DOI: 10.5061/dryad.5x69p8djr
title: Leaf gas exchange measurement for steady-state stomatal conductance model calibration

description: This dataset supports a methodological investigation into leaf gas
 exchange measurement protocols for calibrating steady-state stomatal
 conductance models. The repository contains 24 data files comprising both
 field measurements and 3D biophysical model simulations. Field
 measurements include steady-state gas exchange data collected with a LICOR
 LI-6800 infrared gas analyzer (IRGA) and non-steady-state survey
 measurements collected with a LICOR LI-600 leaf porometer across three
 plant species: cowpea (Vigna unguiculata), eastern redbud (Cercis
 canadensis), and walnut (Juglans regia). Measured variables include
 stomatal conductance, photosynthetic rate, transpiration, leaf
 temperature, vapor pressure deficit, and photosynthetic photon flux
 density under varying light intensities and environmental conditions.
 Complementary simulated data were generated using leaf-resolving
 biophysical models to quantify measurement discrepancies across different
 stomatal time constants (τ = 900-9000s), spatial sampling strategies
 (single leaves vs. canopy surveys), and temporal protocols (diurnal
 cycles, steady-state vs. non-steady-state measurements). The dataset
 includes light response curves, vapor pressure deficit response curves,
 diurnal simulations, and statistical power analyses examining sample size
 requirements for parameter recovery. These data quantify leaf-to-leaf
 physiological variability (&gt;3-fold under identical conditions),
 systematic errors introduced by stomatal kinetics in parameter
 calibration, and instrument-specific trade-offs between IRGAs and
 porometers. This dataset provides essential benchmarks for developing
 efficient gas exchange measurement protocols and assessing the reliability
 of stomatal model parameter estimates in crop and land surface modeling
 applications.
description: # Leaf gas exchange measurement for steady-state stomatal conductance
 model calibration This repository contains gas exchange measurement data
 used to generate the figures in the associated manuscript. The data
 includes both measured (IRGA and porometer) and simulated gas exchange
 parameters for various plant species under different environmental
 conditions. #### Overview The dataset comprises leaf-level and
 canopy-scale gas exchange measurements along with model simulations. Data
 were collected using infrared gas analyzers (IRGA) and leaf porometers,
 with complementary simulations performed to validate stomatal conductance
 models. #### File Naming Convention Files are named according to the
 figure they correspond to in the manuscript: *
 `Figure[N]-[Instrument/Method]-[Description].[ext]` Where: * `[N]` =
 Figure number in manuscript * `[Instrument/Method]` = Data collection
 method (IRGA, Porometer, Simulated) * `[Description]` = Brief description
 of the experiment or data type * `[ext]` = File extension (.csv, .txt, or
 .xlsx) #### Data Files **Figure 2 - Steady-State vs Non-Steady-State
 Comparison** * Figure2-Steady-State-IRGA.xlsx: Steady-state IRGA
 measurements * Figure2-Nonsteady-State-Porometer.csv: Non-steady-state
 porometer measurements #### Figure 3 - Species Response Curves (Light and
 VPD) Light response curves: * Figure3-Cowpea-Light.csv: Cowpea light
 response data * Figure3-Redbud-Light.csv: Eastern redbud light response
 data * Figure3-Walnut-Light.csv: Walnut light response data Vapor pressure
 deficit (VPD) response curves: * Figure3-Cowpea-VPD.csv: Cowpea VPD
 response data * Figure3-Redbud-VPD.csv: Eastern redbud VPD response data *
 Figure3-Walnut-VPD.csv: Walnut VPD response data #### Figure 4 - Diurnal
 Simulation * Figure4-Simulated-Redbud-Diurnal.txt: Simulated diurnal cycle
 for eastern redbud canopy #### Figure 5 - Subject Leaf Measurements *
 Figure5-IRGA-Subject-Leaf.csv: IRGA measurements on the subject leaf ####
 Figure 6 - Steady-State and Non-Steady-State Validation Measured data: *
 Figure6-Steady-State-Measured.csv: Steady-state measured data *
 Figure6-Nonsteady-State-Measured.csv: Non-steady-state measured data
 Simulated data: * Figure6-Steady-State-Simulated.txt: Steady-state
 simulation results * Figure6-Nonsteady-State-Simulated.txt:
 Non-steady-state simulation results #### Figure 7 - Single Leaf vs Canopy
 Measurements * Figure7-IRGA-Single-Leaves.csv: IRGA measurements on
 individual leaves * Figure7-Porometer-Canopy.csv: Porometer measurements
 across the canopy #### Figure 8 - Time Constant Simulations Simulations
 with different stomatal time constants (τ): *
 Figure8-Simulated-900tau.txt: Simulation with τ = 900s *
 Figure8-Simulated-3600tau.txt: Simulation with τ = 3600s *
 Figure8-Simulated-9000tau.txt: Simulation with τ = 9000s #### Figure 9 -
 Neighboring Leaf Effects * Figure9-IRGA-Subject-Leaf.csv: IRGA
 measurements on subject leaf during neighboring leaf experiment *
 Figure9-Porometer-Neighboring-Leaves.csv: Porometer measurements on
 neighboring leaves #### Figure 10 - Real vs Simulated Canopy *
 Figure10-Real-Canopy.csv: Measured canopy-scale gas exchange *
 Figure10-Simulated-Canopy.txt: Simulated canopy-scale gas exchange ####
 Data File Formats **CSV Files (.csv)** Comma-separated values with header
 row containing variable names and (where applicable) a second row with
 units. Common variables include: * **gs, gsw**: Stomatal conductance to
 water vapor (mol m⁻² s⁻¹) * **gbw**: Boundary layer conductance to water
 vapor (mol m⁻² s⁻¹) * **E**: Transpiration rate (mmol m⁻² s⁻¹) * **A,
 An**: Net photosynthesis rate (µmol m⁻² s⁻¹) * **Ci**: Intercellular CO₂
 concentration (µmol mol⁻¹) * **Ca**: Ambient CO₂ concentration (µmol
 mol⁻¹) * **Tleaf**: Leaf temperature (°C) * **Tair**: Air temperature (°C)
 * **Q, PPFD**: Photosynthetic photon flux density (µmol m⁻² s⁻¹) * **VPD,
 VPDleaf**: Vapor pressure deficit (kPa or mmol mol⁻¹) * **RH, h**:
 Relative humidity (%) * **Patm, Pa, P_atm**: Atmospheric pressure (kPa)
 **Text Files (.txt)** Tab-delimited or space-delimited text files from
 simulation outputs, with header row containing variable names. **Excel
 Files (.xlsx)** Microsoft Excel format with data in spreadsheet format,
 typically with headers in the first row. **Species Information** *
 **Cowpea** (*Vigna unguiculata*) * **Eastern redbud** (*Cercis
 canadensis*) * **Walnut** (*Juglans* sp.) #### Instrumentation **IRGA
 (Infrared Gas Analyzer)** LICOR LI-6800 steady-state measurements of gas
 exchange parameters including photosynthesis, transpiration, and stomatal
 conductance. **Leaf Porometer** LICOR LI-600 non-steady-state measurements
 of stomatal conductance and transpiration across multiple leaves or
 spatial locations. #### Column Descriptions **Common IRGA Variables** *
 **obs**: Observation number * **time**: Timestamp of measurement *
 **species**: Plant species measured * **gsw**: Stomatal conductance to
 water vapor * **gbw**: Boundary layer conductance to water vapor *
 **gtw**: Total conductance to water vapor * **E_apparent**: Apparent
 transpiration rate * **VPcham, VPref, VPleaf**: Vapor pressure in chamber,
 reference, and at leaf surface * **VPDleaf**: Leaf-to-air vapor pressure
 deficit * **H2O_r, H2O_s, H2O_leaf**: Water vapor concentrations *
 **leaf_area**: Leaf area enclosed in chamber * **Tref, Tmeas, Tleaf**:
 Temperature measurements * **P_atm, Patm**: Atmospheric pressure * **flow,
 flow_s**: Flow rates * **Qamb**: Ambient light intensity #### Common
 Simulated Variables * **leaf**: Leaf identifier * **x, y, z**: Spatial
 coordinates * **zenith, azimuth**: Solar angles * **area**: Leaf area *
 **PPFD**: Photosynthetic photon flux density * **gs**: Stomatal
 conductance * **gbw**: Boundary layer conductance * **Tleaf, Tair**: Leaf
 and air temperature * **RHair**: Air relative humidity * **VPD**: Vapor
 pressure deficit * **A**: Net photosynthesis * **E**: Transpiration *
 **psiL, psiStem**: Leaf and stem water potential * **sunlitivity**: Degree
 of sunlit exposure (0-1) #### Notes * Missing or invalid data are
 typically indicated by specific values (e.g., 999.9, 9999, -9999) or blank
 fields * Timestamp formats may vary between instruments; refer to
 individual file headers for specific formats