A comprehensive evaluation of indicator species of high floristic quality wetlands
Advisors: Dr. Suneeti Jog and Dr. Jason Bried
Zoom link: https://go.illinois.edu/FinzelDefense
Floristic Quality Assessment (FQA) is a popular bioassessment tool, especially in North American wetland ecosystems. The main components of FQA are native species richness and conservatism, the concept that native plant species have varying levels of fidelity to undegraded environmental conditions. FQA generally assumes that entire plant assemblages have been representatively sampled and identified to the species level; this assumption requires a significant level of field botany and taxonomic expertise. Recent findings, however, suggest that FQA metrics [Floristic Quality Index (FQI) and Mean Coefficient of Conservatism (Mean C)] do not require full taxonomic coverage, enabling FQA across a wider range of applications and end users and motivating the evaluation of taxonomic surrogates. Quantitatively validated indicator species, singly or in small combinations, have become a popular option for surrogacy. Building on this realization, I tested indicator species for high floristic quality using a variety of performance criteria and comparing them to other popular floristic quality taxonomic surrogates: dominant species and familiar species. Using two large Illinois wetland datasets, indicator species for high floristic quality (“high” meaning the upper quartile for FQI and Mean C) were identified using a resampling approach to Indicator Value analysis, and then evaluated based on the indicators’ performance, validity, and robustness. Some high-performing candidate indicator species for Mean C, such as Eutrochium maculatum, outperformed dominant species in accurately predicting high floristic quality sites. These data suggest that indicator species can yield reliable floristic quality estimates; however, their breadth is variable when compared to other surrogacy methods. Indicator species performed on-par with dominant species in most cases but failed to compete with the information provided by familiar species. Overall, except for a few indicator species of high Mean C, these findings support the long-standing notion that further ecological information can be gleaned when more species are included in an assessment.
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