Stand development patterns for young planted oak stands on bottomland hardwood restoration sites.
Abstract
Over the last several decades, bottomland restoration efforts have established hundreds of thousands of acres of planted hardwood stands throughout the Southeastern U.S. Much of the initial research focused on planting approaches and early growth and survival, contributing to more effective establishment methods. However, less research attention has been focused on stand development and treatment options for these planted stands as they age. Given that many afforestation stands are approaching 20 years of age or greater and undergoing crown closure, an improved knowledge of stand conditions is needed to evaluate opportunities for silvicultural treatments aimed at enhancing growth, and/or structural or compositional diversity. An increasing demand for such knowledge by landowners is becoming evident particularly by those that have participated in hardwood planting initiatives including the Conservation Reserve Program and Wetlands Reserve Programs (CRP and WRP respectively). This study investigates tree and stand development within young (10 to 20 year old) planted oak stands across a range of stand ages and site conditions in the Lower Mississippi Alluvial Valley. Growth and yield and stand development were evaluated using field surveys of stand characteristics (species, diameter, density, height, and crown measurements) and destructive sampling of individual trees. Our results show that as stands reach 20 or more years of age individual trees begin to interact, crown closure occurs, and conditions approach full stocking (the "A-line") (Goelz 1995). At this point, stems have generally reached merchantable diameters for pulpwood, and self-pruning has, for a stand fully stocked, progressed to one log-length in height (17.3 feet). These results suggest that thinning treatments could be merchantable and desirable from a tree growth perspective, in addition to potentially enhancing desirable stand conditions for wildlife habitat. As such, this information can provide a basis for informing silvicultural treatments aimed at improving stand conditions. Improving our knowledge of stand development, and growth and yield, could prove critical for ensuring the continued commitment of landholders to the management of their hardwood plantings and ongoing participation in these restoration programs.