Boreal forests are among the best-studied ecosystems in terms of litter decomposition and mineralization. In these forests - and in forest ecosystems in general - litterfall is the largest source of soil organic material, in that it can account for more than 50% of net primary productivity (NPP). Due to the low energy environment (low temperature and solar radiation), litter decomposition in boreal forests is slow. In these environments, the initial leaching from leaf litter is generally slow, while microbial degradation is the major decomposition process. The chemical changes of litter biomass in boreal forests have been well documented. The concentrations of N, P, S, Fe, Pb, Cu, and Zn in litter increase with time during decomposition. However, these relationships are empirical and have not been fully explained. The concentration of K normally decreases with time until it reaches a minimum value, and, then, it slowly increases, probably due to the fact that K is the most mobile element among all plant nutrients and its leaching may start as soon as the trees shed their leaves. Mg is another mobile nutrient and its leaching pattern is similar to that of K, though at a slower pace. Ca concentration usually increases in the early stage of decomposition until it reaches a maximum value, and then it decreases. The concentration of Mn, in contrast to most of the other elements, decreases almost linearly throughout the decomposition process.
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