Decomposition of Quercus petraea litter: influence of burial, comminution and earthworms

Litter bags containing one of the following: earthworm cast, intact oak litter (Quercus petraea Matt., Liebl.) plus soil and shredded oak litter (<2 mm) plus soil, were placed on the surface or buried at 7 cm in a forest soil. Over a 2-year period the six treatments were sampled on nine dates and analysed for mass loss, moisture content, C, N, bacterial numbers, fungal hyphal lengths, FDA and mineralization rates (evolution of CO2). orm casts (surface and buried) had reduced moisture fluctuations relative to non-cast (intact or shredded) treatments. Casts maintained higher levels of organic matter and carbon than non-cast treatments (surface or buried) after 2 years of decomposition. However, while both surface and buried casts maintained higher levels of organic matter, bacterial counts in buried cast remained higher than all other treatments (including surface cast) on five of the seven final sampling dates. ing and burial of organic matter did not affect total, cumulative loss of organic matter/carbon from the non-cast treatments. Potential mineralization rates (loss of CO2 at 20°C) from non-cast treatments was influenced by their placement. When temperature and/or moisture became limiting surface non-cast treatments showed reduced losses of CO2 by comparison with buried non-cast treatments. The reverse occurs when the moisture and temperature are not limiting, i.e. surface treatments have greater losses of CO2 than the buried treatments. Thus, both the micro-climatic and soil aggregate effects (and their interactions) were observed to influence the decay dynamics and are discussed in relation to nutrient stabilization/mobilization and microbial populations.