Response of the Alpine Timberline to Residual Permafrost Degradation in Mount Wutai
, Peijie Hou 1, Yan Wang 1, Lisha Qiu 1, Ying Guo 1,2,3,4 and Chengcheng Zhang 1,2,3,4
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsComments to Authors
Authors have presented good work in the article, which can be accepted by following a minor revision. The abstract section of the article seems complete to me, all Important findings are presented in the article.
By reading the abstract, a question arises in my mind: is there any specific method? that you used to assess the impact of permafrost degradation on alpine timberline movement in Wutai Mountain between 2001 and 2021, 2000 to 2014, etc? This study was performed based on the obtained data.
How did the distribution and change of surface frost numbers, as influenced by vegetation and alpine timberlines vary over the 20-year study period in Mount Wutai? Can you elaborate on the mechanisms through which melting permafrost positively influenced the upward movement of the alpine timberline from 2000 to 2014?
What were the primary factors leading to the disappearance of permafrost near the timberline between 2014 and 2021, and how did this affect the movement of the alpine timberline?
What implications do the study's findings have for predicting future changes in alpine vegetation and timberline dynamics in response to ongoing climate change and what will be the role of the NDVI approach in identifying these changes. What What are the potential long-term ecological consequences of permafrost degradation? for alpine ecosystems, based on the findings from Mount Wutai?
Minor
The term NDVI is used several times in the article. I suggest adding the expression of NDVI in terms of bands.
In Fig 2 (c-d) remove R2 value since from the plots it clear that the value of R2 will be less, here I suggest don’t present R2 as it also doesn’t signify anything. In fig 3e its ok to present the value of R2.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsComments and Suggestions for Authors
On the one hand, changes leading to permafrost degradation in the alpine zone were studied using the example of Mount Wutai in Northern China. On the other hand, the thawing of permafrost and climate warming promote the growth of vegetation, which has a beneficial effect on carbon sequestration. The work done is interesting and relevant due to changes in the current climate of the Earth.
General concept comments
Article: The introduction provides a brief, generally accepted overview of the problem. As part of the research, it can be expanded into cartographic work and geographic information systems on this topic. The work is theoretical and deserves attention, but I would like to see in the future a practical part on changing the thickness and type of permafrost, the chemical and material composition of ground ice.
References to literary sources comply with the requirements of the publisher. It is necessary to place spaces between words and references to sources.
Specific comments
1. Lines 13-14 and 39-40. These two sentences contradict each other. Vegetation does protect permafrost; I agree with this statement. With the first sentence I had a misunderstanding of the context. What did the authors mean?
2. Line 71, subsection 2.1. Have any studies been carried out on altitudinal zonation and its classification, that is, changes in natural conditions, natural zones and landscapes? If so, it is important to present these results in subsection 2.1.
3. Line 95, subsection 2.2. What do the authors of the article understand by permafrost degradation, how does it manifest itself in the mountains, what signs of degradation have been recorded? What parameters does the located weather station measure? Are there wells for measuring soil and frozen rock temperatures? Since the rise of soils in the permafrost zone is a key indicator of permafrost degradation.
4. Line 208, subsection 3.2. When calculating the distribution of permafrost and its thickness, was the ice content of the soil taken into account?
5. Lines 324-325. In addition to the indicator sign "bent trees", was solifluction manifested on the slopes?
6. Lines 399-400. Nutrients were not studied in this work, so the proposal needs to be reconsidered.
7. If the authors plan to further study the Wutai site in the future, it is important to conduct ground-based research on this topic in combination with remote sensing. Take into account geomorphology, temperature regime of soils, development of underground ice, if any, because it is not clear from the article whether they are present or not, and other parameters of permafrost. Conduct research on the successional stages of vegetation and relate it to permafrost degradation.
8. Prepare the manuscript in accordance with the requirements of the publisher and the journal https://www.mdpi.com/journal/forests/instructions.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsAlthough the paper seems well done and complete, I cannot recommend its acceptation due to methodological issues.
1. I cannot verify the reliability of the final conclusions because the rightness of the applied model for permafrost prediction has not been tested in the field in any of the years of the study. So, the calculated numbers and the prediction of the permafrost extent remain theoretical imaginations only! Furthermore, the same factor (NDVI) is used to permafrost prediction and then to correlate the predicted value and the timberline extend. This leads to a doubts of a loop.
2. The way of timberline identification is still not clear. Many data/indexes were used, but it is still unclear, how the decision was made if the vegetation variability is a spatial continuity and tree species may occur at various canopy densities (as authors observed on the northern and southern slopes). In other words, what was precisely defined as 'timberline' in these conditions and how it was identified in particular years?
Some minor remarks:
- your paper refers to both above and underground conditions. Therefore, you are suggested to clearly state the medium, when you describes an average (annual) AIR temperatures,
- please apply the terms Mount Wutai or Wutai Mountain consequently.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsAuthors have corrected or extended the manuscript in some aspects. It is much more clear now and can be accepted in its current form.
