
Rare are the occasions when I find myself in an actual
forest in the Ozarks: mossy, moist, north facing slopes, ancient sinkholes, those cool places that we stumble into only occasionally. True forest is rare in the Ozarks. When we think of forests and woodlands in the Ozarks, we must think about fire, how fire moves through the landscape, where it starts and stops--for it's fire that helps shape our natural communities in Missouri.

Last week, while in the deeply dissected St. Francois Mountains, I encountered true forest only twice on my entire visit. Dry mesic igneous forests characterized by ramrod straight white oaks, ferns, mosses, moisture at the ground level exist here in small patches. If, historically, lightning struck a large oak on one of the broad ridges in the St. Francois Mountains (though lightning fires were less common in Missouri as they were in Arkansas), imagine that fire creeping downhill, moving slowly through the oak leaf litter, through the black oak leaves, shrubby oaks and rank forbs. At some point in that fire's life, it will extinguish on its own. Sometimes it would travel downslope until it reached Big Creek, but giant cane grows along the shoreline of Big Creek; giant cane is a seriously flammable grass that pops and crackles when it meets fire. But when that fire meets a forest, it may trickle through, chew up some leaves, but eventually go out-die-extinguish in a whimper. Fire does not pick up steam in a forest.

In parts of the St. Francois Mountains, dry mesic igneous forest exists in a small patch matrix of moist igneous cliffs, igneous talus, and, on the upper reaches, dry mesic igneous woodland. But the distinction between woodland and forest is evident to anyone who knows fire well enough, if you understand how fire moves through a landscape. Would fire race through that north slope that hardly sees the light of day and, therefore, has no drying time between rain events? Would fire travel over the thick bed of wet moss and ferns where leaf litter is negligible because of the area's natural ability to decompose even tough oak leaves in a matter of weeks?
Having spent ample, ample time in Ozark woodlands, I rely on my senses to help me determine which natural community I'm in: in short, I know forest when I see it. But since I can't go into the St. Francois Mountains with each of you to show you those diagnostic characteristics, I'll copy the definition of dry mesic igneous forest from Paul Nelson's landmark publication,
The Terrestrial Natural Communities of Missouri:
This natural community typically has three distinct strata: canopy (65-85 ft.), understory (5-15 ft.), and ground flora (0-3 ft.). The generally closed canopy (90-100% closure) has moderate to optimum growth with tall clear trunks. The understory is thick, consisting of generally well developed shade tolerant trees. The ground cover contains mixes shade-adapted forbs and grasses....It is best developed on north or east facing slopes. Soils are shallow to moderately deep silt loams, well drained, and very strongly acid to moderately acid...These soils formed over and from the underlying Precambrian-age rocks of the St. Francois Mountains.
Now, just using Paul's description of a dry mesic igneous forest as a guide, you may fall into the same trap I have, that of considering unburned woodlands as forest. You see, there's very little fire in the St. Francois Mountains these days, at least compared to the flammable Niangua Basin, so some areas that merely haven't seen fire in twenty years could have dogwoods, pawpaws, little forest-dwelling plants. Apply a little fire to the area and the fire-intolerant understory plants will die. Again, think of how fire moves through a landscape: would forest exist on a dry ridgetop or on a dry south facing slope? Most likely not. In the Ozarks, fire dictates the natural community type.
So, this is a woodland, not a true forest:

This, too, is not a forest, but a dry-mesic woodland:

Think like a fire when trying to classify your natural communities--where would fire move on the landscape? Where would it extinguish on its own? Forest is not very common in the Ozarks, but where it exists, it's a splendid world of weeping mosses and ferns, big boulders of lichens and mesic soils that stick to your boots.