How to Simulate Carbon Sequestration Potential of Forest Vegetation? A Forest Carbon Sequestration Model across a Typical Mountain City in China
Round 1
Reviewer 1 Report
I've reviewed the manuscript submitted to Remotesensing titled “How to simulate carbon sequestration potential of forest eco-2 systems? An FCS model across a typical mountain city in China”. The scientific and accurate assessment of carbon sequestration in artificial forests has important scientific and practical implications for environmental protection and climate change mitigation. This study attempted to develop an effective carbon sequestration potential model and reveal the spatiotemporal evolution trend and driving factors of carbon sequestration potential. This inter-disciplinary study is novel and well-suited to the Journal. However, I think the manuscript still need revision in some methodology, scientific expression and viewpoint discussion before accepted by the journal.
General comments：
1. In fact, only the carbon accumulation by NPP is considered in this study, which is just part of the carbon sequestration in forest system. The soil，root，microorganisms are important carbon pools in forest system as well. The study provided a fuzzy definition of carbon sequestration in the forest system. So, revised the title and accurately describe what the carbon sequestration represents in the study.
2. Introduction—There were mainly common knowledge about forest ecosystems is important carbon sink, forest management is a significant approach, and so on. I think there need to summarize some research advance about the model used in the study, carbon sequestration by NPP and the driving factors, which would improve the depth and scientificity of the study.
3. Methodology—clearly differentiate between carbon status (or storage), carbon sequestration rate, carbon density, and carbon sequestration, which is directly reflect the carbon sequestration by NPP. For example, I confused, does the carbon storage and sequestration rate in forest land systems refer to the net primary productivity of vegetation?
4. Methodology —Line170: I think it is not precise enough to use a DEM with a spatial resolution of 1000 m to assess regional areas.
5. Methodology— Specific description of carbon sequestration model (FCS) that used in the study. It is better to give definition and significance about the FCS in the conclusion section.
6. Discussion— from the subheading, they focus on “comparative analysis of carbon sequestration models”, “path to enhance carbon sequestration potential” , I think these are good. However, it is not enough to support the conclusion where is just changes in storage, rate and spatiotemporal differences of carbon sequestration. So, what are the cognition about the models and the path, which are practical and scientific significance from the research.
7. Conclusion— In my opinion, the abstract and conclusion are reversed. The abstract should provide a summary of the main results obtained from the research. And, the conclusion should summarize cognition based on the main results.
Minor comments:
Line 27: Is the average value for the whole study area or unit area of 0.01 Tg C/a to 0.20 Tg C/a, you need clear descriptions.
Line I44: I don’t think that forest system will contribute to the carbon peaking.
Line 167: Figure 1，I don’t recommend you to use the map of China. Avoiding disputes over national maps.
Line 594: what is the definition of “per capita carbon sequestration rate” ? How to get it?
Minor editing of English language required
Author Response
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Reviewer 2 Report
The article details an interesting study on the estimation of C sequestration potential of a forest region in China. The author used a modeling approach trough the CASA and a FCS model to simulate different climate change scenarios from 2010 to 2060. The paper is of potential interest, and the addressed topic falls within the scope of the journal. However, there are some important issues to be improved in terms of the of the presentation itself, novelty of the work, and its potential application to other case studies.
While the methods appear to be sound, some basic details are needed to better understand by the reader. For example, in results section the estimation of C extensively refers to the forest area of the study site, but there is no place where the reader can get the extension of such area.
The introduction needs a clearer statement of the research gap or problem that the study aims to address. While the authors highlight the importance of accurate estimates of C sequestration potential for future environmental policy, it would be helpful to explicitly state what specific gaps or limitations exist in current approaches or knowledge. It is not clear what main objective is, whether the estimation itself of the amount of C stored or the C sequestration rate, or the modeling approach. The latter is for me much more interesting than the estimation itself. But an implementation of validation procedure would be beneficial. Furthermore, the authors need to add the discussion section of the manuscript and evaluate the work with reference to similar studies from the field of C estimation at landscape levels and its variation under climate change scenarios.
Author Response
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Reviewer 3 Report
Comments for author File: 
Comments.pdf
This study focused on future change in NPP over mountainous regions at the fine scale, using the CASA model. They found a decreased NPP at the end of this century. While this manuscript has the potential to make a meaningful contribution, I have identified three areas that require improvement. Additionally, there are several minor points that I have listed below, with the aim of enhancing the clarity and accessibility of this manuscript.
Initially, the use of ‘carbon sequestration potential of forest ecosystem’ can be misleading. We usually refer to potential changes in forest ecosystem carbon stock, but not changes in NPP, when talking about carbon sequestration potential at the ecosystem scale. Here the authors refer to changes in forest vegetation NPP and also mention the results of changes in C stock, which makes me quite confused. Changes in NPP do not consider soil respiration, land use change, disturbance, or management. Please clarify in the title and through the manuscript.
Second, many previous studies have utilized CASA to analyze NPP changes. What are the innovations in this article? For example, does the manuscript employ a localized parameterization scheme? Have you conducted research at a finer scale? Consider the vegetation intrinsic growth rate at the local scale? Please highlight these features in the abstract and throughout the full text.
Third, about the driving factors of changes in NPP, the authors consider climate, economics, and society. How about the impact of ecological restoration projects, like forest protection and afforestation? Please add some analysis or at last, discuss it.
Minor:
1. Line 297 and the forthcoming section: spatiotemporal pattern evolution of the carbon storage?
The word ‘evolution’ is unsuitable. Please consider changing it to the spatiotemporal pattern dynamic.
2. Result section, I feel quite confused about what are you mapping. Do you mean carbon storage or NPP? How do you simulate NPP and C stock using the CASA model? Please clarify. Please note that changes in NPP do not equal changes in vegetation biomass C stock.
3. Figure 9 is hard to follow, please use the name of each variable directly and plot them in a descending manner, this also applies to Figure 10.
4. Line 514, the carbon density of forests does not always increase as with forest age, it will face saturation. That’s why we need forest management to prolong the carbon sequential time!
Author Response
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Round 2
Reviewer 1 Report
This manuscript has been improved, and answered the main questions and comments. Now, there were still some minor errors need to be corrected.
1. The key words almost were about carbon, and how about the FCS model and research area. Do you think the reader could find the paper by check the key words “carbon”? Because there are thousands of paper key words are connected with carbon. I think should reconsider the key words meaning.
2.Fig 9: it is better to delete the value on the column.
3.In fig 3, 8 and 9, the scale step of the vertical axis can be enlarged to avoid too close arrangement of values
Author Response
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Reviewer 2 Report
My comment respect the extension of the study site (Chongqing) was based on the need to better understanding the storage potential by area unit (e.g. Mg ha-1) and the rate of C sequestration (e.g. Mg ha-1 year-1) of such forests.
I would suggest to use hectare (ha) instead of hm2.
Author Response
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Reviewer 3 Report
Thank you for making changes to your article. The revised submission is improved and your edits clarify all of my comments.
If possible, I hope you could clarify that you aim to calculate forest vegetation biomass, not NPP, in the abstract.
Except that, I have no further comments and recommend this piece for publication.
Please carefullt polish the wording before publish.
Author Response
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