To understand the dynamics of fire in red pine ( Pinus resinosa Ait.) forest ecosystems that once dominated areas of the northern Lake States, we dendrochronologically reconstructed the fire regime prior to European settlement (pre-1860), after European settlement (1860–1935), and postrefuge establishment (post-1935) for different portions (wilderness and nonwilderness) and landforms (sand ridges and outwash channels) of the Seney National Wildlife Refuge (SNWR) in eastern Upper Michigan. Using data from 50 sites, we found that the cumulative number of fires showed a slow rate of accumulation from the 1700s to 1859, a steeper pattern suggesting higher fire occurrence from 1860 to 1935, and a return to fewer fires after 1935. Prior to European settlement, the fire cycle (FC) of sand ridge landforms interspersed within a poorly drained lacustrine plain in the Seney Wilderness Area was 91–144 years. This was longer than on glacial outwash channel landforms (53 years) and on sand ridge landforms interspersed within lacustrine plains located outside of the wilderness (47 years). The FC was also shorter (30 years) during this period and has subsequently increased (149–1090 years) after SNWR establishment. Differences in fire regimes among landform types were minor relative to the temporal variation in fire regimes among the three time periods.

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The effects of clear-cutting on the vegetation and soil of an ecosystem dominated by eastern hemlock (Tsugacanadensis (L.) Carr.) were studied at four locations along the boundaries of the Sylvania Recreation Area (Ottawa National Forest) in western Upper Michigan, U.S.A. The position of commercially clear-cut areas along the boundaries of the relatively undisturbed 8500-ha tract provided the opportunity to examine the probable effects of clear-cutting after an average of 46 years afterward. Clear-cutting resulted in the virtual elimination of hemlock from the overstory; it was replaced by a mixed forest of red maple (Acerrubrum L.), yellow birch (Betulaalleghaniensis Britt.), sugar maple (Acersaccharum Marsh.), and balsam fir (Abiesbalsamea L.). The ecological species groups characteristic of the ground cover of the uncut plots were not substantially different from the groups now present on the clear-cut plots. The thickness, mass, and nutrient (K+, Mg2+, Ca2+) contents of the forest floor decreased significantly, and the acidity and nutrient contents of the upper mineral soil increased slightly. The replacement of hemlock by hardwoods has slowly decreased the acidity and apparently increased the rate of nutrient cycling. It appears that without major disturbance, such as fire, hemlock is not likely to regain dominance following clear-cutting owing to failure to regenerate naturally.