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Halldorsson G.,Soil Conservation Service of Iceland | Sigurdsson B.D.,Agricultural University of Iceland | Hrafnkelsdottir B.,Agricultural University of Iceland | Hrafnkelsdottir B.,Icelandic Forest Research | And 3 more authors.
Icelandic Agricultural Sciences | Year: 2013

This paper is a review of the history of the introduction of arthropod herbivore species to Iceland since the beginning of the 20th century. A total of 27 new arthropod herbivore species on trees and shrubs have become established in Iceland during this period. One of the introduced pest species, the pine woolly aphid, has been considered to be the major cause of the almost total eradication of the introduced Scots pine in Iceland. The rate of introduction was found to be highest during warm periods. Outbreaks of pests in birch woodlands were also found to be most severe during warm periods. Other pest species have shown changes in outbreak patterns since 1990. The consequences of these findings for isolated native forest ecosystems and a growing forest resource in Iceland are discussed.

Tanner L.H.,Le Moyne College | Nivison M.,Le Moyne College | Arnalds O.,Agricultural University of Iceland | Svavarsdottir K.,Soil Conservation Service of Iceland
Applied and Environmental Soil Science | Year: 2015

Experimental plots were established on severely eroded land surfaces in Iceland in 1999 to study the rates and limits of soil carbon sequestration during restoration and succession. The carbon content in the upper 10 cm of soils increased substantially during the initial eight years in all plots for which the treatments included both fertilizer and seeding with grasses, concomitant with the increase in vegetative cover. In the following five years, however, the soil carbon accumulation rates declined to negligible for most treatments and the carbon content in soils mainly remained relatively constant. We suggest that burial of vegetated surfaces by aeolian drift and nutrient limitation inhibited productivity and carbon sequestration in most plots. Only plots seeded with lupine demonstrated continued long-term soil carbon accumulation and soil CO2 flux rates significantly higher than background levels. This demonstrates that lupine was the sole treatment that resulted in vegetation capable of sustained growth independent of nutrient availability and resistant to disruption by aeolian processes. © 2015 Lawrence H. Tanner et al.

Jensen E.H.,Icelandic Meteorological Office | Helgason J.K.,Icelandic Meteorological Office | Einarsson S.,Soil Conservation Service of Iceland | Sverrisdottir G.,University of Iceland | And 2 more authors.
Landslide Science and Practice: Spatial Analysis and Modelling | Year: 2013

Historic, post-eruptive debris flows of remobilised volcanic ash are rare in Iceland, being restricted to explosive eruptions. Volcanic ash slurry from the southern slopes of the icecapped Eyjafjallajökull volcano on 19 May 2010 is the first lahar observed in Iceland since the 1947 Hekla eruption. This study focuses on the volume of sediment transported, the size and hydrological behavior of watersheds, and the resulting erosion. The analysis is based on: (1) direct measurements of the 19 May lahar; (2) direct measurements of ash fallout; (3) aerial and ground-based imagery; (4) topographic data from an airborne LIDAR survey; (5) airborne synthetic-aperture radar; and (6) precipitation data. The volume of the lahar in the Svadbælisa channel was estimated at 200,000 m3. This flow originated from crown and flank failures, similar to slab avalanches, with water-saturated, fine-grained ash as the slip surface. Several ash-laden floods occurred in Svadbælisa and neighboring channels during the summer of 2010. None, however, were as saturated as the 19 May lahar. An increased number of small debris flows were also recorded some blocking roads to farms. Precipitation during the summer of 2010 was not higher than average and therefore does not explain this increased erosion. Large quantities of volcanic ash mantle the lower slopes of the icecap. Ash in the ablation zone is expected to be transferred down-slope in the next few years inducing the erosion to the root of the mountain endangering homes and infrastructure. Fieldwork during the summer of 2010 has resulted in a map showing the volume of ash above and below the ablation zone of the main catchments and recorded erosion events. This data was used to assess the hazard and the need for immediate actions. © Springer-Verlag Berlin Heidelberg 2013.

Marteinsdottir B.,University of Iceland | Marteinsdottir B.,University of Stockholm | Thorhallsdottir T.E.,University of Iceland | Svavarsdottir K.,Soil Conservation Service of Iceland
Plant Ecology | Year: 2013

In infertile environments, the spatial scale and distribution of favourable microsites may be an important determinant of vegetation patterns. Such patterns may be persistent although the association and causality may only be detectable during initial establishment. In this study we investigated experimentally how spatial variation on two different scales and species-specific traits affected seedling survival at an early successional site on Skei{eth}arársandur, a 1,000 km2 homogeneous glacial outwash plain in SE-Iceland. Seedlings of eight native species were transplanted into six different micro-topographical combinations: three types of microsites (lee side of small stones and cushion plants, and control), located within two topographical features (shallow depressions and surrounding flats). Seedling survival was then recorded. Only 11 % of transplanted seedlings survived through the second winter, however seedlings that survived past the second growing season were likely to persist. Survival rates varied by species and were positively linked to seed size. Seedling survival was only weakly associated with spatial variation. The strongest association found was that survival was sometimes higher on flats compared to depressions. Sand accumulation in depressions might lower seedling survival there. We conclude that early plant establishment at the site, and the emergent vegetation mosaic, is most likely produced by the interaction of stochastic factors, such as the sand storms that intermittently rage across the plain and species-specific properties like seed size. However, in better-vegetated areas of Skei{eth}arársandur depressions often have higher moss and vascular plant cover than nearby flats, suggesting that moss may control vegetation patterns seen later in succession. © 2013 Springer Science+Business Media Dordrecht.

Agustsdottir A.M.,Soil Conservation Service of Iceland
Natural Hazards | Year: 2015

Living in Iceland, a highly volcanically active island with a historical eruption frequency of 20–25 events per 100 years, involves risks from lava, pyroclastic flows, tephra-fall, and floods from glacier/snow-covered volcanoes. Volcanic eruptions can have detrimental effects on human health, societies, and ecosystems. Eruptions in 2010–2011 proved the value of pre-event planning for some natural hazards. An additional focus is needed on pre-disaster mitigation responses for the effects of tephra-fall on vegetation: As outlined under the UNISDR Hyogo/Sendai Framework for Action, healthy ecosystems and environmental management are key actions in disaster risk reduction (DRR). Iceland’s most serious environmental problem is the degraded state of common rangeland in the highlands, where tephra-fall has been catastrophic. Tephra (airborne volcanic material) affects hydrology, air quality, and ecosystems by direct burial or post-eruptive transport, extending its influence far beyond the initial eruption area. Resilience to tephra-related disturbances depends on an ecosystem’s overall health. Tall, vigorous vegetation has greater endurance; its initial survival is more likely, while sheltering minimizes secondary transport and hastens recovery. Areas that are sparsely vegetated and already stressed are more vulnerable; there, tephra remains unstable and can cause further damage. Reclaiming vulnerable land and building healthy ecosystems, as represented by the Hekluskógar project, improve the ability of these areas to endure tephra-fall, increasing their resilience and reducing the associated costs to society. Successful DRR for tephra-fall, through the revegetation of degraded land, will require effective governance, multi-sector coordination, and the alignment of policies on land use, agriculture, natural resource management, and climate change mitigation. © 2015, The Author(s).

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