Acorn yield and masting traits of red oaks in the lower mississippi river alluvial valley

We studied five species of endemic red oaks (Section Erythrobalanus) in hardwood bottomlands of the Mississippi Alluvial Valley (MAV), including cherrybark, Nuttall, pin, water, and willow oaks. Ecologists and managers need reliable estimates of acorn yield and masting traits to assess potential forest regeneration and estimate foraging carrying capacity of these habitats for waterfowl and other wildlife. We designed a study to reliably estimate red oak acorn yield in five states in the Mississippi Alluvial Valley over 4 consecutive years (2009 -2013) and evaluate the components of masting (i.e., synchrony and temporal variability). The mean annual individual tree yield was 424 kg (dry)/ha (35.1 acorns/m² crown area) across all sites and years. Our yield estimates provide heretofore unreported estimates of average seed yield (seeds/m² canopy) and mass (kg/ha) from red oaks for five of the largest contiguous bottomland hardwood forests remaining in the MAV. In our study, red oaks yielded more acorns on average and showed less annual variability than studies of other red oaks in North America. We found no evidence that annual population-level red oak acorn yield was synchronized at sites across the scale of the MAV. However, synchrony increased with decreasing distance between sites, and we found a large degree of interspecific synchronicity within four of our five sites. We believe that local scale influences such as edaphic resources, weather, and genetics drive within-site yearly patterns in acorn yield. Managers have a greater likelihood of lessening the effect of periodic seed failures in the MAV if they manage for a diversity of site-adapted red oak species as opposed to favoring monocultures or few species.