Ecology: Concepts and Applications 4th Edition by Manual Molles

Exercise 3

In chapter 6, we emphasized how the C 4 photosynthetic pathway saves water, but some researchers suggest that the greatest advantage of C 4 over C 3 plants occurs when CO 2 concentrations are low. What is the advantage of the C 4 pathway when CO 2 concentrations are low? As we shall see in chapter 23, the atmospheric concentration of CO 2 has been increasing for the last century or so. If this trend continues, and if the interactions between C 4 and C 3 plants are influenced by atmospheric CO 2 concentrations, how might the geographic distributions of C 3 and C 4 plants change?