Changes in Substrate Composition during Decomposition

Abstract

The mass loss of the organic compounds appears to be selective with water solubles degraded (or leached) first, followed by cellulose and hemicelluloses. For these compounds, the concentrations decrease or remain about constant whereas that of Acid Unhydrolyzable Residue (AUR)/lignin increases as decomposition proceeds. In general, it appears that concentrations of the main nutrients nitrogen (N), phosphorus (P), and sulfur (S) increase. For N, the concentration increases irrespective of changes in absolute amount. Also, concentrations of the main heavy metals increase (e.g., copper (Cu), lead (Pb), and iron (Fe). In contrast, as potassium (K) is leached its concentration decreases heavily. The concentration changes for nutrients such as calcium (Ca), magnesium (Mg), and manganese (Mn) appear to have variable patterns with Mn concentrations decreasing over the early stage whereas it increases in the late stages. A special study on Mn concentrations and Mn release in pine and spruce litter indicated a clear difference between the two genera.