Floristic Quality Assessment Indices for Colorado Plant Communities May 29, 2007 Colorado Natural Heritage Program Colorado State University 254 General Services Building Fort Collins, CO 80523 Floristic Quality Assessment Indices for Colorado Plant Communities Prepared for: Colorado Department of Natural Resources Division of Wildlife, Wetlands Program 6060 Broadway Denver, CO 80216 U.S. Environmental Protection Agency, Region 8 1595 Wynkoop Street Denver, CO 80202-1129 Principal Author: Joe Rocchio Colorado Natural Heritage Program Warner College of Natural Resources Colorado State University 254 General Services Building Fort Collins, Colorado 80523 Colorado Floristic Quality Assessment Panel Dave Anderson1, David Buckner2, Kathy Carsey3, Dina Clark4, Janet Coles5, Denise Culver6, Craig Freeman7, Brad Johnson8, Steve Kettler9, Gwen Kittel10, Peggy Lyon11, Joe Rocchio12, Harvey Sprock13, and Gerould Wilhelm14 (moderator) Cover photograph: Pedicularis groenlandica, Castilleja rhexifolia, Carex aquatilis, Clementsia rhodantha, and Arnica mollis. Photo by Joe Rocchio. Copyright © 2007 Colorado State University Colorado Natural Heritage Program All Rights Reserved 1 Colorado Natural Heritage Program 2 ESCO Associates, Inc. 3 U.S. Forest Service 4 Botanical consultant 5 U.S. National Park Service 6 Colorado Natural Heritage Program 7 Kansas Natural Heritage Inventory 8 Colorado State University 9 U.S. Fish and Wildlife Service 10 NatureServe 11 Colorado Natural Heritage Program 12 Colorado Natural Heritage Program 13 U.S. Natural Resources Conservation Service 14 Conservation Design Forum, Inc. EXECUTIVE SUMMARY The primary objective of the Clean Water Act is to "maintain and restore the chemical, physical, and biological integrity of the Nation's waters," which includes wetlands. Wetlands in Colorado have not only been lost from the landscape but have and continue to be impacted or degraded by multiple human activities associated with water use, transportation, recreation, mineral extraction, grazing, urbanization, and other land uses. In order to make informed management decisions aimed at minimizing loss or protecting wetland acreage, quality, and function credible data on the ecological condition of these wetlands need to be collected (U.S. EPA 2002a). In order to prioritize management, protection, and restoration activities an efficient and effective method is needed to identify high-quality wetlands, monitor restoration projects, and assess the effects of management activities. It is not practical to measure every human impact to wetlands since these disturbances are numerous and complex. However, measuring the integrity of the biological community provides a means to evaluate the cumulative effect of all the stressors associated with human disturbance. The distribution of vegetation across the landscape serves as an indicator of various biotic and abiotic processes, including anthropogenic disturbance (Taft et al. 1997; U.S. EPA 2002b). Spatial and temporal human disturbances have a strong role in determining which plant species are able to survive and/or compete in a particular site. Thus, the composition of vegetation growing at a particular site integrates spatial and temporal impacts and can serve as an indicator of ecological integrity or condition. The concept of species conservatism is the foundation of the Floristic Quality Assessment (FQA) approach to monitoring and assessing ecological communities. The core of the FQA method is the use of “coefficients of conservatism” (C value), which are assigned to all native species in a flora following the methods described by Swink and Wilhelm (1994) and Wilhelm and Masters (1996). C values range from 0 to 10 and represent an estimated probability that a plant is likely to occur in a landscape relatively unaltered from pre-European settlement conditions. In other words, the species has a wide ecological tolerance and may be found almost anywhere. A C value of 10 is assigned to species which are obligate to high-quality natural areas and can’t tolerate any habitat degradation whereas a 0 is assigned to species with a wide tolerance to human disturbance. The proportion of conservative plants in a plant community provides a powerful and relatively easy assessment of the integrity of both biotic and abiotic processes and as such is indicative of the ecological integrity of a site (Wilhelm and Ladd 1988). The Floristic Quality Assessment (FQA) is a method which uses plant composition or specifically the overall conservatism of species present at a site, as an indicator of ecological condition. The FQA method, originally developed for the Chicago region, uses the proportion of conservative plants in a plant community to assess the degree of "naturalness" of an area (Swink and Wilhelm 1979, 1994). The FQA has been developed and successfully tested in 11 States and Provinces. The FQA provides a means to evaluate floristic integrity of a wetland over time, or to compare quality of wetlands of a similar type (e.g. same ecological system (Comer et al. 2003). Once each species has been assigned a C value, a few different FQA indices can be used to assess the floristic integrity of an area. These indices can be calculated using only native species as well as including non-native plants resulting in variations of three core indices: Mean C, Floristic Quality Index, and the Adjusted Floristic Quality Index. Floristic Quality Assessment Indices for Colorado Plant Communitieis The FQA provides a unique approach to ecological monitoring and assessment which moves beyond simple measures of species richness and abundance and provides an estimate of the quality of native plants at a site (Herman et al. 1997). Under the assumption that plants effectively integrate spatial and temporal human impacts to ecological systems, the FQA indices provide a cost-effective means of assessing ecological condition. The FQA indices also provide consistent, quantitative measures of floristic integrity, can be used in any plant community, do not require extensive sampling equipment (only a competent botanist), and can be applied to existing data sets. The FQA indices can be used for a variety of regulatory and non-regulatory assessment and monitoring applications. For example, FQA index scores can be used to conduct ambient monitoring of wetland condition within a targeted area, can be used to prioritize wetlands (or other ecosystems) for protection, restoration, or management efforts, and can be used to monitor the effectiveness of these actions. The FQA indices can also be used for specific wetland regulatory needs such permitting decisions associated with Section 404 of the Clean Water Act. Some U.S. Army Corps of Engineers districts currently use FQA indices for wetland assessment associated with permitting and mitigation activities tied to Section 404 of the Clean Water Act. The objecitves of this project were to assign coefficients of conservatism for each species in Colorado’s flora and then test the ability of these coefficients in detecting degradation of floristic integrity resulting from human disturbance of Southern Rocky Mountain wetlands. To accomplish these objectives, the following tasks were completed: A panel of botanical and ecological experts with field-based knowledge of Colorado’s flora was assembled (i.e. Colorado Floristic Quality Assessment Panel); The Colorado Floristic Quality Assessment Panel (Panel) convened for a one day workshop to review the process of assigning coefficients of conservatism; The Panel then individually assigned coefficients for those species which they were familiar with; The coefficient assignments were assembled for data analysis; Although coefficients were assigned to the entire Colorado flora, testing of the FQA indices only occurred for a few wetland types found in the Southern Rocky Mountain ecoregion (riparian shrublands, fens, extremely rich fens, slope wet meadows, and riverine wet meadows); Vegetation composition from wet meadows, fens, and riparian shrublands exposed to varying degrees of human disturbance were sampled; Coefficients of conservatism were plugged into multiple FQA indices and calculated for each vegetation sample plot; The FQA indices were correlated to a semi-quantitative human disturbance index to discern their effectiveness in detecting floristic change resulting from human impacts. C values were assigned by a panel of Colorado’s botanical experts. In order to provide some independent measure of the accuracy of these assignments a subset of species were also assigned C values based on their frequency of occurrence along the human disturbance gradient. An independent measure of C values was assigned to those native species which occurred in three or more of the sample plots (sensu Cohen et al. 2004 and Mushet et al. 2002). These C values were derived by averaging the Human Disturbance Index score from each plot that each of these species occurred in. This value was relativized to a value between 0-10 and used as an empirically defined C value. ii Floristic Quality Assessment Indices for Colorado Plant Communitieis A field study was conducted to determine if a subset of the assigned C values (Appendix D) were able to detect loss of floristic integrity in wetlands with increasing human perturbations. The study entailed sampling vegetation plots from wetlands exposed to varying degrees of human- induced disturbance; calculating FQA indices from each of these plots; scoring the severity, type and amount of human disturbance