Indirect effects of precipitation on litter decomposition of Quercus mongolica

The effect of precipitation variation on chemistry of Quercus mongolica leaf litters was examined by analyzing litters of Mongolia oak saplings under 4 precipitation gradients, and the decomposing process of these leaf litters in Q. mongolica dominated forest was assessed using litter bag method. The results showed that under less precipitation, the litter had a higher decomposition rate, and its N, P and K mineralized quickly. The initial concentrations of N, P, and K increased, while that of lignin decreased significantly. With increasing precipitation, the mineralization rates of N, P and K in litter decreased. Its initial N concentration decreased, while the relative content of lignin increased. The mass loss patterns of four type litters fitted exponential model, and the decomposition rate could be well predicted by their lignin/N ratio. The decomposition rate of the litters with higher lignin and lower N was best related to their N concentration, while that of the litters with lower lignin and higher N was strongly correlated with their lignin concentration. It was proved that precipitation had a significant effect on the litter substrate quality of Q. mongolica, and thus, changed the decomposition process of the litter indirectly.