Pinyon pine make up nearly 60 percent of Utah's forest cover. The tenacious pines are found growing in a 5,000 to 7,000 foot altitude range in a desert type ecosystem. The harsh environment, at times, stresses even the healthiest trees and aids engraver beetle infestation. The recent lack of rainfall follows on a 20 year period of increased precipitation. Drought conditions slow the pinyon pine's sap producing ability. The tree's sap usually slows the beetles from boring into the tree's bark. Millions of pinyon pine, located on the Colorado Plateau, have succumbed to these two natural enemies.