Community composition of soil microarthropods of acid forest soils as affected by wood ash application

The responses of soil microarthropod communities of acid forest soils to wood ash-application was studied both in a sixty years old pine forest stand (wood ash dose: 3000 kg ha(-1)) and in laboratory microcosms (wood ash dose: 5000 kg ha(-1)). We also tested whether microarthropod communities stressed with wood ash were more sensitive to an additional disturbance, drought, than the microarthropod communities in the ash-free soil. Microarthropods were sampled five times during the field experiment and four times during the laboratory experiment. At each sampling the abundance and community structure of microarthropods were analysed. In the field the number of collembolans, and in the laboratory the number of mesostigmatid mites decreased after ash-treatment. Although in both experiments the number of oribatid mite species was lower in the ash-treated than in the control soil, principal component analysis revealed no changes in the community structure of micro arthropods after the ash application. Drought had no influence on soil microarthropods. It is concluded that soil microarthropods, at least at the community level, are rather resistant to substantial changes in soil pH even though changes at the species level can take place, and that microarthropods stressed with wood ash are not more susceptible to other disturbance (drought) than microarthropod communities in the ash-free soils.