Element loss and retention during litter decay in a red spruce stand in Maine

Abstract

Litter decay in a Maine red spruce ecosystem was examined to determine the importance of decomposition as a recycling pathway for the trace metals Al, Mn, and Fe versus the major nutrients N, P, Ca, and Mg. The experimental design included litterbags containing the following species: red spruce (Picearubens Sarg.), red maple (Acerrubrum L.), white pine (Pinusstrobus L.), and mixtures of all three. Although decomposing litter was an important source of P, Mg, and Mn, the litter acted as a sink for Al, Fe, and N. Calcium showed a variable, species-dependent pattern. During the 2-year study, there was no net mineralization of Al, Fe, or N. The estimated net accumulations of Al and Fe during the first 24 months of litter decomposition were 0.58 and 0.50 kg ha−1, respectively. By comparison, the net accumulation of N during the same period was approximately 3.43 kg ha−1. Evidence suggests that Al and Fe accumulation are controlled by abiotic adsorption on humified litter, whereas N retention is controlled by microbial immobilization.