Fig. 5
From: Stomatal conductance limited the CO2 response of grassland in the last century
Effect of spring meteorology on δ18Ocellulose. Relationship between δ18Ocellulose deviation from period mean and accumulated annual precipitation (a), average vapor pressure deficit (VPD) (b), average relative humidity (RH) (c), and average temperature (d) during the spring growing period (1 April to 30 June). δ18Ocellulose deviation values represent the difference between yearly averages of all samples from grass-rich or dicot-rich treatments and their respective 15-year averages during period 1 (1917–1931, filled circles) and period 2 (2004–2018, empty circles). The continuous lines and the shadowed areas indicate the regression line for the relationship ± CI95%