Relationships between vegetation type, peat hydraulic conductivity, and water table dynamics in mountain fens

Abstract

AbstractThe ecohydrologic function of fens is characterized by feedbacks between biological and hydrologic processes. Vegetation composition is one important factor that is both responsive to the site hydrologic regime and, by providing the organic material that determines peat hydrophysical properties, influences hydrologic conditions. In this study, we investigated the relationship between vegetation type and peat soil hydraulic conductivity in fen wetlands within the Rocky Mountain National Park, Colorado. We used ponded infiltration tests to estimate the saturated hydraulic conductivity of near‐surface peat in mountain fens with differing vegetation, including large‐sedge fens dominated by Carex aquatilis and Carex utriculata, small‐sedge fens dominated by Eleocharis quinqueflora, and fens with an abundance of woody plants and mosses. Estimated hydraulic conductivities were lowest at the fens dominated by E. quinqueflora, with a median value of 1·3 × 10−3 cm s−1 compared with 1·3 × 10−2 and 9·6 × 10−3 cm s−1, respectively, at the large‐sedge and woody fens. These data help explain historical water table observations at each fen. The E. quinqueflora‐dominated fens in our study area maintain a high water table with saturated conditions throughout the summer growing season. Other fens with higher‐conductivity peat show a more dynamic water table that is below ground surface by late summer. Copyright © 2015 John Wiley & Sons, Ltd.