Tree Rings and Aerial Imagery Illustrate a Multi-Century Trend from Open Lands to Closed Forest at Eagle Valley, Southwest Wisconsin, USA

An environmental history of Eagle Valley Nature Preserve, situated among the bluffs of the Mississippi River in southwest Wisconsin, USA, describes a dynamic landscape with multi-century ecological trajectories shaped by the interacting effects of climate and human engagement with the land. Crossdated tree-ring establishment dates of cut stumps of eastern redcedar (Juniperus virginiana) trees hint at possible afforestation in the 1300s and 1400s CE following reorganization of the Mississippian mound-building culture. Historical observations from the seventeenth century describe an open landscape with only scattered trees restricted to ravines and other areas protected from passing prairie fires. Outer ring dates on redcedar stumps indicate early 1800s harvest dates and illustrate impacts of European landuse that occurred decades before the General Land Office Survey at this location. Oak (Quercus macrocarpa and Q. alba) and eastern redcedar establishment dates in the mid-1800s suggest a change in disturbance regime related to shifting landuse initiated by European colonization, while twentieth century aerial imagery illustrate a continued trajectory toward closed-canopy forest and simplified landscape patterns. Increasing moisture availability over recent decades and the cessation of grazing likely amplified these changes. Based on tree-ring data and field observations, it appears likely that the forests covering much of Eagle Valley today represent the first closed-canopy system to occur at the site in at least a millennium. Current land stewardship activities to maintain and expand prairie and savanna communities are working against a multi-century trend toward increasing forest cover and landscape closure at a regional scale.