U.S. Joint Fire Science Program


Date of this Version


Document Type



Fire Science Brief, Issue 33, January 2009


US government work.


The Great Lakes region is characterized by diverse ecosystems born of significant glacial activity, a substantial and growing population density characteristic of the east, and until recently, some confusion about how historic and modern fire regimes of the area fit together. Dave Cleland and colleagues used extensive data sources including General Land Offi ce (GLO) Survey data and modern literature to create models and maps that explain how the fire regimes associated with landscape ecosystems have changed from a pre-European era to modern times. They found that historic rotations of forest fires ranged from only a few decades to more than a millennium, while modern day fire rotations are an order of magnitude longer for each landscape type. Interestingly, landscapes that were once the most fire resistant remain so, while those that were once more fire prone are still most vulnerable to fire even though the rotation intervals are far longer. Human activity explains the great change in fire rotation length, and has important implications for managers and planners. Maps showing historical fire regimes in the 60-million acre area offer information on fire risk, as well as vegetation, habitat, soils, and more. Cleland says that because the research relied on the detailed historic GLO data, it turned out to be the “best data set” he had ever worked with.