Documenting Two Centuries of Change in Longleaf Pine (Pinus palustris) Forests of the Coastal Plain Province, Southeastern USA

Abstract

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.

Differentiating Historical Open Forests and Current Closed Forests of the Coastal Plain, Southeastern USA

“…Before Euro-American settlement and accompanying land use changes, longleaf pine (Pinus palustris) open woodlands were the dominant ecosystem across the Coastal Plain Forests 2024, 15, 532 2 of 18 ecological region in the southeastern United States (Figure 1; [14][15][16]. Historical accounts, early forest reports, and limited reconstructions of historical tree surveys characterized the Coastal Plain as longleaf pine savannas and woodlands with interspersed grasslands and wetlands [15][16][17][18][19]. Savannas and woodlands were two-layered, featuring longleaf pine at low densities in the overstory and a species-diverse herbaceous layer, making savannas continuous in structure with grasslands.…”

“…Euro-Americans cleared historical forests and altered fire regimes before either were well documented [31]. Longleaf pine ecosystems provided pasturelands, lumber, and chemical products such as turpentine [16,34,35]. A general pattern of land use may have occurred where livestock herders first primarily used existing open ecosystems for forage, followed by conversion to row crop agriculture [32,35].…”

“…Steam-powered technology, railroads, and inexpensive land prices coincided to escalate tree removal ('cut-out and get-out') between 1880 and 1920, from which longleaf pine forests did not naturally recover [36]. Land uses of chemical extraction for naval supplies, lumbering, and intensive livestock grazing or agriculture resulted in extensive areas without mature longleaf pines [16]. Longleaf pine regeneration was hindered by lack of mature trees, sporadic cone production, limited seed dispersal, fire exclusion, and seedling depredation by feral livestock, chiefly the hogs that saturated the land [15].…”

“…Longleaf pine regeneration was hindered by lack of mature trees, sporadic cone production, limited seed dispersal, fire exclusion, and seedling depredation by feral livestock, chiefly the hogs that saturated the land [15]. Of the 25-to-30 million ha of longleaf pine woodlands in the Coastal Plain at Euro-American settlements, about 2 million ha exists currently [16,20].…”

“…Indeed, the use of longleaf pine for naval supplies and other purposes in early Euro-American settlements before documentation means that northern boundaries in the easternmost states may never be known [15]. Historical maps of longleaf pine distributions were developed based on assessments after Euro-American land use had already removed forests [16]. Several studies have examined longleaf pine forests recorded by historical land surveys conducted generally during the first half of the 1800s to record and sell land, although some eastern states were not surveyed with grid-based methods [16].…”