The effect of microarthropods on litter decomposition depends on litter quality

• Mesofauna assemblages were interchanged among three litter types in microcosms.
• Microarthropod density and litter mass loss were detected after 3 and 12 months.
• Density of mesofauna depended on litter type irrespective of their origin.
• Origin of mesofauna influenced pine litter decomposition.
• Decomposition of oak litter depended on microarthropod density.

Many studies have investigated whether microbiota has been adapted to decompose a given litter type but we have limited information about the specific role of microarthropods in litter decaying processes. This experiment studied functional redundancy of microarthropods in a litter decomposition system by interchanging mesofauna among three different litter types. The study hypothesized that total microarthropod densities would be lower in foreign litter type than in original (‘home’) litter; and litter with foreign mesofauna would decompose slower than with native one. Scotch pine (Pinus sylvestris), Turkey oak (Quercus cerris) and black locust (Robinia pseudoacacia) litter were stored in microcosms with original microbiota. Microarthropods from the same (‘home’) or different (‘foreign’) type of litter were inoculated to microcosms. Litter mass loss and total density of collembolans, oribatid and other mites were recorded at the end of incubation (3 and 12 months). Litter quality determined total density of microarthropods irrespective of the origin of animals. Litter mass loss values differed in the three litter types. For pine litter, the origin of microarthropods had significant effects on litter mass loss. In oak litter, mainly microarthropod density influenced decomposition. Neither the origin nor the density of animals influenced the decomposition rate of black locust litter. Litter quality may have determined the different patterns of decaying. Mesofauna may enhance litter decomposition stronger in recalcitrant litter than in high-quality litter.