Session Information
| Session | Poster Session | | Date | Monday (2008-04-07) | | Time | 5:00 PM - 7:00 PM | | Room | Grand Terrace |
Presentation Information
| Presenter | Kimberley Brosofske | | Title | Composition and diameter differences between line and corner trees in the General Land Office (GLO) Survey data for northern Michigan, USA | | Affiliation | Michigan Technological University | | Authors | Kimberley Brosofske, David Cleland, Sari Saunders, Ann Maclean | | Keywords | GLO survey, Historic forest landscape, Historic forest reconstruction, Michigan, Witness trees | | Presentation Type | Poster | Abstract:
The original General Land Office Public Land Survey records represent a unique and widely-used source of information about the early settlement landscapes of the United States, but instructions to surveyors at the time likely resulted in biases in species selection and diameter of witness trees recorded at section and quarter-section corners (“corner trees”). Trees recorded along section lines (“line trees”) were under fewer explicit restrictions and probably contain less bias. We quantified species and diameter differences between corner and line trees in northern Michigan to identify potential bias in the corner trees that could affect reconstructions of historic forest composition or structure. We performed chi-square tests on contingency tables to test for compositional differences and used the Wilcoxon test to identify diameter differences. We conducted analyses within the overall study area, regional subsets (the Upper Peninsula [UP] and the northern part of the Lower Peninsula [NLM]), and biophysical unit subsets. We found differences (p<0.05) in species composition between line and corner trees for nearly all analysis units. Generally, the corner trees contained a greater proportion of American beech and sometimes white oak, northern white cedar, and tamarack, and a lower proportion of conifers (balsam fir, hemlock, pines) and sugar maple. Differences were greatest where beech was a common species, such as in NLM and the more mesic biophysical units. Where differences were found, corner tree diameters were generally smaller than those of line trees, although some of the upland conifers had larger corner trees. Both species composition and diameter were ecosystem-dependent. Corner trees of dominant species tended to be larger than line trees in the xeric, highly disturbed biophysical units and smaller than line trees in the more mesic, infrequently disturbed biophysical units, suggesting bias in corner trees was related to disturbance regime. Because preferences for certain species and diameters were obvious in the corner trees, we suggest that line trees, where available, may be a more accurate data source for information on historic forest landscapes. |
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