Fire and the development of oak forests

Author: Abrams, M. 

Source: BioScience Vol. 42, No. 5, May 1992

This review article summarizes research on oak dominated forests both before and immediately after European settlement in eastern North America. The author examines the effects of fire and human activity on eastern forests by exploring conditions that facilitated or perpetuated oak dominance. The goal of this review was to gain insight into current and future conditions and their potential affects on oak forests.

Abrams discusses paleoecological studies that show oak domination of eastern forests starting around 12,000 years ago during warmer, drier periods that may have increased the incidence of fire. Most upland oaks show phsyiological adaptations (thick bark, sprouting ability, resistance to rotting, and acorn generation for fire-created seedbeds) that allow them to survive on nutrient-poor sites with periodic fire and drought. Periodic fire also suppresses the growth of most later successional species such as maples. Native American burning practices and other disturbances may have increased oak dominance, but Abrams also discusses the expansion of oaks into the tallgrass prairie region, northern hardwood forests, mixed-oak forests of the mid-Atlantic region, southeastern coastal plain and Piedmont forests that took place after European settlement.

Abrams concludes that oaks in the eastern region are being successionally replaced by other species, despite observations of a substantial amount of oak seedlings. In areas where fire was excluded during the 20th century, oak dominance has been lost. The inverse was also seen. Forests that burned periodically maintained oak dominance. Abrams uses this as indirect evidence that fire played a vital role in maintaining oak dominance before European settlement.

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