Carbon isotope trends across a century of herbarium specimens suggest CO2 fertilization of C4 grasses

• DOI: 10.1111/nph.19868
• Publication Date: 2024-05-30T06:19:11Z
• Authors: Isa del Toro; Madelon F. Case; A. Tyler Karp; Jasper A. Slingsby; A. Carla Staver
• Keywords: Carbon fibers

Summary Increasing atmospheric CO 2 is changing the dynamics of tropical savanna vegetation. C 3 trees and grasses are known to experience fertilization, whereas responses by 4 more ambiguous. Here, we sample stable carbon isotope trends in herbarium collections South African reconstruct 13 discrimination. We found that showed no discrimination over past century but increased their through time, especially since 1950. These changes were most strongly linked rather than rainfall climatology or temperature. Combined with previously published evidence grass biomass has ‐dominated savannas, these suggest increasing water‐use efficiency due fertilization may be plant–water relations. thus a neglected pathway for anthropogenic global change ecosystems.