Dust deposits along the North Sahara-Europe axis: consequence on forest ecosystem fertilization

Marie-Pierre Turpault1, Emeline Lequy1, Anna Avila2, Malika Boudiaf3, Sébastien Conil4
1 INRA, Biogéochimie des Ecosystèmes Forestiers, F-54280 Champenoux, France
2 CREAF, Univ Autonoma de Barcelona
3 Laboratoire Ressources Naturelles, Faculté Des Sciences Biologiques et Sciences Agronomiques, Université Mouloud Mammeri Tizi-Ouzou Algérie
4 Andra, R&D Division, Centre de Meuse-Haute-Marne, Route départementale 960, 55290 Bure, France.

P 3.21 in Fluxes between the atmosphere and ecosystems

Poster Session 2 on Tuesday, 16:30-18:00

Aeolian dust, defined here as the solid particulate fraction of bulk atmospheric deposition, is generally not measured or taken into account in the nutrient budget of forest ecosystems. However, in low-nutrient ecosystems, this nutrient input can contribute to tree nutrition (Avila et al., 1998; Lequy et al, 2012; 2013). The Sahara Desert is considered as one of the main sources of dust in Europe. To determine the influence of the distance from Sahara on Aeolian dust deposition and its nutrient content, we sampled dust deposits with passive collectors every month during at least one year in three forest sites along a Sahara – Europe axis: in Northern Algeria, in Northeastern Spain and in Northern France. The openfield bulk deposition samplers consisted in 0.22 m² polyethylene funnels directly connected to 20 L cans. Solid particles were separated from rainwater by centrifugation. Aeolian dust deposition drastically differed between the different sites, with 564, 130 and 39 kg.ha-1.yr-1 in Northern Algeria, Northeastern Spain and Northern France, respectively. In France, deposition followed a seasonal pattern with a high deposition from spring to early autumn and a low deposition in winter (Lequy et al.2013). In contrast, deposition in Algeria considerably varied between every sample, for example decreasing from 170 kg to 1 kg between two consecutive months. In Spain, a seasonal pattern was observed as well as a great variation probably due to Saharan dust storms or local erosion. The chemical composition of Aeolian dust greatly varied between the sites and the dates of sampling. High deposition samples in Algeria contained generally more calcium than in the other sites. The inputs of nutrients decreased with the distance to Sahara, from 25.2 to 0.3 kg.ha-1.yr-1, 7.2 to 0.6 kg.ha-1.yr-1, 6.5 to 0.3 kg.ha-1.yr-1, and 1.9 to 0.2 kg.ha-1.yr-1 for Ca, K, Mg, and P, respectively. These nutrients, generally labile, came likely from small-size and weatherable minerals (Lequy et al. 2013).

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Lequy E., Conil S., Turpault M.-P., 2012. Forest Ecology Management, 267, 240-252.
Lequy E., Legout A., Conil S. Leclerc E., Turpault M.-P., 2013. Atmospheric Environment, 80, 281-289.

Letzte Änderung 19.06.2014