Short-term and long-term effects of bacterivorous nematodes and nematophagous fungi on carbon and nitrogen mineralization in microcosms

摘要

A microcosm experiment was carried out to quantify the effects of organisms at various trophic levels on C and N mineralization after the addition of crop residues to arable soil. The effects of the bacterivorous nematodesRhabditissp. andAcrobeloides bütschliiand of the nematophagous fungiArthrobotrys oligosporaundDrechmeria coniosporaon soil respiration and N mineralization were measured over 6 months at 20°C. In the presence of nematodes, C mineralization was increased during the first month and subsequently reduced; N mineralization was increased during the first 2 months and then reduced. The results support the assumption that nematodes influence C mineralization mainly indirectly by affecting bacterial activity, and N mineralization mainly directly by mineralizing bacterial biomass.A. oligosporacontributed directly to C mineralization. The effect of both fungi on N mineralization was indirect and resulted from the reduction in the numbers of nematodes. The results showed that the effects of nematodes and nematophagous fungi and the mechanisms behind the effects may vary strongly in time, and are correlated with the type of organic matter decompose