Fig. 2: Soil warming effects on ¹⁴C values and rates of soil CO₂ efflux during the dry and wet season in 2019.

a ¹⁴C of respired CO₂ from single time-point measurements for n = 2/plot (total n = 10). The mean Δ¹⁴C value of air samples collected from the sites in this study in 2019 was −4 ± 3‰ and is indicated by the dotted reference line (mean) and gray shading (±standard error). Effects of experimental warming and season were tested using a three-way repeated measures ANOVA with collar type, treatment, and season (Supplementary Table 2). This test indicated a significant treatment by season interaction (p = 0.02), and a multiple comparisons test with a Holm adjustment indicated a significant effect of experimental warming in the wet season (p = 0.03) but not in the dry season (p = 0.33). b Monthly average total soil-respired CO₂ flux for March and October 2019 (n = 5 paired plots). Effects of experimental warming and season were tested using a two-way repeated measures ANOVA with treatment and season (Supplementary Table 3). This test indicated significant main effects for treatment (p = 0.03) and season (p = 0.03). The figures show plots warmed by +4 °C (WARM) and controls (CTRL). Solid lines indicate medians, dashed lines indicate means, ends of boxes show the upper (Q3) and lower (Q1) quartiles, whiskers indicate minimum and maximum ranges (calculated from quartiles), solid points are individual observations. Asterisks indicate statistically significant differences between control and warmed plots where p ≤ 0.05 whereas NS indicates non-significant differences (p > 0.05).