Main content area

Effects of experimental drying intensity and duration on respiration and methane production recovery in fen peat incubations

Estop-Aragonés, Cristian, Blodau, Christian
Soil biology & biochemistry 2012 v.47 pp. 1-9
carbon dioxide, fens, gas exchange, methane, methane production, peat, peat soils, soil respiration, soil water, temperature, water table
Drying and rewetting to a variable extent influence the C gas exchange between peat soils and the atmosphere. We incubated a decomposed and compacted fen peat and investigated in two experiments 1) the vertical distribution of CO₂ and CH₄ production rates and their response to drying and 2) the effects of temperature, drying intensity and duration on CO₂ production rates and on CH₄ production recovery after rewetting. Surface peat down to 5 cm contributed up to 67% (CO₂) and above 80% (CH₄) of the depth-aggregated (50 cm) production. As CO₂ production sharply decreased with depth water table fluctuations in deeper peat layers are thus not expected to cause a substantial increase in soil respiration in this site. Compared to anaerobic water saturated conditions drying increased peat CO₂ production by a factor between 1.4 and 2.1. Regarding the effects of the studied factors, warmer conditions increased and prolonged drying duration decreased CO₂ production whereas the soil moisture level had little influence. No significant interactions among factors were found. Short dry events under warmer conditions are likely to result in greatest peaks of CO₂ production rates. Upon rewetting, CH₄ production was monitored over time and the recovery was standardized to pre-drying levels to compare the treatment effects. Methane production increased non-linearly over time and all factors (temperature, drying intensity and duration) influenced the pattern of post-drying CH₄ production. Peat undergoing more intense and longer drying events required a longer lag time before substantial CH₄ production occurred and warmer conditions appeared to speed up the process.