Four years of litter input manipulation changes soil microbial characteristics in a temperate mixed forest

Abstract

Aboveground litter not only is an important source of nutrients to soil microbes but also regulates the microclimate in topsoil. How the changes in aboveground litter quantity would affect the microbial biogeochemical cycles is still unclear. Here we conducted a litter input manipulation experiment in a temperate mixed forest to investigate how different amounts of litter input affect soil organic carbon (SOC) and soil respiration via their regulation on soil microbes. We found that although neither SOC stock nor soil CO2 efflux was affected by litter manipulation, soil microbial characteristics had responded after four years of litter addition or removal treatments. Microbial biomass carbon (MBC) in the O horizon was higher in litter addition plots than in litter removal plots as a result of the changed availability of labile C under litter treatments. Both double litter and no litter treatments changed microbial compositions, which was probably due to the increased soil pH in no litter treatment and the increased labile C in double litter treatment. The null change in soil respiration could be attributed to the offset between the negative effect of decreased substrate and the positive effect of increased temperature on soil respiration in litter removal plots. Due to the important role of soil microbes in carbon cycling, the altered microbial properties under litter manipulation treatments suggested the inevitable changes in biogeochemical cycling in the long run and call for long-term studies on SOC dynamics in the future.