Pedogenesis and landscape relationships of a Holocene age barrier island

• Soil morphology and pedogenesis was studied on a Holocene age barrier island.
• Topographic transects spanned drainage classes and ranged in age, 1–228 years.
• Pedogenesis was expressed as organic matter accumulations and changes in color.
• Landform instability and weathering resistant parent materials limit pedogenesis.
• Morphology was a function of soil age and moisture and corresponded to vegetation.

Soil characteristics and pedogenic processes are relatively unstudied on Holocene age barrier islands in the Mid-Atlantic region of the United States. The objective of this study was to assess how landform stability and hydrologic conditions (water availability) influenced pedogenesis in barrier island soils. Ten topographic transects were established on different barrier island landforms (i.e., washover fan, back-barrier flat, barrier flat, and dune field) which ranged in age from 1 to 228 years. The topographic transects spanned drainage conditions, ranging from very poorly to excessively drained. The primary evidence for pedogenesis across the chronosequence was in the accumulation of organic matter, expressed in the formation of A and O horizons. Pedogenic development was restricted by the young age and weathering resistant nature of the soil parent material. The close proximity of the water table to the soil surface was associated with greater organic matter inputs from vegetation and slower decomposition under anaerobic conditions, which together led to increased accumulation of organic carbon in lower, wetter landscape positions. Frequency and duration of saturation also impacted subsoil development, producing subtle, but noticeable color differences between oxidized and reduced horizons.