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Nitrogen (N) exerts strong effects on litter decomposition through altering microbial abundance and community composition. However, the effect of N addition on plant–soil interactions such as home-field advantage (HFA: enhanced decomposition at a home environment compared to a guest environment) in relation to litter decomposition remains unclear. To fill this knowledge gap, we conducted a reciprocal litter transplant plus N addition experiment in Mytilaria laosensis and Cunninghamia lanceolata plantations for two years in subtropical China where anthropogenic N input is amongst the highest in the world. We found positive HFA effects (in which the calculation incorporates litter of both species) with litter mass loss 11.2% faster at home than in the guest environment in the N addition (50 kg N ha−1 yr−1) treatment, but no significant HFA effects were found in the control treatment. The magnitude of the HFA effect on carbon (C) release increased with N addition, while that on N release decreased. The HFA effects on phosphorus, potassium, calcium, sodium, and magnesium release were positive overall, but varied through time and the magnitude of the effects were different among elements. The greater HFA effects in the N addition treatment were associated with greater differences in microbial biomass and community composition between home and guest environments than in the control treatment. Our results indicate that anthropogenic N enrichment could lead to enhanced HFA effects, through modification of microbial communities, and thereby affect C sequestration and N cycling in subtropical forests.

We investigated microbial biomass and composition (lipid profile), mineral N pools and soil physicochemical parameters in the top 5-cm soils 19 years after reforestation of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) woodland with itself or a native broadleaf species, Mytilaria laosensis. The results suggested that tree species transition had a large impact on microbial biomass and a small impact on the composition of the microbial community as indicated by the relative abundance of individual lipid biomarkers. Between November 2011 and October 2012, there was on average 50% greater microbial biomass carbon (C) measured by the fumigation extraction procedure under M. laosensis than under C. lanceolata. A one-time measurement of phospholipid fatty acids in soil samples collected in May 2012 suggested M. laosensis plots had greater content of individual lipid biomarkers than C. lanceolata plots. Using a litter manipulation experiment, we found that the increases in content of lipid biomarkers under M. laosensis can be attributed to changed litter chemistry. Analysis of soil mineral N pools indicated that there were significantly lower NH 4 + and NO 3 − pools as well as potential net N mineralization rates in M. laosensis soil than in C. lanceolata soil. The relationships among N dynamics, soil chemistry and microbial properties were analysed. The results suggested tree species induced differences in soil N mineralization rates and mineral N pools were related to labile C availability, soil C:N ratio and the composition of the microbial community. Our data of mineral N pools and soil δ15N implied that the transition of land use from C. lanceolata to M. laosensis leads to an enhanced N retention in the plantation.