Summer Drought Delays Leaf Senescence and Shifts Radial Growth Towards the Autumn in Corylus Taxa

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study provides valuable insights about role of drought stress in delaying leaf senescence and shifting radial growth towards the autumn in Corylus taxa. Please find my detailed comments below for revision of the manuscript:

1. Line 22-24: There is some kind of contradiction in explaining results. Firstly, authors saying that severely affected plants with drought displayed the largest delay in leaf senescence and on the other hand, giving the statement that “severity of visual drought symptoms and delay in leaf senescence did not show a linear relation”. If the most severe group had the longest delay, in what way is the relation not linear? The authors should clarify it.
2. Line 32-34: The phrase “prolongs it in time” is little awkward. You should consider rephrasing it to “prolongs the growth period”. Moreover, consider rephrasing the phrase “water limiting conditions” to water limited conditions for improving the clarity.
3. Line 33-34: You stated that “Provenances adapted to high altitudes may hold an advantage under water limiting conditions”.  But it’s strange because your experiment included only one high-altitude provenance (Spanish-Pyrenean). How can you conclude this result based on this?  Need to clarify it also.
4. Line 40-43: The starting of introduction is clear but first sentence is quite long. You should shorten this sentence for better readability.
5. Line 105: Changing “phenophases” to “phonological events” will be more easily understandable for readers.
6. Line 109: In material and method section, there is numbering error in sub-section. For example: “Drought Treatments” and “Measurements and observations”, both are numbered sub-section as 2.2.
7. Line 110: The Plant material section provides a lot of ecological and distributional information about Corylus species. The methods should primarily describe the plant material used in the experiment e.g. provenances, ages, how many of each. Other information you should remove or move to introduction section unless it directly relates to experimental material.
8. Line 153: You have missed important detail about sample size used in the study e.g. How many plants in each group. Although Figure 1 indicating the number in each category but providing the number of replicates used in each group would clarify the experimental replication.
9. Line 169: The figure caption usefully defines abbreviations. Ensure that these abbreviations are also explained in the text when first used so that readers should not have to refer back to the figure caption.
10. Line 345: Figure 3 is not explicitly mentioned in the text. Please ensure that all figures are numbered sequentially and cited. Please provide the full definitions for the abbreviations used in Table 1.
11. Line 509: On suggestion is that you start your discussion by begin summarizing your hypothesis and key finding of your results.

      12. Line 603-604: Suggestion is to rephrase it for clarity like this “Both aspects should be                considered in carbon cycle models under climate change scenarios”. 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The study gives useful insights on Corylus taxa's drought responses, with strong methodology and unambiguous conclusions.  Addressing the concerns below would enhance its theoretical and practical contributions.  Minor changes are suggested before publishing.

 The summary summarizes the work briefly, however it might mention explicitly the climatic implications of delayed leaf senescence and skewed radial growth for carbon sequestration modeling.

 The introduction clearly contextualizes drought legacies, but it could also highlight the originality of investigating Corylus taxa in comparison to previous research on other plants such as Fagus sylvatica or Quercus.

 The description of the typical garden environment is detailed, however the pot size (4-liter) may impede root growth, potentially influencing drought sensitivity.  This constraint has to be noted.

 The drought treatment period (30 days) is reasonable, however the reasons for ending the therapy at near-total desiccation should be stated in further detail to support the stress severity level.

 Figure 1 is obvious, but a legend explaining the abbreviations (e.g., "Be_ave") immediately in the graphic would improve accessibility.

 The visual stress symptom rating method is well-defined, although inter-observer variability in scoring should be addressed, maybe with calibration data.

 The statistical analysis is sound, however the basis for pooling drought symptom ratings (e.g., scores 1-3) in certain models has to be explained, since it may mask subtle responses.

 Table 1 displays initial height/diameter variances, although the biological relevance of these minor changes (e.g., a 10 cm height difference) for drought response is unknown.

 The Spanish-Pyrenean provenance's delayed stress symptoms (Figure 5) are attributed to smaller size, but additional causes (e.g., stomatal control) should be considered.

 The idea that decreased leaf size is adaptive to drought lacks direct proof; correlative data (for example, leaf water potential) would support this conclusion.

 The resprouting results (Figure 6a) are intriguing, but the low resprouting rate in controls (3.9%) raises concerns regarding baseline stress levels in the greenhouse environment.

 The 21-day delay in leaf senescence for severely impacted plants (Figure 7) is impressive, but it raises questions about whether this is a survival strategy or a stress-induced malfunction.

 The bud burst delay (Figure 8a) associated to previous drought severity is an important result, although the mechanism (e.g., carbohydrate dynamics) has not been empirically verified.

 The shift in radial growth to autumn (Figure 9b) is described as compensatory, but the overall impact on yearly growth should be evaluated to support this conclusion.

 The debate of Spanish-Pyrenean provenance's benefit during drought is hypothetical in the absence of long-term fitness evidence.

 The study lacks a direct comparison of hydraulic features (e.g., xylem embolism) among provenances, which might explain differences in drought responses.

 The additional figures (e.g., stomatal density) are mentioned but not critically analyzed in the main text, missing a chance to connect morphology and function.

 The phrase "compensation growth" is commonly used, however it should be defined specifically in the context of drought recovery.

 The study design fails to account for potential carry-over effects from the 2018 temperature experiment, which might complicate drought responses.

 The randomisation of plants in the common garden is acknowledged, but microclimatic variation (e.g., greenhouse location) should be considered as a possible bias.

 The absence of mortality during a drought is significant, but it might be due to the sapling stage; the application to mature trees is unknown.

 The debate might benefit by comparing autumnal growth changes to other species (e.g., Quercus) to determine generality.

 The document quotes "Blumstein 2024" in the discussion, however this reference is not included in the bibliography.

 The ethical and practical concerns of utilizing potted saplings (e.g., root limitation) in drought experiments should be considered.

 The lack of changes in stomatal features (Table S1) contradicts the provenance-specific drought responses; this inconsistency should be addressed.

 The term "disproportionally larger delay" (in senescence due to extreme stress) is subjective; statistical effect estimates might clarify this argument.

 The study's significance to climate change might be increased by correlating the findings to expected drought frequency/intensity in Europe.

 The paper is well-written, although occasionally verbose (e.g., Methods); refining the wording would increase clarity.

Comments on the Quality of English Language

The manuscript is generally well-written and informative; however, certain sections—particularly the Methods—tend to be overly verbose. Streamlining the language by eliminating redundant phrasing and simplifying complex sentence structures would enhance overall readability and improve clarity for the reader.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I have thoroughly evaluated the revised manuscript and find that the authors have adequately addressed all the reviewer comments. The methodology, analysis, and presentation are now sound and meet the journal's standards. I recommend the manuscript for publication in its current form.