Pre-Colonial and Modern Tree Data from Nine Northeastern States 1620-2008

The northeastern United States is a predominately-forested region that, like
most of the eastern U.S., has undergone a 400-year history of intense logging,
land clearance for agriculture, and natural reforestation. This setting affords
the opportunity to address a major ecological question: How similar are today’s
forests to those existing prior to European colonization? Working throughout a
nine-state region spanning Maine to Pennsylvania, we assembled a comprehensive
database of archival land-survey records describing the forests at the time of
European colonization. We compared these records to modern forest inventory data
and described: (1) the magnitude and attributes of forest compositional change,
(2) the geography of change and (3) the relationships between change and
environmental factors and historical land use. We found that with few
exceptions, notably the American chestnut, the same taxa that made up the
pre-colonial forest still comprise the forest today, despite ample opportunities
for species invasion and loss. Nonetheless, there have been dramatic shifts in
the relative abundance of forest taxa. The magnitude of change is spatially
clustered at local scales (less than 125-km) but exhibits little evidence of
regional-scale gradients. Compositional change is most strongly associated with
the historical extent of agricultural clearing. Throughout the region, there has
been a broad ecological shift away from late successional taxa, such as beech
and hemlock, in favor of early- and mid-successional taxa, such as red maple and
poplar. Additionally, the modern forest composition is more homogeneous and less
coupled to local climatic controls.