Litter decomposition along a primary post-mining chronosequence

The aim of this study was to describe the decomposition of litter along a successive series of sites developed at a post-mining overburden deposit over 12, 21 and 45 years, representing the early, mid and late stages of succession. Litter decomposition was largely dependent on the initial composition of the litters. The tree litter of the mid and late stages decomposed faster than the grass litter of the early stage, with 64, 60 and 35 % of mass lost over 2 years, respectively. The contents of hot-water-soluble C and N, which were the best predictors of litter decay rates, were relatively stable over time in all litters. Neither the nutrient content nor the plant biopolymer composition exhibited convergence during decay, indicating that the litter-derived soil organic matter most likely carries a legacy of the original vegetation. In contrast to the litter chemistry, the development of the microbial community was largely specific to the decay stage and consistent among the litters, showing decreasing fungal dominance in time. Extracellular enzymes were found to be of limited value in the prediction of litter decay rates, chemical transformation or microbial community composition.