Fig. 4: Correlations (r) between SOC molecules and biogeochemical drivers.

Pearson correlations between the total sum of solvent-extractable compounds (free lipids), hydrolysable compounds (ester-bound lipids), cutin and suberin monomers, pyrogenic carbon, and lignin phenols (mg g peat⁻¹) and biogeochemical predictors soil organic carbon concentration (SOC; mg g peat⁻¹)^17,43, nitrogen concentration (soil N; mg g peat⁻¹)⁴³, carbon:nitrogen ratio (soil C/N; mg g peat⁻¹)⁴³, net primary productivity (NPP; g C m⁻² year⁻¹)¹⁷, aboveground net primary productivity (ANPP; g C m⁻² year⁻¹)¹⁷, fine-root biomass (g m⁻²)¹⁶, and maximum distance to the water table (water depth; cm)^17,47 in the surface peat (0–30 cm depth) following 4 years of warming and 2 years of elevated atmospheric CO₂ concentrations. Corrected significance at p < 0.05 is represented with *p < 0.01 is represented with **, and p < 0.001 is represented with ***. The maximum distance (value) to the water table (relative to the hollows) was assessed from 2016 to 2018. The maximum values occurred in late summer (mid‐August to mid‐September). Additional descriptions of biogeochemical predictors and any data transformations are provided in the Methods.