A chronosequence approach to estimate the regional soil organic carbon stock on moraines of two glacial fore-fields in SE-Iceland

Abstract

SOC has received increased attention over the last decades because of its role as an option to mitigate the effects of increased anthropogenic greenhouse gas emissions. In Iceland, the loss of vegetation and soil due to land-use and natural processes has left large areas as barren deserts. Land restoration actions have the primary goals to prevent land degradation and restore lost ecosystems but the ancillary benefits of SOC accumulation with regard to COP 21 are obvious. Natural vegetation succession is active in areas being exposed by glacial recession since the end of the Little Ice Age in ∼1890. Here, we attempt to estimate the current regional SOC stock on undisturbed moraines in front of two glaciers in SE-Iceland, using surface age, soil properties and vegetation cover data. RapidEye images were used to estimate the surface area of two vegetation classes with <50% and >50% cover. Regional SOC stock was calculated using soil data and the sum of the area of each cover class for each time-zone. The rates of SOC accretion reached the maximum values of 0.004−0.009 kg C m−2 yr−1. The regional SOC stock for the two glacier fore-fields was estimated at 1605 Mg C (0−10 cm) for Skaftafellsjökull (396 ha) and 1106 Mg C (0−5 cm) for Breiðamerkurjökull (632 ha). The current annual increase in the moraine SOC stocks was estimated at 20.7 Mg C yr−1 for Skaftafellsjökull and 19.7 Mg C yr−1 for Breiðamerkurjökull.