Drying-rewetting events reduce C and N losses from a Norway spruce forest floor

摘要: Abstract Periods of prolonged summer drought are likely to be expected for this century, with possibly strong effects on carbon (C) and nitrogen (N) mineralization in soils. Drought generally reduces rates, but the possibility excess pulses during rewetting raises question about net effect drying–rewetting events. In experiment, we measured C N undisturbed soil columns that were either kept under continuously moist conditions (control) or subjected drying-rewetting. We had three treatments (D1–D3) different drying intensity (increasing from D1 D3) uniform (4 mm d−1). Soil taken a Norway spruce forest Bavaria, Germany. The CO2 fluxes control treatment groups identical before drying. Over 80 d period, total emissions D1, D2, D3 only 72, 52 43% control, respectively. Rewetting resulted fast increase approx. same level as control. could not restore moisture dry presumably because preferential flow water repellency organic matter. No significant 40 d period was observed. Adding up emitted 88, 71 67% by Measurements dissolved (DOC) did show minor differences between columns, indicating no accumulation DOC took place period. Radiocarbon signature indicated reduced decreasing availability new substrate became bioavailable. Net over course whole experiment 77, 65 52% nitrification virtually zero whereas ammonification continued at levels. summary, found reduction increased intensity.