WYOMING ROCKY-MOUNTAIN FOREST SOILS - MAPPING USING AN ARC INFO GEOGRAPHIC INFORMATION-SYSTEM/

In the western USA, wildland soil survey areas are often large, and th e resources of money, personnel, and time required for conventional so il survey techniques are in short supply, We evaluated an alternative methodology for producing soil maps through a process of transecting, model construction, and projection onto a map base using ARC/INFO geog raphic information system (GIS) technology. We conducted this study in the Libby Creek watershed in Wyoming where soil distribution (Cryobor alfs, Cryoborolls, Cryaquolls, Cryaquents, Cryochrepts, and Cryorthent s) is a function of geology, slope stability, and vegetation. The GIS- generated soils map was compared with existing general (Order 4) and d etailed (Order 3) soils maps prepared for the U.S. Forest Service (USF S). Discrepancies noted between the GIS-generated map and USFS maps in cluded: Cryochrepts were the dominant soil on the GIS map (44%), but c omprised only 15% on the USFS detailed soils map; Cryumbrepts occupied 19% of the USFS general soils map but only 2% on the GIS-derived soil s map; and no Cryumbrepts were delineated in the study area on the USF S detailed soils map. Only two of the eight Cryumbrepts sampled occurr ed within Cryumbrept delineations on the USFS general soils map. Of th e 37 pedons sampled and classified along the five transects across Lib by Creek watershed, 11 (30%) corresponded to named soils of mapping un its in the USFS general soils map, and 20 (54%) coincided on the USFS detailed soils map, Results of this study suggest transecting and GIS- based mapping can be an effective technique for producing general soil s maps, and can aid in placing soil boundaries for detailed soils maps .