The Mosaic of an Ozark Forest

“Three hundred ninety-five feet south,” says Susan Farrington as she glances at her GPS device and hikes downhill through a 13-year-old clear-cut portion of southeast Missouri Ozark forest. She pushes away brown, dying blackberry bushes and grapevines and passes under thin, regenerating 20- to 30-foot-tall oak and hickory trees. “You should’ve seen this area a few years ago,” she says over her shoulder.

Back then a dense tangle of vegetation made traveling difficult, but now it’s shriveling away as the developing forest canopy shades out the early succession plants, revealing a familiar forest-floor assemblage. Farrington glides through the developing saplings’ trunks and over scattered woodland detritus and thin soil to reach the goal: a 1-square-meter ground flora study plot marked by stakes abutting a black hickory tree.

This square-meter plot, or quadrat, is one of the 16 quadrats at vegetation plot 70 on site 3 of the Missouri Ozark Forest Ecosystem Project, known as MOFEP. It helped Farrington to determine that clear-cuts may actually be good for ground flora diversity, at least in the short term. With abundant light reaching the ground after a clear-cut, open woodland plants reemerge.

During the summer of 2009, Farrington, a Missouri Department of Conservation resource scientist, led a crew that catalogued more than 500 species of plants in the 16 quadrats associated with each of the 648 vegetation plots scattered throughout the project’s 9,200-acre study area. MOFEP crews also inventoried trees, mammals, hard and soft mast (acorns, seeds, nuts, berries, fruit), birds, insects, amphibians and reptiles, carbon flux and more. Someone, if the project persists, will kneel to inventory the plants at the same quadrat of site 3’s plot 70, along with all the other plots’ quadrats, 80 years from now.

MOFEP asks two simple, yet ambitious questions: What effect do different timber harvesting techniques have on elements of a forest ecosystem at a landscape scale? And how do forest ecosystems change?

Creating The Experiment

The project has a roundabout beginning. Twenty years ago (1989) at an MDC meeting on brown-headed cowbird parasitism of Neotropical migrant birds’ nests in Ozark forests, the question arose: Do clear-cut harvests in extensive, mature forests, like those found in the Ozarks, increase cowbird parasitism? (Cowbirds lay their eggs in other birds’ nests, forcing the foster parents to raise them at the expense of their own young, hence “parasitism.”) Steve Sheriff, a biometrician with MDC who helped design the MOFEP experiment, remembers the group had a quick “Aha!” moment. They decided to conduct a traditional experiment to determine, beyond mere correlation, just what effect forest fragmentation had on cowbird parasitism.

“Everybody sat there kind of stunned,” remembers Sheriff, and for good reason. An experiment is much more complicated than a study, yet it offers well-built, stronger insights. As the group warmed to it, ideas flew out, and it was decided that the experiment should include amphibians, reptiles, deer, turkey, butterflies and soft mast production. In a snap, the Neotropical songbird spark had roared into an ecosystem-wide fire. Over the next year, the group developed the study’s focus and found suitable MDC land in Carter, Reynolds and Shannon counties to host the project.

The Setting

Nine sites of about 1,000 acres each, in close proximity to one another, were chosen for the experiment. Each site was mostly forested, with minimal edge or disturbance, and mostly free from any harvest or other management activities for at least 40 years. The nine sites are grouped into three blocks, and within each block, one site receives even-aged forest management, another receives uneven-aged forest management and the third is no-harvest forest management. Even-aged forest management uses clear cutting, which removes an entire stand of trees, to regenerate the forest. Uneven-aged forest management removes single scattered trees or small groups of trees to regenerate the forest and no-harvest forest management serves as a control for the experiment. Because timber forests in the Ozarks are managed in 100-year cycles, or rotations, roughly the lifespan of many of the species in current oak-hickory forests, MOFEP is designed to continue for at least 100 years, but there’s hope that it will extend to 200 or 300.

For several years before the first round of harvests in 1996, MOFEP researchers collected voluminous baseline site data that ranged from soil type to landscape structure to ecological history to flora and fauna composition, all to be used as a background with which to compare the post-harvest data. As one MOFEP researcher wrote, the pre-treatment study “is the largest summary of Ozark forest conditions ever assembled.”

Big Design, Big Challenges

With its broad design, MOFEP operates with the understanding that overall complexity, founded on biological diversity, leads to sustainability. To really understand the effects of a particular timber harvest method on even just one bird species, the effects have to be understood, as well, on the trees the bird lives in, on the insects the bird eats, the plants those insects eat, the soil those plants thrive in, the bacteria and microorganisms that maintain that soil, and the landscape in which all of this is nestled.

The MOFEP experiment, therefore, seeks to integrate multiple aspects of an Ozark forest ecosystem, including biotic (living) and abiotic (nonliving) components, in as many as 30 independent studies that are integrated together in one research design. MOFEP focuses on these pieces from a landscape perspective; changes will be analyzed as they occur throughout a 1,000-acre site, not just where a harvest occurs. By measuring site-wide data for each harvest treatment and then comparing it with the data from the no-harvest sites, researchers can deduce the effects timber harvests have on the forest ecosystem and its parts.

Each block of three sites makes up its own experimental unit and thus presents an opportunity for comparing each of the three units’ individual results. The experiment is set up as an adaptive one, as insights emerge through the life of the experiment, resource managers can adjust management practices and methods can change, such as harvest frequency, survey methods or even research focus.

MOFEP places a magnifying glass over this generation’s use of the forest, which also reflects that of the last generation. Data from MOFEP show that even without timber harvests, Ozark forests are changing.

The MOFEP sites, like most of the Missouri Ozarks, are second-growth forests, a repercussion of the area’s turn-of-the-20th-century vast timber harvests, in which first shortleaf pine, and then oaks and hickories, were heavily cut. Because the forest essentially re-sprouted from this early 20th-century clear-cut, most of MOFEP’s mature trees were 60 to 80 years old at the project’s inception in 1989. Faster-growing red oak group species like black oak and scarlet oak (24 and 21 percent of all trees on MOFEP land, respectively) now dominate the forest, and, in accordance with typical 100-year lifespans of the red oak group, are nearing maturity. Among younger trees, however, white oak trees dominate the forest (currently 21 percent of all trees in MOFEP). White oak trees number nearly twice that of black and scarlet oak, because they grow better in shade.

The disappearance of trees in the red oak group could affect wildlife as well as timber. Although red oaks flower every year, it takes two years for their acorns to mature, while white oaks produce mature acorns from their flowers yearly. Given the area’s susceptibility to late frosts that kill or decimate an oak’s flowers and thus its acorn production, this difference in acorn maturity helps to ensure a yearly acorn crop.

MDC resource scientist Randy Jensen has been a part of MOFEP since fieldwork began on the project in 1990. In the years before and after harvests, the trees in all 648 of MOFEP’s half-acre vegetation plots are catalogued. On these plots, Jensen has overseen the assembling of a database that now encompasses 96,000 individuals of 50 trees species.

Predominantly former pine and white oak open woodland, MOFEP areas now contain more densely stocked oaks (72 percent) and hickories (19 percent). In part because of a lack of regular disturbance like fire (which used to be much more frequent), shortleaf pines now make up only 9 percent of MOFEP’s trees, an estimated 30 percent of their pre-1900 numbers. All other tree species in MOFEP’s inventory combined make up less than 1 percent.

Jensen oversees research of MOFEP’s over story. His crew inventories trees, their species, their crown status, their diameter and their wildlife cavities. They also note if the trees are alive, snags (standing dead trees) or lying in the soil, decomposing. On vegetation plot 71 on site 6, just southwest of Ellington, his seven member crew catalogued the half-acre’s trees early in the fall of 2009. The site is lush, a broad upland waterway that opens from the north side of a hill, gently slopes for 100 yards or so, then crosses a dirt road and drains into Paint Rock creek, which, in about a mile, meets the Current River below Paint Rock Bluff.

The crew finds the plot’s stake-marked center, measures 82.8 feet north to the plot boundary and then moves clockwise, inventorying every tree with a trunk above a 4.5-inch diameter (smaller-diameter trees are measured in a plot’s subplots and quadrats). Several crew members identify trees while the crew leader corroborates and enters information in a PDA-like device that updates a vast tree database. Each catalogued tree has an ID tag nailed to its base, corresponding to its database ID. Thus, life histories of single trees play out every three to four years in Jensen’s ever-growing database.

This opportunity to watch the forest change provided the most surprising insight of Jensen’s MOFEP experience so far—the forest is dynamic. Often it changes, he says, tree by tree, in ways he wouldn’t have expected. Sometimes he’s surprised by which trees grow a lot, which not at all, and which die or fall down. Consequently, once assimilated with research from the other 30 studies, the promise of powerful insights in MOFEP appears true.

However, this integration represents the great challenge of the project. As yet, no one has figured out how to synthesize the varied, intricate, simultaneously inventoried forest components into a single, meaningful ecosystem model. No doubt the task is daunting, and a little premature just 20 years into a 100-year study.

But the questioning goes on: How do timber harvests affect whole forest communities, from the Acadian flycatcher that spends its northern life feeding on its insects and breeding in its trees, to the broad-headed skinks and central newts that live in its leaf litter, to the bacteria that live in its soil, to the tick trefoil and goat’s rue that grow close to its ground, to the shortleaf pine seedlings, moth and butterfly larvae, the beetles, mites, millipedes, copperheads, acorns and berries, white-footed mice, chipmunks, sulphur, carbon itself, all which eat, are eaten, reproduce, live, die and otherwise interact in this Ozark forest life?

MOFEP is a good start.