Geography – Vegetation and soils in arid environments | e-Consult

Answer: C3 and CAM plants represent fundamentally different strategies for coping with drought. The key difference lies in their photosynthetic pathways and stomatal regulation.

C3 plants are the most common type of plant. They fix carbon dioxide directly in mesophyll cells during the day when stomata are open. This leads to photorespiration, a process that wastes energy and water. During drought, C3 plants often close their stomata to reduce water loss, but this also limits CO2 uptake, slowing down photosynthesis. Advantages of C3 plants include efficient photosynthesis when water is available and relatively fast growth rates. Disadvantages are their susceptibility to photorespiration and reduced photosynthetic rates during drought.

CAM plants have evolved a mechanism to overcome the limitations of C3 photosynthesis in arid environments. They open their stomata at night to take in CO2, which is then stored as an organic acid. During the day, stomata close, and the stored CO2 is released for photosynthesis. Advantages of CAM plants are their ability to minimize water loss and maintain photosynthetic rates during drought. Disadvantages include slower growth rates due to the slower rate of CO2 uptake and the energy cost of storing and releasing CO2.

Here's a comparison table:

In conclusion, both C3 and CAM plants have evolved effective strategies for drought survival, but they differ in their mechanisms and trade-offs. The choice of strategy is influenced by the specific environmental conditions and the evolutionary history of the plant species.