Olafur Arnalds

The icelandic 'Rofabard' soil erosion features.

Soil erosion and desertification are severe problems in Iceland. Erosion processes are numerous, and more than one can occur at each site, resulting in many erosional forms. Erosion forms and an erosion severity scale are the basis for a recent national survey of erosion in Iceland. One of the most distinctive erosion forms in Iceland is an erosion escarpment, termed ‘rofabard’ in Icelandic. Rofabards are formed in thick but non-cohesive Andosols that overlie more cohesive materials such as glacial till or lava. The relatively loose Andosols beneath the root mat are undermined, creating escarpments, or rofabards. The rofabards retreat as a unit, with a fully vegetated and rich ecosystem on top but leaving barren desert in their place. Rofabards are common within a 20 000 km2 area. The Agricultural Research Institute and Soil Conservation Service erosion database suggests that erosion associated with rofabards has denuded 15 000 –30 000 km2 of land that was previously fully vegetated and had fertile Andosols, but is now mostly desert. Erosion rates associated with rofabards are reported as the loss of vegetated land with Andosol mantle, measured as hectares per square kilometre per year. This measure of erosion has more meaning for Icelandic landscapes than the traditional tonnes per hectare per year. Estimated losses of Andosol cover in rofabard areas for the whole country are currently about 230 ha a−1. This rate is about 10 times lower than the rate needed to cause estimated losses of Andosol mantle in rofabard areas since settlement, 1125 years ago. During peak years of soil erosion, losses were probably several thousand hectares per year, but the erosion rates slowed down as extensive Andosol areas have become barren deserts. Copyright

Soil erosion and land use policy in Iceland in relation to sheep grazing and government subsidies

Abstract A recent national erosion assessment programme reveals that soil erosion is more active in Iceland than is witnessed in other European countries. Most of the communal grazing areas in the central highlands are not suitable for grazing by sheep because of poor condition. Agricultural subsidies are a substantial proportion of Iceland’s national budget and the sheep farming is dependent on subsidies. Recently, a landmark agreement was made between sheep farmers and the government, where part of the production subsidies were tied to “quality management”, including sustainable land use. This agreement calls for rapid assessment of all grazing land in Iceland. These challenges have been met by the use of classification of satellite imagery and innovative methods in obtaining farmland boundaries. The subsidy agreement may have more importance for attaining sustainable land use in Iceland than most government initiatives to date. Financial incentives, such as linking subsidies to land condition and improvements, encourage a reduction of grazing pressure on marginal highland areas, but do not lead to exclusion of such grazing practices. We believe that Icelandic rangelands should be divided into two categories: land intended for use (farmland), and land that should be protected from grazing by national law.

Clay minerals of four soils formed in eolian and tephra materials in Iceland

Abstract Clay minerals in a Vitricryand and three Haplocryands derived from eolian and tephra materials in different parts of Iceland and in glacial till samples representative of underlying strata were studied by a combination of methods. The soils are primarily used as rangelands and are highly susceptible to wind erosion. Allophanes, imogolite and poorly-crystalline ferrihydrite are abundant (> 700 g/kg of the clay) throughout the soils, including A horizons. This clay mineralogy would give rise to stable, low-density aggregates that influence the susceptibility of the soils to wind erosion. It also affects chemical properties such as high phosphate retention of the soils, even of the Cryands with relatively low clay contents (160–275 g/kg). Imogolite was found in some but not all horizons of all soils. No particular relationship of imogolite to measured Si/Al molar ratios of the oxalate-oxalic acid soluble fractions of the clays (0.51 to 1.13) was evident. Layer silicate minerals and laminar opaline silicas are either not present or occur in small quantities. Plagioclase, augite and/or their weathering residues were found in the clay and silt separates. Dark-colored glass is predominant in the fine sand throughout the soils and the tills. One till sample had a clay mineral composition similar to the eolian-andic soils, while the other contained smectite and possibly a spherical halloysite-smectite intermediate, but not allophane and imogolite, as major weathering products. The clay mineral composition of these soils and tills was compared with those derived from basic tephras in other regions.

The Nature and Restoration of Denuded Areas in Iceland

Denuded areas in Iceland can be divided into the following categories: glacial deposits, sandy areas, postglacial lavas, alluvial and colluvial materials, and areas covered with pumice. Of these, glacial deposits are most extensive. The paper describes the nature of the denuded areas with emphasis on the glacial deposits. The denuded glacial deposits generally have sparse plant cover (< 5%) and suffer from wind abrasion and cryoturbation. The soils are deficient in organic matter (about 1%). The texture is sand and loamy sand. Despite the lack of organic materials and the coarse texture, the sum of exchangeable cations ranges from 5 to 15 meq 100 g–1 dry soil.Revegetation with agronomic grasses and fertilization under subarctic conditions in the Icelandic highlands has increased the vegetative cover to over 50% after 5 yr of fertilization. Little increase in soil organic matter is apparent after 5 yr.Objectives for revegetation in Iceland include (1) reclamation of disturbed areas; (2) stabilization of mo...

An extreme wind erosion event of the fresh Eyjafjallajökull 2010 volcanic ash

Volcanic eruptions can generate widespread deposits of ash that are subsequently subjected to erosive forces which causes detrimental effects on ecosystems. We measured wind erosion of the freshly deposited Eyjafjallajökull ash at a field site the first summer after the 2010 eruption. Over 30 wind erosion events occurred (June-October) at wind speeds > 10 m s−1 in each storm with gusts up to 38.7 m s−1. Surface transport over one m wide transect (surface to 150 cm height) reached > 11,800 kg m−1 during the most intense storm event with a rate of 1,440 kg m−1 hr−1 for about 6½ hrs. This storm is among the most extreme wind erosion events recorded on Earth. The Eyjafjallajökull wind erosion storms caused dust emissions extending several hundred km from the volcano affecting both air quality and ecosystems showing how wind erosion of freshly deposited ash prolongs impacts of volcanic eruptions.

The soils of Iceland.

Icelandic soils are dominated by Andosols when covered by vegetation, Vitrisols in desert areas (Icelandic classication scheme), and highly organic Histosols in some wetland areas. Andosols are not common in Europe but are found in active volcanic areas of the world. They develop distinctive properties such as high organic content, extremely high water holding capacity and lack of cohesion. Icelandic soils are in many ways special on a global scale due to the environmental conditions for soil development, which include: i) basaltic tephra parent material; ii) steady eolian sedimentation of volcanic materials to the soil surface; and iii) many freeze-thaw cycles acting on frost susceptible soils, causing intense cryoturbation. Iceland has extensive barren desert areas in a cold-humid climate that comprise the largest sandy tephra areas on Earth. Many of the wetland soils have a distinctive combination of andic (volcanic soil properties) and histic (organic) properties. Soil erosion and desertication is more active in Iceland than in any other Northern European country. Erosion has severely degraded many ecosystems with formation of barren surfaces devoid of vegetation in several areas.

Infiltration in Icelandic Andisols: the Role of Vegetation and Soil Frost

ABSTRACT Soil frost formation, snow distribution, and winter/spring/summer terminal infiltration rates (TIRs) were quantified in Icelandic Andisols with contrasting vegetation cover types (grassland, spruce and birch woodland, lupine, and sparsely vegetated lava site). TIRs (mm h−1; determined with double-ring infiltrometers) were generally higher in unfrozen than in frozen soils (102–369 vs. 9–306, respectively in sandy soils; 28–94 vs. 3–72 in finer-textured soils) and differed between land cover types, being consistently highest in birch woodlands. TIR was an inverse function of soil frost depth. Lowest TIRs were associated with deep and dense soil frost, which formed in spruce woodland and grassland communities where snow depth was shallow. Results suggest conditions conducive to erosion by water are most likely to occur during winter warm spells and in spring in vegetation types where snow cover is low or ephemeral. Threefold increases in TIRs occurred one year after livestock grazing was discontinued, suggesting Andisols are hydrologically resilient where vegetation cover is relatively continuous and soil organic carbon content is high.

Desertification: an appeal for a broader perspective

The term ‘desert’ has many meanings, but usually refers to an area with a certain climate, vegetation cover, or desolation. ‘Desertification’ is a vague and often confusing concept because of the many meanings of the term ‘desert’. The current definition by the United Nations confines desertification to arid areas. This rather narrow definition limits political and economic actions and constrains programs aimed at combating desertification or reversing land degradation. In this paper, an Icelandic case history is used to illustrate the limitations associated with climatologically-based definitions of desertification. Severe land degradation can lead to the formation of barren land, a desert, in any climate. Desertification is often initiated when ecosystem resilience is reduced through factors associated with drought and/or human activities. However, other factors, such as cold spells, extreme weather events, volcanic eruptions and other environmental stresses can be equally or more important. Severe degradation of ecosystems in Iceland has resulted in the formation of extensive barren deserts in spite of humid climate. The Icelandic example also illustrates that the loss of soil water storage capacity can be as serious a limitation to ecosystem function in humid climates as it is in dry climatic regimes.

The vegetation and soils of the Thingvallavatn area

Climatic conditions for plant growth are relatively favourable in the Thingvallavatn area compared with the conditions in Iceland as a whole. This is, however. only partly reflected in the characteristics and present state of the vegetation due to soil erosion and deterioration of the vegetation, which has caused tremendous reduction in the agricultural value of the land. The soils around the lake are mostly of aeolian origin, well drained, with a low content of clay and a mineral fraction consisting mainly of volcanic ash. These soils are very susceptible to water and wind erosion (...)

Ecosystem recharge by volcanic dust drives broad-scale variation in bird abundance

Across the globe, deserts and volcanic eruptions produce large volumes of atmospheric dust, and the amount of dust is predicted to increase with global warming. The effects of long-distance airborne dust inputs on ecosystem productivity are potentially far-reaching but have primarily been measured in soil and plants. Airborne dust could also drive distribution and abundance at higher trophic levels, but opportunities to explore these relationships are rare. Here we use Icelands steep dust deposition gradients to assess the influence of dust on the distribution and abundance of internationally important ground-nesting bird populations. Surveys of the abundance of breeding birds at 729 locations throughout lowland Iceland were used to explore the influence of dust deposition on bird abundance in agricultural, dry, and wet habitats. Dust deposition had a strong positive effect on bird abundance across Iceland in dry and wet habitats, but not in agricultural land where nutrient levels are managed. The abundance of breeding waders, the dominant group of terrestrial birds in Iceland, tripled on average between the lowest and highest dust deposition classes in both wet and dry habitats. The deposition and redistribution of volcanic materials can have powerful impacts in terrestrial ecosystems and can be a major driver of the abundance of higher trophic-level organisms at broad spatial scales. The impacts of volcanic ash deposition during eruptions and subsequent redistribution of unstable volcanic materials are strong enough to override effects of underlying variation in organic matter and clay content on ecosystem fertility. Global rates of atmospheric dust deposition are likely to increase with increasing desertification and glacier retreat, and this study demonstrates that the effects on ecosystems are likely to be far-reaching, both in terms of spatial scales and ecosystem components.