Litter chemistry explains contrasting feeding preferences of bacteria, fungi, and higher plants

Litter decomposition provides a continuous fow of organic carbon and nutrients that afects plant development and the structure of decomposer communities. Aim of this study was to distinguish the feeding preferences of microbes and plants in relation to litter chemistry. We characterized 36 litter types by 13C-CPMAS NMR spectroscopy and tested these materials on 6 bacteria, 6 fungi, and 14 target plants. Undecomposed litter acted as a carbon source for most of the saprophytic microbes, although with a large variability across litter types, severely inhibiting root growth. An opposite response was found for aged litter that largely inhibited microbial growth, but had neutral or stimulatory efects on root proliferation. 13C-CPMAS NMR revealed that restricted resonance intervals within the alkyl C, methoxyl C, O-alkyl C and di-O-alkyl C spectral regions are crucial for understanding litter efects. Root growth, in contrast to microbes, was negatively afected by labile C sources but positively associated with signals related to plant tissue lignifcation. Our study showed that plant litter has specifc and contrasting efects on bacteria, fungi and higher plants, highlighting that, in order to understand the efects of plant detritus on ecosystem structure and functionality, diferent microbial food web components should be simultaneously investigated.