Effects of flooding regimes on two impounded bottomland hardwood stands

Abstract

The relationships between flooding regimes, stand structure, regeneration, and tree stress and mortality were evaluated within two overcup oak (Quercus lyrata) — willow oak (Quercus phellos) greentree reservoirs, one impoundment with levees and one without levees. Record rainfall resulted in extensive growing-season flooding in both impoundments; however, the levee system and the topographic relief of the impoundment with levees impeded drainage of surface water and prolonged growing-season flooding. Limited regeneration of all species except overcup oak was observed in both impoundments. In the impoundment with levees, the total number of overcup oak seedlings at peak establishment and overcup oak seedling mortality were related to flooding regimes. In the impoundment without levees, establishment densities were not related to any of the measured environmental variables. Stress and mortality were significantly higher in trees in larger diameter classes, and stress generally increased with flooding. these results suggest that the decision to create GTRs within a stand of naturally flooded bottomland hardwoods should be thoroughly and cautiously reviewed.