The Winona County Historical Society, Winona State University, and Saint Mary’s University of Minnesota’s GeoSpatial Services partnered to develop a digital land cover map from an 1855 Public Land Surveyor’s field notebook for Winona Township. Notes and other records (such as planimetric maps) from Public Land Surveys provide the earliest systematically recorded information about vegetation composition and physical features (soils, rivers and streams, wagon roads, etc.) for surveyed lands across the U.S. The first step in developing the historic land cover or vegetation map was to digitize (i.e., convert to digital GIS data) the survey reference points (corners, quarter points, and meander points) and bearing trees based on information in the original survey notes. GSS analysts reviewed the bearing tree data and other vegetation notes from the original survey to get a general idea of the vegetation types present at the time. Eight community types were ultimately selected for inclusion in the historic land cover map: floodplain forest, dry-mesic oak forest, dry-mesic oak woodland, savanna, prairie, wet prairie, cliff community, and bluff prairie (a subset of dry prairie). A GSS analyst then categorized each survey reference point into one of these vegetation communities. With these survey point vegetation assignments and collateral data, the analyst was able to interpolate and digitize the extent of each vegetation community. The results show that the most common vegetation community in Winona Township at the time of the original PLS was prairie, followed by oak woodland and floodplain forest. In addition to this report, GSS created an Esri Story Map to document the story of this project and provide interested users with access to resulting data products, images and text in a web-based format that supports inquiry and investigation.

A comparison of the historic land cover map to current conditions in Winona Township illustrates several changes due to human influence over time. The town of Winona has expanded greatly, essentially eliminating the historic prairie as well as much of the savanna. Over time, naturally winding stream channels were also straightened and construction of flood control structures on the Mississippi River resulted in the flooding of some river islands. Overall, the 1855 PLS appears to have captured a moment in ecological succession from more open grassland and savanna ecosystems (with the exception of floodplain forests) to denser, wooded ecosystems, likely due to shifts in climate and disturbance regimes.