Analysis and Conservation Implications of Landscape Change in the Wisconsin River Floodplain, USA

River floodplain landscapes are diverse and dynamic, yet little is known about long-term changes in land-cover patterns in these systems. We quantified floodplain land-cover change between the 1930s and the 1990s along nine 12-21-km reaches of the Wisconsin River by analyzing and digitally classifying 200 historic aerial photos corrected against modern orthophotographs. Several metrics of landscape structure were used to determine changes in amount and connectivity of deciduous forest, wetlands, grassland, and agriculture within the 100-yr floodplain. Deciduous forest increased by up to 51% between the 1930s and the 1990s. However, number of patches declined, and edge density increased in almost every reach, indicating that amount and connectivity of forest cover increased but that forest patches became more complex in shape. Grasslands declined, and the number, edge density, and mean size of grassland patches illustrated a progression to fewer, smaller, isolated remnants. Wetland patch dynamics demonstrated complex and divergent patterns, as wetland cover decreased in northern reaches, increased in patch density but not mean patch size in the central region, and increased in both patch density and patch size in the south. Agricultural areas declined in eight of nine reaches, and tended to fragment into fewer, smaller patches. These trends underscore a complicated and dynamic pattern of landscape change over a relatively short time scale. We explored realistic conservation scenarios to determine how disparate strategies would affect floodplain forest connectivity in four of the study reaches. One approach filled gaps in the buffer zone immediately adjacent to the river channel; the other reverted small or large agricultural patches to forest cover. Filling buffer zone gaps resulted in dramatic changes in forest connectivity in one half of the reaches, whereas greatest forest connectivity was gained by reverting agricultural patches to forest in the other half of the reaches. These scenarios emphasize that the way that forest conservation occurs (e.g., filling gaps vs. patch conversion) is just as significant as how much land is actually protected, and the ideal management option must be tailored to the specific land-cover arrangements of a given river reach. In addition to evaluating changes in forest connectivity, the number of landowners that would be affected by conservation strategies was determined. Greatest increases in forest connectivity under the