The Annual Dynamics of the Water Source of an Ammopiptanthus mongolicus Community in the Gobi Desert of the Mongolian Plateau

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors,

I hope you're well. It has been a pleasure to read his work and learn more about his research in water dynamics and isotopes. I want to highlight its clarity in the focus on the diversity of water use, on the soil profile and in the presentation of the results. I have made some suggestions that I think could strengthen your manuscript:

I suggest that the graphs, particularly those in Figure 2, are magnified, it is very difficult to distinguish the points, and greater contrast between shapes and colors is also necessary.

I think the graph format for presenting the results is very clear. In the case of Figure 3, graphs e and f do not match what is detailed in the results text (lines 217 to 224). It would be necessary to modify the values ​​of August 25 and September 25.

It is necessary to modify the date of the year that appears. In figure 4, the values ​​represented correspond to the year 2022 and the figure indicates 2021.

I find the incorporation of existing studies on root distribution cited in the discussion to be very valuable. I value your dedication and effort in this research and I wish you much success in the review and eventual publication of your manuscript.

I send you my best regards.

Author Response

I hope you're well. It has been a pleasure to read his work and learn more about his research in water dynamics and isotopes. I want to highlight its clarity in the focus on the diversity of water use, on the soil profile and in the presentation of the results. I have made some suggestions that I think could strengthen your manuscript:

Comment 1: I suggest that the graphs, particularly those in Figure 2, are magnified, it is very difficult to distinguish the points, and greater contrast between shapes and colors is also necessary.

Response1: Thanks for your suggestion. We modified Figure 2 and enhanced the contrast between different symbols, including shapes and colors.

Comment 2: I think the graph format for presenting the results is very clear. In the case of Figure 3, graphs e and f do not match what is detailed in the results text (lines 217 to 224). It would be necessary to modify the values ​​of August 25 and September 25.

Response 2: Sorry for the mistake. We modified values of Aug. 25 and Sep. 25 based on Figure 3 e-f in Results.

Comment 3: It is necessary to modify the date of the year that appears. In figure 4, the values ​​represented correspond to the year 2022 and the figure indicates 2021.

Response 3: Sorry for the mistake. We modified the legend of Figure 4 as 2022.

Comment 4: I find the incorporation of existing studies on root distribution cited in the discussion to be very valuable. I value your dedication and effort in this research and I wish you much success in the review and eventual publication of your manuscript.

Response 4: Thanks for your suggestion. We did survey about root system of four shrubs in the A. mongolicus community on Gobi. It was not easy and took 10 days labour for Aqing Wang, my master student. We added 2.5 Root sampling in Material and Methods and 3.4 Root distribution in the A. mongolicus community on Gobi in Results with Figure 5, with the relationship between root distribution and water source of four shrubs in Discussion and Conclusion.

Reviewer 2 Report

Comments and Suggestions for Authors

Several questions and remarks regarding the paper by Zhu et al. “The annual dynamic of the water source of an Ammopiptanthus mongolicus community on the Gobi of Mongolian Plateau”.

 

Soil properties, particularly texture, affect the infiltration rate and soil water retention. This study does not contain any information on soil properties. Without knowing the characteristics of the soil, how can the water content of the soil be studied? Provide data on the main physicochemical properties of soils, accounting for the sampling depth.

The characteristics of root system architecture and root distribution along the soil profile determine a plant's ability to absorb water. The authors only mentioned this fact in the Discussion. Why did the authors not study the distribution of plant root systems along the soil profile?

“…the A. mongolicus community had a resource-dependent water use strategy...” (Lines 26-27) I apologise but is there any other tactic that perennials may use in arid environments with a notable lack of plant-available water?

“…water competition of different shrubs should be considered for biodiversity conservation of protected species and vegetation restoration on Gobi.” (Lines 312-314). What will these data play in restoring vegetation and preserving the biodiversity of protected species? First, plant-available water content in different soil levels fluctuates greatly during the season. Second, to better preserve protected species, is it possible for humans to alter or otherwise impact the way that plants compete for water?

Add research limitations and perspectives for future exploration to the Discussion section.

Author Response

Comment 1: Soil properties, particularly texture, affect the infiltration rate and soil water retention. This study does not contain any information on soil properties. Without knowing the characteristics of the soil, how can the water content of the soil be studied? Provide data on the main physicochemical properties of soils, accounting for the sampling depth.

Response 1: Thanks for your suggestion. We introduced soil type, physical and chemistry character in 0−5cm in Material and Methods with a new reference. We also added a supplement table of bulk density, SOC, N, P, K content in 0−100cm depths in the end of the manuscript.

Comment 2: The characteristics of root system architecture and root distribution along the soil profile determine a plant's ability to absorb water. The authors only mentioned this fact in the Discussion. Why did the authors not study the distribution of plant root systems along the soil profile?

Response 2: Thanks. We added 2.5 Root sampling in Material and Methods and 3.4 Root distribution in the A. mongolicus community on Gobi in Results with Figure 5, with the relationship between root distribution and water source of four shrubs in Discussion and Conclusion.

Comment 3: “…the A. mongolicus community had a resource-dependent water use strategy...” (Lines 26-27) I apologise but is there any other tactic that perennials may use in arid environments with a notable lack of plant-available water?

Response 3: Sorry for the mistake. We modified this sentence as: Therefore, four xerophytic shrubs in the A. mongolicus community used soil water in different depths based on their availability to adapt to the annual fluctuation of rain on Gobi.

Comment 4: “…water competition of different shrubs should be considered for biodiversity conservation of protected species and vegetation restoration on Gobi.” (Lines 312-314). What will these data play in restoring vegetation and preserving the biodiversity of protected species? First, plant-available water content in different soil levels fluctuates greatly during the season. Second, to better preserve protected species, is it possible for humans to alter or otherwise impact the way that plants compete for water?

Response 4: Sorry for the mistake. We changed this sentence as: It is suggested that the annual dynamic of rainfall should be considered for biodiversity conservation of protected species and vegetation restoration on Gobi.

Comment 5: Add research limitations and perspectives for future exploration to the Discussion section.

Response 5: Thanks for your suggestion. We add two sentences in Discussion. Geological variation of water source of A. mongolicus community should be explored in the future, including other counties or banners of Nei Mongol, Ningxia, Gansu in China and southern Mongolia. 

Reviewer 3 Report

Comments and Suggestions for Authors

The study of plant adaptation to soil drought is an urgent area of research, especially for arid areas. From this point of view, this paper is relevant, as it draws attention to an important problem. For the Gobi, this is a relevant issue. The paper is well written. The research objectives are clearly formulated. The authors used modern research methods appropriate to the task. The results are clearly presented. The paper itself is of a high scientific standard. Therefore, the reliability of the conclusions is beyond doubt. I don't have any major comments. However, the plant communities of the Gobi Desert are not forest ecosystems. Therefore, the paper is not suitable for the Forests journal. I believe the authors can redirect the paper to the journal Plants, where it can be published.

Author Response

Comments 1: The study of plant adaptation to soil drought is an urgent area of research, especially for arid areas. From this point of view, this paper is relevant, as it draws attention to an important problem. For the Gobi, this is a relevant issue. The paper is well written. The research objectives are clearly formulated. The authors used modern research methods appropriate to the task. The results are clearly presented. The paper itself is of a high scientific standard. Therefore, the reliability of the conclusions is beyond doubt. I don't have any major comments. However, the plant communities of the Gobi Desert are not forest ecosystems. Therefore, the paper is not suitable for the Forests journal. I believe the authors can redirect the paper to the journal Plants, where it can be published.

Reply: Thanks for your advice. A. mongolicus is the only evergreen broad-leave shrub in desert of Asia, belonging to vulnerable species according to IUCN. As the guest editor of special issue of Construction and Maintenance of Desert Forest Plantation, I think it's proper to present this manuscript with other studies in desert. We will discuss this issue with editor.

Reviewer 4 Report

Comments and Suggestions for Authors

The submitted manuscript deals with the issue of water intake of the desert plant Ammopiptanthus mongolicus. The monitored issue is topical, as it is related to the protection of the mentioned species, but it can also be used in the framework of the protection of biodiversity in other arid areas. However, it is a pity that the authors somewhat underestimated the preparation of the manuscript. I recommend editing and supplementing the said manuscript. As part of the experiment, a larger number of plant species were observed than the species Ammopiptanthus mongolicus mentioned in the title, perhaps it would be appropriate to modify the title of the article. In the introductory part and on lines 44 – 48, the term fractionation of isotopes is given, which mainly relates to water, but it is not explained anywhere and it is not entirely clear what the relationship of this parameter is to the issue under investigation. It would be appropriate to supplement the above, including a methodological introduction. As part of the methodology, the course of the weather in both experimental years should be indicated. Graph 1 shows only the data of the observed time period, but the whole year is important for plants, especially with regard to precipitation, which often does not have to be evenly distributed within the year (e.g. the effect of torrential precipitation). Results are based on graphical results. I recommend adjusting the quality of all charts. In graphs 3 – 4, the values ​​of only 2021 are given, while the attempts were determined in two years. Analysis of the second year is missing. Comparisons between years are also missing. Therefore, the results are insufficient. Please explain the term on line 155: phloem water is isotopically enriched by photosynthesis. So how is water enriched by photosynthesis, when the flow of water and assimilates in the vascular bundle is spatially separated? The authors tend to cite older literary sources, but they do not cite them uniformly. Please unify the citations.

Author Response

The submitted manuscript deals with the issue of water intake of the desert plant Ammopiptanthus mongolicus. The monitored issue is topical, as it is related to the protection of the mentioned species, but it can also be used in the framework of the protection of biodiversity in other arid areas.

Comments 1: However, it is a pity that the authors somewhat underestimated the preparation of the manuscript. I recommend editing and supplementing the said manuscript. As part of the experiment, a larger number of plant species were observed than the species Ammopiptanthus mongolicus mentioned in the title, perhaps it would be appropriate to modify the title of the article. 

Response 1: Thanks for your suggestion. We cited articles of other plants in desert ecosystem to present their water source, not only Ammopiptanthus mongolicus. If we cited other physiology and ecology studies about A. mongolicus in the Introduction, it will not be comparable with water source, which is our main topic. 

Comments 2: In the introductory part and on lines 44 – 48, the term fractionation of isotopes is given, which mainly relates to water, but it is not explained anywhere and it is not entirely clear what the relationship of this parameter is to the issue under investigation. It would be appropriate to supplement the above, including a methodological introduction.

Response 2: Thanks for your suggestion. Stable isotope is a common method to investigate water source of plant species, which was stared in 1990s. We add a citation of this method in Introduction [4]. We also modified number of other citations and references.

Comments 3: As part of the methodology, the course of the weather in both experimental years should be indicated. Graph 1 shows only the data of the observed time period, but the whole year is important for plants, especially with regard to precipitation, which often does not have to be evenly distributed within the year (e.g. the effect of torrential precipitation).

Response 3: Although A. mongolicus is an evergreen shrub, it is dormant in winter. In Study site, we have introduced the arid climate of Dengkou County. The total annual precipitation was only 144.5mm and mainly occurred as rain in summer and early autumn. So, we think the daily temperature and precipitation in the growing season is enough for this study. Winter snow is more important in other humid and northern areas, such as Hulun Buir grassland in Nei Mongol.

Comments 4: Results are based on graphical results. I recommend adjusting the quality of all charts. In graphs 3 – 4, the values ​​of only 2021 are given, while the attempts were determined in two years. Analysis of the second year is missing. Comparisons between years are also missing. Therefore, the results are insufficient.

Response 4: Thanks. We have improved the quality of Figure 2. Sorry, we just made a mistake in the legend of Figure 4. The results of 2022 had been presented in Results. We compared the difference between two years in Discussion. If we compared it in Results, the figure would be too complicated.

Comments 5: Please explain the term on line 155: phloem water is isotopically enriched by photosynthesis. So how is water enriched by photosynthesis, when the flow of water and assimilates in the vascular bundle is spatially separated? The authors tend to cite older literary sources, but they do not cite them uniformly. Please unify the citations.

Response 5: In this study, we used isotope technology to compare the annual dynamic of water source of A. mongolicus community on Gobi. The sample method is quite common in isotope ecology. It is not our topic to investigate the physiological mechanism of water enrichment during photosynthesis. So we delete this sentence to avoid ambiguity.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

All responses and revisions made by the authors are clear, thoughtful, and satisfactory.

Reviewer 3 Report

Comments and Suggestions for Authors

I'm not against publishing the paper.

Reviewer 4 Report

Comments and Suggestions for Authors

The authors submitted a revised version of the manuscript following a peer review process. The reviewer's comments have been justified in the attached document. I recommend that future publications should better describe the conditions in the area, given that the article may be read by people unfamiliar with the geography of the area. Similarly, stating that a methodology is used somewhere is fine, but then make sure that it is referenced in the text so that it is easy to follow. The level of graphic design has improved. I think that stating that the second year's evaluation is in a different chapter from the results is a bit striking, but it can be accepted, even though it is not common. It is the year-on-year differences that are often very significant. I still recommend the manuscript for acceptance