All terrain vehicle impacts on a sonoran desert soil. Green, Douglas¹, Fox, Barbara¹, ¹ Department of Applied Biological Sciences, Mesa, AZ, USA

ABSTRACT- The popularity and increased use of all terrain vehicles (ATV's) over the last two decades has raised concern over possible damage to soils of desert ecosystems. The objective of this study was to examine OHV impacts on a dry moist and wet desert soil in central Arizona. Treatment plots were subjected to 1, 10, 25, 50, and 100 passes of the (ATV). A portable rainfall simulator was used to evaluate infiltration, runoff, and sediment production on treatment plots. Results revealed significant differences between increases in soil bulk density, number of ATV passes, soil depth, and soil moisture classes. Wet plots had the greatest increase in mean soil bulk density between 1 and 10 passes. Mean soil bulk density increased with each series of passes to 100 passes for all soil moisture classes except for dry plots, which declined slightly between 50 and 100 passes. Soil bulk density at the 0-5 cm depth was significantly greater than at the 5-10 cm depth in relation to the soil moisture class, with wet plots at the 0-5 cm depth experiencing the highest bulk density increase. Mean runoff from wet treatment plots was higher than dry, moist, and control plots. Sediment yield was highest on the dry plots, with no significant difference noted between moist, wet, and control treatments. Stepwise regression revealed that post-treatment soil bulk density was strongly influenced by soil moisture content and pre-treatment soil bulk density. The results of this study indicate that ATV impact is dependent on soil moisture.

KEY WORDS: Arizona, all terrain vehicles, runoff, compaction