Green tree retention enhances negative short-term effects of clear-cutting on enchytraeid assemblages in a temperate forest

We studied the response of enchytraeid (Annelida: Oligochaeta) community structure to different forest management treatments via an open-field forestry experiment in a managed sessile oak-hornbeam forest in Hungary. The applied forestry treatments were 1) clear-cutting 2) clear cutting with a small patch of retention tree group, 3) gap-cutting, 4) preparation cutting and 5) control (closed mature stand). Our questions were: how did the selected forestry treatments influence the abundance and species richness of enchytraeids two years after the intervention, and how could the worms compensate the altered environmental conditions by vertical movements in topsoil layers (0–12 cm). The effects of the treatments on the species composition of the assemblages and species-specific responses were also analysed. Two years after the treatments, a strong response of enchytraeids was observed in clear-cutting and even more in retention tree group: in both treatments the abundance and the species richness of enchytraeids were reduced. Species did not show vertical movements into deeper layers and were not able to tolerate the altered soil conditions caused by changed microclimate. Gap-cutting and preparation cutting did not differ significantly from control plots. Our study showed that right after the interventions tree retention at the size of one tree height in diameter had no sheltering effect on this important soil decomposer animal community. These results are in contrast with earlier findings in boreal zones, where soil organic layer is considered a well buffered habitat against environmental changes. Oppositely, enchytraeid assemblages in a temperate deciduous forest are more diverse but seem more vulnerable to management-related alterations in soil conditions (soil temperate increment, reduced soil moisture).