Microeconomics of Nitrogen Fertilization in Boreal Carbon Forestry

Round 1

Reviewer 1 Report

Studying the microeconomics of nitrogen fertilization in a boreal forest is an important and interesting topic. Before it can be accepted for publication, some necessary improvements are required:

1.     The introduction is generally simple, further improvement is encouraged

2.     Materials and Method: more details are required, for example, how to calculate basal area, how to conduct the forest inventory, what is the plot size, how to calculate tree volume – allometric model?

3.     Results: too many details, please indicate the main result.

4.     Discussion: results and discussion are mixed in some parts, please clarify.

 

Some minor issues:

P3: repeation of “As the five example stands have been observed at the age of 30…45 years, stem count 1655…2451/ha, and basal area 29…49 m2/ha, they were due for commercial thinning.”

Figures: what does “NF” mean? Not fertilization? More explanation of figures, e.g. 07/10 in Figure 1.

The language is generally OK, but can be improved.

Author Response

Thank you very much.

The Introduction has now been expanded to better clarify the role of forest timber stock in climate change mitigation.

A more detailed account is now given in the experimental and computational procedures.

The Reviewer mentioned that there are too many results. However, it appears that all the results are necessary. It is necessary to report the consequences of all the investigated alternative procedures. Otherwise, the consequences would remain unclear.

The author carefully inspected the content of the chapter “Discussion”. It appears that the limitations of the investigation are discussed, as well as consequences of the Results.  Consequently, it appears that “Results” are not mixed with “Discussion”.

The author carefully inspected the content of the chapter “Results”. It appears that some discussion of immediate operative consequences is given. These discussions relate to very details of any Figure expressing Results. The author thinks such details should appear in the immediate context of any Figure, as the chapter “Discussion” adopts a more generic view into the limitations and consequences of the Results.

Indeed, a sentence from “Materials and Methods” was repeated in the beginning of the “Results”. The statement justified the set of boundary conditions resulting in the introduction of the Results appearing in Figure 1. The author did think the repetition was necessary. However, the advice by the Reviewer has now been followed.

 

Reviewer 2 Report

Summary

The manuscript evaluates the timing and financial return of nitrogen fertilization of spruce-dominated boreal forests. The results show that profitability increases with fertilization, and the timing can affect rotations, timber stock, and carbon storage. This study contributes to understanding the benefits of fertilization in forest stands, especially from a financial perspective. However, the methodology is not detailed and clear enough to understand how and which data was measured and how the estimates were calculated and statically tested. Therefore, I am recommending the editor to reject the manuscript.

General comments:

1) Title: The emphasis placed on carbon sequestration, as indicated by the title and other sections of the manuscript, does not seem to be reflected in the outcomes presented within the study.

2) Material and methods (page 2, first paragraph): The reference for those equations is missing.

3) Material and methods (page 2, second paragraph): Only data from young stands were considered to model different conditions over time. It is unclear how many times these stands were measured for modeling the results of this study. I checked some of the references you cited, and my doubts persisted (here and in the following comments).

4) Material and methods (pages 2-3, paragraphs 4-7): Given that all estimates depend on this model, I missed more details. Is predicting fertilization and thinning with this single model sound even when you did not perform these operations in the evaluated stands? Since the results are modeled estimates, I missed a more robust statistical analysis supporting the credibility of the results. Furthermore, I missed information regarding the software employed to analyze and visualize the results.

5) Results (page 5):  It is challenging to solely contemplate carbon sequestration arising from N fertilization through the lens of tree growth. It is crucial to encompass other dimensions within this assessment, notably the release of gases resulting from nitrogen fertilizer application.

Author Response

Thank you very much.

The Reviewer states that the outcomes of the study do not seem to reflect the study objectives. They do. The Introduction is now expanded to make this clear to everyone.

Indeed, no literature references are given for Equations appearing in page 2.

Equations (1) and (2) are the same: only the input parameters differ. It is stated in the text that the Equations produce the expected value of an observable. Individuals missing knowledge from elementary concepts of probability theory can find the meaning from Wikipedia/expected value, or from any textbook.

Equation (3) gives the return rate on capital, as stated in the text. Similarly, individuals missing knowledge in elementary economics may consult Wikipedia.

The statistical scattering in the paper appears on the right-hand-side of Equations (1) to (3). The left-hand-side of the Equations represent expected values, which are processed thereafter. Correspondingly, there are no treatments of statistical scattering after Eq. (3). Similarly, statistics has been discussed in the study of Bollandsås et al (2008). It has resulted in deterministic growth models, discussing expected values only.

The impression of the author is that research papers should report the procedures applied – commercial names of software products should be avoided.

The carbon sequestration effect does not arise solely from tree growth. Figures 2, 4, 6 and 8 report expected values of the timber stock, and that is where the carbon sequestration effect arises. As the Introduction now has been amended, regarding the effect of the timber stock to climate change mitigation, it hopefully is easier to understand the outcome.

 

Reviewer 3 Report

The manuscript is a highly educated assessment of an important topic.

I recommend rather minor changes and later the publication of the text.

 

Specific comments

Abstract

the topic boron fertilization comes a bit unexpected.

The reduction of microbial activity and its intermediate or lasting effect needs to be elaborated more or ommitted at all.

 

The first lines of the results are a repetition of a sentence only 2 paragraphs above.

 

All figures

instead of placing the caption of the y-axis above it wouzld be better to put it, rotated by 90 deg, along the y axis.

 

In some figure the caption of the x-axis is not placed well, but squeezed to the tick numbers.

It is unusual to place eq 4 and 5 in the Results. Preferably, this information comes in the Methods section.

 

The formatting of the Reference section is not homogeneous. Check for un-intended line breaks!

 

Technically, the text is very good.

Author Response

Thank you very much.

In the area where the data arises from, boron deficiency is a very common problem. This is why the boron fertilization is mentioned. As the topic of the paper is carbon sequestration, the eventual effect of nitrogen on microbial activity deserves to be mentioned. Again, it should be enough to mention it in one sentence; interested readers may consult the references. 

Indeed, a sentence from “Materials and Methods” was repeated in the beginning of the “Results”. The statement justified the set of boundary conditions resulting in the introduction of the Results appearing in Figure 1. The author did think the repetition was necessary. However, the advice by the Reviewer has now been followed.

Thank you for the comments, regarding the Figures. The Figures have now been edited. The only thing where the author disagrees is the alignment of the text stating the observables reported in any Figure: the author strongly prefers horizontal text alignment, instead of vertical.

The Reviewer is correct: placing Equations in the section “Results” is somewhat unconventional. Equation (4) converts the results appearing in Fig. 7 into Fig. 9. The Equation could be placed in the other section, but then it would become separated from its application, impairing readability. Similarly, Eq. (5) clarifies how the results can be converted further.

The paragraph layout of the section “References” has been implemented by the editorial staff of the Journal. The author is unable to figure out what techniques have been used, and how the layout might be modified.

 

Round 2

Reviewer 1 Report

The significance should be further highlighted. 

I am not quantified to assess the language.

Author Response

Thank you very much for your contribution.

Reviewer 2 Report

After reviewing the comments from other reviewers, the author's responses, and the revised version of the paper, I now have a better understanding of the paper's content and its proposed ideas. I believe it is suitable for publication.

Author Response

Thank you very much for your contribution.