PARENT SESSION
Contributed Oral Session 1: Landscape History
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 513 A, Level 5, Palais des congrès de Montréal
The presettlement vegetation of the northeastern United States at various scales.
Cogbill, Charles1, 1 Sterling College, Craftsbury Common, VT
ABSTRACT- Colonial town land surveys provide a heretofore unappreciated empirical reconstruction of the pre-European landscape in the northeastern United States. This study collates over 200,000 witness tree tallies from 690 town-wide lotting surveys from Pennsylvania to New England. The samples are analyzed by spatial mapping, integrated as interpolated trend surfaces, and classified with cluster analysis into a hierarchy of vegetation units. Unbiased town-wide samples average abundance over multiple forest types, but are an ideal scale to reflect integrated proportions of taxa in a landscape. The sample of towns is dense enough to display fine-scale patterns of local vegetation composition, yet extensive enough to display the broad-scale continuum of vegetation formations across the Northeast. The tree genera distributions at various spatial scales are remarkably detailed and arguably more informative than any current range maps. The vegetation units are more realistic than available maps of theoretical natural or potential vegetation. This reconstruction of presettlement vegetation redraws the original vegetation map and resets many preconceptions about the original forest (e.g. overestimation of pine, hemlock, and chestnut and the underestimation of beech and spruce abundance). Significantly, there was a distinct ecotone separating northern and central hardwood forests winding across the Northeast. Apparently this tension zone extended westward to the Midwest and has been spatially relatively insensitive to climate and land use changes over the past 200 years. These historic (ca. 18th century AD) patterns are the most appropriate baseline for both present and future changes induced by pervasive human land use or environmental transformations.
Key words: historical ecology, tree biogeography, land survey, tension zone