A-Ci, photosynthetic capacity and dark respiration data along an elevation/temperature gradient in the Colombian Andes, 2019

The raw A-Ci data was collected using a LI-6800 portable photosynthesis system. Once clamped onto a leaf, conditions inside the cuvette were standardised to 29ᵒC, 65% relative humidity and 410ppm CO2; once stable at gs ≥0.05 mol m-2 s-1, net photosynthesis was measured sequentially at 8 different ambient CO2 concentrations (Ca; 410, 300, 175, 60, 410, 800, 1500, 2000) corresponding to different intercellular Ci concentrations. Light intensity was set to a pre-determined saturating photon flux density (PPFD) for each species, according to A-Q curves collected prior to the A-Ci curves.

Vcmax and Jmax values were estimated by inputting the raw A-Ci data into the ‘plantecophys’ package (Duursma, 2015) in the R environment (v4.2.1; R Core Team, 2022). Once these had been extracted, values were standardised to both 25°C and site growth temperature (Tg) using temperature response values derived from Kumarathunge et al. (2019) and the equation given in the supporting documentation.

Rdark values were also standardised to 25°C and Tg using an exponential fixed Q10 equation (Tjoelker et al. 2001) and including the temperature-dependence of Q10; both equations are given in the supporting documentation.