Fig. 2: Ratios of lignin oxidation (degradation) indices.
From: Climate warming and elevated CO2 alter peatland soil carbon sources and stability
Linear temperature response of lignin oxidation proxy acid-to-aldehyde (Ad/Al) ratio for (a) vanillyl (V), (b) syringyl (S), and (c) vanillyl and syringyl phenols in the surface peat (0–30 cm depth) following 4 years of warming and 2 years of elevated atmospheric CO2 concentrations. The ratios are plotted against average soil temperature measured at 0.3 m below the hollow surface from 2016 to 2018. Colours represent ambient (orange) or elevated CO2 (blue) treatment (n = 5 per treatment). Symbols represent different sampling depths. Lines indicate significant treatment effects p < 0.05. Linear regression with 95% confidence intervals is shown in grey. The absence of a line and/or confidence intervals indicates no significant trend.
