Prolonged warming and drought reduce canopy-level net carbon uptake in beech and oak saplings despite photosynthetic and respiratory acclimation
Data files
Mar 28, 2025 version files 38.56 MB
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Deluigi_2025_-_Aopt_Topt_R25_Q10_water_potentials_and_environmental_conditions.txt
101.96 KB
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Deluigi_2025_-_SPAC_environmental_conditions.rds
32.97 MB
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Deluigi_2025_-_SPAC_plant_traits.txt
35.34 KB
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Deluigi_2025_-_SPAC_simulated_Atot_Agross_tot_and_Rtot.txt
13.58 KB
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Deluigi_2025_-_SPAC_simulated_daily_canopy-level_A_and_R.txt
5.32 MB
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Deluigi_2025_-_Total_leaf_area_and_tree_size.txt
18.59 KB
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Deluigi_2025_-_Water_potentials_and_environmental_conditions.txt
91.15 KB
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README.md
13.60 KB
Abstract
Tree net carbon (C) uptake may decrease under global warming, as higher temperatures constrain photosynthesis while simultaneously increasing respiration. Thermal acclimation might mitigate this negative effect, but its capacity to do so under concurrent soil drought remains uncertain. Using a five-year open-top chamber experiment, we determined acclimation of leaf-level photosynthesis (thermal optimum Topt and rate Aopt) and respiration (rate at 25°C R25 and thermal sensitivity Q10) to chronic +5°C warming, soil drought, and their combination in beech (Fagus sylvatica L.) and oak (Quercus pubescens Willd.) saplings. Process-based modeling was used to evaluate acclimation impacts on canopy-level net C uptake (Atot). Prolonged warming increased Topt by 3.03-2.66°C, but only by 1.58-0.31°C when combined with soil drought, and slightly reduced R25 and Q10. In contrast, drought reduced Topt (-1.93°C in oak), Aopt (~50%), and slightly reduced R25 and Q10 (in beech). Mainly because of reduced leaf area, Atot decreased by 47-84% with warming (in beech) and drought, but without additive effects when combined. Our results suggest that, despite photosynthetic and respiratory acclimation to warming and soil drought, canopy-level net C uptake will decline in a persistently hotter and drier climate, primarily due to the prevalent impact of leaf area reduction.
Physiological measurements
- Filename: “Deluigi 2025 - Water potentials and environmental conditions.csv”
Leaf water potentials at predawn and midday and air temperature and soil moisture conditions measured for each sapling of each species during three campaigns (June, August, September) in 2022 and 2023 in all climatic treatments
-Chamber: code for individual open-top chamber (see Fig. S2 for the experimental design in the Supplementary information)
-Treatment: code for climatic treatment: C = control, D = drought, H = warming, HD = hot drought
-Campaign: measurement campaign (June, August or September) for the two years of measurement (2022, 2023)
-Heating: YES/NO variable for climatic treatments with increased air temperature (+5°C compared to the control)
-Drought: YES/NO variable for climatic treatments with reduced soil moisture (-50% soil water content compared to the control)
-Mixture: mixture combination: Single = one individual of one species (n = 1), Monoculture = four individuals of one species (n = 4), Mixture = two individuals for each species (n = 4)
-Species: code for each tree species: B = beech, O = oak
-Tree: label number of each individual measured sapling for each species in all climatic treatments
-WP_predawn: leaf water potential at predawn (MPa)
-WP_midday: leaf water potential at midday (MPa)
-Tair_lag: Air temperature (°C) of the day before measuring the leaf water potentials at predawn and midday for the measured sapling growing in the respective open-top chamber
-SWC_lag: Soil water content (%) of the day before measuring the leaf water potentials at predawn and midday for the measured sapling growing in the respective open-top chamber
-Tair_mean: Air temperature (°C) of the same day of measurement of the leaf water potential at predawn for the measured sapling growing in the respective open-top chamber
-SWC_mean: Soil water content (%) of the same day before measuring of the leaf water potential at midday for the measured sapling growing in the respective open-top chamber
- Filename: “Deluigi 2025 - Aopt Topt R25 Q10 water potentials and environmental conditions.csv”
Temperature response curves parameters extracted from temperature response curves of photosynthesis and respiration measured for each sapling of each species during three campaigns (June, August, September) in 2022 and 2023 in all climatic treatments, with respective air temperature and soil moisture conditions of the day of measurements or previous days (1,3,15 and 30 days of interval).
-Campaign: measurement campaign (June, August or September) for the two years of measurement (2022, 2023)
-Chamber: code for individual open-top chamber (see Fig. S2 for the experimental design in the Supplementary information)
-Treatment: code for climatic treatment: C = control, D = drought, H = warming, HD = hot drought
-Heating: YES/NO variable for climatic treatments with increased air temperature (+5°C compared to the control)
-Drought: YES/NO variable for climatic treatments with reduced soil moisture (-50% soil water content compared to the control)
-Mixture: mixture combination: Single = one individual of one species (n = 1), Monoculture = four individuals of one species (n = 4), Mixture = two individuals for each species (n = 4)
-Tree: label number of each individual measured sapling for each species in all climatic treatments
-WP_predawn: leaf water potential at predawn (MPa)
-WP_midday: leaf water potential at midday (MPa)
-Tair_2m_mean: average daytime air temperature (°C) measured at 2m height inside each individual chamber during the day of measurement of the temperature response curves of photosynthesis and respiration for each measured sapling growing in the respective open-top chamber
-Tair_1d_mean: average daytime air temperature (°C) measured at 2m height inside each individual chamber the day before the day of measurement of the temperature response curves of photosynthesis and respiration for each measured sapling growing in the respective open-top chamber
-Tair_3d_mean: average daytime air temperature (°C) measured at 2m height inside each individual chamber three days before the day of measurement of the temperature response curves of photosynthesis and respiration for each measured sapling growing in the respective open-top chamber
-Tair_15d_mean: average daytime air temperature (°C) measured at 2m height inside each individual chamber fifteen days before the day of measurement of the temperature response curves of photosynthesis and respiration for each measured sapling growing in the respective open-top chamber
-Tair_30d_mean: average daytime air temperature (°C) measured at 2m height inside each individual chamber thirty days before the day of measurement of the temperature response curves of photosynthesis and respiration for each measured sapling growing in the respective open-top chamber
-SWC_2m_mean: average daytime soil water content (%) measured inside each individual chamber during the day of measurement of the temperature response curves of photosynthesis and respiration for each measured sapling growing in the respective open-top chamber
-SWC_1d_mean: average daytime soil water content (%) measured inside each individual chamber the day before the day of measurement of the temperature response curves of photosynthesis and respiration for each measured sapling growing in the respective open-top chamber
-SWC_3d_mean: average daytime soil water content (%) measured inside each individual chamber three days before the day of measurement of the temperature response curves of photosynthesis and respiration for each measured sapling growing in the respective open-top chamber
-SWC_15d_mean: average daytime soil water content (%) measured inside each individual chamber fifteen days before the day of measurement of the temperature response curves of photosynthesis and respiration for each measured sapling growing in the respective open-top chamber
-SWC_30d_mean: average daytime soil water content (%) measured inside each individual chamber thirty days before the day of measurement of the temperature response curves of photosynthesis and respiration for each measured sapling growing in the respective open-top chamber
-Aopt: photosynthetic rate at the thermal optimum of photosynthesis (µmol m-2 s-1)
-Topt: thermal optimum of photosynthesis (°C)
-R25: respiration rate measured at a standard temperature of 25°C (µmol m-2 s-1)
-Q10: thermal sensitivity of respiration
- Filename: “Deluigi 2025 - Total leaf area and tree size.csv”
Plant total leaf area and sapling size measured for all saplings of each species in all climatic treatments in 2022-2023
-Year: year of measurement
-Chamber: code for individual open-top chamber (see Fig. S2 for the experimental design in the Supplementary information)
-Treatment: code for climatic treatment: C = control, D = drought, H = warming, HD = hot drought
-Species: code for each tree species: B = beech, O = oak
-Mixture: mixture combination: Single = one individual of one species (n = 1), Monoculture = four individuals of one species (n = 4), Mixture = two individuals for each species (n = 4)
-Tree: label number of each individual measured sapling for each species in all climatic treatments
-numb_leaf: number of leaf counted for each sapling
-leaf_size: average leaf size (cm2) estimated from 10 individual pictures taken at different heights of the sapling
-WT_LA: plant total leaf area (m2) estimated by multiplying the number of leaves by the average leaf size
-height: sapling height (cm)
-DBH: sapling diameter (mm), measured at 20 cm from the ground
SPAC model simulation
- Filename: “Deluigi 2025 - SPAC_ environmental conditions.RDS”
Environmental conditions measured inside each individual open-top chamber in 2022-2023 used for the SPAC simulation
-Chamber: code for individual open-top chamber (see Fig. S2 for the experimental design in the Supplementary information)
-TIMESTAMP: date and time of measurement (format: YYY-MM-DD HH:MM:SS)
-Ta: air temperature (°C) measured at 2m height
-RH: relative humidity (%) measured at 2m height
-VPD: vapor pressure deficit (kPa) calculated from air temperature and relative humidity measurements
-Pa: atmospheric pressure (kPa)
-PPFD: photosynthetic photon flux density (µmol m-2 s-1)
-SWR: short wave radiation (W m-2)
-Psi_soil: soil water potential (calculated from soil water content) (kPa)
-WS: wind speed (m s-1)
-Ca: atmospheric CO2 concentration (ppm)
- Filename: “Deluigi 2025 - SPAC_plant traits.csv”
Plant traits used for the SPAC simulation
-Acclimation_type: type of acclimation included in the SPAC model: all = all traits (i.e., average values of ToptVcmax , ToptJmax, R25, Q10, and LAI for each species, climatic treatment, and year), only_LA = only acclimation of total leaf area, but not photosynthesis and respiration, only_AR = only acclimation of photosynthesis and respiration, but not total leaf area
-Year: year of measurement
-Chamber: code for individual open-top chamber (see Fig. S2 for the experimental design in the Supplementary information)
-Treatment: code for climatic treatment: C = control, D = drought, H = warming, HD = hot drought
-Species: code for each tree species: B = beech, O = oak
-vcmax: carboxylation capacity at 25°C (µmol m-2 s-1)
-jmax: electron transport capacity at 25°C (µmol m-2 s-1)
-vcmax_Topt: thermal optimum (°C) of vcmax
-jmax_Topt: thermal optimum (°C) of jmax
-vcmax_Tmax: maximal temperature (°C) of vcmax
-jmax_Tmax: maximal temperature (°C) of jmax
-R25:respiration rate measured at a standard temperature of 25°C (µmol m-2 s-1)
-Q10: thermal sensitivity of respiration
-LAI: leaf area index (m2 m-2) calculated from the measured total leaf area (m2) divided by the compartment area (6 m2)
-g0: minumun leaf stomatal conductance (mmol m-2 s-1)
-s_f: stomatal sensitivity to leaf water potential
-m: proportionality factor between stomatal conductance and photosynthesis
-Psi_f: leaf water potential for stomatal closure (point of stomatal closure) (kPa)
-flush_date: date of leaf flush in spring
-fall_date: date of leaf senescence in autumn
- Filename: “Deluigi 2025 - SPAC simulated daily canopy-level A and R.csv”
SPAC output of daily simulated photosynthetic and respiration rates for each species in all climatic treatments in 2022 and 2023
-Species: code for each tree species: B = beech, O = oak
-Chamber: code for individual open-top chamber (see Fig. S2 for the experimental design in the Supplementary information)
-Treatment: code for climatic treatment: C = control, D = drought, H = warming, HD = hot drought
-Date: date, format M/D/YYYY
-Month: month of the year, format YY-Mon (Mon = month abbreviation: Jan, Feb, …)
-Year: year of measurement
-A_day: avreage simulated net photosynthetic rate (µmol m-2 s-1), averaged for each date
-A_day_se: standard error of the averaged net photosynthetic rate
-R_day: avreage simulated respiration rate (µmol m-2 s-1), averaged for each date
-R_day_se: standard error of the averaged respiration rate
-Agross_day: avreage simulated gross photosynthetic rate (µmol m-2 s-1), averaged for each date
-Agross_day_se: standard error of the averaged gross photosynthetic rate
-Tair: air temperature (°C) measured at 2m height
-VPD: vapor pressure deficit (kPa) calculated from air temperature and relative humidity
-PPFD: photosynthetic photon flux density (µmol m-2 s-1)
-Psi_soil: soil water potential (kPa) calculated from soil water content
-acclimation: type of acclimation included in the SPAC model: all = all traits (i.e., average values of ToptVcmax , ToptJmax, R25, Q10, and LAI for each species, climatic treatment, and year), only_LA = only acclimation of total leaf area, but not photosynthesis and respiration, only_AR = only acclimation of photosynthesis and respiration, but not total leaf area
- Filename: “Deluigi 2025 - SPAC simulated Atot Agross tot and Rtot.csv”
Yearly sum of the hourly modeled canopy-level net photosynthesis, gross photosynthesis and respiration for each acclimation level, climatic treatment, and species over two years of measurement
-Species: code for each tree species: B = beech, O = oak
-Chamber: code for individual open-top chamber (see Fig. S2 for the experimental design in the Supplementary information)
-Treatment: code for climatic treatment: C = control, D = drought, H = warming, HD = hot drought
-Year: year of measurement
-Atot: Yearly sum of the hourly modeled canopy-level net photosynthesis (gCO2)
-Rtot: Yearly sum of the hourly modeled canopy-level respiration rate (gCO2)
-Agrosstot: Yearly sum of the hourly modeled canopy-level gross photosynthesis (gCO2)
-acclimation: type of acclimation included in the SPAC model: all = all traits (i.e., average values of ToptVcmax , ToptJmax, R25, Q10, and LAI for each species, climatic treatment, and year), only_LA = only acclimation of total leaf area, but not photosynthesis and respiration, only_AR = only acclimation of photosynthesis and respiration, but not total leaf area
-Drought: YES/NO variable for climatic treatments with reduced soil moisture (-50% soil water content compared to the control)
-Heating: YES/NO variable for climatic treatments with increased air temperature (+5°C compared to the control)
delta_C: difference between the Atot of each climatic treatment (D, H and HD) and the control (C)