Fig. 7.3.

How does a mixing model work? Example of a one-isotope mixing model using δ13C to estimate the importance of C3 trees/shrubs and C4 grasses to a hypothetical grasshopper species. Three possible scenarios are presented: (a) the grasshopper feeds exclusively on C4 grasses, so its δ13C, after correction using appropriate trophic discrimination factors, fully overlaps with that of C4 grasses; (b) the grasshopper diet is 80% C3 trees/shrubs and 20% C4 grasses, so its corrected δ13C is closer to C3 plants; and (c) the grasshopper feeds equally on both C3 and C4 plants, so its corrected δ13C is halfway between the δ13C values of the two potential sources.