Soil and Nitrogen Loss from Oregon Lands Occupied by Three Subspecies of Big Sagebrush

Abstract

Measurements of runoff and soil loss from simulated high-intensity rainstorms are reported for shrub interspaces of 3 sites occupied by each of 3 subspecies of Artemisia tridentata (big sagebrush) in each of 4 locations in eastern Oregon. A. tridentata ssp. wyomingensis sites as a group had significantly higher soil loss than A. tridentata ssp. vaseyana sites. Comparisons of means within locations showed nonsignificant differences between land supporting big sagebrush subspecies except at Frenchglen. Soil loss was positively correlated with runoff, percent bare ground, and vesicular soil porosity; but it was negatively correlated with medium and coarse sand and coarse fragments in the surface soil and with organic ground cover. Aridisols lost more soil than Mollisols. Habitat types did not appear useful for indexing soil loss from these sites. Surface soil morphology, however, correlated with large significant differences in soil loss and may be a useful index. Organic and ammonium nitrogen loss was not correlated with a subspecies of A. tridentata, but did correlate with soil erosion and many of the soil features that affect soil erosion. Amounts of nitrogen lost do not appear to be critical.