2.2 Leaf water potential, gas exchange, height measurement and mortality record
To detect the effects of drought duration, all measurements and sampling were always carried out directly before the next watering (Fig. S3).
Three plants from both nutrient and all drought treatments were randomly selected from each sub-sub-plot and three mature leaves from each selected plant were used for water potential and gas-exchange measurements during the drought treatment in 2018. The midday leaf water potential (ψleaf) was measured between 12:00 and 14:00 h on 5 August 2018 (Fig. S3), with a Scholander bomb (Model 600 pressure bomb; PMS Instrument Company, Albany, NY, USA). Net-photosynthesis (Aleaf) was measured on 6 August and 28 September 2018 (Fig. S3), and after rewetting in the following year on 24 June 2019, with a LiCor 6400 system (LI-COR, Lincoln, USA). Aleafwas measured at 400 µmol mol-1 CO2, 1200 µmol m2 s-1 photosynthetically active radiation, ca. 65% relative humidity and 25°C air temperature.
Plant height of each individual was measured on 30 May 2018 (initial height), on 1 October 2018 (end of the treatment), and on 8 October 2019 (after one recovery season) (Fig. S3), and height increments were calculated.