Question

how have CAM plants reduced the effects of photorespiration?

Answer 1

Ok, so CAM plants close stomata during the day to conserve water, but also prevents CO2 from getting in. It opens stomata during the night and carry out Calvin cycle

In CAM plants, Calvin cycle predominates over photorespiration, or actually, no photorespiration occurs in CAM. The reason is very simple,photorespiration occurs in light.