Table II.

The breakdown of total leaf CO2conductance (gleaf) into its components, stomatal (gs) (from gas exchange) and internal (gi) (from Δ13C, plus error from 95% confidence limits of the slopes)

Speciesgleaf

gs
      
     gi

gw

gch
gch/gwCAleaf
Tobacco0.1550.2240.50 (0.12)1.12 (0.33)0.900.8623
Soy0.1410.2530.32 (0.05)1.31 (0.45)0.420.3318
Oak0.1020.1660.27 (0.09)0.35 (0.04)1.133.22,0162-a

With Δ18O, g i is further partitioned into wall conductance to C cs,g w, and the residual conductance within the chloroplast, (g ch). All units are mol CO2 m−2 s−1. The ratio of chloroplast to wall conductance is also showng ch/g w. AverageCA leaf activity is shown for comparison (μmol m−2 s−1).

    • F2-a In the absence of direct CA measurements in the oak species used here, CAleaf is estimated from the average CA activity observed other oak species (see text).