Changes in Vegetation Coverage and Migration Characteristics of Center of Gravity in the Arid Desert Region of Northwest China in 30 Recent Years

Round 1

Reviewer 1 Report

The study is interesting and deals with actual topic in times of climate change and can help with arid area conservation. I recommend it for publication after minor revision which will make it more readable and interesting and which will better explain conservation implications.

Introduction: Add some studies dealing with similar topic and better explain the aim of your study to make Introduction more interesting for readers and skip the methodological details here.

Lines 34-39: So many general sentences at the beginning of Introduction, try to be more concrete, maybe start directly with vegetation in arid areas and importance of remote sensing technologies to study it.

Line 50: Please, explain what is the NDVI and what information it can provide.

Line 60, 61: Not necessary to write such methodological details in Introduction, move it to Methodology section, write it more generally here (e.g. long term research in this area repeated in seven periods).

Line 110-111, Table 1: different names are used for levels of vegetation coverage, please change it.

Figure 1: small, not readable numbers

Table 3, Table 4: Consider if these tables are necessary, I think that they include similar information as presented Figures. They should be omitted or removed to Supplement.

Discussion: I missed guidance for desertification control, ecological restoration and protection here which is one of the aims mentioned in Introduction.

Author Response

Response to Reviewer 1 Comments

 

The study is interesting and deals with actual topic in times of climate change and can help with arid area conservation. I recommend it for publication after minor revision which will make it more readable and interesting and which will better explain conservation implications.

 

Thanks a lot for the constructive suggestions by the Reviewer 1. Based on these suggestions, we improved our manuscript in the revised version, with changes marked by yellow. Please see our point-to-point responses below.

 

 

Point 1: Introduction: Add some studies dealing with similar topic and better explain the aim of your study to make Introduction more interesting for readers and skip the methodological details here.

 

Response 1: As the reviewer suggested, we added more studies and improved the expressions to make the Introduction more interesting in the revised version.

 

Point 2: Lines 34-39: So many general sentences at the beginning of Introduction, try to be more concrete, maybe start directly with vegetation in arid areas and importance of remote sensing technologies to study it.

 

Response 2: Done. In the revised version, we improved the expression here for more concrete of the Introduction. See lines 35-37: “As a comprehensive indicator for environmental changes [1], changing of vegetation coverage is closely related to the global material energy, material biochemical cycles and landscape patterns [2-5]”.

 

Point 3: Line 50: Please, explain what is the NDVI and what information it can provide.

 

Response 3: We explained the meaning and importance of NDVI in the revised version. See lines 47-49: “Shortened by NDVI, normalized difference vegetation index is generally used to anticipate the vegetation dynamics in space and time scales [12]”.

 

Point 4: Line 60, 61: Not necessary to write such methodological details in Introduction, move it to Methodology section, write it more generally here (e.g. long term research in this area repeated in seven periods).

 

Response 4: As we also descript these methodological details in Methodology section, we improved the expression here for a more gental description. See lines 60-61.

 

Point 5: Line 110-111, Table 1: different names are used for levels of vegetation coverage, please change it.

 

Response 5: Done. We unified the expression for moderate coverage between lines 110-111 and Table 1. We also unified this throughout the whole manuscript.

 

Point 6: Figure 1: small, not readable numbers.

 

Response 6: We replaced Figure 1 by a clearer and enlarger version to make it more readable.

 

Point 7: Table 3, Table 4: Consider if these tables are necessary, I think that they include similar information as presented Figures. They should be omitted or removed to Supplement.

 

Response 7: As the reviewer suggested, we removed Tables 3 and 4 to Supplementary Materials as Appendix table 1 and table 2 in the revised version.

 

Point 8: Discussion: I missed guidance for desertification control, ecological restoration and protection here which is one of the aims mentioned in Introduction.

 

Response 8: We re-organized this section of Discussion in the revised version to make it clearer. See lines 255-258: “In this study, the increasing of vegetation coverage in southeast and south of the arid desert region of Northwest China is helpful to formulate long-term effective desertification control, ecological restoration and protection, and ecological sustainable management”.

 

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript is about very important topic. The methodology need to be more detailed especially the vegetation center of gravity model. This aspect is not well explained evengh it is an essential part.

The result part is ok for the analysis of the vegetation cover. For the section about the vegetation center of gravity model, the is need to explain more and rework the illustartion of this part.

The discussion section is poor and need more efforts. The authors advance facts such as improvement and degradation and no supports for these facts are provided. What are the factors behind degradation and improvement. The authors should provide arguments to explain the changes observed.

The section conclusion need to be redone.

My comments are in the file

Comments for author File: Comments.pdf

Author Response

Response to Reviewer 2 Comments

 

Thanks a lot for the constructive suggestions by the Reviewer 2. Based on these suggestions, we improved our manuscript in the revised version, with changes marked by yellow. Please see our point-to-point responses below.

 

 

Point 1: Line 54, write: Until

 

Response 1: Done.

 

Point 2: The figure 3 showed clearly that the severe degradation decreased and is more localized in some spots. What factors are behind this decrease?

 

Response 2: Figure 3 indicates the dynamic change of vegetation coverage during each 5 years, i.e., 1990-1995, 1995-2000, 2000-2005, 2005-2010, 2010-2015, and 2015-2020. We described the detailed calculation in the “Analysis of dynamic change of vegetation coverage” of “2.3. Data Analysis”. From this figure, we can see the severe degradation greatly decreased during 1990-1995, indicating the vegetation coverage was largely improved during this period. This improvement is not obvious during other periods, with more localized in some spots. The factor behind could be the vegetation coverage was largely improved in big scale during 1990-1995, and localized improved during the the nearing periods.

 

Point 3: To me there is contradction between Figure 3 and Figure 4. For figure 3, degradation decreased with advancing time while figure 4 showed a increasing trend of the the area of degradation. What are your explanations?

 

Response 3: The results of Figure 3 and Figure 4 are not contradict, because the contents they express are different. Figure 3 is the dynamic change of vegetation coverage during each 5 years, i.e., 1990-1995, 1995-2000, 2000-2005, 2005-2010, 2010-2015, and 2015-2020. We cannot summarized that degradation decreased with advancing time because dynamic change is a value during each period. On the contrary, Figure 4 summarized the trend of the area of the four grades of vegetation coverage in the arid desert region of Northwest China.

 

Point 4: Figure 5. I would try to put all the four types of vegetation in the same figure with different colors would shaw better the trends of each type of vegetation

 

Response 4: Done as the reviewer suggested. We put all of the four types of vegetation in the same figure with different colors in the revised version (i.e., new Figure 5). Thanks a lot for the valuable suggestion by the reviewer, as we also find this expression feeling much better.

Figure 5. Migration of center of gravity of vegetation coverage in the arid desert region of Northwest China

 

Point 5: Line 221. What do you mean by soil aridity?

 

Response 5: Here we mean the effects of precipitation and transpiration. The possible misunderstanding could be resulted from our unclear expression. In the revised version, we improved the expression here. See lines 214-215: ”The direction of vegetation migration may be affected by precipitation and transpiration of arid desert region of Northwest China”.

 

Point 6: Line 223. No support for this fact. Need of data support or reference of studies.

 

Response 6: Done. As the reviewer suggested, we added reference to support the discription. See lines 215-219: “As one of the most sensitive areas to climate changes and anthropogenic activities [14, 32], the arid desert region of Northwest China was characterized by increasing in slight and severe vegetation coverage but decreasing in moderate vegetation in this study (Table 2, Figure 2)”.

 

Point 7: Line 224. No support for this fact. Need of support ..

 

Response 7: We reorganized the expression of this sentencce and cited the corresponding table and figure in the revised version. See lines 216-219: “As one of the most sensitive areas to climate changes and anthropogenic activities [14, 32], the arid desert region of Northwest China was characterized by increasing in slight and severe vegetation coverage but decreasing in moderate vegetation in this study (Table 2, Figure 2)”.

 

Point 8: Line 225. What do you mean by to polarize?

 

Response 8: As the vegetation coverage in the arid desert region of Northwest China increased in slight and severe grade but decreased in moderate grade. Slight and severe grades are the two edge in the classification of this study. Thus, we concluded this is a trend of polarize, which means the vegetation coverage became either slight or severe grade. We improved the expression in the revised version to make it clearer, in lines 219-220: “This indicates that changing vegetation coverage started to polarize, i.e., the vegetation coverage became either slight or severe grade”.

 

Point 9: Line 227. You need data to support this fact about precipitation and temperature.

 

Response 9: Done. We added references and improved the description of precipitation and temperature in the revised version. See lines 222-226: “The precipitation of arid desert region of Northwest China was demonstrated to have an increasing trend from southeast to northwest [14]. Meanwhile, the temperature in the arid desert region of Northwest China increased by approximately 0.3 °C per decade in the past 50 years [33]. The polarized vegetation change could be resulted from the fast-increasing precipitation and temperature [34, 35]”.

 

Point 10: Line 233. You need to provide support for the improvement claiming.

 

Response 10: Done. We added support and improved the description in the revised version. See lines 230-232: “Thus, the vegetation improvement in southeast and south could result from the improvement of precipitation and humidity [14, 36]”.

 

Point 11: Line 235. Having greater population does not result in an vegetation improvement. You may get the opposite effect. Be more clear when explaining the improvement of the vegetation.

 

Response 11: Done. We reorganized this expression in the revised version to make it clearer in lines 232-235: “The south and southeast (Inner Mongolia and Qinghai province) have greater population and subsequent anthropogenic activities, which could also lead to higher vegetation improvement by farming, planting trees and grasses for a better living environment”.

 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Most of my comments are satisfaid