Settlement-Era Gridded Tree Composition, Northeastern US: Level 2

This is a data product of the estimated composition of tree taxa
at the time of European and Euro-American settlement of the
northeastern United States. Composition is defined as the proportion
of stems larger than approximately 20 cm diameter at breast height
in 22 taxonomic groupings, generally at the genus level. The data
come from settlement survey records that provide raw data that are
transcribed and then aggregated spatially, giving count data. The
domain is divided into two regions, eastern (Maine to Ohio) and
western (Indiana to Minnesota). Public Land Survey point data in the
western region are aggregated to a regular 8 km grid, while data in
the eastern region, from Town Proprietor Surveys, are aggregated at
the township level in irregularly-shaped local administrative units.
The product is based on a Bayesian statistical model fit to the count
data that estimates composition on a regular 8 km grid. The
statistical model allows us to estimate composition at locations
with no data and to smooth over noise caused by limited counts in
locations with data. Critically, it also allows us to quantify
uncertainty in our composition estimates. We expect this data product
to be useful for understanding the state of vegetation in the
northeastern United States prior to large-scale European settlement.
In addition to specific regional questions, the data product can also
serve as a baseline against which to investigate how forests and
ecosystems change after intensive settlement. This material is based upon
work supported by the National Science Foundation under grants #DEB-1241874,
1241868, 1241870, 1241851, 1241891, 1241846, 1241856, 1241930.