Large-scale pinyon Ips (Ips confusus) outbreak in Southwestern United States tied with elevation and land cover

During a severe drought, a large-scale outbreak of pinyon ips between 2002 and 2004 in the southwestern United States, resulted in over 3 million ac of damage to pinyon pine forests in the southwestern United States. Previous studies suggest that damage was most severe in stands that encroached in lower elevation ecosystems. To gain a regional perspective on the outbreak, we did a geographical analysis of ips damage in association with land cover and elevation. Our analysis indicates that the overall distribution of the ips damage mirrors the distribution of pinyon-juniper woodlands in the region, with more intense damage occurring at higher elevations in Utah and Arizona, where pinyon pines are more common and have likely become denser with time. Our results suggest during droughts even historical stands of pinyon pine are at risk of pinyon ips damage, not just stands at the ecological extreme.