Diverse Understory Vegetation Alleviates Nitrogen Competition with Crop Trees in Poplar Plantations
Round 1
Reviewer 1 Report
I must admit that much of my low ratings of this manuscript arises from the extremely poor English usage. This is not meant as a harsh criticism, for I understand that English is not the primary language for the authors. However, acceptability of a manuscript has to consider the readership of the journal. It was simply hard to follow what the authors were trying to say. Thus, I recommend a complete rewriting with input from a colleague whose primary language is English.
Also related to readership is that Forests is a truly international journal. Accordingly, authors should put their findings into a broader context. For example, plantation forestry in the US typically eschews (and therefor eliminates) the development of any herb layer vegetation. In fact, a novel finding in the present study is that understory vegetation is compatible with plantation forestry.
The manuscript also lacks important, pertinent literature on the ecology of forest understory communities. Inclusion of these will not only add to the informational quality of the manuscript, it will also help expand a broader scope. Gilliam (2007--BioScience) discusses several aspects of ecosystem significance. Elliott et al. (2015--Ecosystems) discusses its functional role. In fact, Oxford University Press published an entire book on this topic in 2014, with several chapters germane to this study.
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
Dear Authors,
the manuscript sent to me for review touches on an important, interesting and poorly known subject in the field of forest science. In my opinion, the research shows a high level of cognition. In general, I rate the manuscript highly, but I have a few minor comments that will allow for its improvement:
1. Abstract is a bit too long, maybe it could be shortened a bit.
2. In the Keywords section, you should not include words from the title of the paper.
3. Introduction is satisfactory, and the purpose of the research is properly defined.
4. Materials and Methods is logical and clear, although very detailed, maybe it could be shortened a bit?
5. Results are presented clearly, but in Figure 1 the X axis has an illegible description and in Figures 2a and 3a there is no description of the X axis.
6. In the Discussion chapter, it is not necessary to refer to the Tables and Figures discussed earlier in the Results chapter.
7. Author Contributions section should be prepared according to Template of Forests Journal.
In addition, the entire manuscript should be re-examined for TEMPLATE compliance.
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
This paper describes an experiment how the diversity of the understory vegetation affects competition for nitrogen between trees and understory in a polar plantation. This is an interesting topic that deserves study. The interaction between diversity and nutrient cycling and retention is a topic that is interesting both from theoretical and practical/management viewpoint. I would maybe have liked to see a treatment where understory was removed by mowing at intervals. Mowing makes grassland biodiversity higher, I do not know if this is also the case for understory. Could that be mentioned in discussion?
There are a number of minor language errors, the authors are encouraged to get language proof reading.
Abstract: The description of results is somewhat complicated. Try to make clearer, and only mention important results.
Fig 1: I don’t understand the last bars, May-Jun. 2018 2019. The others are chronological, why are these here?
L 312 sundry- what does that mean here?
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors have failed to address my concerns. Problems with English usage have not been corrected and, thus, is still highly problematic. Only one suggested reference was added, and that was poorly incorporated into the text. I recommend rejection.
Author Response
Please see the attachment
Author Response File: Author Response.docx
Round 3
Reviewer 1 Report
The authors have undertaken a substantial revision of their manuscript, resulting in notable improvements. I recommend acceptance.
