Table 2.

Indirect effects of the elevation in atmospheric [CO₂] on the dark CO₂ efflux of leaves on a dry mass basis based on literature surveys

Reference	E/A	No. of species	Observations
Amthor (1997)	0·96	21	26 studies, crop and herbaceous and woody wild species
Davey et al. (2004)	1·07	7	1 study, crop and herbaceous and woody wild species
Drake et al. (1997)	0·95	17	15 studies, crop and herbaceous wild species

Elevated-over-ambient (E/A) refers to the ratio of rate of leaf dark respiration of plants grown in elevated CO₂ to the rate of plants grown in current ambient CO₂, when measured at a common CO₂ concentration. Under these conditions, effects of gas exchange leaks should not be affecting the comparison of rates of respiration from plants grown at ambient and elevated CO₂.