Nutrient leaching after a simulated fire in a Pinus resinosa forest.

Abstract

Fire is an important disturbance mechanism in the forests of Northern Michigan, opening space for regeneration and succession of new species. Burning the surface organic layer of the soil releases nutrients into the soil in the form of nitrogen (as ammonium and nitrate), phosphate, and metal ions like calcium, magnesium, and potassium. We investigated the potential losses and distributions of these nutreints after a simulated forest fire and susequent rainfall in a red pine forest by reconstructing the major soil horizons (organic, leaching, and deposition) in combination in columns in a lab, adding burned organic matter to the experimental columns and unburned organic matter to the control. We simulated an inch of rainfall and collected the water that leached through the columns to determine the amounts of nutrients and their distributions between the soil horizons. We found that the different nutrients distributed in different patterns in both the experimental and control columns. Nitrate moblized out of the organic horizon after a burn and was retained in the leaching layer, while ammonium was partially volatilized in a burn but leached out in a higher amount from the leaching horizon than was leached in from the organic horizon due. Phosphate was almost completely volatilized in the burn treatment but was retained in the leaching horizon in the unburned control, and cations increased out of the organic layer after a burn, with some retained in the leaching horizon.