Cuvette temperature during measurement varied systematically from low (10 °C) to high (40 °C) by 5 °C increments, and measurements were taken systematically in order from low to high temperature. Seedlings were allowed to acclimate for at least 20 min for each new temperature, before recording data. The attachment points of the shoot to the cuvette walls were taped (adhesive putty) to avoid leaks into and out of the cuvette. Photosynthesis (An) was measured under saturating photosynthetically active radiation (PAR = 1000 µmol m−2 s−1) and at 400 µmol mol−1 of CO2. Following An measurement, the light source was turned off and Rd was recorded after at least 15 min of darkness. The vapor pressure deficit (VPD) in the conifer chamber ranged from 0.6 to 3.6 kPa. During measurement, the entering air passed through the drierite column (anhydrous calcium sulphate) to maintain the air humidity (RH) below 75 % at the lower temperature (10 °C). At higher temperatures, a minimum RH of 45 % was maintained by adding water vapour to the air inside the plastic chamber. For each sample, data required to build An–T and Rd–T curves were collected generally within 4–5 h.