Trends of Grassland Resilience under Climate Change and Human Activities on the Mongolian Plateau

Round 1

Reviewer 1 Report

Comments on MS titled “Trends of Grassland Resilience under Climate Change and Human Activities on the Mongolian Plateau”.

 

The authors calculated grassland resilience on the Mongolian Plateau for 2000-2021 using the kNDVI, quantified grassland resilience using a newly proposed "critical slowing down" indicator with a machine learning algorithm and compared the driving forces for these changes between Inner Mongolia and Mongolia. They found grassland resilience on the Mongolian Plateau is positively correlated with precipitation and negatively correlated with temperature. The decline in grassland resilience is most obvious in areas with higher grazing intensity. Inner Mongolia has a more serious decline in ecological resilience than Mongolia.

 

Overall, this study is well-structured. But some revisions are necessary for publication in Remote Sensing. My major concern is the writing of the MS is not clear. Specific comments are as follows.

-Abstract. In results, the characteristics of grassland resilience are missing. In other words, the corresponding findings related to “3.1. Grassland Resilience of the Mongolian Plateau” should be added in abstract.

-Introduction. Many sentences are similar in writing or follow same pattern. For example, Levine et al. predicted that the…(line 27), Zhou et al. found that…(line 29), Gazol et al. selected…(line 36)…, Xiao et al. quantified…(line 38-39)…, Sturm et al. explored the relationship…(line 42)…, Seddon et al. developed a…(line 44). Many similar sentences in the following two paragraphs, too. Please revise these expressions to improve the writing in English.

Figure 1. Subfigures a b c d, white means what? Non-grassland area? But in line 119-120, savanna was classified as grassland. Confusing. So, what is it? Explanation in legend or caption is necessary. In addition, put (a)(b)(c)(d) above the subfigures not below them. Please check and revise all figures of this MS.

Datasets. Line 124, climate data is for 2000-2021, but Aridity index data is for 1970-2000 (Line 129). Unmatched. Considering climate change over past decades is obvious, in my opinion, they cannot used together in this study.

Human Activity Data. Human activities only include population and livestock. How about land use, including cropland land, built-ups, and mining? In previous studies (See references follows) many other factors were considered for human activity mapping. In addition, the population data is available for 2000 and 2020, how about livestock data? For what year? 2010. Unmatched again. Finally, the livestock data is a global scale dataset. Uncertainties exist at regional scale.

 

Li, S., Zhang, Y., Wang, Z., & Li, L. (2018). Mapping human influence intensity in the Tibetan Plateau for conservation of ecological service functions. Ecosystem Services, 30, 276-286. doi:10.1016/j.ecoser.2017.10.003 (This study is also focused on grazing area of China)

Venter, O., Sanderson, E. W., Magrach, A., Allan, J. R., Beher, J., Jones, K. R., . . . Watson, J. E. M. (2016). Sixteen years of change in the global terrestrial human footprint and implications for biodiversity conservation. Nature Communications, 7. doi:10.1038/ncomms12558

 

--Methods. Calculation of Resilience. What is resilience of grassland ecosystem. A definition is necessary. The authors just describe kNDVI and lag-one TAC in this section. Nothing is related to resilience of grassland ecosystem. What’s the relationship between lag-one TAC and resilience of grassland ecosystem?

Resilience Driver Analysis and Trend Calculation. Line 169 and Table 1. Reference 17 is for forest ecosystem. Is it applicable to grassland ecosystem?

Figure 2. So many abbreviations. It is recommended to define them in caption of figure 2 for readers.

Figure 4a. Spatial map of the long-term TAC. What’s the white area? No data?

Figure 4c. Low, middle, high grazing intensity mean what? Sheep unit lower than what is low? Greater than what is high? Spatially, where they located? No any descriptions. Similar comments for figure 6a and figure 6d.

--Discussion. Line 338-341. Consistent or inconsistent, why? By comparison with previous studies, the reads want to know the advantages of this study. Same comments for line 362-364.

In my opinion, discussion should be focused more on spatial trends in this study, because the authors said that in Introduction (Line 77 , while little is known about the spatial trends).

Comments on MS titled “Trends of Grassland Resilience under Climate Change and Human Activities on the Mongolian Plateau”.

 

The authors calculated grassland resilience on the Mongolian Plateau for 2000-2021 using the kNDVI, quantified grassland resilience using a newly proposed "critical slowing down" indicator with a machine learning algorithm and compared the driving forces for these changes between Inner Mongolia and Mongolia. They found grassland resilience on the Mongolian Plateau is positively correlated with precipitation and negatively correlated with temperature. The decline in grassland resilience is most obvious in areas with higher grazing intensity. Inner Mongolia has a more serious decline in ecological resilience than Mongolia.

 

Overall, this study is well-structured. But some revisions are necessary for publication in Remote Sensing. My major concern is the writing of the MS is not clear. Specific comments are as follows.

-Abstract. In results, the characteristics of grassland resilience are missing. In other words, the corresponding findings related to “3.1. Grassland Resilience of the Mongolian Plateau” should be added in abstract.

-Introduction. Many sentences are similar in writing or follow same pattern. For example, Levine et al. predicted that the…(line 27), Zhou et al. found that…(line 29), Gazol et al. selected…(line 36)…, Xiao et al. quantified…(line 38-39)…, Sturm et al. explored the relationship…(line 42)…, Seddon et al. developed a…(line 44). Many similar sentences in the following two paragraphs, too. Please revise these expressions to improve the writing in English.

Figure 1. Subfigures a b c d, white means what? Non-grassland area? But in line 119-120, savanna was classified as grassland. Confusing. So, what is it? Explanation in legend or caption is necessary. In addition, put (a)(b)(c)(d) above the subfigures not below them. Please check and revise all figures of this MS.

Datasets. Line 124, climate data is for 2000-2021, but Aridity index data is for 1970-2000 (Line 129). Unmatched. Considering climate change over past decades is obvious, in my opinion, they cannot used together in this study.

Human Activity Data. Human activities only include population and livestock. How about land use, including cropland land, built-ups, and mining? In previous studies (See references follows) many other factors were considered for human activity mapping. In addition, the population data is available for 2000 and 2020, how about livestock data? For what year? 2010. Unmatched again. Finally, the livestock data is a global scale dataset. Uncertainties exist at regional scale.

 

Li, S., Zhang, Y., Wang, Z., & Li, L. (2018). Mapping human influence intensity in the Tibetan Plateau for conservation of ecological service functions. Ecosystem Services, 30, 276-286. doi:10.1016/j.ecoser.2017.10.003 (This study is also focused on grazing area of China)

Venter, O., Sanderson, E. W., Magrach, A., Allan, J. R., Beher, J., Jones, K. R., . . . Watson, J. E. M. (2016). Sixteen years of change in the global terrestrial human footprint and implications for biodiversity conservation. Nature Communications, 7. doi:10.1038/ncomms12558

 

--Methods. Calculation of Resilience. What is resilience of grassland ecosystem. A definition is necessary. The authors just describe kNDVI and lag-one TAC in this section. Nothing is related to resilience of grassland ecosystem. What’s the relationship between lag-one TAC and resilience of grassland ecosystem?

Resilience Driver Analysis and Trend Calculation. Line 169 and Table 1. Reference 17 is for forest ecosystem. Is it applicable to grassland ecosystem?

Figure 2. So many abbreviations. It is recommended to define them in caption of figure 2 for readers.

Figure 4a. Spatial map of the long-term TAC. What’s the white area? No data?

Figure 4c. Low, middle, high grazing intensity mean what? Sheep unit lower than what is low? Greater than what is high? Spatially, where they located? No any descriptions. Similar comments for figure 6a and figure 6d.

--Discussion. Line 338-341. Consistent or inconsistent, why? By comparison with previous studies, the reads want to know the advantages of this study. Same comments for line 362-364.

In my opinion, discussion should be focused more on spatial trends in this study, because the authors said that in Introduction (Line 77 , while little is known about the spatial trends).

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript analyzed the influence factors of grassland resilience from the aspects of climate change and human activities based on a “critical slowing down” indicator with a machine learning algorithm. And then, different grazing intensities and climate regions were evaluated the attributions to grassland resilience in Inner Mongolia and Mongolia. The research is evaluable for making further ecological restoration measurements on Mongolia Plateau.

Some specific suggestions are listed in the followings:

1)       Give the specific explains for every variance in equations, such as variance N in Eq.1, yn in Eq.3, ……

2)       Add y-label in Fig.4 c & d, and other figures. Legends are needed in Fig.4 c & d for the distribution median. I think a dash line may be better than the thin line to distinguish it and zero. The same for Fig.8.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Monitoring the state of grasslands is an important task, and the most effective tool for these purposes is the use of remote sensing. The purpose of study is to explore the spatial distribution pattern, change trend and driving factors of grassland resilience on the Mongolian Plateau. The assessment of grassland sustainability was carried out using the kernel-normalized difference vegetation index (kNDVI) calculated for the Mongolian highlands from 2000 to 2021. The results showed that pasture resilience in the Mongolian Highlands is positively correlated with precipitation and negatively correlated with temperature.

The manuscript is extremely well-written and should be considered for publication.

Line 102. The text in the legend in Figure 1 is very small.

Author Response

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Author Response File: Author Response.docx

Reviewer 4 Report

The paper investigates grassland resilience and the effecting parameters on the Mongolian Plateau. The abstract gives adequate information. The paper presents the aim of the study and provides the related literature. Some parts also should be clarified in the manuscript and the discussion part needs to be extended. Thus, the authors should answer the questions and suggestions given below;

1.      What is the period and resolution of the land cover data? They should be given in the paper.

2.      In equations 1 and 2 the parameters should be described.

3.      In the title of Figure 2 write down what CA, CB, and VA are.

4.      Figures 5a and 7a: give the numbers of the samples

5.      It is better to interpret the human activity data, it is not clear how the population is distributed spatially.

6.      Lines 305-307: ETD.CV is almost stable, please check the comment on this.

7.      In the discussion, population growth is stated and shown in Figure 8b. However, it is not supported by quantitative analysis. In the figure, add the increase and decrease with percentage annually or total for the period studied. Add the names of the countries to the maps.

8.      Please give details on “inconsistent uses”. It is not clear.

9.      Line 345: It is mentioned as the study provides an early warning of ecological resilience loss. However, it only provides the current situation and a monitoring analysis of the region. An early warning is more complicated (i.e. forecasting, prediction, and risk assessment).

10.  Line 354: Please be clearer and add a value for the positive correlation.

11.  Lines 355 and 357: the discussion should be clear, and give quantitative values to support your statement.

 

12.  Line 403: Forest resilience is stated in the conclusion, however, it is not mentioned previously. Which part analysis the forest resilience in the paper?

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Thank you for the revisions. Although the manuscript improved, the data mismatch I raised wasn't solved. So I suspect that there is a lot of uncertainty in the results of this study. In addition, the human activity factor is not comprehensively considered. Mining is also an important human activity in Mongolia, but the authors do not consider it. Finally, there is also much room for improvement in the writing of manuscript.

There is much room for improvement in the writing of manuscript.

Author Response

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Author Response File: Author Response.docx

Reviewer 4 Report

The authors considered the suggestions and improved the paper, including additional information. The questions are answered properly. I would recommend the revised manuscript for publication. 

Author Response

Thank you for your recognition of our work.