Natural Volatile Organic Compounds (NVOCs) Are Greater and More Diverse in UK Forests Compared with a Public Garden
Round 1
Reviewer 1 Report
Generally, this research is based on good science and aims to answer some interesting and important research questions. Although this article will eventually be published, as it does provide valuable contributions to this research field, there is still work to be done.
Major comments:
1. The introduction should be restated. The author should think more about why not just what. The importance of this research should be strengthened. In addition, what is the progress in evaluating and measuring natural volatile organic compounds?
Are NVOCs significantly different? How does this conclusion contribute to the current research field? What does this mean? The author should enrich the background and motivation of this article in the introduction.
2. My primary concern is the lack of depth in setting up the analysis and the use of some language and jargon that was unfamiliar to me. Some concepts in the article are difficult for me to understand, especially the section of methods and results, which makes me feel a little disorganized and difficult to read.
a. It is recommended to increase the overall location distribution map of the research area.
b. In the method, a flow chart to describe the procedure of the experiment is needed.
c. Clarification of experimental instruments should be supplemented in the form of tables. (For example, the precision, origin, model, etc. of the instrument)
d. For the plants around the sampling point, the Latin names of these plants and the plant data should also be reported. The reason why Latin names are reported is that internationally, any Latin name corresponds to only one plant, and any plant has only one Latin name. This ensures the uniqueness and universality of scientific name and avoids the phenomenon of synonymy or homonymy. The plant data (crown width, height, DBH, leaf area, leaf thickness, etc.) are reported because whether tall or short vegetation is related to the release of NVOCs.
3. The results of the study are too brief because the information it conveys is not comprehensive.
4. The discussion in this paper is incomplete. The authors focus on their results and the methods they use. It can benefit from more attention outside the model. More importantly, discuss the contribution of this article to forests for public health and how these results guide the theory. In addition, the limitations of this study should be supplemented. Future directions should be discussed. I suggest you highlight the current research's challenges and limitations to ensure that the results are correctly interpreted in these contexts - you have cited some literature. Still, there are many more that further explore this.
5. Conclusions_In this part, the author does not clearly state what kind of scientific conclusions the paper has come to. At the same time, through the author's research and data analysis, what is the innovation of this paper? I didn't see any explanation for it.
More importantly, in the conclusion part, references should not be cited. Please use concise and powerful language to summarize the basic work views, facts, data, and information, reflecting the value of the research results.
Minor comments:
1. Please write the study type in the title.
2. In Table 2, there are only chemical names. Should it include more information?
3. Also, there are minor grammatical errors; please conduct thorough language editing.
4. The statement of interest, data availability, and author's contribution is not clearly clarified.
Author Response
Please see attachment.
Reviewer 2 Report
Dear Editors,
Dear Authors,
presented manuscript deals with determination (by GC-MS) of volatile organic compounds in forests' air as a way to measure its potential benefits for human health. Although, there is a merit in this topic the study execution/presentation and overall conclusions clearly need improvement so to be publishable.
Major problem is that volatiles of interest (terpenes, terpenoids, etc.) are hardly to be found even in moderate quantities in deciduous forests (see suggested papers on European forests air flux/volatile emissions and other comments in the pdf file). Moreover, the study lacks of sound botanical description of the studied sites and inclusion only of the English names pf the plants doesn't help either. The Introduction and discussion should be re-written in this respect. Comparison regarding the volatiles found in the tested forest and the control is not presented (maybe there is a Supplement that is not provided) and conclusions related to time and duration of sampling could not be substantiated without accounting the species diversity and abundance. I would advise re-submission of the manuscript after complete revision of the text and the tables.
Comments for author File: 
Comments.pdf
Author Response
Dear reviewer
Thankyou for your valuable comments. We have corrected your points noted in the pdf and re-written parts of the text. The botanical names have all now been included and the tables have been updated with % abundances.
In answer to your comment "Major problem is that volatiles of interest (terpenes, terpenoids, etc.) are hardly to be found even in moderate quantities in deciduous forests" - The majority of the UK's semi-ancient and Natural ancient woodland is a mix of deciduous and evergreen trees and very diverse. This was very much a preliminary study and when possible, we would like to research the air in plantations to compare it against ancient woodland. A cross-study will be helpful for a wide variety of reasons but we feel this study will contribute to the understanding of air within UK forests.
Thankyou again for your helpful critique. Hopefully the paper is much improved.
Reviewer 3 Report
I understand that this is a preliminary study and a communication about it.
Nevertheless, I would like to ask the authors to show the map of the sampling sites.
Author Response
Thankyou for your comments. We have now included a map of the sampling site (figure 1).
Reviewer 4 Report
PLEASE CHECK THE ATTACHED PDF FILE.
Comments for author File: Comments.pdf
Author Response
Dear reviewer thankyou for your kind comments and detailed notes. All minor grammatical errors have been corrected.
We have now included relative percentages in table 2 for ease of comparison.
In the discussion we have now included some detailed evidence to the health benefits of limonene, carvone and elemene.
Round 2
Reviewer 1 Report
The resolution of Figure 1 is too low to see the words clearly, so the author is suggested to revise it.
The name of Table 2 is in the wrong position. The table name should be in front of the table.
Author Response
Thankyou for your comments. We have improved the resolution of the map and also corrected the legend for table 2.
Reviewer 2 Report
There are some improvements in the manuscript. See recommendations in the file.
Comments for author File: Comments.pdf
Author Response
Thankyou for your comments. We have addressed all your points including adding information around benzene, benzoic acid, removing repetition in the discussion and including more references on European forests.
All minor typos also corrected
