Influence of Soil Animals and Metals on Decomposition Processes: A Microcosm Experiment
- Goran Bengtsson *,
- Maria Berden and
- Sten Rundgren
Metal pollution may reduce both the density and diversity of litter-and mor-living soil invertebrates. The consequences of this reduction for decomposition processes in coniferous forest soils were studied in a laboratory microcosm experiment, where the influence of soil fauna and metals were examined. Soil columns were prepared with litter, mor, and mineral soil, and the indigenous microorganisms from two field sites approximately 300 and 8000 m from a brass mill. The columns were used during a 10-wk experiment with enchytraeids and microarthropods added. Presence of animals increased C and N mineralization and enhanced leaching of dissolved organic C and nutrients by 20 to 30%. All of the reduced mass lost due to metal pollution and 20 to 35% of the reduction in leachate quantities of organic C and inorganic nutrients could be explained by reduced animal activity. The calculated decomposition rate constants predicted a delay in decomposition in the metal-polluted soil by a factor of 10. With five replicates, an 18% difference in mass lost due to a doubling of the background concentration of metals could be detected by the microcosm method with a probability of 0.90.
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