Soil fertility changes following clearcut and whole-tree harvesting and burning in central Michigan

Soil fertility (available Ca, Mg, K, P, and total N) was evaluated at the time of and 1 and 5 years after clearcut and whole-tree harvest of adjacent oak-aspen forests. Surface mineral soil at both sites showed increased K and decreased N concentrations 1 year following harvest. A wildfire that burned both sites shortly thereafter generally increased the nutrient concentrations at each site, but smaller increases occurred at the whole-tree harvest site. Five years after cutting (4 years after burning) soil Ca and P levels at both sites were higher than the concentrations at the time of harvest, while K and N were similar to original levels. Calcium and Mg concentrations at the clearcut site were 88 and 75% higher than the levels at the whole-tree site 5 years after harvest. The increased soil fertility observed could provide a valuable nutrient supply to the succeeding forest stand, but net nutrient outputs through harvest and burning could also eventually reduce the already low productivity of these sites