Forest landscape change in the northwestern Wisconsin Pine Barrens from pre-European settlement to the present

Natural disturbance patterns can provide useful information for ecosystem management. Our objective was to provide a detailed spatial picture of the pre-European settlement vegetation cover for the northwestern Wisconsin Pine Barrens and to compare it with the present vegetation cover. We analyzed the presettlement conditions using an extensive data set comprised of U.S. General Land Office surveyor records from the mid-19th century and related it to the vegetation cover in 1987 as depicted in a Landsat satellite forest classification. Changes were quantified by calculating differences in abundance and relative importance of tree species at presettlement time and today. Our results revealed a strong decline of jack, red, and white pine (Pinus banksiana Lamb., Pinus resinosa Ait., and Pinus strobus L., respectively), accompanied by an increase of oak (Quercus spp.), trembling aspen (Populus tremuloides Michx.), and other hardwood species. Certain vegetation types, e.g., red pine and oak savannas, were removed from the landscape. The forest density gradient of the presettlement landscape with open savannas and woodlands in the South and denser forests in the North disappeared. These changes, especially the increase in forest cover, are ecologically significant because numerous species are adapted to open habitat, which was previously created by fire, and their populations are declining.