Journal article
Thermal tolerance of Acer campestre (field maple) under heat and drought stress derived from chlorophyll fluorescence
- Abstract:
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Climate change is increasing the frequency of extreme heat events, making the thermal tolerance of urban trees critical for sustainable city landscapes. We quantified how hydration status influences heat tolerance in $Acer\ campestre$ (field maple) by measuring chlorophyll-fluorescence based dark-adapted thermal tolerance values for the onset ($T_{\mathrm{crit}}$) and 50% reduction ($T_{50}$) of photosystem II efficiency. Measurements were taken at four time points under controlled conditions, with the final measurement including drought stress followed by rehydration of the sample leaves. Linear mixed-effects modelling revealed that treatment significantly affected $T_{\mathrm{crit}}$ ($F_{(2,49)} = 27.6$, $p < 0.001$) but not $T_{50}$ ($F_{(2,49)} = 2.22$, $p = 0.12$). $T_{\mathrm{crit}}$ declined from 41.2--44.5$^\circ$C under well-watered conditions to about 30.4$^\circ$C during drought, then recovered to approximately 44.3$^\circ$C after 24 hours of rehydration. $T_{50}$ remained relatively stable (47--49.9$^\circ$C) across treatments. Principal component and clustering analyses confirmed hydration status as the main driver of variation (PC1 = 80.4% of variance; PERMANOVA $F = 5.47$, $p = 0.001$). A positive correlation between $T_{\mathrm{crit}}$ and $T_{50}$ ($r = 0.61$, $p < 0.01$) indicated coordinated but distinct protective mechanisms operating across stress levels. These findings demonstrate that short-term hydration has a greater influence on photosynthetic heat tolerance than prior drought exposure. $Acer\ campestre$ shows high physiological plasticity, with rapid recovery of $T_{\mathrm{crit}}$ after rehydration, suggesting that maintaining soil moisture through targeted irrigation could significantly enhance tree resilience to increasing urban heat extremes.
- Publication status:
- Published
- Peer review status:
- Peer reviewed
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(Preview, Version of record, pdf, 2.4MB, Terms of use)
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- Publisher copy:
- 10.1007/s00468-026-02762-x
Authors
- Publisher:
- Springer Nature
- Journal:
- Trees More from this journal
- Volume:
- 40
- Issue:
- 3
- Article number:
- 66
- Publication date:
- 2026-04-17
- Acceptance date:
- 2026-03-13
- DOI:
- EISSN:
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1432-2285
- ISSN:
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0931-1890
- Language:
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English
- Keywords:
- Pubs id:
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2394824
- Local pid:
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pubs:2394824
- Deposit date:
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2026-03-25
- ARK identifier:
Terms of use
- Copyright holder:
- Khan et al
- Copyright date:
- 2026
- Rights statement:
- © The Author(s) 2026. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.
- Licence:
- CC Attribution (CC BY)
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