WWRC 97-06
Wyoming Rocky Mountain Forest Soils: Mapping Using an ARC/INFO Geographic Information System
Abstract
In the western USA, wildland soil survey areas are often large,
and the resources of money, personnel, and time required for conventional
soil 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 geographic information system (GIS) technology.
We conducted this study in the Libby Creek watershed in Wyoming
where soil distribution (Cryoboralfs, Cryoborolls, Cryaquolls, Cryaquents,
Cryochrepts, and Cryorthents) is a (unction of geology, slope
stability, and vegetation. The GIS-generated soils map was compared
with existing general (Order 4) and detailed (Order 3) soils maps
prepared for the U.S. Forest Service (USES). Discrepancies noted
between the GIS-generated map and USFS maps included: Cryochrepts
were the dominant soil on the GIS map (44%), but comprised
only 15% on the USFS detailed soils map; Cryumbrepts occupied
19% of the USFS general soils map but only 2% on the GIS-derived
soils map; and no Cryumbrepts were delineated in the study area on
the USFS detailed soils map. Only two of the eight Cryumbrepts
sampled occurred within Cryumbrept delineations on the USFS general
soils map. Of the 37 pedons sampled and classified along the five
transects across Libby Creek watershed, II (30%) corresponded to
named soils of mapping units 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 soils maps, and can aid in placing
soil boundaries for detailed soils maps.
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