Stem Heating Enhances Growth but Reduces Earlywood Lumen Size in Two Pine Species and a Ring-Porous Oak

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This is a really interesting project with important implications, and with a little work can be a very strong paper.

Larger concerns:

This manuscript is currently billed/marketed primarily as a heat treatment experiment with some modeling (the dendrochronology isn't even mentioned in the abstract). I suggest repackaging the emphasis as a dendrochronology and modeling study supported by heat experimentation.  Building the paper on the heat treatment experiment with only 2 treated specimens of each species for one season that occurred 13 years ago creates a weak foundation.  To me, the dendrochronology and modeling are the real selling points and the heat experiment provide interesting and strong support. 

A heat treatment of 18-22 degrees Celsius was applied over the entire winter season.  This is more than an early onset of spring, it is a lack of winter which some trees may need.  I would like to see some discussion added about why low temperatures were completely excluded and the potential impacts.

Large tables with many R^2 values associated with dendro-climate analysis are difficult for my brain to process.  There are many graphing options (some included in the programs used in this study) that allow the visualization of correlation and partial correlation results that I find much easier to comprehend (although they are still complicated).  I suggest examining tables 3 and 4 to determine what data could be visualized in a figure. 

Smaller concerns:

Table 1 threw me off a bit. I don't like having results in the methods section.  Perhaps, splitting this table in 2 moving the results to the results section would help.  Also, this table presents xylem onset dates, but you haven't discussed how these were measured yet. I also found the letters confusing.  What is the difference between a and b? 

I would like to see some discussion added about how a narrow band of heat 1.3m from the ground represents environmental warming which is exposed to the entire tree.

This is a small complaint, but I prefer the methods to be chronological.  You present the heat treatment first.  Then, the pre-treatment measurements.  Why not present the methods in the order they were completed? 

I think that Figure S2 could be pulled into the paper.  However, as this journal has an international focus, a better location map would be helpful. 

 

 

Comments on the Quality of English Language

I know we aren't supposed to review grammar.  However, there are a number of issues throughout, which I suspect are related to language, that are distracting or even confusing. Here is a list of lines with issues:

89/90, 91, 107, 109, 110, 111, 117 (I disagree), 118, 155-157, 166, 190 (only after treatment or before?), 197, 221, 247, 351, 383, 575

Author Response

Reviewer 1

This is a really interesting project with important implications, and with a little work can be a very strong paper.

 

• We thank you for your positive comments on our study.

 

Larger concerns:

This manuscript is currently billed/marketed primarily as a heat treatment experiment with some modeling (the dendrochronology isn't even mentioned in the abstract). I suggest repackaging the emphasis as a dendrochronology and modeling study supported by heat experimentation.  Building the paper on the heat treatment experiment with only 2 treated specimens of each species for one season that occurred 13 years ago creates a weak foundation.  To me, the dendrochronology and modeling are the real selling points and the heat experiment provide interesting and strong support. 

 

• We understand your queries, but the novelest aspect of the study is the heating experiment; albeit we acknowledge the limitation of using only 2 heated trees. Making the paper framed on the dendrochronological and modeling results would make it more robust but less novel given that these two aspects have been well studied before.

 

A heat treatment of 18-22 degrees Celsius was applied over the entire winter season.  This is more than an early onset of spring, it is a lack of winter which some trees may need.  I would like to see some discussion added about why low temperatures were completely excluded and the potential impacts.

 

• We added some discussion on this aspect. Note that we intended to advance spring phenology by imposing a “strong” heating treatment given the continental (cold winter) conditions of the study sites.

 

Large tables with many R^2 values associated with dendro-climate analysis are difficult for my brain to process.  There are many graphing options (some included in the programs used in this study) that allow the visualization of correlation and partial correlation results that I find much easier to comprehend (although they are still complicated).  I suggest examining tables 3 and 4 to determine what data could be visualized in a figure. 

 

• The revised ms. contains 8 figures (we added the map based on the comments of both reviewers), which we consider it is enough. We have kept both tables but improved their presentation by highlighting significant values or models with high R2 values.

 

Smaller concerns:

Table 1 threw me off a bit. I don't like having results in the methods section.  Perhaps, splitting this table in 2 moving the results to the results section would help.  Also, this table presents xylem onset dates, but you haven't discussed how these were measured yet. I also found the letters confusing.  What is the difference between a and b? 

 

• We respectfully disagree because there are also enough tables. We prefer keeping the table as it is because it introduces phenology dates which are necessary to understand the rest of results. We better explained how xylem onset dates were obtained. The letters show differences between heated and non-heated stems as it is stated in the legend.

 

 

I would like to see some discussion added about how a narrow band of heat 1.3m from the ground represents environmental warming which is exposed to the entire tree.

 

• We provided some discussion on this aspect because we acknowledge that heating a stem portion is completely different from heating the canopy, branches or roots of trees

 

This is a small complaint, but I prefer the methods to be chronological.  You present the heat treatment first.  Then, the pre-treatment measurements.  Why not present the methods in the order they were completed? 

 

• We moved the heating section after the pre-treatment sections as you suggested.

 

I think that Figure S2 could be pulled into the paper.  However, as this journal has an international focus, a better location map would be helpful. 

 

• We added Fig. S2 to the main text as you suggested.

 

Comments on the Quality of English Language

I know we aren't supposed to review grammar.  However, there are a number of issues throughout, which I suspect are related to language, that are distracting or even confusing. Here is a list of lines with issues:

89/90, 91, 107, 109, 110, 111, 117 (I disagree), 118, 155-157, 166, 190 (only after treatment or before?), 197, 221, 247, 351, 383, 575

 

• We revised these grammatical issues. Thanks a lot for noting them.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors,

Your manuscript addresses topical issues of plant growth in a changing climate. You have used different approaches - anatomical and physiological biochemical to answer the question of what happens during local heating of the stem of two species of pines and oak, which have different ecological strategies. The use of the Vaganov-Shashkin model to describe the radial growth of tree trunks is successful. The prediction of spring phenological changes in tree growth in the future is also of great interest.
However, there are some questions:
1. You described in detail the change in the lumen size of large vessels and the thickness of their cell walls. However, you do not provide data on the number of vessels, both large and small, in the unit area of the cross section. It would be interesting to understand whether heating of the trunk changes this indicator. I also wonder if the total projective surface of all vessels in the trunk has changed? How will the hydraulic capacity change in this case. 2. Also  the data on the content of structural polysaccharides and lignin in unheated and heated samples could be important for understanding the changes you studied.
3. Line 248 - correct the missing letter in the sapwood.

Its significance will be higher if you show data on the number of vessels, their total lumen area, and structural polysaccharides and lignin.

Author Response

Dear authors,

Your manuscript addresses topical issues of plant growth in a changing climate. You have used different approaches - anatomical and physiological biochemical to answer the question of what happens during local heating of the stem of two species of pines and oak, which have different ecological strategies. The use of the Vaganov-Shashkin model to describe the radial growth of tree trunks is successful. The prediction of spring phenological changes in tree growth in the future is also of great interest.

 

 

• We thank you for your positive comments on our study.

 

However, there are some questions:

1. You described in detail the change in the lumen size of large vessels and the thickness of their cell walls. However, you do not provide data on the number of vessels, both large and small, in the unit area of the cross section. It would be interesting to understand whether heating of the trunk changes this indicator. I also wonder if the total projective surface of all vessels in the trunk has changed? How will the hydraulic capacity change in this case. 2. Also the data on the content of structural polysaccharides and lignin in unheated and heated samples could be important for understanding the changes you studied.

 

Its significance will be higher if you show data on the number of vessels, their total lumen area, and structural polysaccharides and lignin.

 

• We thank you for noting these lacking data. Regrettably, we do not have measurements on these variables. We have indicated in the revised discussion that it would be interesting to measure them in further studies.

 

3. Line 248 - correct the missing letter in the sapwood.

 

• We corrected it.

Reviewer 3 Report

Comments and Suggestions for Authors

Review

I  thank for this review the MS is adequately presented. I enjoyed review the article .

 

L23 Is there a possibility to mention of increasing of temperature?

 

The introduction is focused according to objective, which is appropriately written and the hypothesis is supported. Some observation can be considered:

L85 lumen area and cell-wall thickness. Add “and”

Some references are older and then can updated.

 

Materials and methods

The information presented in this section permitted their reproduction. Some observation can be considered.  

Some important figure (S1, S3, S4 and S5) can be relocated in materials and methods part. These information are important.

L113-116 Is there a possibility to presented this information in table or figure?

L158 the figure S2 can be relocated in this part.

L169 is there a possibility to mention how many degrees was increased of temperature?

L188-192 some part of title represents footnote of table

L221-225 IDEM

 

Results

 

Some important figure can be relocated in materials and methods part. These information are important.

 

L374-380 some part of title represents footnote of table

L502-505 IDEM

Author Response

I  thank for this review the MS is adequately presented. I enjoyed review the article .

 

• We thank you for your positive comments on our study.

 

 

L23 Is there a possibility to mention of increasing of temperature?

 

• We revised it.

 

The introduction is focused according to objective, which is appropriately written and the hypothesis is supported. Some observation can be considered:

 

L85 lumen area and cell-wall thickness. Add “and”

 

• We added it.

 

Some references are older and then can updated.

 

• We revised them.

 

Materials and methods

 

The information presented in this section permitted their reproduction. Some observation can be considered. 

 

Some important figure (S1, S3, S4 and S5) can be relocated in materials and methods part. These information are important.

 

L158 the figure S2 can be relocated in this part.

 

Some important figure can be relocated in materials and methods part. These information are important.

 

• We moved fig. S2 to the main ms. but we cannot move more figures given that the revised ms. already contains 8 relevant figures.

 

L113-116 Is there a possibility to presented this information in table or figure?

 

• Again, we have several tables which precludes adding more information as additional tables.

 

L169 is there a possibility to mention how many degrees was increased of temperature?

 

• Yes, this is shown in Fig. S3, and we indicated in the revised ms.

 

 

L188-192 some part of title represents footnote of table

L221-225 IDEM

 

• We moved part of the legends to the footnote as suggested.

 

Results

L374-380 some part of title represents footnote of table

L502-505 IDEM

 

• We moved part of the legends to the footnote as suggested.