Figure 1.

Water vapour pressure deficit of the ambient air (VPD, grey bold line) and air temperature (T, black dotted line) at Hesse II (beech (Fagus sylvatica) and oak (Quercus petraea)) (a), Hartheim (pine (Pinus sylvestris)) (b), Tumbarumba (Alpine ash (Eucalyptus delegatensis)) (c), and Lötschental (larch (Larix decidua)) (d–f) before and during the experimental period. (d) and (e) indicate the June and July sampling periods in the valley site and (f) the sampling period at the treeline site in Lötschental. The frames indicate the time periods of sampling and measurement