NDVI-Based Vegetation Dynamics and Response to Climate Changes and Human Activities in Guizhou Province, China

Round 1

Reviewer 1 Report

Dear authors,

In your study, the approach is similar with other researches (mentioned and not). Some advantage of your work is a little more recent time series, however it is not very sufficient in perspective. At the same time, an important part is missed in your analysis (see note to lines 277-278).

line 56-58: "Autumn vegetation greenness showed negative connection to precipitation owing to the cloudy day with precipitation preventing solar radiation reaching to ground in northeastern part of China". Perhaps, more suitable explanation for northeastern part of China is that the autumn vegetation greenness decresases correspondingly to autumn decrease of day length. This correspondence is well-studied  for plants in non-tropic regions (https://biology.appstate.edu/fall-colors/fall-color-science-essay-daylength-temperature-and-precipatation).

lines 84-85: not only studies [37-39] dealed with spatio-temporal vegetation dynamics in the province. At least, also [https://core.ac.uk/download/pdf/269282568.pdf], [https://link.springer.com/article/10.1007/s11356-021-14988-y], [https://ieeexplore.ieee.org/abstract/document/5568119], [https://www.frontiersin.org/articles/10.3389/fevo.2022.844437/pdf], and some others. (By the way, your reference [52] (cited in lines 654-655) is the same as [37]). However, few or none previous studies used time series extended up to 2021 that is now a distinction of yours. Of course, monitoring ongoing in parallel with ecological restoration is important. 

lines 95-97: this statement contradicts the information mentioned in lines 650-656

Section 2.3.5 vs. Section 3.3.2: the declared (sect. 2.3.5) NDVI regression from temperature and precipitation is not demonstrated as formula (Sect. 3.3.2).

lines 273-276: "When the residuals trend is insignificant, NDVI variations are mainly explained by the climate changes. However, it indicates that changes in NDVI are not completely accounted by climatic factors and may have been induced by human activities when the trend of NDVI residuals is significant." This is a contradictory and unjustified discourse (maybe, it is mainly caused by a grammar mistake?). Why does INSIGNIFICANT trend of residuals (between climate-predicted and observed NDVI) mean that some OTHER predictors influence NDVI??? To verify the statement in the second phrase, NDVI regression from other predictor(s) should be built and the  corresponding trend(s) of residuals should be analyzed.

Do you comletely understand the difference between NDVI trend and residual trend?

Table 4: structure and content of the table are distorted and unclear because of this. That is why the main result and conclusion of the study (discussed in the Section 4 and declared in lines 700-703) have remained undemonstrated.

lines 277-278: "contribution degree of climatic trend and human activities are quantificationally examined in this study". The said quantification is not demonstrated for human activity (in the Section 3.4). To demonstrate this, you should directly analyse land-use cover change (LUCC - see [31]) between 2000 and 2021, and further compare pixel transformation (for example, from GRA and CRO to forest classes) to NDVI changes. Although Liu et al. (2021) did not conduct this kind of analysis, it would be the only independent verification of the discussed impact of human restoration activity.

Moreover, according to the scope of the journal "Forests", it is strongly desirable to map changes of afforested area explicitly.

line 384: "the vegetation type with larger decreasing trend". This is unexect statement, because implied in this phrase are croplands and grasslands (see the beginning of the phrase in line 382), however the two types have light increasing trends (see Fig. 3b).

lines 658-661: the same information as in lines 68-73

lines 700-703: the statements on human contribution to the observed NDVI trends are not proven in the study (see notes above).

 

Some other notes on presentation quality:

Fig. 1: both maps are non-colored

lines 324-325: in cap of Fig. 2, there is no explanation what the diagram (e) presents. 

Fig.3 (b): symbols for the categories "Savannas" and "Woody Savannas" are too similar, that is why the diagram is not clear enough. Other symbols, which are more obviously distinct, should be used.

Fig. 5 (b, d): in the applied color scale, it is not good decision to use dark-green color for the most unsustainable places while, on pictures 5a and 5c, the same color highlights the highest values of Hurst Index. Perhaps, it would be more logical to invert colors of categories 0-8 on pictures 5b and 5d. 

line 474: The words "and precipitation" are missed in the first line of the cap of Fig. 6 (cf. with line 566, for example). 

Fig. 6 (b,c and e,f): desirable is to uniform color scale in maps and bar histograms. The current color difference strongly confuses a reader who compares the maps to the frequence bars. 

line 524: the same note on the cap of Fig. 7.

Some notes on grammar:

line 23, 699: "strongly dominated" or "strongly influenced"??? (for example, see line 666)

line 61: what is "hotpot"???

lines 64-67: too long phrase with repeated words

line 401: should be "studied" instead "studying"

line 649: collocation "vegetation dynamics" would be more appropriate than "vegetation activities" (for example, see line 55)

line 527: "denote that". The word "that" should be removed from this collocation. Instead, the word "correspondingly" should be added in the end of the phrase (in line 531).

line 577: should be "following" instead "follows"

lines 577-578: there is no need to write the same formula twice. You can say "calculated following the equation ... in both cases"

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript NDVI-based vegetation dynamics and response to climate 2 changes and human activities in Guizhou Province, China addresses a topic of great interest to the scientific community, since it analyzes the variation of NDVI through time and its relationship with climate.

 

MATERIALS AND METHODS

Figure 1a does not show the elevation gradient on the map, only in legend.

In figure 1b, the distribution of colors corresponding to the type of vegetation is not shown on the map, only in legend.

 

 

on line 158, it is mentioned that the vegetation type information was interpolated from 500m to 250m, how was the process? was the information rescaled? was any covariate used? explain

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Dear authors,

The explanations in your reply and the conducted manuscript revision are enough. It would be worth to put  your additionally plotted diagrams (fig. R1C) in the manuscript, but let it will be on your opinion.

Newly revealed are some mistypes:

line 24: should be "human"

fig. 7, titles of diagrams c & f: should be written "Statistics"

line 581: should be "means that the"

line 645: there is no the diagram (e) in fig. 10

line 664: should be "decidous broadleaf"

Author Response

Please see the attachment.

Author Response File: Author Response.docx