Millions of acres of Missouri bottomland forests have been cleared for agricultural production, creating some of the state's most productive farmland. However, this practice has resulted in a dramatic decrease in the acreage of this diverse land type. Only 20 percent of the bottomland forests that once existed in the United
Bottomland forests can be very productive for landowners and maintain important wildlife habitats. |
In keeping with its mission to promote research on agroforestry practices that improve the production and protection of agricultural and forest lands, one of the Center's research initiatives is to investigate methods for establishing oak and other hardwood tree species in floodplains. The reestablishment of oak in these areas provides several benefits to landowners, including diversifying native forests; combining timber, acorn production and the management of wildlife habitat for recreational operations; and restoring waterfowl habitats using integrated agroforestry practices. In addition, bottomland forests intercept pollutants from both ground and surface water and protect streambanks from erosion while offering invaluable protection against flood damage to levees. Last year, UMCA scientists participated in a project team including the U.S. Forest Service and the University of Missouri Department of Forestry in a study to evaluate regeneration methods for establishing oaks in floodplains. Several key findings emerged from this study that continue to be valuable to land and forest owners:
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- Oak can be established in former bottomland crop
fields by planting large container grown oak seedlings
with a cover crop of redtop grass, producing a 98 percent
survival rate after 4 years.
- Rabbit damage, a major cause of regeneration failure, was greatly reduced in the redtop fields as the wildlife habitat became more open to rabbit predators (raptors). - Acorn production in large container seedlings of swamp white oak that were only 18 to 24 months old is phenomenal compared to production in natural oak stands, which often do not produce acorn crops for 20 to 30 years. This is a major benefit to landowners who are seeking acorn production for wildlife purposes, and it is important in providing a local seed source that makes possible natural regeneration of oak in the future. |
Based on this research, the Center for Agroforestry and its collaborators hosted a spring workshop detailing the current state of our knowledge on restoring hard mast species to major river floodplains. The workshop was supported through the Missouri Department of Conservation (MDC) Forest Land Enhancement Program funds. In addition to presentations by experts and researchers, the day concluded with a tour of the MDC Plowboy Bend Conservation Area in Moniteau County, Mo., where there is a large scale UMCA research effort looking at RPMŪ seedlings for oak regeneration in bottomlands.*
Doug Wallace, USDA Natural Resources Conservation Service state forester, presented an overview of bottomland hardwood management. Wallace cited several important benefits of restoring bottomland forests, including maintaining habitat for whitetailed deer, wild turkey and threatened bird species including the bald eagle. Soil quality is another beneficial landscape attribute of bottomland forests.
"Bottomland forests grow on some of Missouri's most productive soils," said Wallace. "These sites typically have greater volume growth, higher site indexes,and shorter rotation cycles than many upland forest sites."
Wallace said a management plan for the treatment of a forested property is one of the most important tools available to a landowner. Management prescriptions should be specific, based on physical site information and current stand information (inventories). Site information should include soil survey data, land elevation and topographical features, including tree species and the land feature associated with each species. Plant and animal species inventories should also be conducted to enable landowners to develop activities that will encourage and support these species.
Dan Dey, USDA Forest Service research scientist and a primary UMCA research collaborator for the oak reestablishment studies, explained some objectives of species selection for bottomland forests. Species can be selected for five distinct land management objectives: timber production; nut production; wildlife habitat; agroforestry; and levee protection.
For timber production, black walnut and oak can be managed for high value specialty products, including veneer and saw logs. Recreational hunting and lease hunting may be profitable objectives for managing timber for wildlife production, including whitetailed deer and waterfowl hunting. When planting for bottomland forest restoration, it is important to match a species site needs and flood tolerance capacity to the conditions of the planting site. Species that are highly flood tolerant include swamp white oak and burr oak. Pin oak and pecan are moderately flood tolerant, while black walnut is not tolerant to flooding. Species suitable for bottomland plantings in agroforestry practices include swamp white oak, bur oak, pin oak and shell bark hickory. In the southeastern region (bootheel) of Missouri, willow oak, nuttall oak, cherrybark oak and overcup oak may be effective.
Dan Dey (far right), U.S. Forest Service, talks with landowners at the bottomland reforestation workshop. Dey is researching the benefits and methods of reestablishing oaks in floodplains. |
In bottomland hardwood plantings, it is often recommended that the initial number of seedlings planted be much greater than the future density desired (often expressed as treesper- acre). This helps ensure that in the natural process of mortality, whether from rabbit, deer, or periodic flooding, enough trees survive to create a forest comprised of desirable species. Given the dynamics of bottomland environments, larger seedlings, like RPMŪ, can give a distinct advantage to the landowner desiring oak and other hardwood species in that setting. However, due to the higher cost associated with RPMŪ seedlings and their management, it is not always feasible to plant seedlings beyond the number necessary for reaching your longterm goals.
Agroforestry practices provide the landowner many beneficial options during the growth and development of reforested bottomlands. The practice of alley cropping involves planting widely spaced rows of trees, then farming the resulting alleyways, allowing for maximum utilization of the land while the forest is developing. The trees will also benefit from the use of fertilizers applied to the cropped area. A landowner interested in developing waterfowl habitat might create a raised bed on which to establish the hard mast producing RPMŪ, oak or pecan trees, with the intention of flooding the cropped alleyways between the raised tree beds. This creates shallow water impoundments that are excellent habitat for migratory waterfowl. In both of these scenarios, the planting configuration utilizes a much more open planting of trees and does not require as many seedlings per acre as other reforestation efforts.
*RPM, or Root Production Method, is a patented process that involves the air pruning of roots throughout the growth of the seedling. For more information, visit www.fknursery.com
Additional information on bottomland hardwood forest restoration, including species for agroforestry plantings and economics, will be available in the fall 2004 issue of Green Horizons. Doug Wallace can be reached at (573) 876-0908; or email doug. wallace@mo.usda.gov. Dan Dey can be reached at (573) 875- 5341, ext. 225; or by email at ddey@fs.fed.us.