Dynamic Fire Regimes and Forest Conditions Across Three Centuries in a Shortleaf Pine-Oak Forest in the Ouachita Mountains, Arkansas, USA

In the interior highlands of the eastern United States, there is evidence that fire was frequent in some forests during the eighteenth and nineteenth centuries before declining drastically in the twentieth century. To better understand past fire regimes and how they shaped forest dynamics during periods of change, we conducted a dendroecological study at Lake Winona Research Natural Area (LWRNA), a 110-ha unlogged forest dominated by shortleaf pine (Pinus echinata Mill.) in the Ouachita Mountains of Arkansas. We used remnant wood and living tree cores to construct a multicentury record of fire occurrence and tree recruitment. Our results indicate the forest at LWRNA passed through multiple fire regime transitions that altered forest dynamics. During the protohistoric period (1701-1834), prior to widespread European American settlement (EAS), fire was frequent, but limited sample depth results in greater uncertainty regarding fire frequency and forest conditions. During EAS (1835-1929), fire was very frequent and tree establishment was dominated by shortleaf pine. After 1930, effective fire protection led to establishment shifting toward increasingly fire-intolerant hardwoods. Evidence of temporal variations in the fire regime, age structure, and contemporary composition broaden our understanding of reference conditions in this pine-oak forest and demonstrate that fire management could be used to restore a range of vegetation conditions from frequently burned pine- and oak-dominated woodlands to fire-excluded, closed-canopy mesophytic communities.