Mesophication of Oak Ecosystems: The Consequences of Altered Fire Regimes

Oak, represented by a variety of species, is a common tree throughout the Eastern Deciduous Forest.  Oak’s success, in terms of abundance and wide distribution, has been linked to disturbance, specifically fire.  Oak possesses various physiological traits allowing it to thrive in landscapes frequented by drought and fire.  These traits include taproots (deep water access), thick bark (protection), rot resistance (if injured), and the ability to re-sprout and grow rapidly (fire response). Oak is an opportunistic species that readily takes advantage of forest disturbance by quickly colonizing openings where seed sources exist. Oak encourages fire by the leaf litter it produces. The historic disturbance regime (including Native burning) supporting oak changed dramatically when Europeans arrived in America.  During early exploitation of forest resources, increased cutting and burning facilitated oak regeneration and dominance. Afterwards, a shift to eradicate wildfire had a negative effect on this genus.  Oak performs poorly in today’s shaded understory conditions and is being readily replaced by shade-tolerant, fire-sensitive species such as sugar and red maple, basswood, beech, and black gum throughout its range. This transition from oak to mesophytic trees is termed mesophication.