Red oak acorn yields in green-tree reservoirs and nonimpounded forests in Mississippi
Although bottomland hardwood forests in southeastern United States are among the most productive ecosystems in North America, indigenous flora, wildlife, and system dynamics have been altered and affected by natural and anthropogenic effects. Historic spatio‐temporal dynamic flooding in hardwood bottomlands caused managers to create green‐tree reservoirs (GTR; i.e., impounded forested tracts) to enhance predictability of seasonal inundation chiefly for waterfowl habitat and hunting. Bottomland red oaks (Quercus spp.) are valuable trees for wildlife that consume acorns they produce. There was inconsistent evidence in the scientific literature, so we tested the null hypotheses of no differences in annual yield, percentage of sound acorns, and proportion of ‘high‐yielding’ red oaks in GTRs and nonimpounded naturally flooded forests (NFF) in western and east‐central Mississippi, USA, during autumn–winter, 2008–2012. Mean annual yields of sound acorns from GTRs and NFFs at Noxubee National Wildlife Refuge and Delta National Forest had overlapping confidence intervals in all years of our study; however, percentages of sound acorns were greater in GTRs in 3 of 8 site‐year comparisons. We also found conflicting results between study sites regarding which flood regime had the greatest proportion of highyielding oaks. Our results demonstrate differences in total acorn yield by red oaks may be neither statistically nor biologically different between GTRs and NFFs in Mississippi; however, the proportion of sound acorns may be greater in GTRs relative to NFFs in some years. Future research may determine whether these phenomena are related to surviving trees producing increased seed propagules in response to long‐term flooding stress in GTRs or residual trees possessing traits for increased acorn production in some years. Nonetheless, deleterious effects from persistent or prolonged within‐ and among‐year flooding of GTRs are well‐documented, suggesting managers should consider these possible consequences in sustaining and regenerating lowland red oak populations.