Effect of pH on Leaf Decomposition in Low Alkalinity Lakes

Abstract

Two microcosm experiments were conducted to study the effects of low pH on leaf decomposition in low-alkalinity lakes. In the first experiment, a mix of oak and birch litter was incubated for six months in water from Little Rock Lake, Wis., at pH 5.0 and 6.5. In the second experiment, maple litter was incubated for three months in water from Round Pond, Mass. at pH 4.0, and in water from Walden Pond, Mass. at pH 6.0. In both experiments, litter weight loss was less at the lower pH. However, the initial carbon loss from maple litter at pH 4.0 was faster than at pH 6.0 in the second experiment. Calcium and magnesium leaching were greater at the lower pH in both experiments, suggesting that low pH may also be associated with increased leaching of individual elements. Data on ionic inputs to Little Rock Lake from leaves demonstrate the potential importance of leaves as a nutrient source to seepage lakes, or any lakes in which leaf inputs may be significant.