DOI: 10.16904/envidat.720
title: Hydraulic stress limits thermal acclimation in trees under chronic drought

description: Plant ecophysiological and associated environmental data for two tree species (*Fagus sylvatica* and *Quercus pubescens*) grown for five years in a factorial open-top climate chamber experiment (Model Ecosystem Facility, Birmensdorf, Switzerland) to test the long-term effects of heat (+5 °C) and soil drought (irrigation reduced by 50%). n = 4 trees per species and treatment, n = 48 trees total.
 Included data sheets:
- Environmental_Data.csv: Chamber-level environmental recorded every 10 minutes
- Tleaf.csv: Leaf temperatures recorded every 10 minutes
- Gas_exchange.csv: Leaf-level gas exchange data taken diurnally on four days during the growing season
- Leaf_traits.csv: Leaf functional traits
- TSMs_HSMs.csv: Photosynthetic thermal tolerance and leaf water potential data, summarized also in terms of leaf thermal safety margins and hydraulic safety margins, collected 3-4 times during the growing season
- Scorch.csv: Leaf-level leaf scorching data, including leaf thermal safety margins and scorching occurrence and presence, summarized by date
description: Resource Title: README.txt
 Size: 8090 bytes
 Format: text/plain
 URL: https://www.envidat.ch/dataset/8780a01e-98aa-46bb-9938-ba8e0568fa20/resource/1f818ee5-bfba-4996-b8fb-e6dc1c96fbb4/download/readme.txt
 Description: README file with more information about the dataset.
description: Resource Title: Environmental_Data.csv
 Size: 19996344 bytes
 Format: text/csv
 URL: https://www.envidat.ch/dataset/8780a01e-98aa-46bb-9938-ba8e0568fa20/resource/8113d780-83c8-43bd-a823-f726ad3f21ab/download/environmental_data.csv
 Description: Chamber-level abiotic data recorded every 10 minutes.

Variable List: 
 - Time (MM/DD/YYYY HH:MM)
 - Chamber: open-top-chamber ID
 - Treatment: chamber abiotic treatment (C = control, H = heated, RM = reduced soil moisture, H_RM = heated and reduced soil moisture)
 - Heating: Yes or no
 - RM: Reduced soil moisture, yes or no
 - Tair: Air temperature (degrees C)
 - Tair_sd: Standard deviation of air temperature
 - RH: Relative humidity
 - RH_sd: Standard deviation of relative humidity
 - VPD: Vapor pressure deficit (kPa)
 - Tsoil: Soil temperature (degrees C)
 - Soil_m: Volumetric soil water content (m^3/m^3)
 - PPFD: Photosynthetic photon flux density (micromoles m^-2 s^-1) *collected from a weather station next to the open-top-chambers (50% intensity inside chambers)
 - windspeed: (m/s) *collected from a weather station next to the open-top-chambers
description: Resource Title: Scorch.csv
 Size: 129956 bytes
 Format: text/csv
 URL: https://www.envidat.ch/dataset/8780a01e-98aa-46bb-9938-ba8e0568fa20/resource/e153f13e-330e-4c0a-8cff-59e625dc7e7c/download/scorch.csv
 Description: Tree-level leaf scorching occurrence and severity data summarized by date with daily leaf thermal safety margins.

Variable List: 
 - TreeID: Unique identifier for individual trees
 - Date (MM/DD/YYYY)
 - Heating: Yes or no
 - RM: Reduced soil moisture, yes or no
 - Treatment: chamber abiotic treatment (C = control, H = heated, RM = reduced soil moisture, H_RM = heated and reduced soil moisture)
 - Species: Tree species
 - Tleaf: Leaf temperature (degrees C) *measured by an infrared sensor integrated into the Cavicam
 - Tcrit: Critical thermal threshold of Photosystem II (degrees C) *daily entries inherit the Tcrit measured onthe next measurement date and applied to the interval preceding it (or are forward-filled when Tcrit could not be estimated in August or September)
 - TSM: Leaf thermal safety margin (difference between Tcrit and Tleaf, in degrees C)
 - Scorch_binary: Binary indicating whether scorching occurred on that date (0 = no, 1 = yes)
 - Percent_affected: Percent of the camera window affected by scorching during a scorching event
description: Resource Title: TSMs_HSMs.csv
 Size: 15217 bytes
 Format: text/csv
 URL: https://www.envidat.ch/dataset/8780a01e-98aa-46bb-9938-ba8e0568fa20/resource/6c897b79-4cc6-46f5-87f0-83275921ede9/download/tsms_hsms.csv
 Description: Tree-level photosynthetic thermal tolerance, leaf water potentials, thermal safety margins, and hydraulic safety margins measured 3-4 times per tree during the growing season.

Variable List: 
 - TreeID: Unique identifier for individual trees
  - Species: Tree species
 - Campaign: Month of the growing season in which data was collected
 - Heating: Yes or no
 - RM: Reduced soil moisture, yes or no
 - Treatment: chamber abiotic treatment (C = control, H = heated, RM = reduced soil moisture, H_RM = heated and reduced soil moisture)
 - Waterpotential: midday leaf waterpotential (MPa)
 - WPtlp: Waterpotential at leaf turgor-loss-point (MPa) *Measured by Mas, E., Cochard, H., Deluigi, J., Didion-Gency, M., Martin-StPaul, N., Morcillo, L., Valladares, F., Vilagrosa, A., & Grossiord, C. (2024). Interactions between beech and oak seedlings can modify the effects of hotter droughts and the onset of hydraulic failure. New Phytologist, 241(3), 1021-1034. https://doi.org/https://doi.org/10.1111/nph.19358 
 - HSM: Hydraulic safety margin (difference between WPtlp and Waterpotential, in MPa)
 - Tcrit: Critical thermal threshold of Photosystem II (degrees C)
 - T50: High leaf temperature at which Photosystem II function declines by 50% (degrees C)
 - Tleaf.max: Maximum leaf temperature during the week preceding thermal tolerance measurement
 - TSM.min: Minimum leaf thermal safety margin during the week preceeding thermal tolerance measurement (difference between Tcrit and Tleaf.max, in degrees C)
description: Resource Title: Leaf_traits.csv
 Size: 7772 bytes
 Format: text/csv
 URL: https://www.envidat.ch/dataset/8780a01e-98aa-46bb-9938-ba8e0568fa20/resource/eaf9d8ce-80f5-489f-af97-e80760927aee/download/leaf_traits.csv
 Description: Tree-level leaf functional trait data.

Variable List: 
 - TreeID: Unique identifier for individual trees
 - Chamber: open-top-chamber ID
 - Treatment: chamber abiotic treatment (C = control, H = heated, RM = reduced soil moisture, H_RM = heated and reduced soil moisture)
 - Heating: Yes or no
 - RM: Reduced soil moisture, yes or no
  - Species: Tree species
 - Leaf_width (cm)
 - Leaf_area (cm^2)
 - Stomatal_density (count per cm^2)
 - Pore_length: Stomatal pore length (micrometers)
 - Guard_cell_width: Stomatal guard cell width (micrometers)
 - Leaf_thickness (mm)
 - Epidermal_thickness (mm)
 - Parenchyma_thickness (mm)
 - Parenchyma:Epidermis: Ratio between parenchyma and epidermal thickness
 - Reflectance: Reflectance of photosynthetically active radiation (400-700), fraction
 - Transmittance: Transmittance of photosynthetically active radiation (400-700), fraction
 - Absorptance: Absorptance of photosynthetically active radiation (400-700), fraction
 - Absorbance: Optical absorbance of photosynthetically active radiation (400-700 nm), unitless
 - g1: Medlyn-style stomatal slope calculated with Licor LI6800 data
description: Resource Title: Gas_exchange.csv
 Size: 4424 bytes
 Format: text/csv
 URL: https://www.envidat.ch/dataset/8780a01e-98aa-46bb-9938-ba8e0568fa20/resource/df082744-69a0-49b6-81b7-c3f02d24c9f0/download/gas_exchange.csv
 Description: Leaf-level gas exchange collected diurnally for each tree on 4 days of the growing season and summarized to growing-season mean.

Variable List: 
 - TreeID: Unique identifier for individual trees
 - Chamber: open-top-chamber ID
 - Species: Tree species 
 - Treatment: chamber abiotic treatment (C = control, H = heated, RM = reduced soil moisture, H_RM = heated and reduced soil moisture)
 - Heating: Yes or no
 - RM: Reduced soil moisture, yes or no
 - gsw.mean: Mean stomatal conductance to water vapor (mol m^-2 s^-1)
 - E.mean: Mean transpiration rate (mol m^-2 s^-2)
 - Tdiff.mean: Mean difference between leaf and air temperature on the day of Licor measurements
 - lnE.mean: Mean of the natural log of the transpiration rate
 - lnE.mean~Tdiff.mean_slope: The slope of the linear least-squares relationship between the natural log of lnE.mean and Tdiff.mean
description: Resource Title: Tleaf.csv
 Size: 28028436 bytes
 Format: text/csv
 URL: https://www.envidat.ch/dataset/8780a01e-98aa-46bb-9938-ba8e0568fa20/resource/1860aa5f-68f2-4889-b0c9-bd907e48111f/download/tleaf.csv
 Description: Tree-level leaf temperature data recorded every 10 minutes.

Variable List: 
 - Timestamp (MM/DD/YYYY HH:MM)
 - TreeID: Unique identifier for individual trees
 - Chamber: open-top-chamber ID
 - Treatment: chamber abiotic treatment (C = control, H = heated, RM = reduced soil moisture, H_RM = heated and reduced soil moisture)
 - Heating: Yes or no
 - RM: Reduced soil moisture, yes or no
  - Species: Tree species
 - Tair: Air temperature (degrees C)
 - Tleaf: Leaf temperature (degrees C)
 - Tdiff: Leaf-to-air temperature differential (degrees C)