Characteristics and Driving Factors of Precipitation-Use Efficiency across Diverse Grasslands in Chinese Loess Plateau
Dan Undersander
Round 1
Reviewer 1 Report
line 19 change "had significantly positive correlated" to "were positively correlated"
line 40 change "Vegetation types is" to "Vegetation types are"
line 126 'envelops' should be 'envelopes'
Line 287 remove 'some'
More information on weather data needs to be provided. How far were the 26 weather stations from the 81 sites? What kind of equipment was at the station? how often were weather measurements taken? We note that precipitation may vary by 100% over 1 kilometer and temperature may vary by 3 to 5C, especially if altitude varies.
Collected a lot of biological data and presented none of it. What were the most contributing species in each pasture type?
Quality of English is very fine.
Author Response
Dear Reviewer:
We deeply appreciate the time and effort you have spent to review our manuscript, entitled “Characteristics and driving factors of precipitation-use efficiency across diverse grasslands in Chinese Loess Plateau (agronomy-2510469)”. We thoroughly revised our manuscript according to the comments. We hope that it will be satisfied with the revisions in our manuscript. The point-to-point responses to comments are as follow and also can be seen in the attachment.
Point 1: line 19 change "had significantly positive correlated" to "were positively correlated".
Response 1: Thanks for your comments. We have changed "had significantly positive correlated" to "were positively correlated" in line 19 in the revision manuscript.
Point 2: line 40 change "Vegetation types is" to "Vegetation types are"
Response 2: Thanks for your comments. We have changed "Vegetation types is" to "Vegetation types are" in line 40 in the revision manuscript.
Point 3: line 126 'envelops' should be 'envelopes'
Response 3: Thanks for your comments. We have changed "'envelops" to "'envelopes" in line 126 in the revision manuscript.
Point 4: Line 287 remove 'some'
Response 4: Thanks for your constructive comments. We have removed 'some' in line 287 in the revision manuscript.
Point 5: More information on weather data needs to be provided. How far were the 26 weather stations from the 81 sites? What kind of equipment was at the station? how often were weather measurements taken? We note that precipitation may vary by 100% over 1 kilometer and temperature may vary by 3 to 5 C, especially if altitude varies.
Response 5: Thanks for your constructive comments. We have added the locations of the 26 meteorological stations in figure 1 in the revision manuscript. And the details of stations information were supplied in Table S2. The selected meteorological stations were roughly evenly distributed near the sampling sites (Fig. 1). The nearest distance between the sampling sites and the adjacent meteorological stations was about 10 km, the furthest distance was 113 km, and the average distance was 53 km, which generally reflected the temperature and rainfall conditions around the sample sites. The specific monitoring equipment of each meteorological station is not provided by the data center. However, the monitoring equipment in most meteorological stations were much the same, mainly rain gauges, thermometers, hygrometers, barometers, anemometers and so on. And the automatic observation project of the National Meteorological Observatory makes continuous observations 24 hours a day.
Point 6: Collected a lot of biological data and presented none of it. What were the most contributing species in each pasture type?
Response 6: Thanks for your constructive comments. We have provided the basic information of the 81 sampling sites which not only including the “sites location, longitude, latitude, altitude, precipitation, temperature etc.”, but also including biological data such as “grassland types, dominant species, annual net primary productivity, below-ground biomass, coverage, height, biodiversity, etc.” in Table S1. These measured biological data provide precious first-hand information for us to objectively understand the processes and functions of grassland ecosystems in arid and semi-arid regions. Moreover, in our study, meadow grassland (MG) is comprised by perennial mesophytic and xeromesophytic species, such as Bothriochloa ischaemum, Artemisia giraldii, and Artemisia sacrorum, etc; temperate grassland (TG) is commonly dominated by xeromesophytic and mesoxerophytic species, such as Stipa bungeana, Stipa grandis and Lespedeza davurica etc; desert grass-land (DG) occurs in the central and northern regions, where xerophytic and strongly xerophytic species dominate, such as Agropyron cristatum, Cleistogenes songorica and Agriophyllum squarrosum etc. We have added the above information in the materials and methods section in the revision manuscript.
Point 7: Comments on the Quality of English Language. Quality of English is very fine.
Response 7: Thanks for your constructive comments. The manuscript has been revised and polished by a native English speaker before submission.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The paper approaches an issue of high interest, precipitation-use efficiency, respectively.
The material and methods are clearily described.
Results and dicussions are presented in a proper manner.
Conclusions. We suggest the autors presenting conclusions in a manner, which corresponds to objectives proposed., and emphasize the scientific novelty brought by their research.
Author Response
Dear Reviewer:
We deeply appreciate the time and effort you have spent to review our manuscript, entitled “Characteristics and driving factors of precipitation-use efficiency across diverse grasslands in Chinese Loess Plateau (agronomy-2510469)”. We thoroughly revised our manuscript according to the comments. We hope that it will be satisfied with the revisions in our manuscript. The point-to-point responses to comments are as follow and also can be seen in the attachment.
Point 1: The paper approaches an issue of high interest, precipitation-use efficiency, respectively.
Response 1: Many thanks for the affirmation of our manuscript.
Point 2: The material and methods are clearily described.
Response 2: Many thanks for the affirmation of our manuscript.
Point 3: Results and dicussions are presented in a proper manner.
Response 3: Many thanks for the affirmation of our manuscript.
Point 4: Conclusions. We suggest the autors presenting conclusions in a manner, which corresponds to objectives proposed., and emphasize the scientific novelty brought by their research.
Response 4: Thanks for your comments. According to the reviewer's suggestion, we have added the results of the grassland ANPP, species diversity and PUE changes with the precipitation gradient in the conclusion, thus echoing the objectives of this paper. The revised conclusion is as follows. “Our study illustrates that the grassland ANPP, species diversity and PUE increased significantly across precipitation gradient on Chinese Loess Plateau. MG had the highest ANPP and PUE among the three grassland types, and the lowest were that of DG. Both MG and TG had higher coverage, plant diversity and BGB than that in DG. BGB, vegetation coverage and diversity showed significantly positive correlations with the spatial distribution of PUE. The HI performed better than the MAP in explaining the variations of PUE, which it mainly affected PUE indirectly through community characteristics such as BGB, coverage and diversity. Our study highlights the need for further studies to clarify the distinct mechanisms at work in soil characteristics and abiotic-biotic interactions in controlling PUE at both local and regional scales. The re-sults have important implications for the management and conservation of grasslands in the context of ongoing climate change”.
Author Response File: Author Response.docx
Reviewer 3 Report
The manuscript "Characteristics and driving factors of precipitation-use efficiency across diverse grasslands in Chinese Loess Plateau" by Zongping Ren, et al. aims to investigate the spatial variation and controlling factors of precipitation use efficiency in 81 natural arid and semiarid ecosystem sites along a precipitation gradient.
Abstract. The term plant of grassland must be included at the beginning of the abstract. Otherwise, it can be written about other organisms.
Introduction. This is a very short section that can be complemented with other studies on how semiarid and arid ecosystem varies in other latitudes; for example, how the water pulses control the plant growth of grasslands, as previously reported.
Material and methods. Table 1 should be moved to the results. Specify the method (reference) used for plant identification in field and expert cases. Provide a reference for the equations presented in plant diversity calculations. The mean annual precipitation of each site must be indicated in this section. Specify how ANPP was calculated (in a separate line, now presented with other calculations), preferably before the 2.3 section.
Specify model fit is used in Fig 6. Include description, software, fit, general model, and all path analysis information (fig. 7).
Results. Use the same colors in Fig 1 for Figures 2, 3, and 4.
Fig. 5, Linear regression? – The response variable (PUE) cannot be explained by one of the variables that was used in its calculation (ANPP). This produces multicollinearity.
Fig. 6 – Specify the fit used.
Stepwise regression - By definition, a variable used to calculate a second variable (MAP and ANPP were used to calculate PUE) cannot be included as its indicator. This produces multicollinearity. Additionally, the order of the variables is relevant to the calculation. Justify the selected order.
Path analysis - By definition, a variable used to calculate a second variable (MAP and ANPP were used to calculate PUE) cannot be used as its indicator (MAP->PUE, and ANPP->PUE). Regression weights above 1 (ANPP->PUE) indicate a violation of the model; this is caused by the argument before. This produces multicollinearity.
Discussion.
Most of the discussion is based on invalid results. This section must be rewritten.
Is there a reason why Fig. 7 is included in the discussion? This is a result. There is an essential lack of information regarding the construction of path analysis. These models must include valid hypothesis to test, accepted ranges of model fit, and not violate the model principles (regression weight above 1).
Specific comments
Remove dots before affiliations.
L118 - remove the extra dot
L181-185 - must be moved to the description of the results
L197 – Superscripts
L238- Correlation or linear regression?
L262 – The text does not correspond with the presented in Table 2.
L79 - superscript
L88, L90-91, L93-94 - All species names must be in italics
L109 - Typo: tape
L177 – L191 – check typos in this section: perform instead of did (L188), were instead of was (L190).
L265, L266 – Superscripts
Author Response
Dear Reviewer:
We deeply appreciate the time and effort you have spent to review our manuscript, entitled “Characteristics and driving factors of precipitation-use efficiency across diverse grasslands in Chinese Loess Plateau (agronomy-2510469)”. We thoroughly revised our manuscript according to the comments. We reanalysed the data based on the reviewers' comments, modified and supplemented some figures, and rewritten some of the findings and discussions based on the above modifications. We hope that it will be satisfied with the revisions in our manuscript. The point-to-point responses can be seen in the attachment.
Author Response File: 
Author Response.pdf
Round 2
Reviewer 3 Report
The authors have made extensive corrections to the manuscript to improve the presentation of their work, as well as the validity of their findings in a satisfactory manner. I have no further comments.
