Early stage development of selected soil properties along the proglacial moraines of Skaftafellsjökull glacier, SE-Iceland

Abstract

Soil development was studied along a chronosequence in 2010 in a proglacial environment in SE-Iceland. We investigated morphological, physical, chemical and mineralogical changes in the soil representing over 120-year period. In total, 54 sampling sites were distributed along three moraines deposited in 1890, 1945 and 2003. For comparison, samples were collected from a nearby downy birch (Betula pubescens Ehrh.) forest, representing soils in a mature ecosystem likely to establish on the moraines in the future. After 120years since deglaciation and formation of AC horizon sequence, bulk density decreased from 1.36gcm−3 to 1.07gcm−3. Concentrations of soil organic carbon (SOC) and total nitrogen (N) increased with time, from being ~zero up to 1.77% of SOC and 0.10% of N. Soil pH (H2O) declined rapidly and was the only soil property that attained a steady state compared to that under the birch forest. The concentration of oxalate extractable Al and Fe increased over time although at a slower rate of change compared to that for other soil properties. Freshly exposed moraines contained a considerable amount of the extractable elements, indicating a relative abundance of poorly crystalline Al- and Fe-phases in the subglacial moraines. The data support the conclusion that after 120years of soil formation, proglacial soils are still young and may yet need one or two centuries to develop properties typical of well drained volcanic soils.