Submitted to: International Society of Ecological Modeling Annual Meetings
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2001
Publication Date: August 6, 2001
An hypothesis for understanding the stability of the Northern Chihuahuan Desert landscapes is that the distribution of soil resources changes from spatially homogeneous in semiarid grasslands to heterogeneous in invading shrublands. Fallout Cesium-137 was deposited uniformly across the landscape during the 1950's and 1960's and was quickly adsorbed to soil particles, thus any redistribution of Cs-137 across the landscape would be due to soil redistribution. The concentration of fallout Cs-137 in soil profiles collected from different vegetation types (Grass, Mesquite, Tarbush, Tobosa) at the USDA-ARS Jornada Experimental Range in Northern Chihuahuan Desert in New Mexico was determined. At the Grass, Tarbush, and Tobosa sites, Cs-137 was uniformly distributed across the sites. At the Mesquite sites, Cs-137 was concentrated in the dune area under mesquite shrubs with little to no Cs-137 in the interdune areas. Cesium-137 data support the hypothesis that significant soil redistribution has occurred at the mesquite dune sites but at the Tarbush and Tobosa shrub sites the Cs-137 data do not support any major redistribution of soil resources. High concentrations of Cs-137 in the biological soil crust (0-5mm) at the Tarbush shrub sites indicate that biological soil crust contribute to the stability of these sites.