Rainfall interception by mountain big sagebrush (Artemisia tridentata spp. vaseyana): Dryland shrub canopy cover affects net precipitation

Canopy interception loss is an important component of the water budget for many ecosystems, and may be particularly influential in semi-arid shrublands where water is limiting. In this experiment, we quantified interception loss by mountain big sagebrush (Artemisia tridentata spp. vaseyana) using simulated rainfall events in the field. Various levels of canopy cover and rainfall intensities were tested to measure their effects on net precipitation and interception loss. Additionally, the comparisons were made between three methods of measuring shrub cover to enhance the scalability of results. Stands of sagebrush from 20% to 50% canopy cover intercepted 18.5 +/- 12.5% of incoming precipitation. Percent interception loss differed by 13.7% between the high and low cover classes, indicating that net precipitation may be significantly reduced under mature, dense stands of sagebrush. Hemispherical photography was a viable method for estimating canopy cover in this vegetation type. Interception loss by sagebrush was 14% lower on average than pinyon and juniper measured in the same watershed. Results from this study quantified the effects of sagebrush canopy on rainfall interception and improved understanding of vegetation dynamics in the sagebrush steppe.