Abstract
Arbuscular mycorrhizal fungi (AMF) have been shown to positively and negatively affect plant litter decomposition. The use of litter types with different quality and different observation periods might be responsible for these contradictory results. Therefore, we performed a 10-week laboratory experiment with 7 litter types differing in their C:N ratio, and tested for effects of litter quality and the presence of AMF on litter decomposition. We found that decomposition of plant litter with higher C:N ratios was only beginning and was stimulated by AMF, whereas decomposition of plant litter with lower C:N ratios had already progressed and was decreased by AMF. With this study we show that not only litter quality is important for effects of AMF on litter decomposition, but also the stage of litter decomposition.
