Dominant Impacting Factors on Water-Use Efficiency Variation in Inner Mongolia from 2001 to 2018: Vegetation or Climate?

Round 1

Reviewer 1 Report

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

This study quantified the spatial and temporal variations of water use efficiency (WUE) in Inner Mongolia during 2001-2018 as well as their controlling factors (e.g., leaf area index and precipitation), using various statistical methods such as grey relational analysis and ridge regression. Overall, this manuscript falls within the scope of Remote Sensing, and it is well organized and reads very well. I only have a few minor comments or suggestions.

Line 23: change “Leaf area index (LAI) and precipitation were the most important to WUE in…” to “Leaf area index (LAI) and precipitation were the most important factors influencing WUE in…”

Line 77-84: In addition to multiple regression residual analysis and ridge regression, path analysis method has also been widely used to examine the complex relationships and interactions between multiple factors in ecological studies. I have attached two papers using path analysis to analyze the relative contributions of independent variables to dependent variables and reveal complex interactions between them. You may want to add this method to your Introduction and cite the following references in your paper.

Gang, C., Wang, Z., You, Y., Liu, Y., Xu, R., Bian, Z., Pan, N., Gao, X., Chen, M. and Zhang, M., 2022. Divergent responses of terrestrial carbon use efficiency to climate variation from 2000 to 2018. Global and Planetary Change, 208, p.103709.

Line 125-128: You may need to add scatter plots to the supplementary material to show site-scale validation results.

Line 148: Change ” Following the figure top down, First, ……” to “Following the figure from top to down, first, ……”

Author Response

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Reviewer 3 Report

This paper provides an interesting study on the spatial and temporal variations in WUE and their controlling factors in Inner Mongolia, China. The GLASS GPP and ET products were used in estimating regional WUE for different land covers. Generally, this paper is well-written and falls within the scope of Remote Sensing. The methods are sound and the results are reasonable. I think the paper deserves publication after proper revision.

  My major concern in the paper is the controlling factor analysis of the temporal trend in WUE. The paper concluded that the increase in WUE was mainly due to the increasing trend in the LAI. However, because CO2 concentration has a positive effect on GPP and the GLASS GPP product has incorporated such an impact of the increasing trend of CO2 on GPP during 2001-2018. Therefore, it is possible that CO2 other than the LAI is the major cause of the increase in WUE. The authors need to discuss such an issue. Also, in the discussion section, the authors mainly compared their results with the studies that also focus on the arid and semi-arid regions, it may be interesting to compare the results of this study with the results from humid regions in China (For example, Estimating the Gross Primary Production and Evapotranspiration of Rice Paddy Fields in the Sub-Tropical Region of China Using a Remotely-Sensed Based Water-Carbon Coupled Model. Remote Sensing, 2021, 13(17)).

Author Response

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Round 2

Reviewer 1 Report

The authors have modified the following manuscript to a great extent. However, there are still some questions needed to considered for the improvement of this manuscript to be published in the Remote Sensing journal. 

1. The keyword(s) must be reflected either in title or in abstract. In this regard, some keywords have not been reflected. 

2. The abstract in not very much inline with conclusions, especially  while describing  the results. In the conclusion section, more focus is the on  geographical and vegetation types, however, in the abstract, the vegetation  and climatic factors are more focused. Kindly bring unanimity between the two sections for the presented results. 

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

The authors have fully addressed all my concerns.

Author Response

Thanks for your invaluable comments on our manuscript.