Foliar litter is the main input of organic C into forest soils and litter decomposition is one of the most important processes determining the amount of organic C remaining in the forest floor. Soil and site properties are crucial for litter decomposition. They determine the composition of the leaves which, in turn, affects its decomposition. Furthermore, litter decomposition depends on environmental conditions like temperature and precipitation. The complex interactions between these manifold properties did often not allow to quantify effects of the parent soil material on litter decomposition although it affects both properties of the leaves and the dynamic of soil processes. In our study we aimed to quantify the effect of the parent soil material on decomposition of different types of litter. We wanted to distinguish between direct effects of the parent soil material and indirect effects caused by tree nutrition and therefore by different composition of the litter. Therefore, we collected different types of litter (beech, hornbeam, maple) from two sites where soils developed from granite and basalt. Then, each type of litter from each site was exposed in the field at the granite and the basalt site for up to 18 months. Mass loss and contents of nutrients were analyzed in the litter bags after 2, 4, 6, 9, 12, and 18 months. We found significant effects of litter species and the parent soil material. Hornbeam litter was degraded faster than maple litter. Beech litter was the most stable one. In most cases litter derived from the basalt site was faster decomposed in comparison to litter from the granite site. However, we found the opposite for maple litter. From our results we conclude that direct effects of the parent soil material are more important on litter decomposition than indirect effects via affected leaf properties.
