Ecological properties uniquely dictate molecular-level soil organic matter composition in a temperate forest in Central Europe with variation in litter deposition.

Global climate change has increased temperatures and elevated atmospheric CO₂ concentrations in many forests, which can impact plant productivity. This changes both the quantity and quality of litterfall and root inputs to soil organic matter (SOM) and alters soil carbon (C). This study examined how litter exclusions (No Litter, No Roots, and No Inputs) and additions (Double Litter and Double Wood) altered soil C dynamics and SOM composition. Soil samples were collected from a temperate forest in Hungary (the Síkfőkút Experimental Forest) after 20 years of experimental litter manipulation. Elemental analysis, targeted SOM compound techniques, nuclear magnetic resonance (NMR) spectroscopy and microbial biomass and community composition measurements were used to characterize alterations to SOM stabilization and destabilization processes. Our results contrast other similar long-term detrital manipulation experiments of the same timeframe, with increases in soil C for both Double Litter and Double Wood, and evidence for enhanced microbial decomposition still occurring. In North America, aboveground inputs are more influential for soil C stabilization in coniferous forests, while belowground inputs are more important in temperate forests. However, this temperate forest in Central Europe is unique in that the specific ecological properties (such as litter quality, mean annual temperature and precipitation) dictated these processes instead. This highlights the differing responses detrital manipulation to forest soils across varying climatic and edaphic gradients and the sensitivity of SOM composition to changes in detrital inputs in different ecosystems.