Assessing ecological restoration potentials of Wisconsin (USA) using historical landscape reconstructions

Historical landscape reconstructions provide baseline information for evaluating current land management regimes and restoration potentials. We assessed the historical landscape composition and structure of the state of Wisconsin (U.S.A.). This knowledge forms a basis for delineation of potential spatial distribution of forest species and landscape structures before major human-induced changes, quantification of the spatial extent and intensity of change in habitats and landscapes, and identification of target areas for ecological restoration (e.g., threatened ecosystems). Methods included two conceptually and methodologically different vegetation classifications. The classifications rely on the original U.S. Public Land Office Surveys conducted during the nineteenth century to sell land to Euro-American settlers. The subjective classification method we examined was R. W. Finley's "Original Vegetation of Wisconsin." This classification accounts for qualitative information such as early land surveyors' descriptions of ecosystems (e.g., distinctions into wet and dry prairies). However, the classification is hard to reproduce because some criteria are not strictly hierarchical or exclusive. Numerical cluster analysis was used as an objective classification method. This method offers reproducible, quantitative results and full hierarchical distinction between the classes. Qualitative information, however, is not accounted for in the objective numerical approach and may thus be viewed as less complete when representing local landscape details. Both classifications represent major vegetation characteristics consisting of a complex mosaic of forests (coniferous, mixed coniferous-deciduous, deciduous, and swamps), savannas (oak and pine), and prairies. The objective classification indicates that savannas cover two times more (40%) and prairies six times less area (2%) compared with the subjective classification (savanna, 20%; prairie, 12%). We address the applications of these classifications to current and potential restoration projects, including eastern hemlock (Tsuga canadensis), wetland/riparian, savanna, and prairie ecosystems.