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RESEARCH PRODUCT

Interactions between enchytraeid (Cognettia sphagnetorum), microarthropod and nematode populations in forest soil at different moistures

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Abstract Very little is known about the effects of microclimatic conditions on interactions within soil faunal communities. The aim of the experiment was to examine how the different functional components of the faunal community in coniferous forest soil affect each other at different moisture levels. Forest humus was defaunated by heating, adjusted to three water contents, distributed into glass jars and reinoculated with microflora and microfauna. Sets of 10 jars were inoculated with (1) Cognettia sphagnetorum, (2) Cognettia with Folsomia candida (Collembola), (3) Cognettia with a mixed community of microarthropods, (4) Folsomia alone, (5) mixed microarthropods alone, and (6) Cognettia with large gamasid mites (predators). The microcosms were incubated at +16°C and destructively sampled after 8 and 18 weeks. Microarthropods (mixed community) reduced the numbers of Cognettia. Folsomia showed a variable effect on enchytraeids, depending on time and moisture. Predatory mites had no effect on enchytraeid numbers. The presence of Cognettia, in turn, showed no effect on Folsomia, total Acari or Collembola, nor on individual species. The numbers of nematodes were highest with Cognettia alone. In the presence of Folsomia the nematode populations were greatly depressed, especially at medium and high moistures. Folsomia increased the amount of NH+4 in the soil, but otherwise there were no consistent differences between the treatments in terms of N mineralisation.