Tree diversity regulates soil respiration through elevated tree growth in a microcosm experiment

Soil respiration is an essential component of carbon (C) cycling in terrestrial ecosystems. Despite increasing awareness of the significance of aboveground-belowground interactions, little is known about tree diversity effects on soil respiration and the underlying mechanisms. Here, we conducted a 105-days microcosm experiment in a climate chamber to test the effects of tree diversity (1, 2, and 4 species) on soil respiration. We expected tree diversity to affect soil respiration through changes in tree growth and surface litter decomposition (indicated by the litter mass loss). Our results show that soil respiration varied among the four focal tree species and increased with tree species richness. Path analysis revealed tree growth as the main mechanism driving soil respiration and explaining the tree diversity effect in this short-term experiment. Our results indicate that tree diversity and particular tree traits regulate C dynamics through balancing C storage (plant productivity) and C release (soil respiration).