2008 Joint Meeting of The Geological Society of America, Soil Science Society of America, American Society of Agronomy, Crop Science Society of America, Gulf Coast Association of Geological Societies with the Gulf Coast Section of SEPM

Paper No. 2
Presentation Time: 8:25 AM

Feedbacks Between Aeolian Processes, Vegetation Productivity, and Nutrient Flux in Deserts

OKIN, Gregory S.1, LI, Junran2, ALVAREZ, Lorelei2, PETERS, Debra P.C.3 and D'ODORICO, Paolo2, (1)Department of Geography, UCLA, Los Angeles, CA 90095, (2)Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, (3)USDA-ARS Jornada Experimental Range, Las Cruces, NM 88013, okin@ucla.edu

Wind is a key abiotic factor that influences the dynamics of arid and semiarid systems. A series of experiments and models will be presented that show the important feedbacks that exist between aeolian processes and biotic process in deserts. Wind impacts vegetation by both changing the composition of the soils, mainly by winnowing fines from erosional areas and redeposition of fines in deposition areas, and by direct physical effects on plants. The former leads to significant loss and redistribution of soil organic matter and plant nutrients as well as the disruption of nutrient cycling process. The latter leads to burial, pedestaling, leaf stripping and branch abrasion that lead to increased plant mortality. There is significant evidence that this leads to state changes in deserts, namely replacement of grasses by shrubs, which in turn create landscapes that are far larger emitters of dust. Changes in aridity have, in the past, caused changes variations in dust emission associated with vegetation state changes and, models suggest, aeolian processes will be increasingly important in vegetation change and dust emissions in deserts.