Research ArticleCLIMATOLOGY

Rising CO2 drives divergence in water use efficiency of evergreen and deciduous plants

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Science Advances  11 Dec 2019:
Vol. 5, no. 12, eaax7906
DOI: 10.1126/sciadv.aax7906
  • Fig. 1 Major study areas and iWUE values across biomes in historical and contemporary samples.

    (A) Major study areas. (B) Historical and contemporary iWUE at 355 and 400 ppm atmospheric CO2 concentration respectively arranged by increasing averaged iWUE values. Boxplots show median (center line), mean (red dot), interquartile range (IQR), 1.5 times of IQR (whiskers), and outliers (black dots). Numbers in brackets are the number of leaves. All iWUE gains are likely to be larger than zero.

  • Fig. 2 iWUE gain (∆iWUE) and its relationship with mean annual temperature (MAT) and leaf mass per unit area (LMA).

    Dotplots represent mean of posterior distributions (n = 6000 samples), CI95%. Red line is the fitted regression. (A) ∆iWUE of deciduous and evergreen plants in biomes arranged by increasing MAT. (B) Differences between evergreen and deciduous ΔiWUE (ΔiWUEe-d) versus MAT, ΔiWUEe-d = 11 – 0.4MAT, r2 = 0.70. (C) ΔiWUEe-d versus average difference of evergreen and deciduous LMA (LMAe-d), ΔiWUEe-d = −2.0 + 0.14 LMAe-d, r2 = 0.80. (D) Boxplots of deciduous and evergreen LMA across biomes for combined historical and contemporary samples arranged by increasing MAT. All P(LMAevergreen > LMAdeciduous) ≥ 0.95. (E) Comparison of the rate of iWUE gain per unit of CO2 concentration (ΔiWUE/ΔCO2) for total deciduous and evergreen samples [P(ΔiWUE/ΔCO2 evergreen > ΔiWUE/ΔCO2 deciduous) = 0.87]. (F) Scatter plot of LMA versus MAT of evergreen and deciduous plants for combined historical and contemporary samples, n = 2031 leaves.

  • Fig. 3 Average slopes of iWUE responses to rising atmospheric CO2 concentration (ΔiWUE/ΔCO2) from published data.

    Dotplots represent mean of posterior distributions (n = 6000 samples), CI95%. (A) ΔiWUE/ΔCO2 from published tree ring δ13C data for the various time intervals between 1970 and 2013 for evergreen (n = 29 trees) and deciduous trees (n = 23 trees). (B) Result from (A) separated into bioclimatic zones showing higher average iWUE gain in evergreen (n = 24 trees) than in deciduous trees (14 trees) in the boreal-temperate zone, but the opposite in the tropical zone (deciduous n = 9 trees; evergreen n = 5 trees) [P(ΔiWUE/ΔCO2 deciduous > ΔiWUE/ΔCO2 evergreen) = 0.95]. (C) ΔiWUEc/ΔCO2 calculated from published leaf δ13C data collected between 1981 and 2005 for deciduous (n = 470 species sites) and evergreen (n = 1053 species sites) species.

  • Fig. 4 In situ field infrared gas exchange analyses experiments showing the change of in vivo measurements of iWUE (∆iWUE), photosynthesis (∆A), and stomatal conductance (∆gs) in response to a shift in cuvette CO2 concentration of ~355 ppm (simulated historical) to ~400 ppm (contemporary ambient).

    Dotplots represent means of posterior distributions (n = 6000 samples), CI95%. Evergreen n = 135 leaf samples (33 species); deciduous n = 119 leaf samples (31 species). (A) Dotplots of ∆iWUE in evergreen and deciduous leaves. (B) Dotplots of ∆A in evergreen and deciduous leaves. (C) Dotplots showing average ∆gs in evergreen and deciduous are unlikely to be higher than zero at CI95%.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/12/eaax7906/DC1

    Fig. S1. Historical and contemporary leaf functional trait plots through the origin.

    Fig. S2. iWUE gain (∆iWUE) of deciduous and evergreen plants in biomes for growth habit, arranged by increasing MAT.

    Fig. S3. iWUE gain (∆iWUE) of deciduous and evergreen plants in biomes for habitat group, arranged by increasing MAT.

    Fig. S4. The changes in the ratio of leaf intercellular (ci) to ambient CO2 (ca), Δci/ca, in evergreens and deciduous species in biomes, arranged by increasing MAT.

    Fig. S5. iWUE change (∆iWUE) of deciduous and evergreen plants versus MAT change (∆MAT) and VPD change (∆VPD) in biome growth habit and habitat group.

    Fig. S6. Scatter plot of Nmass versus MAT for combined historical and contemporary samples of evergreen and deciduous plants.

    Fig. S7. Trend of iWUE from tree ring data along increasing atmospheric CO2 concentration between the years 1970 and 2013.

    Fig. S8. Evergreen and deciduous iWUE plotted against atmospheric CO2 concentration showing slope of response.

    Fig. S9. Kernel density plots of leaf life span (month) of deciduous and evergreen plants in the boreal-temperate and tropical biomes.

    Table S1. List of species studied, their leaf habit (evergreen, deciduous), habitat (understory subcanopy and open canopy), and growth habit (shrub and tree).

    Table S2. Summary of historical and contemporary site location, vegetation type, and collection date in alphabetical order by biome and site name.

    Table S3. Historical and contemporary samples showing average LMA in evergreen and deciduous group within biome and probability of evergreen LMA larger than deciduous LMA, P* = P(LMAevergreen > LMAdeciduous).

    Table S4. Average iWUE change (ΔiWUE) in biome between two time points 1988–1991 and 2013–2015 with CI95% from posterior distributions in Bayesian analysis.

    Table S5. Average iWUE gain (ΔiWUE) in evergreen and deciduous plants within biome with CI95% from posterior distributions in Bayesian analysis.

    Table S6. Shrub and tree, average iWUE gain (ΔiWUE) in evergreen and deciduous plants within biome, with CI95% from posterior distributions in Bayesian analysis.

    Table S7. Understory-subcanopy and open-canopy habitat, average iWUE gain (ΔiWUE) in evergreen and deciduous plants within biome, with CI95% from posterior distributions in Bayesian analysis.

    Table S8. Average annual air temperature change and average annual VPD change of biomes between two time periods 1988–1991 and 2013–2015 with CI95% from posterior distributions in Bayesian analysis.

    Table S9. Average of coefficients of Model 1 and Model 2 with CI95% from posterior distributions in Bayesian analysis.

    Table S10. Slope of iWUE response to atmospheric CO2 concentration (ΔiWUE/ΔCO2) for individual trees arranged by leaf habit, species, and references.

    Table S11. Pearson correlation matrix (lower half panel in gray) and significance (upper half panel) between iWUE, VPD, precipitation, temperature, altitude, and latitude.

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Historical and contemporary leaf functional trait plots through the origin.
    • Fig. S2. iWUE gain (∆iWUE) of deciduous and evergreen plants in biomes for growth habit, arranged by increasing MAT.
    • Fig. S3. iWUE gain (∆iWUE) of deciduous and evergreen plants in biomes for habitat group, arranged by increasing MAT.
    • Fig. S4. The changes in the ratio of leaf intercellular (ci) to ambient CO2 (ca), Δci/ca, in evergreens and deciduous species in biomes, arranged by increasing MAT.
    • Fig. S5. iWUE change (∆iWUE) of deciduous and evergreen plants versus MAT change (∆MAT) and VPD change (∆VPD) in biome growth habit and habitat group.
    • Fig. S6. Scatter plot of Nmass versus MAT for combined historical and contemporary samples of evergreen and deciduous plants.
    • Fig. S7. Trend of iWUE from tree ring data along increasing atmospheric CO2 concentration between the years 1970 and 2013.
    • Fig. S8. Evergreen and deciduous iWUE plotted against atmospheric CO2 concentration showing slope of response.
    • Fig. S9. Kernel density plots of leaf life span (month) of deciduous and evergreen plants in the boreal-temperate and tropical biomes.
    • Table S1. List of species studied, their leaf habit (evergreen, deciduous), habitat (understory subcanopy and open canopy), and growth habit (shrub and tree).
    • Table S2. Summary of historical and contemporary site location, vegetation type, and collection date in alphabetical order by biome and site name.
    • Table S3. Historical and contemporary samples showing average LMA in evergreen and deciduous group within biome and probability of evergreen LMA larger than deciduous LMA, P* = P(LMAevergreen > LMAdeciduous).
    • Table S4. Average iWUE change (ΔiWUE) in biome between two time points 1988–1991 and 2013–2015 with CI95% from posterior distributions in Bayesian analysis.
    • Table S5. Average iWUE gain (ΔiWUE) in evergreen and deciduous plants within biome with CI95% from posterior distributions in Bayesian analysis.
    • Table S6. Shrub and tree, average iWUE gain (ΔiWUE) in evergreen and deciduous plants within biome, with CI95% from posterior distributions in Bayesian analysis.
    • Table S7. Understory-subcanopy and open-canopy habitat, average iWUE gain (ΔiWUE) in evergreen and deciduous plants within biome, with CI95% from posterior distributions in Bayesian analysis.
    • Table S8. Average annual air temperature change and average annual VPD change of biomes between two time periods 1988–1991 and 2013–2015 with CI95% from posterior distributions in Bayesian analysis.
    • Table S9. Average of coefficients of Model 1 and Model 2 with CI95% from posterior distributions in Bayesian analysis.
    • Table S10. Slope of iWUE response to atmospheric CO2 concentration (ΔiWUE/ΔCO2) for individual trees arranged by leaf habit, species, and references.
    • Table S11. Pearson correlation matrix (lower half panel in gray) and significance (upper half panel) between iWUE, VPD, precipitation, temperature, altitude, and latitude.

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