Author
Pierson Jr, Frederick | |
Blackburn, Wilbert | |
Van Vactor, Steve |
Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/1/2007 Publication Date: 11/20/2007 Citation: Pierson Jr, F.B., Blackburn, W.H., Van Vactor, S.S. 2007. Hydrologic impacts of mechanical seeding treatments on sagebrush rangelands. Rangeland Ecology and Management, 60:666-674. Interpretive Summary: The use of rangeland drills and other implements can aid the recovery of degraded rangelands by reducing annual grass competition. However, mechanical seeding treatments can alter runoff and erosion rates of a site by altering surface soil and vegetation characteristics. This study was designed to investigate how mechanical seeding implements impact runoff and erosion and determine how long such impacts last. A cheatgrass-dominated study site was burned and seeded with native grasses and shrubs in the fall of the year. An amazon-drill and a disk-chain seeder were used to provide varying levels of surface soil disturbance. The disk-chain created the largest increase in runoff and erosion that lasted for three growing seasons following treatment. The amazon drill had less impact on runoff and erosion that lasted only two growing seasons following treatment. The rapid hydrologic recovery of the sites following treatment was primarily due to the rapid accumulation of surface vegetative litter. While the initial goal of using mechanical seeding treatments to enhance recovery of native grass species failed, cheatgrass provided sufficient production to rapidly replenish surface litter cover necessary for rapid hydrologic stability of the site. Technical Abstract: On degraded rangelands mechanical seedbed preparation can aid in recovery of native species by reducing annual grass competition. Mechanical seeding treatments, however, can affect both the hydrologic and erosion condition of a site by altering surface soil and vegetation characteristics. This study was designed to investigate the nature and persistence of hydrologic and erosion impacts caused by different rangeland seeding treatments, and to identify interactions between such impacts and related soil and vegetation properties. A cheatgrass-dominated study site was burned and seeded with native grasses and shrubs in the fall of the year. An amazon-drill and a disk-chain seeder were used to provide varying levels of surface soil disturbance. The disk-chain created the largest reduction in infiltration and increase in sediment yield that lasted for three growing seasons following treatment. The amazon drill had a lesser impact that was insignificant after the second growing season following treatment. The hydrologic recovery of the treatments was strongly correlated with litter dynamics. The seeding treatments were unsuccessful at establishing seeded plant species and the site once again became dominated by cheatgrass. While the initial goal of using mechanical seeding treatments to enhance recovery of native grass species failed, cheatgrass production provided sufficient biomass to rapidly replenish surface litter cover necessary for rapid hydrologic stability of the site. |