Bottomland hardwood habitat and resources in Bayou Meto Wildlife Management Area are extremely important for maintaining ecological functions and values in the Bayou Meto Basin and upper Mississippi Alluvial Valley. Bottomland hardwood forests have been extensively destroyed and degraded in the Bayou Meto Basin and most remnant patches are highly fragmented, small, and have altered hydrology. (Hydrology is the scientific study of the properties, distribution, and effects of water on the earth's surface, in the soil and underlying rocks, and in the atmosphere.) Consequently, bottomland hardwood habitats in Bayou Meto Wildlife Management Areas and adjacent private lands are increasingly important to sustain both local and regional plant and animal communities.
Careful management of greentree reservoirs on Bayou Meto is needed in the future because bottomland hardwood habitats in greentree reservoirs are badly degraded, some more than others. Some damage is old and relatively confined to specific areas (e.g. Government Cypress), but other impoundments have recent damage that is expanding rapidly. Greentree reservoirs on Bayou Meto Wildlife Management Area have retained an average of 22.4% red oaks which provide critical resources for many fish and wildlife species, especially wintering mallards and wood ducks. However, tree species composition is shifting to a more water tolerant community dominated by overcup oak and green ash. The presence of green ash is an especially important indicator of prolonged periods of inundation. Another important indicator of prolonged flooding regimes is limited herbaceous cover comprised of rice cutgrass and sedges. Surviving red oak trees in Bayou Meto Wildlife Management Area greentree reservoirs have many indicators of declining tree health. -20.7% of red oaks have basal swelling, 14.0% have evidence of leaf chlorosis, and 22.3% have at least some death of terminal branches (tip die-back). Furthermore, 24.9% of Nuttall oak and 21.0% of willow oak have died. This mortality includes large old trees as well as young regenerated trees. In most greentree reservoir impoundments, few newly regenerated red oaks survive to be larger than 4-6 inches dbh.
Analysis of the data from the 8 greentree reservoirs on Bayou Meto WMA provide important insights into causes of damage and mortality to red oaks and the overall forest species composition. Each impoundment has somewhat unique water management and hydrological regimes and damage is not similar among them. Certain general observations and recommendations are common for all units and suggest the following:
By: Dr. Mickey Heitmeyer, Greenbrier Wetland Services;
formerly with Gaylord Memorial Laboratory, Puxico, MO
1) Flooding occurs earlier and extends later. 2) Early flooding and late drainage cause damage to red oaks. 3) Timing of flooding and drainage have reduced damage relative to flood duration. 4) Lack of independent water control to flood and drain creates situations where flooding occurs earlier or drainage is later than natural conditions. 5) Infrastructure on the Wildlife Management Area has altered natural water flow and created situations where drainages have become obstructed and water has become impounded for long periods. Obstructions include levees across natural channels, under-sized and inappropriately placed water-control structures, debris and dead tree material, silt, and extensive beaver dams and plugs. 6) Regeneration of red oaks is compromised because of prolonged flooding in a few older, relatively even-age, stands have created light limitation for young seedlings.