Evaluating a sampling protocol for assessing plant diversity in prairie fens

Abstract

Prairie fens are globally vulnerable wetlands that are considered a conservation priority due to threats to their high biodiversity and hydrological functions. Establishing a thorough and repeatable plant sampling protocol is critical to evaluating conservation and management initiatives. Our goal was to evaluate a sample methodology designed to assess prairie fen plant diversity and determine if it produced results (1) representative of site diversity, (2) comparable among fens, and (3) efficient to collect. Nineteen fens between 8.5 and 28.4 ha were surveyed twice within one growing season during 2012 and 2013 field seasons using an area-proportional, random design. The turnover in species between spring and summer sampling periods within a site ranged from 8 to 50 %. Sample coverage of total estimated plant species richness ranged from 84.8 to 95.0 % with a mean of 90.1 %. We compared results from our area-proportional, random design to simulated random samples of 10, 15, 20, 25, 30, 35 and 40 quadrats per site. No significant difference was found in sample coverage per fen when using sampling rates of 25, 30, or 35 quadrats per site versus the area-proportional design. Shannon’s diversity index and floristic quality index differed by sample period and number of quadrats sampled per fen. Our sample design produced acceptable levels of coverage and facilitated comparisons across fens. Our methodology could be applied to future research, restoration monitoring, and conservation planning efforts in Midwestern prairie fens.