Monday, February 23, 2009

Organizing the Ozarks

Following my almost-weekly announcement that I was setting out for the Current River Hills, I was asked, maybe for the first time, “so where will you actually be staying?” It dawned on me that afternoon that while I tend to define the Ozarks based on ecological land types and regions, most people give directions based on centrally located towns or landscape features. It’s just that I don’t stay in towns when I’m in the Ozarks, so I don’t know much about them. I know that the charming little town of Van Buren, for example, is in the Current River Hills; Rolla is located on the Central Plateau. Cassville is in the White River Hills.

More importantly, however, I refer to these regions in this medium without providing the reader with a map or a basic point of reference. I very seldom mention nearby towns, mainly because I don’t know where they are (except for the ones that house my canoe outfitters [Eminence: Current River Hills] or have restaurants that serve vegetarian food [West Plains: Central Plateau].) So, I’ve been remiss in my duty to serve as a guide to the region’s diverse landscapes by being genuinely bureaucratic in offering organizational references without providing proper definitions. Hopefully, this post will rectify this omission. Click on the map for a larger view.

In the mid-1990s, The Nature Conservancy embarked on an ambitious project to organize North American landscapes into ecologically-based regions. Employing geology and soil maps, watershed regions, natural communities, Natural Heritage records, and countless other defining regional characteristics, TNC organized the country into 80 ecoregions, thus providing a planning framework to accomplish their long-term conservation goals. Rather than implementing conservation strategies on areas created by political borders, TNC works assiduously to conserve areas defined by a “commonality of physical, biotic and pre-historic factors” where “natural process regimes create a region of biological cohesiveness.”

The Ozarks ecoregion comprises nearly 34 million acres in Missouri (67%), Arkansas (24%), Oklahoma (17%), Illinois (2%) and a sliver of Kansas (.1%). To the west lie the Osage Plains/Flint Hill Prairies and the Crosstimbers and Southern Tallgrass Prairie ecoregions. To the north rests the Central Tallgrass Prairie, or what tiny fragments of it remain out of agricultural production. The Interior Low Plateau includes western Kentucky and Tennesee, and the Mississippi River Alluvial Basin begins in southeast Missouri and stretches south into Louisiana.

But the Ozarks, in conjunction with the Ouachitas (pronounced “Wash-i-taws”) in Arkansas, represent the only highland between the Appalachians and the Rocky Mountains. The Ozark Highland dome has been slowly eroded and uplifted throughout geologic history, resulting in distinctly varied topography ranging from rugged Precambrian igneous knobs to low rolling mountains with imperceptible elevations up to 3,000 ft.

To fully capture the wide range of biological and geologic diversity inherent in the Ozark ecoregion, TNC distinguished 19 subsections defined by the same types of credentials employed by the ecoregional designation. They identified species tied to the natural communities of these regions and defined target species for conservation strategies. The White River Hills, for instance, are dominated by wide bands of extensive limestone glades and dry woodlands. Steep topography allows for small bands of true forest, though the region, like all of Missouri actually, is fire mediated. Trelease’s larkspur grows here, and populations of Eastern collared lizards can be found on the glades.

The Current River Hills, located around the in tact Current River watershed, encompass a large area beginning in high, gently rolling plains once populated by post oak savanna. As the river flows southward, the land steepens and becomes much dissected as it descends into the river valley. This region of the Ozarks represents some of the largest contiguous tracts of woodlands in the state, and a high level of endemism is present here.

The other 17 subsections have their own features, all distinguishing characteristics that make them worthy of conservation and protection. Glaring omissions in my travels this past year include: the Elk River Hills, once characterized by very open woodlands, now seriously degraded from an interruption of anthropogenic fire regimes; Inner and Outer Ozark Borders, mainly because big cities have replaced native vegetation in these regions; and the Missouri River Alluvial Plain, because I grew up around big, channelized muddy rivers and I prefer the clear, fast-moving waters of the Ozarks where you can see your feet nestled among chert gravels and crawfish with red-tipped pincers.


Bill said...

Thanks Allison! This will be helpful.


Allison Vaughn said...

I feel really terrible and lousy for not posting this before. It's fascinating how the Central Plateau snakes around all over the place!

Anonymous said...

My 4th grader is looking information to cite regarding how the Ozark Highlands were formed. We can seem to find anything that says "glaciers, volcanoes or earthquakes". Can you help? Thank you...I'm not smarter than a 4th grader:)

Allison Vaughn said...

The formation of the Ozarks is pretty complex and fascinating. And there's not a lot of public information about it (sadly, I don't think it's taught in Missouri schools, either. So, you shouldn't feel bad about not knowing!) I wrote about the Ozark Uplift and how it was formed back in December 2008 in a post labeled, I think, Uplifting! It's volcanic at its core, and has been eroding for millions of years. It used to be underwater, hence the limestone and dolomite formations (and all the fossils you can find on the side of the road and in creekbeds). The St. Francois Mountains were once a volcanic island in a shallow sea! Also check out the post on glacial relicts where I talk about glaciation...Hey, good luck. The Ozarks are truly magical and fascinating.