Soil Evaluation in Support of Estimating Carrying Capacity and Landscape Degradation at the NTC Fort Irwin, CA

Affiliation(s) PI/CoPI Funded by
DEES

McDonald, Eric
Caldwell, Todd

ITAM, Charis Corporation, Subcontract No. GS-012FG-B

Keywords: soil compaction, Mojave, restoration, revegetation, military, NTC, arid

Project Description

The National Training Center (NTC) is the Army's primary mechanized maneuver training facility, covering approximately 2,600 square km within the Mojave Desert in southern California. One of the greatest challenges to the Department of Defense (DoD) is maintaining the sustainability of military lands in desert environments while maximizing their use for military activities.

The goal of this project is to characterize changes in soil properties resulting from military activities under canopy and interspace locations. Military training exercises at the National Training Center (NTC), Ft. Irwin, California have led to the degradation of large areas of soil cover. Revegetation of these lands by the Integrated Training Areas Management (ITAM) Program requires identification of optimum growing conditions based on the character of the desert soil and the landscape position; hence land managers need a quantifiable measure of soil degradation.

The sampling approach is designed to evaluate important impacts to soil properties under various levels of disturbance or impact. Of primary consideration is the determination of soil parameters that are most affected by military training impacts and degradation of desert lands. This information is especially valuable for developing appropriate Land Rehabilitation and Maintenance (LRAM) strategies and interpreting Land Condition Trend Analysis (LCTA) data for the management of complex ecosystems and landscape dynamics in desert environments.

Results indicate that despite significant increases to bulk density following low and high disturbance, saturated conductivities were only modestly impacted. The soil morphology was highly impacted, particularly on older geomorphic surfaces. Desert pavements were stripped of their silt capped Av horizon and compacted by maneuvers, resulting in little overall change to the saturated conductivity but a large change soils.

Below: Low impact disturbance from a recent tracked vehicle results in a disruption of the surface soil crust to a young soil (Left) and an old pavement soil (Right), decreasing bulk density and increasing hydraulic conductivity.

Low impact disturbance from a recent tracked vehicle results in a disruption of the surface soil crust to a young soil (Left) and an old pavement soil (Right), decreasing bulk density and increasing hydraulic conductivity.

Below: Examples of a high level of soil disturbance for a young surface (Left) and an old desert pavement soil (right). High impact resulted in substantial loss of vegetated cover, and very high bulk densities typical of ITAM restoration sites.

Examples of a high level of soil disturbance for a young surface (Left) and an old desert pavement soil (right). High impact resulted in substantial loss of vegetated cover, and very high bulk densities typical of ITAM restoration sites.

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