Short-Term and Long-Term Responses of Crassulacean Acid Metabolism Plants to Elevated CO₂

Abstract

For the leaf succulent Agave deserti and the stem succulent Ferocactus acanthodes, increasing the ambient CO(2) level from 350 microliters per liter to 650 microliters per liter immediately increased daytime net CO(2) uptake about 30% while leaving nighttime net CO(2) uptake of these Crassulacean acid metabolism (CAM) plants approximately unchanged. A similar enhancement of about 30% was found in dry weight gain over 1 year when the plants were grown at 650 microliters CO(2) per liter compared with 350 microliters per liter. Based on these results plus those at 500 microliters per liter, net CO(2) uptake over 24-hour periods and dry weight productivity of these two CAM succulents is predicted to increase an average of about 1% for each 10 microliters per liter rise in ambient CO(2) level up to 650 microliters per liter.