Reactions to soil acidification in microarthropods: Is competition a key factor?

摘要

Acidification of raw humus soil in coniferous forest areas leads to characteristic changes in the microarthropod community. Certain species are “calciophilic” and decrease in abundance, while others are “acidophilic” and increase in abundance. The simplest explanation for these changes is that population levels are directly related to soil pH. This hypothesis was tested by growing small populations of selected species in monoculture at different pH levels. Three acidophilic species were tested, the collembolanMesaphorura yosii, the oribatid miteNothrus silvestris, and the astigmatid miteSchwiebeacf.lebruni. A slightly calciophilic collembolan,Isotomiella minor, was also included. For all species, population growth was lowest in acidified raw humus. Even acidophilic species seem to have an optimum at a high pH. It is assumed that their success in low-pH soils is due to their ability to compete under these conditions. Competition may be a key factor in microarthropod reactions to soil acidif