Saturated hydraulic conductivity in Sphagnum ‐dominated peatlands: do microforms matter?

Within peatland ecosystems, small deviations in surface elevation result in microforms that differ in depth to water table, plant type and rate of biogeochemical cycling, possibly leading to differences in peat physical and hydrological properties that could feed back to the whole ecosystem hydrological and biogeochemical function. However, hydrological parameters for peatland microforms have not been quantified. This study determined bulk density, pore size distribution and saturated hydraulic conductivity (K sat ) at hummocks and hollows of four, Sphagnum ‐dominated Canadian peatlands. Study sites included both a bog and poor fen in each of Alberta and Quebec allowing for investigation of differences in peat hydrophysical properties between microforms across a range of Sphagnum ‐dominated peatlands. Hydraulic conductivity was determined in the laboratory on peat from the surface (0.03–0.08 m) and the saturated zone (0.20 m below the local water table position). Peatland type, climate region, microform and depth of peat were all significant descriptors of variation in K sat . Deeper peat was less conductive than surface peat. Hummocks generally had higher K sat than hollows at both surface and saturated zones, although differences between microforms varied between sites. Differences in K sat between samples were correlated with bulk density, von Post humification and macroporosity. These results indicate that there are microtopographical differences in peat hydrophysical properties; however, the strong decline in K sat with depth indicates that differences in the local water table, resulting in a change in depth of water flow, is likely a stronger control on local K sat than microform type. Copyright © 2014 John Wiley & Sons, Ltd.