Using witness trees to assess forest change in southeastern Ohio

In 1787, the U.S. Congress authorized the sale of the "Ohio Company Purchas e", ca. 5000 km(2) in Appalachian Ohio. The land was surveyed using a towns hip and range system shortly thereafter. Data on > 5600 witness trees were transcribed from the survey records, and witness tree locations were plotte d on a digital map. This information was used to evaluate presettlement for est composition and structure and to investigate vegetation-site relationsh ips before widespread alteration of the forests had taken place. Presettlem ent conditions were compared with present conditions using forest inventory and analysis (FIA) data. Two hundred years ago, the forests of southeaster n Ohio were dominated by large individuals of Quercus alba L., Carya Nutt. spp., Quercus velutina Lam., and Fagus grandifolia Ehrh. These four taxa ac counted for 74% of all witness trees. Although almost 70% of the region is forested today, the second-growth forest has witnessed a decrease in Quercu s and Carya and an increase in Acer saccharum Marsh., Acer rubrum L., and m any early successional species in smaller size classes. Despite the signifi cant shift in forest composition and structure, species in general seem to be occupying similar positions in the present-day landscape compared with t he presettlement forest; topographic variables most strongly control specie s occurrence in this landscape.