Distribution and Dynamics of American Beech in Coastal Southern New England

Fagus grandifolia (American Beech) is uncommon along the coast of southern New England, but occasionally forms unusual monodominant stands with higher beech abundance than is typical for inland areas. This study documents the distribution of beech on Cape Cod and nearby coastal islands, and evaluates environmental and historical factors that are likely to influence its distribution. Tree-ring data from six beech forests in the study region were used to determine age structure and to assess the importance of disturbance history for beech forest development. Beech is irregularly distributed across the coastal region. It is most common and abundant on moraines and in areas that are close to water bodies, presumably as a result of reduced drought stress and increased protection from wildfire. The largest monodominant beech forest (approximately 1000 ha) known from the eastern US occurs on Naushon Island, but few stands elsewhere in the region exceed 5 ha. In the six intensively studied forests, the relative importance of beech has increased in recent decades. Decreased establishment of oaks and other associated species in the 20th century has presumably resulted from regional declines in forest harvesting and fire. Increased beech dominance in the 20th century corresponds with episodic beech establishment and growth release after several hurricanes in the 1920s–1950s. Thus, unlike the small-scale gap dynamics characteristic of beech in the extensive northern hardwood forests of northern New England and New York, large-scale wind disturbances apparently contribute to local beech dominance in coastal New England where beech is otherwise uncommon.