Several studies on the mechanisms of acclimation in C3, C4 and CAM plants to global changes such as temperature and CO2 level fluctuations are extensively discussed. There is no distinct separation on the reported effects between the three pathways due to the involvement of many factors when studying climate change and the distribution of species in biomes of varied climate patterns; lack of data and understanding of the concepts in climate change is often cited by researchers. Though if we were to generalize a specific pathway of photosynthesis as being the most positively associated with climate change, which pathway should be considered?
@ Jan, I think C4 photosynthetic pathways generally benefit more from the effects of climate change than C3 and CAM photosynthetic pathways.
Due to the more unpredictable weather patterns that global climate change is bringing, I would say that none of the 3 plants photosynthetic metabolisms is at an advantage.
With rise in temperature the productivity of C4 plants would increase, while those of C3 plants would decrease due to increase in rate of 'photorespiration'. Thus plants with C4 pathway of photosynthesis would be benefited from climate change.
C4 would benefit from increased temperature and CO2. In the C4, the CO2 compensation point is very low (zero or nearly zero), reflecting their very low levels of photorespiration. In fact, the enzyme used by C4 "the PEPcase" has no affinity to oxygen and, therefore, although the increased temperature forces plants to close stomata, a process resulting in decreased CO2 for photosynthesis, the PEP-carboxylase has no affinity to oxygen and cannot therefore fix it to increase the photorespiration rate. This is the great difference with C3 plants which uses an enzyme called Rubisco which is carboxylase and oxygenase. When the plant closes the stomata to reduce transpiration rate under high temperature, the Rubisco is able to fix the oxygen instead of CO2 and thus increasing photorespiration which is unfortunately an energy-consuming pathway and thus resulting in low productivity in C3 plants.