Abstract
The pinyon-juniper woodland is a wide spread vegetation type in the southwestern United States that is estimated to cover from 30 to 40 million hectares. They pinyon-juniper vegetation provides a source of fuel, building materials, charcoal, pine nuts, christmas trees and folk medicines. About 80% of the acreage is grazed by livestock and wildlife. In Utah, this ecosystem is a large component (62,705 km2 or 28.6%) of the vegetation. Particularly in the Utah National Parks, the pinyon-juniper woodlands valued for their watershed, aesthetic and recreational values. Over the past several years extensive foliar damage to Utah juniper (Juniperus osterosperma (Torr.) Little) has been observed in the Natural Bridges National Monument. The characteristic pattern is for the distal foliage to become chlorotic and die. Mortality progresses along twigs until whole branches or even the entire tree dies. Reports of similar foliar damage has been reported in Canyonlands National Park, Arches National Park, Mesa Verde National Park, Colorado National Monument, areas near Cedar City in southwestern Utah and in eastern Nevada, which would indicate that the foliar damage is a widespread problem. The cause for the foliar damage is unknown. The loss of juniper trees in the national parks in southern Utah would have a dramatic ecological impact and would be an aesthetic blight in the parks. The purpose of this investigation is to determine the cause of the die-off of Utah junipers and suggest management options concerning the juniper die-off problem.