Abstract: Across the central and eastern U.S., historically fire-adapted oak savannas and woodlands are shifting to dense, multi-layered, closed-canopy forests of shade-tolerant, fire-sensitive, and/or opportunistic tree species. One possible explanation for this shift is mesophication, a multi-phased process by which fire exclusion encourages the densification of stands by encroaching tree species (i.e., mesophytes), whose traits then create shadier, cooler, and wetter understory conditions and a leaf litter fuel bed that dampens fire, allowing mesophytes to self-perpetuate while hindering regeneration of pyrophytic tree species. Our research identifies mechanisms of mesophication and consequences for restoring and conserving upland oak landscapes. 

Bio: : Dr. Heather D. Alexander is an associate professor of forest and fire ecology and the Dwain G. Luce Endowed Professor of Forestry in the College of Forestry, Wildlife, and Environment at Auburn University, where she teaches classes in forest ecology and forest fire management. Her research program at Auburn focuses on understanding forest ecosystem vulnerability in the face of changing fire disturbance regimes using observations across natural gradients and field-based experimental manipulations. She has studied fire effects on the composition, structure, and function of oak, mixedwood, and pine forests of the eastern U.S. for 20 years and has a strong interest in understanding the implications of mesophication for carbon dynamics and forest flammability.