Potential Vegetation Criteria for Identifying Reference-Quality Wetlands in the South-Central United States

Abstract

Reference criteria are needed for wetland monitoring and assessment programs. We used field-collected vegetation data from non-forested wetland sites in the south-central United States to establish preliminary criteria for identifying reference-quality wetlands in future surveys. Our analysis included three parts: (1) preliminary reference verification and metric ranking using boxplots and standardized effect size, (2) updating the putative reference sample and metric selection using Test Site Analysis, and (3) establishing reference criteria from best-metric confidence intervals and indicator species combinations. The Floristic Quality Assessment Index most clearly distinguished the reference wetlands; an index value of at least 20 is recommended for future reference designations in the study region. Other potential reference criteria include a maximum of 3-5 % bare ground in the 100 m buffer, a moderately sensitive species assemblage (mean conservatism>5.0), a small percentage (<10 %) of tolerant species (coefficient of conservatism≤2), and high native richness (>22 species). Five single species, four pairs, and one triplet combination were extracted as potential indicators of reference sites from 70,375 combinations of 75 candidate species, offering an efficient alternative to sampling entire vegetation communities. The analysis framework in this case study could be useful for similar projects in other regions.

Rapid Buffer Assessment Fails to Predict and Classify Wetland Floristic Quality in Oklahoma

“…Crane (2014) similarly concluded that buffer metrics in the USA-RAM did not reliably predict vegetation diversity for Oklahoma depressional wetlands, and Bried et al (2014) showed mismatches between the USA-RAM buffer assessment and vegetation-based wetland quality classes in Oklahoma. Wetland assessment and classification in general appears to be challenging across Oklahoma due to a high degree of environmental and climatic variability (Hoagland 2000;Dvorett et al 2012Dvorett et al , 2013.…”

“…For the former, we established a 0.5-ha assessment area (usually a 40-m radius circle) in the most interior accessible part of the wetland or used the whole patch at smaller (<0.5 ha) sites. We recorded each vascular plant species rooted within or overhanging five 100-m 2 plots arranged depending on size and shape of the patch or assessment area (USEPA 2011b; Bried et al 2014). We recorded additional vascular species when observed during travel between plots or along transects in each cardinal direction to the wetland edge.…”

“…We used the criteria from Bried et al (2014) to initially differentiate Breference^and Bnon-referenceb ased on FQAI, C, native species richness, and percentage of tolerant (C ≤ 2) species. The reference group cutoffs included FQAI >21, C > 5, percent tolerant <10, and native richness ≥23, while the non-reference cutoffs included FQAI <12, C < 4, percent tolerant >19, and native richness ≤10 ).…”

Resident‐immigrant dichotomy matters for classifying wetland site groups and metacommunities

“…For example, Bried et al . () extracted plant indicators of reference‐class wetlands from over 70 000 single, pair and triplet combinations of 75 candidate species, offering a shortcut around sampling entire vegetation communities in future surveys.…”

Testing a rapid Floristic Quality Index on headwater wetlands in central Pennsylvania, USA

“…One of the best intensive assessment tools deployed in the MidAtlantic Region and beyond is Floristic Quality Assessment (FQA) (Bourdaghs, 2012;Bried et al, 2014;Cohen et al, 2004;Cretini et al, 2012;Lopez and Fennessy, 2002;Matthews, 2003;Mushet et al, 2002;Nichols et al, 2006). FQA uses measures of the plant community to derive an estimate of ecological condition and is based on the premise of plant species "conservatism' -a measure of each individual species' tolerance to human-mediated disturbance and its fidelity to habitat integrity (Taft et al, 1997).…”