Abstract
Prior to European settlement vast areas of the eastern U. S. deciduous forest were dominated by oak species. Evidence indicates that periodic understory fire was an important ecological factor in the historical development of oak forests. During European settlement of the late 19th and early 20th century, much of the Eastern United States was impacted by land clearing, extensive timber harvesting, severe fires, the chestnut blight, and then fire suppression and intensive deer browsing. These activities had the greatest negative impact on the once dominant white oak, while temporarily promoting the expansion of other oaks such as red oak and chestnut oak. More recently, recruitment of all the dominant upland oaks waned on all but the most xeric sites. Mixed-mesophytic and later successional hardwood species such as red maple, sugar maple, black birch, beech, black gum and black cherry are aggressively replacing oak. At Fort Indiantown Gap in southeast Pennsylvania, periodic burning over the last 50 years resulted in sites with lower tree density and a higher proportion of overstory oak species than unburned stands. Oak saplings averaged 875 per ha in burned forests and 31 per ha in unburned forests. Red maple had overstory importance of 7 percent and 24 percent in burned and unburned stands, respectively. The leaf litter of many oak replacement species (e.g., red maple, sugar maple, black birch, beech, black gum and black cherry) is less flammable and more rapidly mineralized than that of the upland oaks, reinforcing the lack of fire. The trend toward increases in non-oak tree species will continue in fire-suppressed forests, rendering them less combustible for forest managers who wish to restore natural fires regimes. Moreover, many of the oak replacement species are now growing too large, both above and below ground, to readily kill with understory fire. This situation greatly differs from the western United States, where fire suppression during the 20th century has made a variety of conifer-dominated forests more prone to stand-replacing fire. Thus, forest supervisors in the East who wish to use fire as a management tool in oak forests need to act sooner rather than later.
Parent Publication
Keywords
historical ecology,
disturbance,
succession,
fire suppression,
oak replacement
Citation
Abrams, Marc D. 2006. Ecological and ecophysiological attributes and responses to fire in eastern oak forests. In: Dickinson, Matthew B., ed. 2006. Fire in eastern oak forests: delivering science to land managers, proceedings of a conference; 2005 November 15-17; Columbus, OH. Gen. Tech. Rep. NRS-P-1. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 74-89.
