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High latitude dust is an important contributor to the global dust cycle, which affects the radiative balance of the atmosphere. The frequency and severity of dust events are driven by variables such as wind speed, precipitation, temperature, surface cover type, and volcanic activity. The extent of impact of glacial retreat is yet to be determined, but glacial outburst floods, known as jökulhlaups, have been suggested to be a significant factor in the seasonal pattern of dust activity, with major jökulhlaups being attributed as a cause for an increase in dust activity in their subsequent year. However, in examination of ten meteorological stations from 1950 to 2009, there does not appear to be sufficient evidence that jökulhlaups are a significant driver of Iceland’s dust activity. Additionally, taking into account a larger range of dust codes, contributions from Icelandic dust plumes are found to be greater than previously assumed, with an average of 128 dust days per year as compared to a previously determined average of 34 dust days annually., This work was funded by the SIT (School for International Training) Study Abroad Program, a Program for World Learning, Iceland, and Greenland: Climate Change and the Arctic. The preparation of this manuscript was funded by the Icelandic Research Fund (Rannis) Grant No. 152248-051.

The appearance of a flood deposit in the geomorphological and sedimentary record is a product of the both the processes operating during the flood, and those that occur afterwards and overprinting the deposit with a record of ‘normal’ processes. Nearly half of the total discharge of the November 1996 jökulhlaup on Skeiðarársandur was discharged through the Skeiðará river. The flood deposits have been extensively reworked since, up until 2009 when the channel was abandoned, effectively leaving the Skeiðará as a terrace, when retreat of Skeiðarárjökull directed meltwater to the adjacent Gígjukvísl river system. This paper describes the creation and modification of jökulhlaup barforms in the Skeiðará river, relating the changes to post-flood fluvial processes and glacier retreat. Large compound bars formed from the amalgamation of unit bars up to 1.5 km long. The location of the compound bars was governed by the macro-scale topography of the flood channel, and their size by upstream channel width in accordance with bar-scaling theory. Jökulhlaup bars are therefore scale invariant and formed in a similar fashion to braid bars in non-jökulhlaup braided rivers. Post-flood fragmentation and reworking of the bars consistently increased the length-width ratio of preserved bar fragments from approximately two and one half to over five. These observations increase our understanding of the preservation potential and final form of jökulhlaup deposits and provide the basis for an improved model for the recognition of jökulhlaup deposits in the geomorphological and sedimentary record. L’apparition d’un dépôt de crue dans l’enregistrement géomorphologique et sédimentaire est à la fois le produit des processus qui fonctionnent lors de la crue, mais également de ceux opérant après l’événement. Ces derniers remanient le dépôt de crue et surimposent à l’archive sédimentaire un enregistrement géomorphologique de processus fluviaux ‘normaux’. Près de la moitié du volume d’eau total engendré par le jökulhlaup du Skeiðarársandur de novembre 1996 a été évacué par la rivière Skeiðará. Depuis, les dépôts de crue ont été largement remanié. En 2009, le recul glaciaire du Skeiðarárjökull a provoqué la capture du chenal de crue de la Skeiðará par la rivière voisine de Gígjukvísl, formant ainsi une terrasse préservant les formes fluviales. Ce document décrit la formation et la modification de la morphologie des bancs de jökulhlaup dans la rivière Skeiðará par les remaniements fluviaux post-crue et le recul glaciaire. Les grands bancs composites ont été formés à partir de la fusion de bancs unitaires jusqu’à 1,5 km de long. La localisation des bancs composites est commandée par la macro-topographie du chenal de crue. Leur taille dépend de la largeur du chenal en amont conformément à la « bar-scaling theory ». Ainsi, les bancs de jökulhlaup présentent une invariance d’échelle et sont formés de la même manière que les bancs des cours d’eau en tresses non-affectés par les jökulhlaups. La fragmentation post-crue et le remaniement des bancs a invariablement augmenté le rapport longueur/largeur des fragments conservés des bancs de deux et demi à plus de cinq. Ces observations complètent notre compréhension du potentiel de préservation et de morphologie finale des dépôts de Jökulhlaup. Elles contribuent également à poser les bases d’un modèle amélioré pour la reconnaissance des dépôts de jökulhlaup dans les enregistrements géomorphologiques et sédimentaires.

Initial plant establishment is one of the most critical phases in ecosystem development, where an early suite of physical (environmental filtering), biological (seed limitation, species interactions) and stochastic factors may affect successional trajectories and rates. While functional traits are commonly used to study processes that influence plant community assembly in late successional communities, few studies have applied them to primary succession. The objective here was to determine the importance of these factors in shaping early plant community assembly on a glacial outwash plain, Skeiðarársandur, in SE Iceland using a trait based approach. We used data on vascular plant assemblages at two different spatial scales (community and neighborhood) sampled in 2005 and 2012, and compiled a dataset on seven functional traits linked to species dispersal abilities, establishment, and persistence for all species within these assemblages. Trait‐based null model analyses were used to determine the processes that influenced plant community assembly from the regional species pool into local communities, and to determine if the importance of these processes in community assembly was dependent on local environment or changed with time. On the community scale, for most traits, random processes dominated the assembly from the regional species pool. However, in some communities, there was evidence of non‐random assembly in relation to traits linked to species dispersal abilities, persistence, and establishment. On the neighborhood scale, assembly was mostly random. The relative importance of different processes varied spatially and temporally and the variation was linked to local soil conditions. While stochasticity dominated assembly patterns of our early successional communities, there was evidence of both seed limitation and environmental filtering. Our results indicated that as soil conditions improved, environmental constraints on assembly became weaker and the assembly became more dependent on species availability., This study was funded by Icelandic Research Fund (grants nr. 040263031 and 090255021). BM work was supported by the University of Iceland Innovation Fund. The study has been supported by the TRY initiative on plant traits (http://www.try-db.org).

The coastal sand-dunes of Iceland, between Myrdalsjökull and the eastern fjords. In spite of good conditions (strong winds, abundant clastic deposits), the coastal dunes of south-eastern Iceland are not very bulky. Only the fields of small sandy mounds are wide-spread. In many places the wind courses are quite changeable and often push the sands into the sea. Moreover, some dunes have been destroyed by the numerous jökulhlaups washing the coastal plain., En dépit de conditions favorables (vents puissants, abondants sédiments détritiques, ...), les dunes littorales du sud-est de l'Islande sont peu volumineuses. Ce sont les champs de buttes sableuses qui sont les mieux représentés. En de nombreux endroits, les vents sont très mobiles ; ils repoussent souvent les sables vers la mer. En outre, certaines dunes ont été détruites par les nombreux jökulhlaups qui balaient la pleine littorale., Bodéré Jean-Claude. Les accumulations dunaires littorales d'Islande entre le Myrdalsjökull et les fjords de l'est. In: Hommes et Terres du Nord, 1989/3. Régions arctiques et subarctiques. pp. 147-153.