758-0355
The FQI is an indicator of natural area plant biodiversity used widely in the
Chicago Region. Each plant in the flora has been assigned a “C-value” or
coefficient of conservatism. To calculate the FQI of a wetland, a complete
flora inventory must be taken or a statistically valid sample using multiple
quadrants. The computer-based program provides a basic for plot sampling.
After the inventory has been compiled the native mean C can be calculated
by summing the C values for native plants and dividing by total number of
native plants in the inventory (N). The FQI is then calculated by the formula:
FQI = native C vN or C * N ½
Native Community Quality
Quality FQI
Low
Medium
High
16.0
The FQI is influenced by plant rating, size of the area sampled, completeness
of the floristic inventory, and hence, the total number of native species (Table
10). Since the FQI does not take into account adventive, or non-native
species, the “weediness” of an area cannot be determined by the FQI alone.
Adventive data is presented along with native data in the computer program.
These data should be submitted to the Administrator in the format shown in
the example below, even if the FQI is hand-calculated (Figure 20).
Kane County Technical Guidance Manual 82