Disturbance, succession, and structural development of an upland hardwood forest on the interior low plateau, Tennessee

Abstract

An appreciation for the importance of structural complexity, combined with the acknowledgment that stands with complex structures are uncommon compared to pre-European settlement estimates, has led to a growing interest in restoring late-successional forests. The success of these projects is dependent upon our understanding of the variability of late-successional structure and the disturbance events that produced this structure. We quantified woody species composition, stand structure, canopy disturbance history, and Quercus establishment and canopy accession patterns to document processes that resulted in the structural conditions of an upland hardwood forest in Tennessee. The forest established in the mid-1800s and exhibited structural characteristics that were within the range of what has been reported from other late-successional forests in the region. The forest overstory was dominated by Quercus prinus, but Acer saccharum was the most abundant species. Quercus recruitment was continuous from stand initiation through the 1950s. The vast majority of Quercus trees that established prior to 1880 established in closed canopy conditions, whereas most Quercus trees that established after 1880 established in high light environments. Quercus establishment in canopy gaps resulted in multi-aged Quercus populations in the forest. We documented three forest-wide disturbances during development (1922, 1945, and 1973). The 1922 forest-wide disturbance coincided with an establishment pulse of largely understory taxa, and the broad-scale event of 1945 corresponded with an establishment pulse of A. saccharum. Our results provide benchmarks for a region that lacks other reference conditions and can be used to inform structure and process based restoration approaches.