Soil microorganisms at the windthrow plots: the effect of post-disturbance management and the time since disturbance

Wind disturbance is a major natural driver of forest dynamics in a large part of Europe and can affect soil properties in different ways and for different time. The present study focuses on the effects of post-disturbance management of windthrow plots in the Tatra Mountains, Slovakia, on soil microorganisms ten years after the disturbance. Their comparison with the microbial characteristics at a new windthrow plot caused by strong wind in 2014 was also carried out. Three research plots differing in the way of their management after the windstorm in 2004 (EXT, salvage plot; FIR, salvage plot affected by fire; NEX, unsalvaged plot) and the plot destroyed by strong wind in May 2014 (REX) were used for study. Ten soil samples were taken from the mineral A-horizon (depth: 0-10 cm) at each plot in autumn 2014. In soil samples, soil chemical and microbial characteristics (microbial biomass C, basal and substrate-induced respiration, N-mineralisation, catalase activity, richness and diversity of soil microbial functional groups based on the Biolog approach) were determined. Ten years after the disturbance we still observed significant differences in microbial characteristics between FIR and the other plots, with higher microbial activity at the FIR, while no significant differences were found among the other plots. The results indicate that at a higher altitude the effect of fire on soil microorganisms is more distinct than removing or not removing of fallen trees and persists even over a decade.