Satellite Evidence for Divergent Forest Responses within Close Vicinity to Climate Fluctuations in a Complex Terrain

Round 1

Reviewer 1 Report

Please see the attachment.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

 

Comments:  

Line 17 -18. Need to mention which satellite data is used for doing this research.

Line 19, 38, 169, 255. The authors have used climate drivers and climate factors in the manuscript. Please use “climatic drivers” mean a small area while climate drivers means global climate. Do it for the entire manuscript and restructure sentences if required.

Line 23, 167, 168, 219, 231, 250, 269. Please removed Forest from “Forest EVI”. It’s understood that EVI is related to Forest. Do it for the entire manuscript and restructure sentences if required.

Line 46. How is global warming can benefit forest growth at high latitudes by pushing the tree line northward in the Northern Hemisphere?  This is supporting global warming is benefitting human existence. What I understood is tree line moving northward melt ice. I agree it can benefit forest growth. Restructure the sentence two.

Line 59-60. Restructure the sentence

Line 66.  Please use “climate stress” in a different way. Restructure the sentence. Do it for the entire manuscript and restructure sentences if required.

Line 70-72. Previous global studies mentions by the author, but single study is referred and cited. Please cite the relevant articles. (At least cite three articles)

Line 76-77.  The authors used three climatic drivers, but only mention two in the aim of the study, why?

Line 145.  Why 2001-2016 is used solar radiation, while temperature and precipitation data was for 20 (2001-2020) years?

Line 201.  Please check this (i.e. 2002-2003 and 2010), is it’s for three years.

Line 378.  The authors mentioned the climatic models in abstract, but did not cite a single paper in Introduction or in discussion section. Please cite, include in introduce climatic models and discuss climatic models as well.  Restructure the sentence accordingly.

Please move the Figure S3: in the main manuscript and how is the area of the positive and negative correlations?  (Insert Figure S3. after line 310). Please also add a table or mentions s well for this area statistics in percentage.  Please see papers

1.        Song, Lisheng; Li, Yan; Ren, Yanghang; Wu, Xiuchen; Guo, Bo; Tang, Xuguang; Shi, Weiyu; Ma, Mingguo; Han, Xujun; Zhao, Long (2019). Divergent vegetation responses to extreme spring and summer droughts in Southwestern China. Agricultural and Forest Meteorology, 279(), 107703–. doi:10.1016/j.agrformet.2019.107703.

2.        Singh, B.; Jeganathan, C.; Rathore, V.S.; Behera, M.D.; Singh, C.P.; Roy, P.S.; Atkinson, P.M. Resilience of the Central Indian Forest Ecosystem to Rainfall Variability in the Context of a Changing Climate. Remote Sens. 2021, 13, 4474. https://doi.org/10.3390/rs13214474

 

3.     Herrmann, Stefanie M; Didan, Kamel; Barreto-Munoz, Armando; Crimmins, Michael A (2016). Divergent responses of vegetation cover in Southwestern US ecosystems to dry and wet years at different elevations. Environmental Research Letters, 11(12), 124005–. doi:10.1088/1748-9326/11/12/124005.

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

The authors have analyzed time series remote sensing derived Enhanced Vegetation Index (EVI) and linked it with forest growth by using three climatic parameters such as temperature, precipitation and solar radiation. As per the current form, the manuscript needs improvement. The specific comments are given below.

 

Major Comments:

1)      Abstract: In L18/18, delete 500 m resolution since climate data resolution is not mentioned

2)      Introduction is not properly contextualized. It needs great improvement in explaining all existing approaches for assessing climate-vegetation interactions. Moreover, in L50, why was only one non-climatic factor introduced? There is no review related to other facts like the role of nutrients and soil quality, etc discussed    

3)      Objective of the study is not clearly defined like why solar radiation is not included here

4)      Novelty of the study is not clearly defined before writing the objectives

5)      Section 2.2.2: CRU based climate drivers are at 0.5 degree resolution. However, EVI is at 500 m resolution. How realistic is making relationships between EVI and these climatic drivers?

6)      Results: Authors denoted correlations as r & R. Are capital R different?

7)      Fig 2: Only maximum r is given which was computed I think based on zonal average of all pixels. What about maximum r at pixel level?  It will be better if author presents spatial maps.  Moreover, these r values are not robust given the spatial resolution of climatic parameters coarse

8)      Section 3.4: R = 0.09. What is R here  

9)       Discussion needs improvement by including robustness of results, validation of pattern observed  & limitation of the study. Add similar studies conducted over the Tibetan plateau and India. For example

·         https://doi.org/10.1038/s41893-019-0220-7

·         https://doi.org/10.3390/cli8080092

·         https://doi.org/10.1088/1748-9326/aaa866

 

Minor comments

1.      L105: Write like Normalised Diff …(NDVI)

2.      L150: Are TEM, PRE, and SWD standard abbreviations

 

3.      L202: POpt and ROpt during 2001-2016 was -0.822  0.034 (n = 33,453 for all forested pixels). Why until 2016 is selected here ?

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 4 Report

This paper is well written, with experiments correctly carried out and clearly presented. It aims to study the climate change effect on vegetation growth, however, what it reveals is how regional variations in biophysical conditions such as temperature, precipitation, and solar radiation affect vegetation growth, just as how it was described in lines 339-341. To study the climate change effect on vegetation growth, a more proper design is to monitor changes in vegetation growth after a climate event, such as drought, floods, or abnormal temperature or precipitation.  Therefore, I recommend changing the title to, for example, vegetation growth in response to diverse climate conditions. A couple of minor comments are included in the following:

line 57-59, photosynthesis process and vegetation leaf structure causes vegetation to absorb light in red spectral region and reflect light in near-infrared spectral region.
line 64-65, please provide references
lines 77, change respond to response
line 104, please justify why use coarse spatial resolution data from MODIS (500m) instead of Landsat sensor (30m) with higher spatial resolution.
line 210-211, this sentence is not right, please rewrite.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 5 Report

An important gap is in the definition of: “complex terrain”. It is never specified what is meant by this term and the heterogeneity of the terrain is not evaluated in the manuscript as a discriminating parameter in the results. 

A piece of essential information such as the total extent of the study area and its reliable graphical representation is missing. (Fig.1 is not very readable).

Referring to climatic characteristics, it is not clear whether these represent a specified range and how these ranges are distributed in space. A graph of the climate variables distribution would be appropriate.

The authors defining the climatic variables of the area refer to “average precipitation”, but the correct way to refer to precipitation is ‘’cumulative precipitation'’ for a given interval of time. It is also unclear whether climate data from weather stations were used to validate those downloaded from the CRU model.

As far as statistical analyses are scarce and superficial too. Pearson’s correlation alone cannot indicate causality. Pearson’s correlation measures the strength of the linear relationship between two variables. It has a value between -1 to 1. Authors associated the correlation analysis with further statistical analyses such as regression models or structural equation modelling (SEM). However, the r values reported in the study are not statistically significant (p values are not reported and r values are very low) (lines 225 – 226) for supporting the conclusions drawn. On these bases, in my opinion, it is not possible to define a time-lag effect. Furthermore, the use of an “average correlation coefficient” is non-sense, and it is not suitable for the conclusions drawn.

Although the idea of being able to determine the driver climate factors of forest EVI is good, and the methodology for assessing the correlation between the variables pixel by pixel has its potentiality, it is not possible to affirm that the climatic parameters considered here "…affect forest growth significantly in east China", because no other variables have been evaluated, and the combined contribution of the variables has not been evaluated (e.g., through partial correlations). The statistical analyses showed only a strong relationship between climate parameters and forest growth, which is already known in the literature.

The method used in defining the effect of climate change is limited to those pixels/areas where the effect of climate change may have been significant, despite the temperature/precipitation/solar radiation not exceeding the established thresholds.

The authors write about the high or low of the forest EVI values, but the trend of EVI in different regions is not shown, and it is not evaluated whether the increase or decrease is statistically significant on not (e.g., non-parametric tests such as the Mann-Kendall test).

In the paragraph concerning the assessment of the effect of elevation, it is not clear how this is considered. The authors should clarify whether the analysis is conducted differently on regions where different climatic drivers are identified, and it is not clear what is meant by the assumption made to lines 210-211. Further in-depth statistical analyses are suggested to support section 2.3.4.

Finally, a recurring question is: does the influence of variables change only between complex terrain or different forest types? It is not clear throughout the text which of the two circumstances is being evaluated, considering that forest types are declared exclusively in section 2.1.

Finally, the paper needs a thorough revision of the English language.

In conclusion, the work presented here has potential, despite this, there are deep gaps that make it unsuitable for publication.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 6 Report

The topic is meaningful in the manuscript titled as “Satellite evidence for divergent forest responses to climate change within close vicinity in East China with complex terrain”. In this manuscript, the relationships between forest growth and climate factors were explored to demonstrate forest responses to climate change are homogeneous across regions using EVI extracted from time series Modis images. However, the methods of this paper are rather easy and clear, and the results are uninspiring. In a word, the innovation of this paper is insufficient.

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The manuscript is sufficiently improved. 

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 3 Report

After reading the revised manuscript, I find that the authors have addressed all comments and queries. The manuscript has improved significantly.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 4 Report

In my previous review, I recommended not to use climate change as context, since the focus of the paper is on the "divergent forest growth response to a SIMILAR climate condition within a close distance", quoting the authors' words. Climate change refers to long terms shifts in temperature and climate condition, due to natural events or human activities especially from burning fossile fuels. This paper didn't address the issue of vegetation response to climate change, but rather to local climate conditions. I think much of the contextural information in the introduction needs to be adjusted to fit the content of this paper, while using climate change and vegetation response as background is rather misleading.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 6 Report

The revised manuscript has been greatly improved. Though, some sentences have been added in the conclusions to make the innovation more clearly, the innovation of this paper is insufficient in the part of abstract. Before publication, the innovation should be further considered for readers.

Author Response

Please see the attachment.

Author Response File: Author Response.docx