POST-EUROPEAN SETTLEMENT FOREST CHANGES IN OSCODA AND OGEMAW COUNTIES, MICHIGAN

摘要

Witness trees from Ogemaw and Oscoda counties were used to identify presettlement forest composition in order to compare how different historical land uses altered early settlement and present-day forests. Presettlement forests in Ogemaw County were dominated by Tsuga canadensis (17%), Pinus banksiana (13%), and Fagus grandifolia (12%). Oscoda County was dominated by Pinus banksiana (42%) and Pinus resinosa (16%). Tsuga canadensis was significantly (P = 0.05) associated with sandy loams in depressions; Fagus grandifolia was significantly associated with sandy loams on uplands; Pinus banksiana was significantly associated with sandy plains; and Pinus resinosa was significantly associated with sandy uplands. Both counties were logged of Pinus strobus and valuable hardwoods in the late 1800s. In the early 1900s, farms were established on the cutover hardwood sites. Temporary use of these logged sites for agriculture prevented successful regeneration of hardwoods. Thus, following agricultural declines in the 1930s, Pinus banksiana seedlings invaded these abandoned farmlands. Other cutover sites experienced repeated slash fires, which also favored the invasion of the fire-adapted Pinus banksiana. In contrast, pre-European settlement Pinus banksiana sites were not logged; however, these sites experienced fire suppression during the last 70 years and fire-intolerant early successional hardwoods have invaded these sites. This study demonstrated the strong influence of soils and topography on the distribution of pre-European settlement vegetation in northern lower Michigan, but post-European settlement species distribution has been more influenced by land use history.