Hydric Soil Field Indicators for Use in Mid-Atlantic Barrier Island Landscapes

Abstract

Hydric soils in Holocene-aged barrier island landscapes in the Mid-Atlantic region of North America lack morphologies typically associated with saturated and reducing conditions. Furthermore, many better drained (nonhydric) soils have low chroma colors due to parent material effects, making identification and delineation of wetlands problematic. Our objective was to develop field indicators that could be used to effectively recognize hydric soils in these environments. Soils along 10 topographic transects were evaluated at Assateague Island National Seashore, Maryland. Transects spanned a gradient of topographic positions from dune crests to interdunal swales. Water tables and reducing conditions were monitored to determine hydric status. Soil descriptions along each transect were used to identify morphological features indicative of soil wetness. Of 16 monitored and documented hydric soils, only five met recognized field indicators. Hydric soils were best identified by the presence of matrix colors with chromas less than 2 in mineral soils or the presence of at least 1 cm of muck (Oa horizon). On the basis these characteristics, we propose two new indicators restricted for use in Holocene-aged barrier island landscapes in the Mid-Atlantic region. These indicators will allow identification of hydric soils, improving the accuracy and ease of delineation of wetlands.