Dispersal of bacteria and stimulation of permafrost decomposition by Collembola

Abstract. Contrary to most soils, permafrost soils have the atypical feature of being almost entirely deprived soil fauna. Abiotic constraints on fate carbon after thawing are increasingly understood, but biotic remain scarcely investigated. Incubation studies, essential estimate effects thaw cycling, typically measure consequences in isolation from topsoil and thus do not account for altered interactions because e.g. colonization by Microarthropods facilitate dispersal microorganisms soil, both their cuticle (ectozoochory) through digestive tract (endozoochory), which may be particularly important considering that microbial community composition can strongly constrain biogeochemical processes. Here we tested how a model species microarthropod (the Collembola Folsomia candida) affected aerobic CO2 production over 25 d incubation. By using stock cultures grown or an arctic topsoil, aimed assess potential endo- ectozoochory bacteria, while gypsum sprayed with suspensions would allow observation only ectozoochory. The presence introduced bacterial amplicon sequence variants (ASVs) absent no-Collembola control, regardless microbiome manipulation, when presence–absence metrics (unweighted UniFrac metrics), resulted increased richness. However, these ASVs did induce changes as whole (accounting relative abundances, weighted UniFrac), might become detectable longer term. was 25.85 % Collembola, about half could attributed respiration based rates measured absence soil. We argue rest respired considered priming effect i.e. stimulation active decomposers. Overall, our findings underline importance processes need explore additive interactive other food web groups deprived.