<b looked pretty different circa 1800. To the west of the Cannon River, dense forest, the “Big Woods,” stretched for miles while open prairie and oak savanna dominated the landscape to the east. These neighboring ecosystems supported radically different plant and animal life. The Big Woods were full of hardwoods while the prairie was home to species such as big bluestem grass and prairie chickens.
At first glance, the coexistence of these ecosystems seems illogical. Their soil was the same and rainfall was similar… Why weren’t they identical systems? The answer is beautifully simple: fire. Prevailing southern winds pushed fires north and west. This maintained the open prairies to the east of the Cannon River. The river acted as a firebreak protecting the forest on its western banks. Fire has been an integral part of Minnesota’s ecosystems for millennia. It maintains prairie ecosystems by eliminating brush and small trees. This process also recycles nutrients and removes old growth to make space for new plant life. Prairie plants have evolved under the influence of fire. Native prairie plants will re-sprout after being burned while those sensitive to fire, such as many Big Woods species, will end up charred.
Many Great Plains Native Americans used fire to clear land for easier travel and to manage game. When Europeans arrived in Minnesota in the 1800s, they dramatically decreased the number and impact of fires. European settlers actively put out fires, their plowed agricultural fields acted as firebreaks, and they drove many Native Americans farther west. By 1850, the area that would become the Arb had changed dramatically. As fires became more rare, forests started encroaching upon the prairies. Though many factors, such as agriculture, have contributed to altering our landscape, fire, and the lack thereof, has played a substantial role. Today, the Cannon River no longer has different ecosystems on its two banks.