Structural and Compositional Change in Great Smoky Mountains National Park since Protection, 1930s–2000s

When Great Smoky Mountains National Park (GSMNP) was placed under strict protection in 1934, about 20 % of the landscape was old-growth forest that had never been logged or farmed, and about 80 % was second growth recovering from logging and settlement. We might expect that the structure of GSMNP’s old-growth forests today would capture the natural range of variation of these southern Appalachian forests, subject only to localized natural disturbances such as landslides, flooding, windthrow, ice storms, and fire. Despite protection, however, multiple indirect, diffuse anthropogenic disturbances including exotic pests, atmospheric deposition, changes in herbivory, and changes in fire regime have continued to affect both old-growth and successional GSMNP forests. Here, we employ a mid-1930s vegetation survey and a compilation of more recent vegetation datasets (1990s–2000s) to compare the historic and present-day range of variation in GSMNP forest structure and composition. Widespread changes in structure reflect succession from historical disturbance and the overlay of continued disturbance, including in formerly undisturbed areas. Species indicative of disturbance and reduced fire frequency are abundant across the landscape in patterns reflecting the legacy of historical disturbance types, continued disturbance, and the interaction of these disturbances with environment.