2.4 | Parameter estimation
VCMax and JMax were calculated from the
diffusion-error-corrected A-Ci curves with the ‘fitaci’
function from the ‘plantecophys’ package (Duursma 2015) in R version 3.5
(R Development Core Team, 2018), which uses the Farquhar, von Caemmerer,
and Berry (FvCB) model (Farquhar, von Caemmerer & Berry 1980; von
Caemmerer & Farquhar 1981). There was no sign of triose-phosphate
utilization limitation so this was not considered in the calculations.
In the absence of reliable, temperature-dependent estimates of mesophyll
conductance (gm, representing the ease of
CO2 transfer from the substomatal cavity to the site of
carboxylation in the chloroplast) for this species, gmwas assumed to be infinite. Therefore, the calculated
VCMax and JMax values slightly
underestimate the chloroplastic rates. For RLight, Γ*
and additional parameters of the FvCB model we used default estimates
from the ‘fitaci’ function that are derived from e.g., Bernacchi,
Singsaas, Pimentel, Portis Jr & Long (2001) and Medlyn et al. (2002).