Forest ecosystem re-organization underway in the southwestern United States: A preview of widespread forest changes in the Anthropocene?

Abstract

This paper addresses an important set of issues currently facing the forests of western North America - the intersection of 20th Century land use legacies and the emerging impacts of climate change on drought, forest stress, wildfire, and ecosystem change. The presented information comes from a variety of sources in the scientific literature, with a focus on the Southwest United States, particularly including observations from my home landscape of the Jemez Mountains in northern New Mexico. Historic fire suppression and two regionally wet climate periods fostered widespread buildups of forest densities and fuel loads since ca. 1900. With the recurrence of drought conditions coupled with warmer temperatures since the late 1990s, the overgrown forests in the Southwest have been subject to wildfires and tree mortality episodes of historically unprecedented extent and severity, along with emergent shifts in vegetation patterns. Currently observed trends are indicative of early-stage ecosystem reorganization in response to historic land management practices combined with recent novel climate stresses. This convergence of climate stress, human land use patterns and histories, and disturbance trends in the southwestern United States may foreshadow widespread forest ecosystem changes more broadly in North America, and globally.

Parent Publication

• Forest conservation and management in the Anthropocene: Conference proceedings

Citation

Allen, Craig D. 2014. Forest ecosystem re-organization underway in the southwestern United States: A preview of widespread forest changes in the Anthropocene? In: Sample, V. Alaric; Bixler, R. Patrick, eds. Forest conservation and management in the Anthropocene: Conference proceedings. Proceedings. RMRS-P-71. Fort Collins, CO: US Department of Agriculture, Forest Service. Rocky Mountain Research Station. p. 103-123.