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).