Litter decomposition: Little evidence of the "home-field advantage" in a mountain forest in Italy

We tested the "home-field advantage" hypothesis, i.e., that leaves decay faster under the parent tree species in European beech, Douglas fir, and Turkey oak stands in a mountain forest in Italy. The fate of leaves in buried litterbags was monitored for one year to document their carbon (C) and nitrogen (N) dynamics, chemical structure, and associated microbial community. The three litter types lost C continuously at a similar rate, regardless of the species they were buried under. On the other hand, the N losses varied among litter types, and beech even gained a small but significant amount of N in the first 3-6 months. Differences between the litters were evident in the alkyl region of the nuclear magnetic resonance spectra and smaller in the aromatic and aryl acids regions. By the end of the experiment, all litters had lost substantial quantities of carbohydrates, lignin, proteins, and lipids, particularly oak litter. The richness and diversity of bacterial and fungal communities increased with time. Litter type had the greatest impact on microbial community composition in the first months of decomposition; afterwards, the stand type had a greater influence on the assemblage of decomposer microorganisms. Overall, this study provides little evidence in support of the home-field advantage hypothesis, which could be valid only for oak. Instead, our findings indicate that the chemical composition of litter is the main factor affecting the early stages of litter decomposition. Tree species and soil properties within the stand play an important role in the advanced stages of decomposition since these factors control the assemblage and functions of the soil microbial community.