OUTDOOR CORNER: DEFINING A NATURAL COMMUNITY

Missouri has 89 types of natural communities within its natural divisions.

A month ago, you may have read my column about Missouri's natural divisions, geographic regions defined by geology, and plant and animal populations. Natural divisions (e.i., Crowley's Ridge, St. Francois Mtns.) cover large areas and within each the landscape varies a lot. This month I will write about a system used to describe and sort the variation within a natural division. This system is called natural community classification.'

A natural community is a set of plants and animals growing and living in a particular place. This set of plants and animals should be distinguishable from other natural communities and will be seen repeated in similar settings across the landscape. In Missouri, we recognize 89 types of natural communities. Approximately 40 occur in Southeast Missouri.

One of the first steps in classifying a natural community is to look at the common plants. Do you see mostly trees and shrubs, or do you see mostly grasses? When you look at an area and call it forest or prairie you are classifying these communities. Some of the broad descriptions of communities found in Southeast Missouri are forest, savanna, glade, prairie and wetland. Forests are dominated by trees. Savannas feature scattered trees and a prairie-like groundcover. Glades and prairies have mostly grasses and wildflowers. Glades are open, rocky hillsides. You can see glades at Johnson's Shut-Ins State Park. Wetlands can have mostly trees (like a swamp), or mostly herbaceous plants (like a marsh).

The second step to describing a natural community is to look at the soil and rock present. Some areas have deep soil, and others have rock near or at the surface of the ground. This in turn will affect the plants and animals living there. Beech trees have to have deep soil to grow in, cactus and columbine can grow right on the rocks. Collared lizards need rocks to hide under and on which to sun themselves; moles need deep soil to burrow into.

In Southeast Missouri, you will find sandstone, granite, chert, limestone and dolomite bedrock. Sandstone, granite and chert make soil and growing conditions acidic. Limestone and dolomite make soil and growing conditions basic. While some plants can grow on both, many plants grow better in one condition or the other. Blueberries and azaleas for example tend to grow well in acid soils.

The third step to describing a natural community is to look at how much water is available. A wetland will have lots of water (often standing water) for all or a large part of the year. You can see this condition at Mingo National Wildlife Refuge. Other communities have more or less water available, but the differences are not as obvious. Areas high on a slope tend to be drier than areas low on a slope. Slopes facing west and south tend to be drier than north and east slopes. Forest types can range from xeric (very dry), dry, mesic (moist), to wet, and can even be described with gradations in between (dry-mesic, wet-mesic). The most common forest type in the Ozarks is dry-mesic and dry forest.

Using these three factors of a natural community, we can now put a name to a community type. Hawn State Park is located on sandstone, thus making the soil acidic. There are both dry and mesic conditions there and forest, savanna and glades are found there. So the natural communities present can be described as dry sandstone forest, mesic sandstone forest, sandstone savanna and sandstone glade.

Some of the plants you will find in the dry sandstone forest are shortleaf pine, black oak and farkleberry (a tall blueberry). In the sandstone savanna, you will have some of the same trees, but also blackjack oak, little bluestem and several native lespedezas. On the glade you find little bluestem, blazing star and mosses. Of course if you go to Hawn State Park, these natural communities will not have clear outlines. Instead they blend into each other and form a larger ecosystem' of forest, savanna and glade.

Another example is at Trail of Tears State Park. Much of the park has mesic forests with deep soil. Red oak, white oak and pawpaw grow there, as well as beech and tulip poplar. Another good example of a natural community is found at Big Oak Tree State Park. This park, in the Mississippi Lowlands, has two examples of bottomland forest. The terrain is fairly level and many areas are very wet. In the wet-mesic bottomland forest there, you will see overcup oak, basket oak, and big shellbark hickory. The wet bottomland forest has bald cypress, swamp red maple, and water oak. The mole salamander also lives here.

Each of these examples shows a very different natural community with very different plant life growing there. Each place has animals living in it that are adapted to that natural community. They represent some of the diversity found in Southeast Missouri and the heritage of natural resources in our region.

Written descriptions of these communities are much less rich than their actual diversity -- most natural communities support 100 or more different plant species and dozens of characteristic animals (not even including the insects!). Being out in a natural community provides a living laboratory for study, a living museum.

It is important not only to describe these communities, but to preserve examples of each one. Otherwise, valuable pieces of our natural heritage will be lost and future generations will not have the opportunity to experience and enjoy the diversity and beauty they contain.

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