Review Reports

Round 1

Reviewer 1 Report

Review Report on the Manuscript Number: forests-2356640 Title: Response of fine-root traits of Populus tomentosa to drought in shallow and deep soil         

The manuscript investigates the response characteristics of fine-root distributions and morphological traits (Populus tomentosa) relative to soil drought of different degrees. The topic seems to be appropriate for the journal of Forests. However, it must be revised before of be considered for publication. In the following, I suggest some possible improvements.

1.      I recommend write more accurate keywords. Like the soil drought and fine roots. Please change them.

2.      The Abstract is a little confusing for readers. The methods used should be presented completely.

3.      Line 58-59, It would be good to add some works about the effect of environmental changes on this type of roots. Please read and add references as follows:

Xin Zhang, Yajuan Xing, Guoyong Yan, Shijie Han, and Qinggui Wang. Effects of precipitation change on fine root morphology and dynamics at a global scale: a meta-analysis. Canadian Journal of Soil Science.2019.

Ryo Nakahata. Time-varying response of fine root growth to soil temperature and soil moisture in cypress and deciduous oak forests. Volume3, Issue2. 2022. Plant-Environment Interactions.

Misagh Parhizkar, Mahmood Shabanpour, Manuel Esteban Lucas-Borja, Demetrio Antonio Zema, Siyue Li, Nobuaki Tanaka, Artemi Cerda. Effects of length and application rate of rice straw mulch on surface runoff and soil loss under laboratory simulated rainfall. International Journal of Sediment Research 36 (2021) 468e478.

4.      Line 133, It would be good to add figure showing the geographical location and aerial map for your experimental site.

5.      The Materials and Methods section: I recommend combine 2.3 to 2.4 sections.

6.      Line 133, Why did you choose this experimental site? According to what? Investigation or other researches?

7.      Line 438-446, it would be better if you could compare with the results of other studies.

8.      Please explain relation and extension of results obtained from the study to natural conditions in larger scales (scaling).

 

Minor editing of English language required

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The paper is interesting and brings new insides in the field of tree fine root physiology and production. The authors offer very important background in modifications of fine root vertical distribution and traits due to drought conditions in the soil. I respect a huge field and laboratory works as well as smart statistical analyses show in the paper. At the same time, the paper is written clearly and is well organized. Hence, just a few corrections would be done in the text before publishing (minor revision).

 

Specific comments:

I recommend showing also English name of the Populus tomentosa (Peking poplar?) in the first mentioning in the text, i.e. in the Abstract and Introduction sections. 

 

Title:

- use always capital letters (as first letter in each word) excepting prepositions and conjunctions. The same would be done in the titles of subsections (correct in 2.1, 2.4, 2.5, 3.1, 3.3, 3.4, 4.1, 4.2, 4.3). 

 

Abstract:

Line 23 – write “(1920 samples)” instead of “(1920 fine-root samples)”

Lines from 37 to 41 – too long sentence, difficult to follow. Try to make it shorter (or make two sentences).

 

Keywords:

Do not repeat the terms with those in the title. Write English name of the species and perhaps “soil drying and rewetting” instead of “soil drought”. Erase “fine roots” and add any other keyword instead.

 

Introduction:

From the line 119 – start a new paragraph. Some info is needless – gives description which would be a part of the Material and Methods section. Thus, I recommend writing the text for instance in this way: 

“Therefore, we conducted a continuous study in a young P. tomentosa plantation with respect to the gradual desiccation of deep soil to solve the following two scientific problems: 1) How does drought affect fine-root distributions…”

 

Material and Methods:

Since the Forests journal is a worldwide magazine, most of the readers do not know much about the Gaotang county etc. Therefore, it might be a good idea to show a map illustrating localization the Gaotang county within China as well as localization of the research site within the county.

Line 191 – it would be nice to show citation giving more info about fine roots traits implemented for distinguishing dead and live fragments.

 

Results:

This section is rather fine. Just, in the title of 3.2 subsection – erase the term “Spatial”. The same would be done in the entire text. I think that expression “vertical distribution” is enough descriptive itself.

 

Discussion:

The title of the 4.1 section – erase “Spatial”,

The text between the lines 368 and 397 is too long. Hence, make two paragraphs rather, e.g. in the line of 387.

The paragraph from 398. Usually Discussion text would first show up own findings and then outputs from other authors. Thus, authors would try to reorganize this paragraph.

Lines around 404. Some findings from Europe showed that even moderate drought might alter vertical distribution of fine roots in drought-sensitive tree species. Therefore, the authors may incorporate statement, something like: “Findings from the European temperate forests proved that even moderate drought altered quantity and vertical distribution of fine roots in Norway spruce (Picea abies L. Karst.), a drought-sensitive and shallow rooted species.” For specific citation, see the paper entitled “Moderate drought alters biomass and depth distribution of fine roots in Norway spruce” in Forest Pathology, 2013, 43(2):114-123.

 

Conclusions:

The last sentence: what do the authors exactly mean with “intensive cultivation technologies”? I suggest adding a short introduction (1-2 sentences) explaining the available technologies. Those will help potential readers to get ideas about human possibility to manage tree vs soil interactions.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

This paper presents data on the reaction of poplar (P. tomentosa) roots to soil drought when growing in plantations. The work is interesting and noteworthy; however, there are a number of queries and comments that want an explanation.

 

It’s not a question, it’s clarification. Were the plants examined actually five to six years old (3.0 m in height and 3.7 cm in DBH, respectively)? And even at that young age, their root systems reached six metres or deeper? For instance, even mature European poplar trees (P. alba, P. tremula, P. nigra, etc.) (both in their native state and in plantations) do not reach this depth (because they form shallow root systems).

Is any information available on how quickly poplar roots elongate? Obtained by authors or other scientists by examination of minirhizotron images or another method? With the use of this information, it is possible to predict how the lateral roots will develop from the main root and how quickly they will grow to a length of 30 cm (the distance from the trunk on which the samples were taken).

Root samples were taken to a depth of six metres. Were the cores extracted mechanically or by hand throughout the research? Could the authors describe the equipment used for soil coring?

First, tree plants respond to drought by altering physiologically rather than at the level of their root systems (changing structure, redistribution by depth, or growing of new roots). Alterations in hormone levels, variations in transpiration intensity, etc. Please add a few paragraphs to the discussion section about physiologically adapting poplars to drought.

Valuation of supplemental materials is impossible. Links to figures (Figure S1 and Figures S2) are provided throughout the text and in the Additional Materials section; however, the actual figures were not loaded into the system.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

All the questions have been answered. With this background, I believe the manuscript can be accepted for publication.