DEGRADATION OF ICELANDIC ECOSYSTEMS Iceland is a 103 000 km2 island in the North Atlantic Ocean between 63 and 66 latitutes. The island is warmed up by the Gulf-stream, and the climate is considered humid cold temperate to low arctic. Precipitation varies between 500 and 2000 mm in lowland areas. Volcanic eruptions are frequent and volcanic ash deposits are widespread. The island is mountainous with lowland areas along the coastline and river plains. About 270 000 people inhabit the island. Iceland was settled around 874 by Vikings, who brought in domestic animals. It is well established that a large portion of the Icelandic deserts was vegetated at the time of settlement. The evidence for this include historical records, Sagas, annals, old farm surveys, old topographical names, relict areas and current vegetation remnants, pollen analyses, and soils buried under desert sand. After the settlement, rapid population growth led to intensive use of fragile ecosystems. Ecosystem degradation included both altered vegetation composition due to grazing, cutting and burning of woodlands, and reduced vegetation cover (formation of barren lands). Decreased vegetation vigour led to increased cryoturbation and solifluction processes that accelerate erosion. . A classified satellite image (47kb) shows that more than 37 000 km2 of the country are now barren deserts with additional 10-15 000 km2 of limited plant production, some of which is caused by volcanic activity. At the time of settlement, Icelandic deserts were only 5000 – 15 000 km2 and vegetated areas much more vigorous than they are now. The barren surfaces of the deserts are very sandy, (image) consisting of volcanic glass, tephra and crystalline materals that are basaltic, colouring the surfaces dark and often almost black. The desert soils are infertile, mostly due to lack of organic matter and nitrogen. Only 0.5-5% vegetation cover is sustained on these surfaces. The very degraded stage of Icelandic ecosystems is somewhat unique with respect to its humid climate. Such severely degraded areas are usually only found in the arid regions of the world. The severe accelerated erosion began soon after the settlement and led to increased population pressure, social unrest and poverty. This is one of the factors that later led to the loss of independence in the 13th century. Poverty remained until this century but full independence was regained in 1944. Erosion in Iceland was not only accelerated by land use early on during the settlement. The climate in Iceland gradually became cooler during the 11th century. Moreover, the ecosystems had already become vulnerable because of the cooling trend since 2500 BP. This resulted in less resistant vegetation which made the ecosystems more vulnerable to erosion than before. Glaciers started to advance because of the cooler climate, and they currently cover about 10% of the country. This resulted in increased tephra production upon rapid cooling of magma by glacial meltwater during eruptions. The glaciers also developed vast outwash planes that serve as sources for sand that feed sand drift areas. Eruptions under glaciers also cause large scale floods that build vast sand deposits at the glacial plains and along rivers. Some glacially covered thermal areas also result in floods at regular intervals. Eruptions spreading volcanic ash on the surface became much more damaging after the settlement, as the vegetation was less resistant to stress of such extent. These factors, often intensified by land use, have resulted in almost total desertification of about 5000 km2 in North-east Iceland, which is perhaps the world's largest sandy area outside of the arid regions. Edited by Olafur ArnaldsandEinar Gretarsson Agricultural Research Institute of Iceland. www.rala.is Last updated on 29/3/2000 by EG