Biogeography of Missouri

The oldest known geological information in Missouri is that glaciers formed the general landscape. It is more well-known though that early human inhabitants shaped the land, most notably by their use of fire to clear forest. This use of fire greatly impacted the flora and fauna that inhabit the forests of Missouri today. Species that could not survive the fires were wiped out or greatly diminished, while species that could survive fire or even depended on fire thrived and are in abundance today. Such species that relied on fire are large nut bearing trees like oak. Fires also contributed to flood plain formation as erosion due to a lack of vegetation after fires made water levels surge in rivers and streams. Also this impacted the groundwater aquifers and soil quality as the water that ran off into rivers did not percolate into the ground loosening soil and recharging aquifers (Nelson).

It is shown that data indicates fire frequency was high during pre-European settlement times and dropped as more European contact occurred. Fire frequency was also high when Osage Indians inhabited the land and dropped when they left. This lowering of fire frequency led to an establishment of dense canopy forests that changed the ecosystem below them. Due to the canopy the sunlight levels changed and whole prairie ecosystems gave in to dense forests (Nelson).

European settlement brought with it large-scale logging, commercial farming, livestock overgrazing, and fire suppression all of which drastically altered the landscape in ways mentioned above. The loss of vegetation because of fires, logging, and overgrazing led to run-off and higher water levels as well as drier soil and smaller aquifers (Nelson).

Natural occurrences such as fire, tornadoes, lighting, hail, ice, and earthquakes also altered the land. Most of these events cleared and destroyed large tracts of forest. Earthquakes formed hills and valleys as they raised or lowered land. Natural occurrences at a catastrophic level resulted in entire forests being decimated leading to secondary succession (Nelson).

Due to the states location, it is subject to large fluctuations in precipitation and temperature. Cold, hot, humid, and dry forces colliding from different directions produce a large variety of weather. The state experiences the full four seasons in all parts (Nelson).

Rivers in prairie ecosystems naturally meandered and winded through the land. This resulted in a constant recharging of groundwater. Due to the human construction of straighter waterways, this groundwater recharging stopped occurring at its natural rate. This resulted in drier soil and smaller aquifers but most importantly more intense flooding because water was not dispersed but instead concentrated and fast moving (Nelson).

Habitat destruction because of fires, flooding, etc. reduced numbers of top predatory species like wolves, black bears, and mountain lions. Also bison were affected by this and reduced in number (Nelson).