Hongxin Dong, Priming effects of surface soil organic carbon decreased with warming: a global meta-analysis
Priming effects of surface soil organic carbon decreased with warming: a global meta-analysis
Plant Soil，23 December 2022
Climate warming can potentially cause more plant-derived organic substrates into the surface soil. The newly produced carbon may accelerate or restrict native soil organic carbon (SOC) decomposition by priming effects (PE), so as to increase the uncertainty of the feedback prediction between climate change and soil carbon pool. However, it is controversial about the direction and driving factors of the PE of surface SOC in the warming world.
In this meta-analysis, we investigated 1680 pairwise PE determined by 13C or 14C isotope labeling method in surface soils across cropland, grassland and forest from 39 warming experiments to generalize the direction and influencing factors of the warming effects on PE.
The meta-analysis showed that warming decreased PE across different ecosystems. The decrease was much greater in forest (effect size: -6.2) than in cropland (effect size: -2.6) and grassland (effect size: -1.7) and was more severe in simple substrates (effect size: -12.1), i.e., small molecules such as glucose and amino acid than that in complex substrates (effect size: -1.7), including plant tissues, residues and pyrolysis products, etc. The effect size of warming on PE was positively correlated with soil clay and pH, while negatively correlated with SOC content, total nitrogen, soil C/N ratio and warming intensity.
These findings emphasize that warming will decrease the primed surface SOC loss, particularly in forest or organic matter-rich soils and larger warming intensity.