## 2 Materials and Methods
### Gas Exchange and Functional Traits Measurements  
From July 2019 to December 2020, we measured leaf-level CO\({}_{2}\) exchange using a LICOR 6400 (LICOR Inc., Lincoln, NE, USA) infrared gas analyser, on a monthly basis, except for August 2019/2020, October 2019 and November 2020. All measurements were made on days with typical weather conditions based on previous days' weather forecasts. We randomly selected trees within the stand and measured light response curves (Lc) for six to ten trees each month. Measurements were made for three pairs of fully developed and healthy needles, from both sunlit (four to eight Lc measurements) and shaded (two to four Lc measurements) branches. A fully sunlit or shaded branch from the selected tree was cut by climbing on the tree and/or using telescopic scissors, and immediately placed in a water bucket where it was recut prior to leaf gas-exchange measurements [57]. Only current year's needles were selected, or needles of the year before, in cases that the current year's needles were not fully developed, by identifying the small and clustered sterile scales that indicate the end of the previous and the beginning of the new growth unit [58]. Light response curves were made using the 6400-02B LED Light Source chamber with red and blue LEDs (665 and 470 nm, respectively). The chamber was set up at ambient conditions of humidity and temperature (provided by the L6400 external sensors), at 400 ppm CO\({}_{2}\) concentration, by using CO\({}_{2}\) cartridges, and systematically changing the rate of photosynthetic active radiation (PAR) between 2000, 1800, 1600, 1400, 1200, 1000, 800, 600, 400, 200, 100, 80, 60, 40, 20 and 0 \(\upmu\)mole quanta m\({}^{-2}\) s\({}^{-1}\) to measure net photosynthesis (\(A_{net}\) (\(\upmu\)mle m\({}^{-2}\) s\({}^{-1}\))). At each PAR level, three logs of \(A_{net}\) were taken after at least a two-minute period during which the needles were left at the specific PAR flux to reach an equilibrium. At the end of each light curve, needles were acclimated under dark conditions for five minutes and an additional reading of leaf dark respiration (Rd (\(\upmu\)mle m\({}^{-2}\) s\({}^{-1}\))) was taken. All sets of Lc measurements began 30 min to 1 h after dawn and ended at least 2 h after noon. Because the area of the needles inserted in the chamber did not fully cover the chamber area, we marked the edge points and corrected our measurements for the leaf area enclosed.  
Each day, the needles used in the gas-exchange measurements were transferred to the laboratory for additional leaf traits measurements. In the lab, needles were treated in wet and dark conditions. One day later we measured wet mass (LWW--g) and thickness (Lth--mm) before scanning the needles with a portable scanner (iScan 900 dpi). Leaf area (LA--mm\({}^{2}\)) of the whole needles as well the marked area of the needles enclosed in the chamber were estimated using the ImageJ image analysis software [59]. We then oven-dried the needles for 72 h at 70 \({}^{\circ}\)C and measured their dry weight (LDW--g). Leaf dry mass per area (LMA--g m\({}^{-2}\)) and Leaf Dry Matter Content (LDMC) were estimated using average LWW, LDW and needle area [57].