Microenvironmental variability differently predicts microorganism‐ and fauna‐driven litter decomposition

Abstract Plant litter decomposition is a key process for ecosystem carbon and nutrient cycling. Growing evidence suggests that substantial variation in litter decomposition occurs at a fine scale, but the contributions of microorganism‐ and fauna‐driven decomposition to this variation, and the relative control of biotic and abiotic drivers over this variation remain virtually unexplored. To address this knowledge gap, we used a spatially explicit network of 113 evenly spread plots in a 9‐ha subtropical coniferous forest to evaluate the variation and controls of microorganism‐ and fauna‐driven decomposition at a scale where macroclimate, dominant vegetation and litter quality are kept constant. Despite keeping dominant decomposition drivers constant, the variation in decomposition was larger than that commonly reported in regional studies and amounted to ca. a third of the variation previously reported at a global scale. Furthermore, whilst abiotic factors including topographic conditions and soil fertility could explain 31% of the variation in microorganism‐driven decomposition, they could not explain any variation in the fauna‐driven decomposition, suggesting contrasting sensitivities of microorganism‐ and fauna‐driven decomposition activity to microenvironmental factors. Synthesis . Our study highlights the need to consider the local‐scale variation in litter decomposition rate using a spatially explicit approach, in order to better identify the factors driving the microbial and faunal pathways of organic matter turnover.