Ecology 5th Edition by Manuel Molles

Exercise 10

In chapter 7, 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 ₂concentrations are low. What is the advantage of the C 4 pathway when CO ₂concentrations are low? As we shall see in chapter 23, the atmospheric concentration of CO ₂has 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 ₂concentrations, how might the geographic distributions of C3 and C4 plants change?