Responses of soil decomposer animals to wood-ash fertilisation and burning in a coniferous forest stand

Responses of soil decomposer animals (enchytraeids and microarthropods) to wood-ash fertilisation (1000 and 5000 kg ha(-1)) and a fire treatment mimicking prescribed burning were studied in a Scots pine stand in central Finland. The experiment was conducted on 30 x 30 m(2) plots, each treatment being replicated four times. Soil animals were sampled throughout the growing season in the third year lifter the treatments. As a rule, numbers of soil animals increased during the study period. Numbers of the only enchytraeid worm species found at the study site, Cognettia sphagnetorum, were lower in the plots with higher ash level and plots which have been burned. In the plots having these treatments, enchytraeid populations increased during the study period. Total numbers of microarthropods were decreased in the plots which had received the most drastic treatments: the higher ash level and burning. Only five species of collembolas responded significantly to these treatments. Multivariate analyses showed, however, significant changes in the collembola community structure of all the treatments. Overall, soil fauna seemed to be quite resistant and resilient against unpredictable disturbances, like ash fertilisation and prescribed burning, the thick humus layer being a major buffer against chemical and physical changes. (C) 2000 Elsevier Science B.V. All rights reserved.