Phytogenic mounds (nebkhas): effect of Tricomaria usillo on sand entrapment in central-west of Argentina

Abstract

Nebkhas, developed by the trapping of sand within the body of a plant, were studied in the Médanos Grandes system, arid central Argentina, during the springs of 2009-2010.In this system, formed by megadunes and overlapping dunes, nebkhas dynamism was analyzed considering their location on windward and lee slopes. In each nebkha, sand movement was studied through erosion pins and considering E, W, N and S orientation. Predominant winds blow from the south-southeast; however, no significant statistical differences were found in the erosion-deposition process, between windward and lee slopes. Nebkhas on the lee show slow growth and those on windward slope moderate deterioration. Tricomaria usillo is the dominant plant species in the nebkha formation process. There are positive relationship between nebkha volume and shrub canopy volume.