gcb2566-sup-0001-FigureS1.pdfapplication/PDF377KFigure S1. Landscape view of the nondeclining Gamueta (GA; see Table 1) site (42°53′N, 0°48′W, elevation: 1400 m). No Abies alba (dark-green crowns) defoliation was detected at this site. The light-green and deciduous crowns correspond to Fagus sylvatica.
gcb2566-sup-0002-FigureS2.pdfapplication/PDF239KFigure S2. Landscape view of the declining Paco Ezpela-high (PE; see Table 1) site (42°45′N, 0°52′W, elevation: 1232 m). This declining site was one of the most heavily affected stands, with 50% of all sampled trees showing severe defoliation. Red and defoliated crowns correspond to declining trees, whereas light-green crowns correspond to F. sylvatica.
gcb2566-sup-0003-FigureS3.pdfapplication/PDF192KFigure S3. Estimation of ambient CO2 partial pressure from values of Ca mole fraction (a) mean May-August air temperature (b) and total barometric pressure (c) Ambient CO2 partial pressure (d) was computed for declining and nondeclining sites, respectively.
gcb2566-sup-0004-FigureS4.pdfapplication/PDF205KFigure S4. Theoretical scenarios for the regulation of plant-gas exchange fractionation during CO2 diffusion through the stomata. (a) Isotopic composition of atmospheric CO2 (Δ13Ca, upper graph) and isotope values of tree rings corresponding to the three scenarios (Δ13C in tree rings, lower graphs). The discrimination Δ is also indicated. (b) Ci/Ca (axis to the left) and Δ (axis to the right), (c) Ci-Ca (axis to the left) and intrinsic water-use efficiency (iWUE, right axis), (d) Ca and Ci.
gcb2566-sup-0005-TableS1.pdfapplication/PDF53KTable S1. Characteristics of the meteorological stations used to describe climatic conditions in declining and nondeclining Abies alba sites.

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