Watershed Restoration in Degraded Pinyon-Juniper Woodlands: A Paired Watershed Study 1996-98(9)

Jacobs, Brian; Gatewood, Richard; Allen, Craig

Restoration studies, conducted in degraded woodland areas of Bandelier National Monument, New Mexico assessed the utility of mechanical treatments to stabilize soils and cultural resources. Piñon-juniper woodland systems have colonized millions of acres of western grazing lands since ca.1850, transforming former grassland and savanna communities into woodlands, and encroaching into the understories of upland forests. A poor understanding of this dynamic vegetation type has limited the success of management initiatives to improve watershed, wildlife, and range conditions, protect cultural resources, and mitigate impending wildfire hazards. In local degraded woodlands, exposed soils predominate and summer monsoons generate unsustainable sediment loss, which threatens embedded cultural resources. In early 1997, mechanical thinning and slash mulching treatments were applied to one of two, paired, 40 ha watersheds. Response to treatment was quantified using both biotic (plant cover and biomass, abundance of arthropods, and ungulate utilization) and abiotic measures (ground cover and changes in soil surface topography). In late 1999, at three years post-treatment, total herbaceous plant cover had increased three-fold over pre-treatment and control levels, while soil erosion rates, as inferred from changes in surface topography, were significantly reduced relative to control.