Fig. 3: Models of amino sugar responses to aridity index and soil C:N ratio. | Communications Earth & Environment

Fig. 3: Models of amino sugar responses to aridity index and soil C:N ratio.

From: Thresholds in aridity and soil carbon-to-nitrogen ratio govern the accumulation of soil microbial residues

Fig. 3

a, b Nonlinear responses of amino sugars to aridity index and soil C:N ratio. c, d Differences of predicted values of variables under aridity and soil C:N ratio thresholds. Data for each variable (a, b) are log-transformed. a, b Black, red, and blue solid lines represent the smoothed trendline fitted by the general additive model (GAM), and the linear fitting on the left and right sides of each threshold, respectively. Black numbers and vertical dashed lines describe the identified threshold. Violin graphs (c, d) show the bootstrap predictions for each variable on each side of each threshold (red plots: regression before the threshold; blue plots: regression after the threshold). Three asterisks indicate a significant difference according to the Mann–Whitney U-test before and after the threshold at p < 0.001.

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