INVESTIGATING THE INFLUENCE OF LAND USE HISTORY ON SAVANNA SOILS IN LOWER MICHIGAN: IMPLICATIONS FOR MANAGEMENT, RESTORATION, AND CONSERVATION

Prior to European settlement, mixed oak savanna was a naturally occurring ecosystem in Michigan’s Lower Peninsula. Maintained by wildfire, these savanna openings likely migrated over space and time on excessively-drained sandy soils. Most of this plant community type has been lost due to early land management practices, especially agriculture and timber. Decades of fire suppression have led to degradation of what remains. Remnant examples are an important part of the ecological landscape and provide refuge for a multitude of early-successional species, most notably the Federally-Endangered Karner Blue Butterfly (KBB; Lycaeides melissa samuelis). Because of this, the US Forest Service implements a variety of management techniques, such as controlled burns, bulldozing, masticating, and partial harvesting, to restore and maintain oak savanna ecosystems. However, attainment of desirable levels of plant species diversity and abundance following restoration activity has proven difficult. We hypothesized that land use history and its influence on soils play a significant role in the potential for restoration success, especially with respect to resultant floristic composition. The purpose of this research was to 1) establish site-specific historic land use and 2) determine impacts on soil morphology, soil chemistry, and current savanna communities in the southern Manistee National Forest. Preliminary results suggest that land use history helps explain variation in soil A horizon thickness, and the presence/absence of important savanna plants such as wild lupine (Lupinus perennis). Preliminary results support our hypothesis that historic land use and its influence on soil morphology significantly impact floristic diversity and abundance in savanna ecosystems. This insight has the potential to help prioritize potential management and habitat restoration sites, and can be incorporated into existing savanna ecosystem management techniques by land managers and government agencies. Soil sample processing is currently underway in the laboratory, and analysis of the effects of land use history on further soil morphological characteristics and soil chemistry will follow.