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Floristic Quality Assessment for Plant Communities of
North Dakota, South Dakota (excluding the Black Hills),
and Adjacent Grasslands


Swink and Wilhelm (1994) identify 4 commonly used applications for the floristic quality assessment system: (1) identification of natural areas, (2) facilitation of comparisons among different sites, (3) long-term monitoring of remnant natural area quality, and (4) evaluating habitat restorations. All 4 applications involve compiling a plant inventory for a site and then calculating and FQI using C values assigned a priori to each taxon (Appendix). For monitoring efforts, these inventories can be duplicated yearly or at other intervals deemed appropriate to capture temporal changes in floristic quality. The sampling unit can be as small as a 0.25 m² quadrat along a transect or as large as an entire natural area. The size of the sampling unit is dependent most often upon project objectives. In the case of an isolated wetland, the unit may be the entire wetland where a botanist would record all species encountered in a complete walkthrough of the basin. However, quadrats randomly placed within each zone may be more appropriate if an assessment of the wetland's plant communities by vegetative zone is the goal. Because sample area and sampling effort can influence floristic quality assessments, it is important to include details of the survey methodology when reporting and FQI. This will facilitate meaningful and consistent subsequent comparisons of floristic quality among areas.

Although and FQI each provide useful information for assessing ecosystem integrity, other measurements can provide additional information and should be included in most assessments of floristic quality. Total species richness, native species richness, percent non-native taxa, and physiognomic composition can also be calculated without additional field work and each can provide information useful in discriminating between sites or in corroborating trends observed in or FQI (e.g., a decrease in may be accompanied by an increase in the percent of non-native taxa).

We limited our checklist to the vascular flora of the Dakotas and assigned the C values based on each species' occurance within this political boundary. State boundaries usually do not follow ecological boundaries, thus the C values we provide should be equally valid in nearby areas with the same vegetation types. The glaciated plains of western Minnesota and northwestern Iowa are prime examples of areas where our C values should be applicable. However, the more remote a site is from our core area of consideration, the more likely it will be that our C values will not reflect local conditions and may render misleading results.

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