Tuesday, November 6, 2007
211-10

Mapping Biological Soil Crust Distribution in the Muddy Mountains Wilderness Area, Nevada.

Amanda Williams, Department of Geoscience, University of Nevada, Las Vegas, 1515 E. Reno, E101, Las Vegas, NV 89119, Brenda J. Buck, Dept. Geoscience, Univ. Nevada - Las Vegas, 4505 Maryland Pkwy, Las Vegas, NV 89154, Brett T. McLaurin, Department of Geoscience, University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154-4010, Henry Sun, Division of Earth and Ecosystem Sciences, Desert Research Institute, 755 E. Flamingo, Las Vegas, NV 89119, Deborah Soukup, University of Nevada-Las Vegas, Geoscience Department, 4505 Maryland Parkway, Las Vegas, NV 89154-4010, and Douglas Merkler, 5820 South Pecos Road, USDA, USDA, Park Place Professional Complex, B A, Ste 4, Las Vegas, NV 89120.

Biological soil crusts (BSCs) are critical features in arid landscapes. Often dominating plant interspaces in arid regions, BSCs influence erosional processes, soil water movement, soil fertility, and seed germination.  Soil lichen, mosses, and cyanobacteria fuse around soil particles creating a delicate desert skin that is highly susceptible to disturbance.  Management of these crusts is often difficult, as the component organisms are easily overlooked and difficult to identify.  In this research, we created a field-based map of BSCs within a portion of the Muddy Mountain Wilderness Area, NV.  This map was compared with two remotely sensed maps, created by applying two established BSC indexes (Karnielli, 1997; Chen et al. 2005).  These indexes were first tested using Landsat ETM (30 m resolution), while we tested these indexes using Quickbird® multispectral satellite imagery (2.44 m resolution).  Both indexes were able to differentiate between crusts dominated by cyanobacteria and those crusts dominated by lichen and moss pinnacles.  Additionally, the indexes were able to moderately differentiate between high moss/lichen cover and intermediate moss/lichen cover.  From these initial results, it appears that the Karnielli (1997) index yields more consistent values for a 3-category mapping system.  While index values may potentially yield BSC organism density results, field based mapping allows for the differentiation of crust surface morphology.  Future work includes the following: (1) Quantifying actual BSC organism densities and comparing them with the BSC index maps; (2) Collection of transect data to determine the factors influencing BSC distribution; (3) Comparing a geomorphic surface map to the field-based BSC map.  This research has the potential to influence the management of BSCs in the Mojave Desert, where little is known about the factors influencing BSC distribution or how to efficiently map their occurrence in the landscape.