Response of Photosynthetic Capacity to Climate Warming and Its Variation among 11 Provenances of Dahurian Larch (Larix gmelinii)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study evaluates an effect of climate warming among 11 provenances of Dahurian larch. The authors concluded that climate warming increased photosynthetic capacity of plants, but the extent of the improvement varied among provenances.

Comments to the manuscript:

Line 83: Table 2 is not mentioned in the text;

Table 2: The title of the last column needs correction;

Lines 142-147: Please, give a reference for this method;

Line 157: Indicate what parameters were defined;

Line 162-166: In the section Materials and Methods, indicate how PNUE, TPU, and gm were found.This study evaluates an effect of climate warming among 11 provenances of Dahurian larch. The authors concluded that climate warming increased photosynthetic capacity of plants, but the extent of the improvement varied among provenances.

Comments to the manuscript:

Line 83: Table 2 is not mentioned in the text;

Table 2: The title of the last column needs correction;

Lines 142-147: Please, give a reference for this method;

Line 157: Indicate what parameters were defined;

Line 162-166: In the section Materials and Methods, indicate how PNUE, TPU, and gm were found.This study evaluates an effect of climate warming among 11 provenances of Dahurian larch. The authors concluded that climate warming increased photosynthetic capacity of plants, but the extent of the improvement varied among provenances.

Comments to the manuscript:

Line 83: Table 2 is not mentioned in the text;

Table 2: The title of the last column needs correction;

Lines 142-147: Please, give a reference for this method;

Line 157: Indicate what parameters were defined;

Line 162-166: In the section Materials and Methods, indicate how PNUE, TPU, and gm were found. 

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors undertook a long-term study of the response of the Dahurian larch to a warming climate.  This study is very straightforward and reports simple physiological parameters and their statistical significance in response to provenance and growth condition change, which will be valuable in informing on the development of the boreal forest in response to climate change.  A few minor points:

Would it be possible to provide standard deviations for the mean data reported in Tables 1 and 2?

The caption of the last column of Table 2 says "January July" and means just July.

Comments on the Quality of English Language

There are a handful of minor typos, but the language is fine.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript of Tian et al. titled ‘Response of photosynthetic capacity to climate warming and its variation among 11 provenances of Dahurian larch (Larix gmelinii)’gives the impression of a finished and well-read work. Despite the fact that the experiment itself was laid down more than 40 years ago, the authors clearly describe the novelty and relevance of this work.

In my opinion, the manuscript can be accepted for publication as presented.

As an observation, despite the detailed description of the planting scheme, it would be good to see a schematic representation. As further research, it can be recommended to the authors to study in more detail the internal morphology of needles and the state of the photosynthetic apparatus of the thylakoid membrane using PAM approaches.

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Overall comments

The manuscript presents a unique and exciting dataset on variation photosynthetic capacity and leaf traits of Dahurian larch among provenances and after 40 years of common garden experiment. As the long-term experiments are very difficult to conduct and monitored, data presented here are highly valuable and should be made accessible to researchers. 

The authors have done a thorough job of designing experiments and measuring leaf and photosynthetic trait parameters with standardized methods. However, the use of the MES site as the "warming" treatment and the JGDQ site as the "control" could be of concerned here because the observed differences can be the results of various differences observed at these two sites. These sites differ in temperature, precipitation, and soil nutrients, all of which can significantly contribute to the variation of photosynthetic capacity. I am not entirely sure we can attribute the observed difference due to the warming alone. A more pertinent point would be the photosynthetic plasticity of these plants and the fairly strong genetic effect from the original provenance. I would suggest revise the interpretation of the warming effect (as one of the causes, not the main driving force). In the specific comments, I provide some editorial suggestions that might be useful for your revisions.

Specific commments

Abstract

• The beginning of the abstract should briefly mention the importance of Dahurian larch, and also the fact that these plants were treated in the long-term warming (40 years!) experiment.
• The abbreviations for the parameters in the abstract should be in the same format as in the text, which uses subscripts.
• L.10: "Seedlings of 11 L. gmelinii provenances were transplanted..." -> did you mean "Seedlings of L. gmelinii from 11 provenances were transplanted..."?
• L.17: "slope of the correlations" is not technically correct. Make sure it is clear whether we are discussing correlation or regression.
• L.19-21: "The effects of warming on Pmax-a, Vcmax, Jmax, and TPU increased and then decreased as the aridity index of the original site increased." -> not clear what this means.
• L.22, 23: Please italicize the species name.

Introduction

• L.39-41: "If photosynthetic capacity can acclimate to new climatic conditions, then climate warming can have a positive or negative effect." -> The statement is very broad here. It would be nice to be a bit more specific.
• The introduction should contain a paragraph explaining why we should be interested in this species.
• The method for "warming treatment" was not explicitly explained in this section. It was understood later that we used MES trees for the "treatment" and the JGDQ as the "control." More explanations would be needed as for why JGDQ should be considered "control" when the sites has a higher mean annual temperature than the natural provenance. I'm also a bit concerned whether we can use the site difference as a proxy for warming, as the precipitation and nutrient levels were also very different between these two sites.
• The effect size (ΔX) should probably be standardized by Xicontrol. Otherwise, the ΔX values can be influence by the mangnitude of the measurements.

Results

• L.175-177: The results looks more like the slopes from regression analysis. If the goal was to compare the slopes between the treatment, the ANCOVA is a more explicit test for this (i.e. you can test whether the slopes are significantly different from each other).
• L.193: Again with correaltion vs. regression?
• L.199 + Figure 4: The method for fitting these non-linear relationships was not stated in the method section. Why did we choose this function for fitting?
• L.225: Are the rest of the leaf traits not related to photosynthetic characters? This lack of relationships should at least be mentioned in this section, or show the results in the supplementary materials. 

Discussion

• L.261: Soil nitrogen could be a major factor here, as you have explained that the increased photosynthesis could be the results of increased leaf nitrogen/SLA here. It is not clear how the "warming" could increase nitrogen uptake. How could be seperate the effect of increased temperature from the increased N here?
• L.284-286: The conclusion of "genetic adapatation to the original habitats" is a bit unclear. Need more explanation here.
• L.293: Not sure if we have enough evidence to suggest the weakening of the warming effect with time.
• L.301: It is interesting that you've chosen aridity index when trying to explore the effect of temperature. Wouldn't the temperature difference from the original habitat be a better indicator in this particular case?
• L.323-325: The effect of soil is likely inherent in this study nonetheless.

References

• Subscripting CO2 in the references numbered 7, 11, 33.
• Italicize genus/species names in the references numbered 8, 20, 21, 22, 23, 27.

Table and Figure

• Make sure that the fonts are consistent in each figure. There appears to be a mix of serif and sans serif fonts in Figures 5, 6.
• Table 2: Aridity index should be included here as well because it was used as one of the explanatory variable later on.
• Table 2: A map showing the locations of these provenances would be helpful for visualizing the differences in their tolerance, but it is entirely optional here. 
• Figures 1,2,3,4,5: Letters for each subpanels (e.g. 1A, 1B, 1C) should be provided.
• Figure 2: Why are there 3 regression lines 
• Table 4: Units for DG and Pp should be reported
• Figure 5: the figure can be enlarged to make sure that the letters above the bars are readible.
• Figure 6: Having multiple parameters in the same graph is difficult to read. Please consider separating each relationships into individual panels.

Comments on the Quality of English Language

The manuscript is well-written in terms of language usage. The text reads smoothly and conveys the intended meaning effectively for the most parts. A few unclear sentences do exist, but can easily be modified in the revision.

Author Response

Please see the attachment

Author Response File: Author Response.pdf