Bioclimatic, soil, terrain, distance to Native American settlement, and historical tree taxon relative abundance data at 8-km resolution for the northeastern United States

Researchers have debated impacts of past Native American land use on
forests including upon tree species composition in northeastern United
States (US), with estimates of impacts ranging from local to regional
extent. This study examines tree relative abundances in
the northeastern US (approx. 420,000 km2) to
assess whether Native Americans influenced geographic distributions of 18
tree taxa prior to Euro-American settlement. We used boosted
regression trees to model abundance patterns and to assess the importance
of distance-based proxies of Native American land use versus environmental
variables. We trained models that included and excluded distance-based
proxies. Abundance estimates from original land survey records (1650-1850
CE) were acquired for taxa at 8 km spatial resolution, and related to
Native American settlement locations (1500-1800 CE) and 27 environmental
variables. When evaluated upon test data, regional-scale models
of relative abundance that included distance-based proxies performed only
slightly better than models that excluded them, with mean improvements in
RMSE of 0.1 percentage points. Models suggest that Native American land
use modestly altered the relative abundance of taxa locally, extending no
more than 50 km from settlement. Models also suggest slight increases near
settlement of a few percentage points in relative abundance for
fire-tolerant and/or dietary taxa (e.g. oak, hickory, and pine), and for
early-successional taxa (e.g. ash). Past Native American
land use had no detectable effect on forest composition across a regional
extent, but increased the abundance of fire-tolerant, shade-intolerant,
and nut-producing trees locally. The Excel-format (.xlsx) dataset here
provides the training and testing data for the BRT models in this
publication. It contains relative abundances of the 18 tree taxa expressed
as a fraction of total number of trees. It also provides bioclimatic (e.g.
annual temperature, annual preciptation), soil (e.g. pH, percent sand),
terrain (e.g. slope), and Native American (e.g. distance to settlement)
variables developed from multiple sources. A column also indicates whether
an observation was part of the training data or the test data. See the
publication and its Supporting Information for full details on the
acquisition and processing of these data, as well as the original
providers of the data. If using these data, please cite both this
dataset's corresponding article, as well as the original providers of
the data. Also provided are ascii-format (.asc) gridded data layers that
were used for making spatial predictions of taxon relative abundances from
BRT models. The original creators/providers of the relative abundance,
bioclimatic, soil, terrain, and Native American data or layers used for
creating the gridded data in this study are: Abel, T. (2016). The
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Historic Contact: Indian People and Colonists in Today’s Northeastern
United States in the Sixteenth through Eighteenth Centuries. University of
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Postcolumbian Iroquois satellite communities and processes of indigenous
autonomy. American Anthropologist, 115(1), 29–43. Milner, G. R., &
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