Forest
Associations and Soil Drainage Classes in Presettlement
Baraga County,
Michigan
Randall J. Schaetzl and Daniel G. Brown
General Land Office (GLO) Survey
notes for Baraga County, Michigan were analysed to determine the composition of
forest associations present circa 1850, sorted out by natural soil drainage
classes. Our study illustrates the
significant effect that soil drainage and wetness have on forest composition,
and provides data on various tree species importance on different classes of
soil drainage.
Our tree data came from witness
trees identified by GLO surveyors. Tree
locations were plotted and overlain onto a modern soil map using a geographic
information system. Each soil mapping
unit was placed into one of seven natural soil drainage classes, and tree data
tallied by drainage class.
Additionally, we identified spatially-contiguous species groupings from
the GLO tree map by developing lists of trees (relative density only) for
randomly placed circular plots within the county. The random plot data were examined using ordination and
classification methods.
Pines, especially jack pine, dominated the very driest sites in the county which had experienced widespread fire. Sugar maple and other shade-tolerant species (primarily hemlock and yellow birch) forested the mesic and slightly wetter sites. Hemlock dominated sites that were either slightly drier or slightly wetter than mesic; these sites still retained sugar maple and yellow birch as common associates. On the wettest sites black spruce was the dominant species; white cedar and tamarack were subdominants. On no soil was white pine the principal species, but it was present on most soil drainage classes. Because many soils were dominated by shade-tolerant climax species, evidence for widespread, nonfire-related disturbance in Baraga County in the early 1800s is lacking. The cluster analysis of random plot data illustrated that this method can produce classes or groupings that are comparable to the natural soil drainage-based classes.