RELATIONSHIPS BETWEEN SOILS AND PRESETTLEMENT FORESTS IN BARAGA COUNTY, MICHIGAN

Soils data and data on the presettlement forests of Baraga County, tak en from the General Land Office (GLO) Survey, were stored and analyzed in a geographic information system (GIS). The purpose of the research was to determine county-wide witness tree distributions and autecolog ical relationships among 14 major tree species and soil wetness and te xture, in this geologically and edaphically diverse region of northern Michigan. In all, 12,760 trees were coded by species, location and di ameter from the GLO data, which were recorded between 1846 and 1853. T ree data were overlain on soil mapping units which were coded by natur al drainage class and particle-size family. All trees located in mappi ng unit complexes (two or more soil types) or within 25 m of certain s oil boundaries were eliminated from further consideration through a se lection/buffering procedure leaving 6210 trees of 14 species for use i n the analysis. Contingency tables were calculated to assess the stren gth and direction of the relationships between each tree species and s oil texture, soil wetness and texture/wetness combinations. County-wid e distributions of species were strongly related to soil patterns, wit h a prominent forest ecotone occurring near the boundary between two d istinct till provinces. Most upland forests were dominated by sugar ma ple and yellow birch; prevalent lowland species included balsam fir, b lack spruce and white cedar. Hemlock was common only near Lake Superio r on sandy tills that lacked a silt cap. Especially notable was the as sociation between a nearly pure stand of jack pine and the dry sandy s oils of the Baraga (glacial outwash) Plains. Evidence for widespread d isturbance by wildfires on the level plains contrasts with the relativ ely long period of only small gap-scale disturbances that existed on m ore rolling, mesic and wet sites.