Additional Cautions on the Use of the Glo Survey Records in Vegetational Reconstructions in the Midwest

Data from the United States General Land Office Surveys are frequently used to reconstruct the vegetation existing at the time of European settlement as a basis for biotic models. The vegetation recorded in those surveys had been influenced not only by climatic conditions considerably colder and more moist than the present, but by frequent, widespread burning as well. The effect of such burning on the distribution and composition of forest vegetation was as great as the climatic effects and must be taken into account when building prehistoric vegetational models in the Midwest.

Vegetational Reconstruction and Climatic Episodes

Data from United States General Land Office Surveys are commonly used to create vegetation models for the American Pioneer period. These models are then used as baselines for understanding past biotic change. It should be realized that many of these surveys were made near the end of a climatic episode (the Neo-Boreal or "Little Ice Age") when world temperatures were much lower than at the present time. These baselines therefore do not represent vegetational responses to a climatic regime like that of the present, and the vegetation models must be interpreted accordingly.