Figure 2: Timeseries of precipitation rate and
δ2H isotopic composition (a), xylem water
isotopic composition in beech, spruce and young spruce trees(b) , and mobile (c) and bulk (d) soil water
isotopic composition at 10, 20, 40 and 80cm depth from April 2020 until
March 2022. We show timeseries of δ2H; similar results
for δ18O are shown in the supplementary material
Figure S1.
Event-based evaluation of isotope signatures in precipitation,
soil and xylem waters
We calculated the fraction of new or recent precipitation (precipitation
from the preceding 30 days - Fnew ) that can be
found in the xylem waters of beech, spruce and young spruce (Figure 3).
For beech δ2H, only 6 out of 19 sampling dates showed
the xylem water to be composed of more than 30% new precipitation; for
spruce and young spruce, those value were 5 and 2 out of 19 sampling
dates, respectively. Higher values of Fnewoccurred during fall and spring (i.e., during September through November
and April through June), at other sampling dates, xylem signatures in
beech, spruce and young spruce mostly showed no detectable influence by
recent precipitation.