Spatial and Temporal Variation in Primary Forest Growth in the Northern Daxing’an Mountains Based on Tree-Ring and NDVI Data
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsDear Authors,
please find comments and suggestions in the attached file.
Comments for author File: 
Comments.pdf
Suggestions for the English language are explained in the attached file.
Author Response
Thank you very much for your professional comments on our article. Based on your valuable suggestions, we have revised our previous draft and responded to the comments individually in the document.
We would like to thank the referee again for taking the time to review our manuscript.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsReview of the manuscript:
Spatial and Temporal Variation in Primary Forest Growth in the Northern Daxing’an Mountains Based on Tree-ring and NDVI Data
Bing Wang, Zhaopeng Wang, Dongyou Zhang, Linlin Li, Yueru Zhao, Taoran Luo, Xinrui Wang
The authors used data on the width of the growth rings of Larix gmelinii and Pinus sylvestris var. mongolica from the northern region of Daxing'an Mountains, China. Used NDVI data and microtopographic information to assess the spatiotemporal dynamics of forest loss due to climate warming. The authors determined forest growth trends based on tree growth decline rates and NDVI time series trends, and topographic patterns of forest decline were analyzed using a C5.0 decision tree model.
As a result, more climate information was contained in the radial growth of trees at higher elevations where the trees were highly influenced by the previous year's climate factors. It was established that since 1759, the trends in the radial growth of trees in the study area have experienced two declines: in 1878–1893 and 1935–1943, which were characterized by the preservation of narrow whorls of the annual ring with growth below average. Changes in NDVI and tree-ring information were similar, and together they indicate a high risk of decline in forest growth after 2010, especially at higher elevations. It has been proven that high temperatures in 2003 had a negative impact on forest growth, which was confirmed by tree ring and NDVI data. The decision tree terrain model results had an accuracy of 0.861, and elevation was the most important terrain factor influencing forest loss.
The work is interesting, especially due to the fact that in the northern latitudes of the planet it has been established that due to climate warming, the forest in general, and certain tree species in particular, are getting better, they are expanding their range to the north and rising up into the mountains. In this work, the authors note the opposite trend - due to warming, it has become bad for the forest, especially at the top of the slopes. In many articles on northeast China and the adjacent territories of Siberia, it has been established that due to the increase in average annual and spring temperatures, the forest as a whole, and the main types of forest-forming trees, is getting better: it rises higher in the mountains, wood biomass increases, etc. . It would be interesting to know whether in previous periods (1878–1893 and 1935–1943), when the authors determined from the thickness of the rings that the forest was in bad shape, were these warm or cold years? Maybe very dry? Like in 2003?
According to the authors, why is it that as the temperature rises, the forest is no worse at the bottom, but at the top? If it became colder, the forest would descend... this is logical, but in this article the opposite trend is described.
Maybe it has to do with the specifics of the Larix and Pinus species being studied? Boreal species in many northern regions become "hot and dry" at the southern edge of their range. Larix gmelinii forms the arctic forest edge in Siberia, on top of kilometers of permafrost, but in dry years the tree does not form thin rings. This is due to the fact that trees draw moisture from thawing permafrost. And the studied region is located close to the southern border of the L. gmelinii range. If the problem in the studied region is precisely droughts, then perhaps this will lead to the retreat of the boreal dendroflora to the north, and in the studied region there is a replacement by a more thermophilic East Asian dendrophora? What trends are currently characteristic of other tree genera - Quercus, Ulmus, Picea?
According to the authors, if temperatures continue to rise and precipitation levels (aridization index) decrease, will the forest be replaced by shrub vegetation or steppes?
The authors of the manuscript should describe these points in more detail in the Discussion.
Author Response
Thank you very much for your professional comments on our article. Based on your valuable suggestions, we revised the previous draft and issued a separate response to the comments in the document. We again thank the reviewers for taking the time to review our manuscript.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsOnly a handful of comments focusing mainly on figure captions and referencing.
Figure 1: caption should acknowledge and explain panels a, b, and c; Study area in panel a and plots in panel c should be better emphasized; the outline and plots are difficult to see
Figure 3: should improve caption explaination of the graph you present.
Figure 4: inconsistent panel reference... Figure 2 caption presents the panel's reference letter and then a description; Figure 4 caption presents a description and then the relevant panel's letter. Furthermore, the authors should indicate in the caption the importance of the year 2003 since it is identified in panel B.
line 252: Consistency in referencing figures. On line 124, the authors use (Figure ) and on lines 249 and 252 the authors use (Fig.); as well as on line 266, 281 and elsewhere.
Figure 6: This figure is potentially confusing; for clarity, the authors should label the Y axis and the NDVI graph should be paneled separately from the sites ZZA - LYC; as well, the figure caption needs to be improved to assist in interpreting the graphs
Author Response
Thank you very much for your professional comments on our article. Based on your valuable suggestions, we have revised our previous draft and responded to the comments individually in the document. We would like to thank the referee again for taking the time to review our manuscript.
Author Response File: Author Response.pdf
