Fig. 1: C4 natural grass coverage estimated by the optimality model.
From: Mapping the global distribution of C4 vegetation using observations and optimality theory
a the ratio of C4 to C3 photosynthesis estimated by the optimality model (AC4/AC3) over global non-woody regions; (b) the relationship between observed C4 coverage (% of grassland) and estimated C4/C3 photosynthetic ratio by the optimality model. C4 coverage observation obtained from difference sources (i.e., TRY, DG datasets; please see methods); gray shaded area indicates the uncertainty range for the relationship between AC4/AC3 and C4 coverage (i.e., 95% confidence interval). The black line represents the regression using both the TRY and DG datasets, while the red and blue dash lines represent the regression using either the TRY or the DG dataset. c C4 grass coverage (% of grassland) over the globe, which can be regarded as the potential C4 area abundance when grassland covers 100% of the land surface; (d) C4 coverage in a climate space of mean annual temperature (MAT: °C) and mean annual precipitation (MAP: mm/yr).
