Revegetation in Icelandic eroded areas: monitoring over a 10-year period

Iceland has a long history of land degradation lasting over a millennium. Prior to human settlement, heath plant communities were widespread, and mountain birch covered around 40% of the country. Today, birch cover about 1% after episodes of degradation and extensive erosion. It is furthermore estimated that 40% of the land cover is still in degraded or eroded state. The drivers behind this shift are both anthropogenic and environmental with considerable interactions. One critical factor is the vulnerability of Andisols, the dominating soil order, due to their lack of particle cohesion and low bulk density. However, Andisols can contain considerable amounts of soil organic carbon and soil water, both contributing to potentially high fertility. Degraded lands, where the Andisols have been lost, do therefore have a high potential for carbon sequestration through revegetation. The project presented here focuses on monitoring soil and vegetation changes in reclamation areas dating back to 1990. The sampling unit is a 10 x 10 m plot located on a random 1x1 km² national grid. Five subplots (50 x 50 cm) are used to collect composite samples and estimate vegetation cover using a modified Braun-Blanquet scale. Soil samples are divided into 0-5, 5-10, 10-20, and 20-30 cm depth intervals. These plots have now been sampled twice within 10 years. C and N content was analyzed in all samples. Preliminary results indicate a general increase in vegetation cover and carbon stocks over the 10-year sampling period but trends do differ depending on approaches and location. This variability highlights the importance of finding the most suitable reclamation approach depending on local environmental and geographical conditions. Further statistical analysis will focus on identifying the key factors affecting changes in carbon stocks and vegetation covers, and how we can use the different reclamation approaches to effectively revegetate the degraded land.