Forest in a Looking Glass
The Missouri Ozark Forest Ecosystem Project (MOFEP) is a landscape-level study of forest management practices and their impacts on plants and animals. Comprising three different treatments (even-aged management, uneven-aged management and control, or no cutting), this project emphasizes learning while managing and is one of the largest integrated studies of its kind in the country. Ten years into its planned 100-year life, the project is already discovering species new to science, relationships only guessed at before, and information and techniques of interest to land managers both within and outside the Department of Conservation.
MOFEP is actually a collaboration of more than 25 studies conducted by many different scientists. This large, diverse project evolved out of one question: What effects would forest management have upon bird communities? With the fragmentation of forests in central Missouri, southern Illinois and elsewhere across America, birds that relied on large, intact forests were being replaced with species that used pasture land, crop fields and forest edge. MOFEP's unique use of a true management experiment is providing valuable answers to this and many other questions.
In 1988, Conservation Department and University of Missouri scientists became interested in examining the effects of forest management on songbirds in the Missouri Ozarks. Discussions about the effects of fragmentation upon the mix and numbers of songbird species generated interest in expanding the proposal to include the entire ecosystem in the study. As MOFEP grew in scope, the planners added studies to complement the bird work, including fundamental productivity of the forest, vegetation composition and the dynamics of other animal communities. The MOFEP study sites, located in Shannon, Carter and Reynolds counties in the southeast Missouri Ozarks range from 776 acres to 1,275 acres. Each of the nine experimental sites received one of the treatments; there are three even aged sites, three uneven-aged sites and three non-treated sites.
Timber harvests, whether even-aged (clearcut and thinning) or uneven-aged (selection cuts) are spread across the landscape so that roughly 10 to 15 percent of a study site is cut every 15 years. Each study site is divided into many smaller units, called stands, for inventory and management. All of the trees in an even-aged forest stand are roughly the same age. An uneven aged forest stand contains at least three age-classes. Control, or non treated, sites receive no cutting on any part of the compartments. The age of trees is not always easy to figure out, so we often judge the character of a multi-aged forest by the presence of different sizes of trees. We have to be careful estimating the age of stands by their diameters and heights, however, because size and age don't always agree.
The Conservation Department is looking to MOFEP to provide valuable lessons to scientists and land managers today, through the life of the project and beyond. Some of the environment and vegetation projects examine genetic variation in plants, the size and species of ground flora and woody plants, soil carbon, soft and hard mast, lichens and fungi. Wildlife studies have looked at amphibians and reptiles, insects in the leaf litter and in the tree canopies, small mammals, and bird communities. Forest management information is coming from studies of tree harvesting, regeneration from stump sprouts and the biology and economics of accidental damage that occurs during timber harvest.
So, what exactly has been going on these past few years? The first measurements were made in 1990. These "pre-treatment" measurements continued with various projects until the first trees were harvested in 1996. Many studies have maintained "post-treatment" data collection up to the present. The next harvests are scheduled for 2011. Clearcutting and thinning affected 26 percent of the total area on sites receiving the even aged management treatment. Selection and group selection harvests affected 57 percent of the total area on sites receiving the uneven-aged treatment.
There are many studies under the MOFEP umbrella today, but we will talk about only a few: birds, amphibians and reptiles, ground flora and lichens.
Dr. John Faaborg of the University of Missouri, Rick Clawson from the Conservation Department and others studied all forest songbirds, but they were especially interested in five species of birds that are found in mature forests (ovenbird, worm-eating warbler, Kentucky warbler, Acadian flycatcher and wood thrush), and with six species that are found in brushy forest openings (blue-winged warbler, hooded warbler, prairie warbler, yellow breasted chat, indigo bunting and white-eyed vireo.) Before the 1996 timber harvest, they collected information on the density and nesting success of the mature-forest species by mapping the locations of singing male birds and finding nests. After the openings were created by the harvest, they also gathered information on both the mature-forest birds and the early successional species. Their goal was to answer two questions: Are these species affected by forest management? And, do they respond differently to the different types of cutting?Cutting down a portion of the mature forest caused the densities of all five mature-forest birds to drop somewhat after the cutting. They have since rebounded. The responses of these birds to the different treatments varied. Wood thrushes seemed to be attracted more to the forest stands near openings in the even-aged sites than to the openings created by uneven-aged management. Ovenbirds and worm-eating warblers, on the other hand, seemed to be more negatively affected by even aged management than by uneven-aged management. Kentucky warblers were positively influenced by both types of cutting, and Acadian flycatchers did not seem to favor one or the other.
The densities of four of the six early successional species increased dramatically within the newly-created habitat. Clawson and Faaborg found that yellow-breasted chats and prairie warblers responded more positively to even-aged treatments than to uneven-aged treatments. Indigo buntings and hooded warblers seemed to respond positively and equally to both treatment types. Blue-winged warbler and white-eyed vireo densities have remained low throughout the study to this point.
The scientists found no significant change in nest success rates between pre-harvest and post-harvest monitoring. Faaborg and Clawson concluded that, within this forest-dominated landscape, forest management does not create edge effects that are a problem for birds.
In addition to attracting the early-successional birds to nest and rear their young, the brushy habitat created in the openings, especially from even-aged treatment, is very attractive to broods of mature-forest species. Rick Clawson suggests that the dense vegetation provides both good foraging habitat and cover from predators for the adults and their young.
The understory, the plant and animal communities that live below the level of the tree canopy, is an important part of the forest. Conservation Department botanist Jenny Grabner and her team looked at the ground layer of vegetation, gathering pre-treatment ground flora data during the summers of 1994 and 1995 and post-treatment data in 1999 and 2000. They looked at the numbers of different species, how much area each species covered and what types of plants dominated the sites. As expected, Grabner observed increases in the number of species and how much ground they covered on cut areas. An unexpected result was a noticeable decline in species richness on uncut areas, possibly due to dry weather over the past three to four years. Annual species, such as horseweed (Conyza canadensis), increased slightly but consistently on even-aged sites. Woody vines, such as grape (Vitis spp.) and Virginia creeper (Parthenocissus quinquefolia), increased everywhere, but most noticeably and consistently on even-aged sites. Common forest legumes, such as the bare-stemmed trefoil (Desmodium nudiflorum), decreased noticeably in harvested areas, possibly as a result of increased competition from more sun-loving plants. Grabner noted that her results did not indicate that the harvests are impacting areas other than those actually cut.
Amphibians and Reptiles
Focusing on 13 species of amphibians and reptiles, Dr. Rochelle Renken and others looked at harvest impacts upon species abundance at both local (in or near a timber harvest sites) and at landscape levels. At the small scale, the study examined the effects of even-aged management by comparing relative abundance among plots located within a clearcut stand, 50 meters away from a clearcut stand and 200 meters away. Sampling both before and after the harvest treatments, Dr. Renken and her associates found that one amphibian species, American toad (Bufo americanus), declined in abundance at the landscape scale for even-aged and uneven-aged treatments. They also declined on no-harvest sites, perhaps suggesting that other factors were influencing these populations. No landscape scale impacts were observed on reptile abundance. While most amphibian species declined and some reptile species increased relative to their numbers before forest stands were clearcut, they only found a "distance-from-clearcut" influence for one species of amphibian, spotted salamander (Ambystoma maculatum), and for two species of lizards: ground skink (Scincella lateralis) and fence lizard (Sceloporus undulatus). Based on her study results so far, Dr. Renken says the initial even-aged and uneven-aged treatments did not adversely affect abundance of amphibians and reptiles in Missouri Ozark forests. These results are encouraging to both resource managers and conservation biologists.
One of the most interesting subjects studied at MOFEP were the lichens. Doug Ladd, of the Missouri chapter of the Nature Conservancy, and colleagues sampled lichens in nine MOFEP areas. They took samples from the forest floor, from the base of the trees, mid-way up the tree trunk and on canopy branches. They found more than 180 different species, three of which had never before been discovered.
More than 50 percent of the species were found primarily on trees, while a third were found mainly on rocks. It was fascinating to see the lichens on trees largely separate by tree location, with some lichen species growing mainly on branches, others on tree trunks and still others at tree bases. Only a quarter of the species occurred across all of these vertical "habitats." Interestingly, while tree species was important in determining which lichens species were present, tree size did not seem to influence lichen species composition. The lichen species present and how many there were depended on whether it was a red oak tree, a white oak tree, or a different species.
The future for MOFEP is bright. Research on the effects of forest management will continue. The interval between harvests, originally expected to be 10 years, has been lengthened to 15 years to reflect the timing of harvest on the rest of Conservation Department lands.
On MOFEP, about 10 percent or so of the forest will be harvested at each entry. These new harvest stands will be different from those harvested in 1996, although some may be adjacent.
With another series of cuts under MOFEP's belt, scientists can see if their conclusions hold up or need to be modified. Some effects will increase due to the increasing proportion of area that has been harvested. Others might not change at all.
There are very few long-term studies of disturbance and forest ecosystems in North America. Fewer still attempt to integrate so many elements into one project. MOFEP will continue to grow in value and importance as time marches on.
To Learn More about MOFEP
- The MOFEP web page.
- John Kabrick and David Larsen. 1999. Aspect Affects Oak and Pine Basal Area and Site Index in Ozark Forests. Missouri Department of Conservation Notes for Forest Managers Report #2.
- John Kabrick and Randy Jensen. 1999. Diameter Growth Rates for Tree Species of Missouri Ozark Forests. Missouri Department of Conservation Notes for Forest Managers Report #3.
- David R. Larsen. 1999. Girard Form Class Trends from the Missouri Ozark Forest Ecosystem Project. Missouri Department of Conservation Notes for Forest Managers Report #4.
U. S. Forest Service Publications:
- Brookshire, Brian and Stephen Shifley. 1997. Proceedings of the Missouri Ozark Forest Ecosystem Project symposium: An experimental approach to landscape research. St. Paul, MN: U.S.D.A. Forest Service North Central Forest Experiment Station General Technical Report NC-193. 378 p.
- Shifley, Stephen and Brian Brookshire. 2000. Missouri Ozark Forest Ecosystem Project: Site history, soils, landforms, woody and herbaceous vegetation, down wood, and inventory methods for the landscape experiment. St. Paul, MN: U.S.D.A. Forest Service North Central Forest Experiment Station General Technical Report NC-208. 314 p.