Effects of clear-cutting on the vegetation and soil of an eastern hemlock dominated ecosystem, western Upper Michigan
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.