We display the influence of pre-European settlement fire on vegetation across Minnesota by harnessing the power of bearing trees as indicators of past fires on the landscape. Species and genera of trees used as bearing trees in Public Land Surveys were categorized as either pyrophilic (fire-adapted) or pyrophobic (fire-sensitive) and the percentage of pyrophilic trees was calculated and interpolated to create a map showing the inferred importance of fire. Ecological units at four spatial scales (province, section, subsection, and landtype association) were examined against our pyrophilic percentage maps, irregularities noted, and line improvements suggested based on the prevailing fire setting (the set of vegetation and topographic conditions under which fires occur or are inhibited) before European settlement. Our maps and analyses for Minnesota, the Chippewa National Forest, and the Superior National Forest provide a strong ecological basis for locating areas where long-term burning left an indelible mark on plant composition, structure, and biodiversity and thus where prescribed burning for ecosystem restoration is most appropriate today.
Thomas-Van Gundy, Melissa A.; Nowacki, Gregory J. 2016. Landscape-fire relationships inferred from bearing trees in Minnesota. Gen. Tech. Rep. NRS-GTR-160. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 32 p.