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Abstract Drought events may increase the likelihood that the plant water transport system becomes interrupted by embolism. Yet our knowledge about the temporal frequency of xylem embolism in the field is frequently lacking, as it requires detailed, long‐term measurements.We measured xylem embolism resistance and midday xylem water potentials during the consecutive summers of 2019 and 2020 to estimate maximum levels of embolism in leaf and stem xylem of ten temperate angiosperm tree species. We also studied vessel and pit membrane characteristics based on light and electron microscopy to corroborate potential differences in embolism resistance between leaves and stems.Apart fromA.pseudoplatanusandQ.petraea, eight species experienced minimum xylem water potentials that were close to or below those required to initiate embolism. Water potentials corresponding to ca. 12% loss of hydraulic conductivity (PLC) could occur in six species, while considerable levels of embolism around 50% PLC were limited toB.pendulaandC.avellana. There was a general agreement in embolism resistance between stems and leaves, with leaves being equally or more resistant than stems. Also, xylem embolism resistance was significantly correlated to intervessel pit membrane thickness (TPM) for stems, but not to vessel diameter and total intervessel pit membrane surface area of a vessel.Our data indicate that low amounts of embolism occur in most species during moderate summer drought, and that considerable levels of embolism are uncommon. Moreover, our experimental andTPMdata show that leaf xylem is generally no more vulnerable than stem xylem.
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Ring‐specific vulnerability to embolism reveals accumulation of damage in the xylem
Summary Human‐caused climate change is predicted to bring more frequent droughts and higher temperatures in the western United States, which threaten ecologically important trembling aspen forests.We used ring‐specific vulnerability curves of aspen branches along two climate gradients to determine whether damages to pit membranes accumulate as the xylem ages.We found that rings older than 3 yr have a significant decline in hydraulic conductivity, especially at average summer water potentials for the species. These differences were not due to differences in the diameter of the vessels, but a difference in how much xylem was active between rings older than 3 yr and 1 yr, suggesting the presence of accumulated damage to pit membranes impairing water transport.Vulnerability to embolism differs across ring age and between wetter and drier populations, underscoring that damages due to drought may accumulate to lethal levels if the xylem does not acclimate to climate change in newer growth.
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- PAR ID:
- 10652202
- Publisher / Repository:
- New Phytologist
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 246
- Issue:
- 5
- ISSN:
- 0028-646X
- Page Range / eLocation ID:
- 2046 to 2058
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1111/nph.70137
