The Environmental History of Skeiðarársandur Outwash Plain, Iceland

Abstract

Abstract - We sketch the Holocene history of Skeiðarársandur outwash plain, southeast Iceland, but concentrate on postlandnam changes. The dramatic human history of the Öræfi farming community is well known, but for the first time, medieval cartularia and late 16th to early 20th century sources are combined to reconstruct the plain's environmental history. We identify trends and agents that have allowed recent ecosystem recovery and decribe the zonation and characteristics of the present major ecosystems. Skeiðarársandur's history represents a state shift in an extreme disturbance regime, but it is also set to become a rare example of subsequent recovery through natural processes, albeit indirectly caused by global warming. The plain's eastern flank at least carried extensive birch forests and riparian meadows in the first centuries after settlement. The first documented catastrope was the A.D. 1362 Öræfajökull eruption, and from then on, increasingly desctructive glacial floods swept across Skeiðarársandur, some covering almost the entire 1000 km2 plain. At least 11 farms were abandoned by 1500, and by the 18th century, the farming community west of Öræfajökull had been reduced from ≥20 to four farmsteads. By the late Little Ice Age, Skeiðarársandur was an exceptionally barren wasteland. Over the past 80 years, fewer and less destructive outburst floods, warming climate, and enhanced seed rain with greater species diversity have facilitated plant establishment and rapid vegetation succession in parts of the plain. In the absence of major disturbances, one of the largest natural birch forest in Iceland may develop on Skeiðarársandur.