OUTDOOR CORNER: MISSOURI'S CHANGING LANDSCAPE

If you traveled across the state of Missouri from Cape Girardeau to the northwest corner, you would see a number of different landscapes. The hills, rivers and plants would change from one area to another. You would see different animals and different rock exposures along your route.

Missouri has a diversity of landforms and these have been described as natural divisions of Missouri. Basically, they outline regions of the state that have a common geology, soil type, topography, and plant and animal populations throughout.

Six natural divisions were defined for the state: Glaciated Plains, Osage Plains, Big Rivers, Ozark Border, Ozark, and Mississippi Lowlands.

The divisions are further divided into sections based again on geology, soils, topography, plants, and animals. Natural Divisions and their sections are useful for understanding the ecology of our state and also to make informed resource management decisions.

Four of the six natural divisions can be found in Southeast Missouri, and as one could expect, this region is exceptionally rich in landscape diversity. Big Rivers, Ozark Border, Ozark, and Mississippi Lowlands Divisions are all found in Southeast Missouri. Below are descriptions of each.

The Mississippi Lowlands is the portion of Missouri often referred to as the "Bootheel." A drop in elevation and a broadening of the Mississippi River floodplain characterize the Bootheel. In Missouri, the Lowlands are almost completely in agricultural production. Previous to extensive clearing and draining (which began in the early 1900's), the Lowlands were covered with forest.

The vegetation would have been similar to the floodplain forests which remain along the Mississippi River in Mississippi and Louisiana. The Crowley's Ridge section of the Mississippi River represents a series of hills strung to the southwest through the Lowlands. Historically these hills were forested, but are now a mixture of forest and field. Small, clear-flowing streams are formed from springs which emerge throughout the hills.

The Lower Mississippi section of the Big Rivers division forms a narrow strip of land along the Mississippi River from St. Louis to the Arkansas border. The Mississippi River has been subjected to significant alterations including channelization and construction of levees.

Channelization deepens the main channel. The levees prevent the river from spreading into broad floodplain forests as it would have historically. This greatly limits the amount of fish spawning habitat along the Mississippi. One of the last remaining floodplain spawning areas along the entire Mississippi River is in the New Madrid Floodway.

The Mississippi River section of the Ozark Border division consists of the steep rugged hills and occasional rolling plains between the Ozarks and the Mississippi River. This section can have deep, productive soils or thin soils. The deep soils are composed of "loess". Loess is a thick layer of silt that was blown up onto the hills during glacial times.

The Ozark division has a hilly topography. A long time ago, this area was all a level plain. The hills were formed as rivers carved through the limestone, dolomite, and sandstone formations in this region.

Most of the Ozark division has thin soils and is very rocky. Historic vegetation was pine and oak-pine forest, as well as glades, woodland, and savanna. In the Lower Ozark section, short-leaf pine and scarlet oak dominate the forests. The rivers here flow mainly to the south and include the St. Francis and Black Rivers.

Smallmouth bass are found naturally in Ozark streams but as these rivers flow into the Lowlands, a population shift to largemouth bass occurs. The St. Francois Mountains section is different from the rest of the Ozarks in that the substrate is igneous (volcanic) rock instead of the limestone and dolomite prominent in the rest of the natural division. The highest point in Missouri is in this section and the elevation can change dramatically (as much as 1000 feet) between a peak and its valley floor.

We are fortunate to have such a diversity of landscapes in Southeast Missouri. An understanding of this diversity can lead to an appreciation for its value. For the next several months I will be writing a series of articles which focus on landscape diversity. I will highlight specific areas of interest and discuss some of our Department's efforts in conserving natural diversity.

-- Janeen Laatsch is a natural history regional biologist with the Missouri Department of Conservation.