MARC D. ABRAMS
BioScience 53 (10), 927-939, (1 October 2003) https://doi.org/10.1641/0006-3568(2003)053[0927:WHATWO]2.0.CO;2
KEYWORDS: witness trees, dendroecology, land-use history, fire, disturbance ecology
Before European settlement, vast areas of deciduous forest in what is now the eastern United States were dominated by oak species. Among these species, white oak (Quercus alba) reigned supreme. White oak tended to grow at lower elevations but was distributed across a broad range of sites, from wet mesic to subxeric, and grew on all but the wettest and most xeric, rocky, or nutrient-poor soils. A comparison of witness tree data from early land surveys and data on modern-day forest composition revealed a drastic decline in white oak throughout the eastern forest. By contrast, other dominant oaks, such as red oak (Quercus rubra) and chestnut oak (Quercus prinus), often exhibited higher frequency in recent studies than in surveys of the original forest. The frequency of red oak witness trees before European settlement was quite low, generally under 5% in most forests. Red oak's distribution was apparently limited by a lower tolerance to fire and drought and a greater dependence on catastrophic disturbances than that of white oak. During the late 19th and early 20th centuries, much of the eastern forest was decimated by land clearing, extensive clear-cutting, catastrophic fires, chestnut blight, and then fire suppression and intensive deer browsing. These activities had the greatest negative impact on the highly valued white oak, while promoting the expansion of red oak and chestnut oak. More recently, however, recruitment of all the dominant upland oaks has been limited on all but the most xeric sites. Thus, the dynamic equilibrium in the ecology of upland oaks that existed for thousands of years has been destroyed in the few centuries following European settlement.