Evaluating taxonomic surrogates for floristic quality assessment of wetlands

Floristic Quality Assessment (FQA) is a popular bioassessment tool, especially in North American wetland ecosystems. The two components of FQA are (1) native species richness and (2) 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 [C̅]) 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. To investigate the potential for indicator species of high floristic quality (“high” meaning the upper quantile of FQI and C̅) I used two wetland plant community datasets, one with 2,800+ sites and one with 250+ sites. Indicator species were identified using a resampling approach to Indicator Value analysis, and then evaluated based on the species’ performance, validity, and robustness. Then, I compared the top indicator species for high FQI and C̅ to other popular floristic quality taxonomic surrogates: dominant species and familiar species. Some high-performing candidate indicator species for C̅ outperformed dominant species in site classification, but no indicator species outperformed the familiar species FQI surrogate. Indicator species mostly performed on-par with dominant species but failed to compete with the 92–96% correct classification provided by 372 expert-assigned familiar species. Overall, except for a few indicator species of high C̅, these findings support the long-standing notion that further ecological information can be gleaned when more species are included in an assessment.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Natural Res & Env Sciences

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Finzel, Matthew

Contributors dc:contributor

• Jog, Suneeti K.
• Bried, Jason T.

• Floristic Quality Assessment
• Wetland
• Floristics
• Fqa
• Conservatism
• Indicator Species
• Rapid Assessment
• Taxonomic Surrogates
• Plant Ecology

Statement dc:rights

• Copyright 2025 Matthew Finzel

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/129641

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F129641