Measurements of microbial biomass, arthropods, and fungal community composition
Litter bags were retrieved and transported in individual plastic bags to the laboratory. For each litter bag, a small subsample of the remaining litter was taken and attached mineral soil was brushed off. Microbial biomass of that small subsample was analyzed using the substrate-induced respiration (SIR) method (Anderson et al . 1978). The microbial respiratory response was measured in an electrolytic O2microcompensation apparatus at hourly intervals for 24 h at 22 °C (Scheu 1992). Microbial biomass was measured after the addition of glucose to saturate the catabolic activity of microorganisms. The maximum initial respiratory response (MIRR: ml O2 g-1DW h-1) was calculated as the mean of the lowest three readings within the first 10 h and the microbial biomass for each litter bag was calculated as Cmic = 38 × MIRR (mg Cmic g-1 DW; Becket al . 1997). After measuring microbial biomass, soil arthropods were extracted from the entire remaining litter by heat and stored in saturated salt solution (NaCl) at -10 °C for further measurement and identification (Pausch et al . 2016). Soil arthropods were counted and identified to class level if possible by light microscopy. The vast majority of arthropods were Acari or Collembola. Fungal community composition in the remaining litter after 8 months were measured using ITS1-ITS2 barcoding primers to sequence the total fungal community (Supplementary Methodology S2), and we calculated the total abundance and Simpson diversity index for each litter bag (Rosenzweig 1995).