DOI: 10.5061/dryad.25b8k25
title: Data from: No role for xylem embolism or carbohydrate shortage in temperate trees during the severe 2015 drought

description: 1. Temperate forests are predicted to experience an increased frequency
 and intensity of climate change-induced summer droughts and heat waves in
 the near future. Yet, while previous studies clearly showed a high drought
 sensitivity of different temperate tree species, the vulnerability of the
 physiological integrity of these trees remains unclear. 2. Here, we
 assessed the sensitivity of six temperate tree species to severe water
 limitation during three consecutive growing seasons including the
 exceptional 2015 central European summer drought and heat wave.
 Specifically, we assessed stem increment growth, sap flow, water
 potentials, hydraulic traits, and non-structural carbohydrate contents in
 leaves and branches to determine how mature temperate trees responded to
 this exceptional weather event and how the observed responses relate to
 variation in xylem embolism and carbohydrate economy. 3. We found that the
 trees’ pre-dawn water potentials reached their minimum values during the
 2015 summer drought and most species reduced their sap flow by up to 80%.
 Also, increment growth was strongly impaired with the onset of the drought
 in all species. Despite the strong responses in the trees’ growth and
 water relations, all species exhibited minimum midday leaf water
 potentials well away from values associated with severe embolism (P50). In
 addition, we detected no distinct decrease in non-structural carbohydrate
 contents in leaves, bark and stems throughout the drought event. 4.
 Synthesis: This study shows that mature individuals of six common central
 European forest tree species strongly reacted to a severe summer drought
 by reducing their water consumption and stopping growth. We found,
 however, no indications for xylem embolism or strong carbohydrate
 depletion in these trees. This suggests, that xylem embolism formation and
 carbohydrate reserve depletion are not routine in temperate trees during
 seasonal strong drought and reveals a low vulnerability of the
 physiological integrity of temperate trees during drought events as we
 describe here.
description: Soil water potential and
 VPD dataThis is the maximum
 daily soil water potential and mean midday VPD data for the period of
 investigation. You'll find daily values sorted by year and day of
 year (DOY).SWP_VPD_Hofstetten14-16.csvK Values 2014-2015These are the K values for sap flow calculations obtained from the sap flow sensor readings on each individual of the different tree species. K values were calculated as explained in the methods section of the manuscript. You will find 10-min-interval data for the years 2014 and 2015.KValuesHofstetten1415.csvDendrometer readingsThese are the 10-min-interval readings of the point dendrometers that were installed on each individual of the different tree species. Values are given in micrometers.DendroHofstetten14-16.csvWP-pWP_2014-2015This is the mean midday and pre-dawn water potential data for the species investigated during 2014 and 2015. You'll find means ± standard error for every measurement day and species.NSC valuesIn this file you find the NSC values in the different compartments of the different species during the summer of 2015. Absolute and relative values are given including standard deviation. The column “nsctype” states whether the values are total NSC, sugar (su) or starch (st).NSC2015.csv