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.

While many tree species occur across the Coastal Plain of the southeastern United States, longleaf pine (Pinus palustris C. Lawson) savannas and woodlands once dominated this region. To quantify longleaf pine’s past primacy and trends in the Coastal Plain, we combined seven studies consisting of 255,000 trees from land surveys, conducted between 1810 and 1860 with other descriptions of historical forests, including change to the present day. Our synthesis found support that Pinus palustris predominantly constituted 77% of historical Coastal Plain trees and upland oaks (Quercus) contributed another 8%. While Pinus still dominates these forests today (58% of all trees), most are now either planted loblolly (Pinus taeda L.) or slash (Pinus elliottii Engelm.) pines. Water oak (Quercus nigra L.), live oak (Quercus virginiana Mill.), sweetgum (Liquidambar styraciflua L.), and red maple (Acer rubrum L.) have increased their proportions compared to historical surveys; both longleaf pine and upland oaks have declined to ≤5% of all trees. Our work also supports previous estimates that longleaf pine originally dominated over 25–30 million ha of Coastal Plain forests. As late as the early 1900s, longleaf pine may still have covered 20 million ha, but declined to 7.1 million ha by 1935 and dropped to 4.9 million ha by 1955. Longleaf pine’s regression continued into the mid-1990s, reaching a low of about 1.3 million ha; since then, restoration efforts have produced a modest recovery to 2.3 million ha. Two centuries of overcutting, land clearing, turpentining for chemicals, fire exclusion followed by forest densification by fire-sensitive species, and other silvicultural influences, including widespread loblolly and slash pine plantations, have greatly diminished the Coastal Plain’s once extensive open longleaf pine forests.