Fungal traits help to understand the decomposition of simple and complex plant litter

Litter decomposition is a key ecosystem process, responsible for the release and storage of nutrients and carbon. Soil fungi are one of the dominant drivers of organic matter decomposition, but fungal taxa differ substantially in their functional ability to decompose plant litter. We used a trait-based approach to better understand functional differences among saprotrophic soil fungi (originating from a natural grassland ecosystem) in decomposing leaf and wood litter. Decomposition strongly varied among phyla and isolates, with Ascomycota decomposing the most and Mucoromycota decomposing the least. In this study, the phylogeny of the fungi in our dataset, but also the ability of fungi to use more complex carbon were important predictors for decomposition. While some enzymes (e.g. laccase and cellulase) influenced decomposition, the majority of enzyme activities was not correlated with decomposition. Thus, we suggest using more directly assessed traits as predictors for decomposition, such as the ability to use carbon substrates, rather than a single enzyme activity, which could misrepresent the degradation potential of certain isolates. The findings of our study offer important new insights for the trait-based prediction of fungal litter decomposition in grassland soils.