Impacts of tracked vehicles on sediment from a desert soil

Off-road military vehicle traffic is a major consideration in the management of military lands. The objective of this study was to determine the impacts of military tracked M1A1 heavy combat tank vehicles on sediment loss from runoff, surface plant cover, and surface microtopography in a desert military training environment. A randomized block design was used which had 10 blocks with 4 plots (0.5 m2) in each block. Each block had randomly selected treatments that included an untreated control, 1 pass by a M1A1 tank under wet seasonal conditions, 3 passes by a M1A1 tank under wet seasonal conditions, 1 pass by a M1A1 tank under dry seasonal conditions, and 3 passes by a M1A1 tank under dry seasonal conditions. Data were analyzed using mean separation and stepwise regression techniques. Most sample periods showed that sediment losses from M1A1 tank treatments, single or triple passes under wet or dry seasonal conditions, did not differ statistically from natural sediment losses under nominal rainfall events. However, comparatively intense rainfall events often generated significantly (P < 0.05) greater sediment losses from the M1A1 tank triple pass treatments. Triple pass M1A1 tank impacts had detrimental effects that could last many years, particularly when disturbances were imposed under dry seasonal conditions. Seasonal drought for the area, occurring 2 out of 3 years during the study period, may have exacerbated the effects of triple pass M1A1 tank impacts. Analysis showed that grass cover, litter cover, and microtopographic variance were highly and negatively correlated (R = -0.62) with cumulative sediment loss. Depending on precipitation availability, a minimum of 3 years for most triple pass M1A1 tank impacts is suggested for suitable vegetation recovery and soil stability. It is recommended that site repetitious M1A1 tank training maneuvers should be conducted with particular attention to site recovery. Furthermore, the influence of climate, drought in particular, should be among the topics addressed by future military training land use models. DOI:10.2458/azu_jrm_v56i4_fuchs