Technical Comments

Response to Comment on “Unexpected reversal of C3 versus C4 grass response to elevated CO2 during a 20-year field experiment”

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Science  10 Aug 2018:
Vol. 361, Issue 6402, eaau1300
DOI: 10.1126/science.aau1300


  • Fig. 1 The CO2 effect on biomass in plots comprising C3 grasses and C4 grasses in relation to total biomass in ambient CO2.

    Biomass (aboveground + belowground, 0 to 20 cm) in ambient CO2 is shown for each year from 1998 to 2017 for plots comprising C3 grasses (open circles) and C4 grasses (solid circles); the CO2 effect on biomass is expressed as the difference in biomass between elevated and ambient CO2. Each point represents data pooled across N treatments and across monoculture and four-species plots (equally weighted) for each functional group (n = 22 plots for each functional group at each CO2 level) in each year. There was no relationship (P > 0.10) between the CO2 effect size and the ambient biomass for all data pooled or for either functional group alone.

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