Title: Mapping to assess revegetation activities and to estimate carbon sequestration: a case study of Krysuvik, Iceland

The study was carried out in Krýsuvík in south-western Iceland where land degraded by heavy sheep grazing is being restored through revegetation by the Soil Conservation Service of Iceland (SCSI) beginning in the 1980s. The objectives of the study were to: (1) compile existing data to make a map of the revegetated areas, (2) establish a geographically identifiable time series of revegetation activities and (3) recalculate the amount of carbon sequestration based on the estimated revised area. An area of 14 km² was selected for the study to re-estimate revegetated areas and carbon sequestration by using remote sensing and GIS techniques. Two aerial photographs of 1989, 1992 and a SPOT 5 image of 2009 were used for digitizing restored areas. A map of the revegetated area was produced by placing the digitized area on top of the SPOT 5 image. The accuracy of the map was assessed using an error matrix, following random sampling techniques. With an overall accuracy of 55%, the map is seen to have a low overall accuracy compared to the recommended overall of 85%. Revegetated areas sizes, and the amount of carbon sequestered were recalculated with and without overlapping for the all SCSI activity area, study areas, and the digitized areas. The results of the study showed that the all SCSI activity areas are much bigger than the activity areas obtained from digitization of images. This may be due to the use of overlapping areas by the SCSI when recording revegetation areas. Overlapping should be excluded when recording revegetation activities to avoid double counting of activity areas which can give rise to an overestimation of carbon sequestration.