Fig. 4: The contribution of C4 vegetation to global photosynthesis.
From: Mapping the global distribution of C4 vegetation using observations and optimality theory
The emergent constraints between the percentage of area occupied and the percentage of global photosynthesis contributed by (a) C4 natural grasses and (b) C4 crops, based on the estimates from an ensemble of the DGVMs; c changes in emergent constraint coefficients (i.e., the slopes of the linear regressions in (a, b) from 2001 to 2019 for C4 natural grasses and C4 crops). The uncertainties in (a, b, c) were quantified as one standard error (i.e., SE) by bootstrapping models when getting emergent constraint; d The contributions of C4, C4 natural grasses and C4 crops to global GPP from 2001 to 2019, whereas the uncertainty was quantified as one SE by bootstrapping the uncertainty range of C4 areas and the uncertainty range of the emergent constraint coefficients.
