Tree Wind Breaks in Central Asia and Their Effects on Agricultural Water Consumption

Round 1

Reviewer 1 Report

It is satisfactory now as far as my original comments.

l. 83 focusses --> focuses
l. 99 letter --> latter

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

This is a revision of a previous version of this manuscript, which assess the impacts of wind breaks on agricultural water use-efficiency, under several crop hybrids, in Central Asia. The study is very interesting and relevant in terms of environmental sustainability, land-use and management, elemental and nutrient cycling, agricultural production, and global water- and food- security. The manuscript is well written and well structured, and the tables and figures are clear and informative. Overall, the manuscript is expected to attract a lot of attention by both land managers and policy makers across the world. I congratulate the authors for implementing this excellent work.

Yet, I would recommend the authors to consider implementing a couple of minor modifications. For example, I would recommend the authors to consider replacing the 'water consumption' along the manuscript' with 'water use' or 'water use-efficiency', which seems to better represent the topic of this study. Also, I am not familiar with the term 'undergrowth'. Would you consider replacing it with 'understory'? Additionally, along the manuscript, wherever you firstly mention an abbreviation, please first insert its full name. For example, in line 24, please write 'reference evapotranspiration (ETo)'. Also, wherever you firstly mention a vegetation genus or species, please insert its scientific (Latin) name before you mention its popular name. For example, this should be inserted for the corn, wheat, potato, and barley (line 87), cotton, rice, and corn (line 88), and poplar (line 90) and elm (line 91). For example, for the corn, please write: 'corn (Zea mays L.)'. Additionally, I could not see any information on the soil across the study region. Could you please insert to the materials and methods section a sentence or two, defining the soil series and describing its major properties (among which, texture is most important).

Author Response

Please see the attachment.

Author Response File: Author Response.docx

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Overall this is a manuscript of very good quality. Some comments:

The justification for the research needs to be strengthened in the Introduction (last paragraph).

Check the caption of Table 6 - there seems to be an error (line 270).

Line 96 ...impact of this type was calculated.... Specify what impact was calculated and how it was calculated.

Line 121 ...field data was collected.... what field data was collected?

Lines 273-275 - this paragraph seems out of place.

Minor editing required in the whole manuscript.

Author Response

Revision of manuscript Thevs et al. Tree wind breaks in Central Asia and their effects on agricultural water consumption

Response to reviewer #1

Comment by reviewer	Response
Check the caption of Table 6 - there seems to be an error (line 270)	A caption was included: Water consumption – evapotranspiration (ET) of crops without tree wind breaks (ETc) and with tree wind breaks of different grid sizes
Line 273-275	Right, this paragraph was removed.
Line 96	This line was changed as follows: As the single row tree wind break from poplars is the most common one for newly planted tree  wind breaks, the impact of this wind break type was calculated for climatic and crop conditions in Ferghana Valley
Line 121	This line was changed into: In this study, field data on micro climate were collected to assess the impact of single row (in Chek Village) and multiple row tree wind breaks (in Temen Suu Village), because these are the two major wind break types in Kyrgyzstan and regions in neighboring countries.

 

Reviewer 2 Report

The paper presents calculations on the water use in crops with wind breaks in Central Asia. The concept of the paper is quite interesting and seems innovative. Using some empirical data on the effect of tree rows on wind speed, the paper calculates potential evapotranspiration at different distances from the wind break. It then uses GIS to integrate the functions over 2-D space and determine the overall water consumption by crops and trees together. The information seems novel to me. Introduction is fine, but materials and methods lacks key information. Materials and methods therefore need further elaboration. See detailed comments. Results show fitted equations but does not show enough data. This makes it impossible for the reader to assess the empirical support for the relationships. The discussion is still immature; I miss a statement on the key findings in the beginning of the discussion, and I don’t think it is necessary to go at great length to state that others have found similar results. It would be more useful if the authors explained how their results expand the envelope of knowledge and lead to potential applications. Overall, the flow of text in most of the paper (except the introduction) can be further improved.

Detailed comments

23 Tree water consumption was determined through sap flow measurements. There is no information on this in the Materials and Methods and Results.

23 Water consumption by trees is expressed in mm, but it remains unclear how this information is integrated with crop water use, accounting for the area of the crops and the ground area covered by the trees. This aspect needs to be made explicit in the materials and methods.

58 Drop “and”

65 I presume that you mean that wind speed was reduced by only 10% (not 90%)?

67 “was”, not “were”

96-113 I found the text on the locations of the study sites hard to follow. Ferghana valley is mentioned in the text but not shown on the map. Please try to shorten and clarify this section. Start by stating the number of sites (four according to Table 6), their names and what is in them.

125 “at”, not “in”

130 the location of the meteorological stations should be stated. Were they at one of the locations or spread over locations? Were they mobile and moved in the landscape? More information is needed.

132 “expressed as”, not “used in”

136 It would be helpful to include formulas for ET0 and ETc, and explain which input variables in these equations were entered as measured, and which were derived from literature. Evaporation as calculated represents the potential evaporation, I presume? It is worthwhile to clarify this. You probably want to indicate that by using windbreaks, crops would be able to produce (almost) the same yield, but using less water. Still, this is a point that the current analysis does not prove, but you can sketch a likely scenario in the discussion.

138 “obtained”, not “inherited”

140-142 Here it looks as if you compare calculation results to empirical data, but I did not see that in results. I have the impression that you use GIS only to integrate information on measured water use by trees with calculated water use by crops to generate landscape level water use. Please clarify.

160 Drop “on”

Table 3 Would it make sense to include Kc values in the table?

207 Drop “underneath in”

210 It would be nice to see more data on climate data at different distances from trees. You mention that the GIS framework takes into account air temperature, aie humidity, wind speed and solar radiation (147). But we do not see the data on measured climate variables. We do see fitted relationships in Table 4, but it would be far preferable to see the data with the fitted relationships.

218-231 It is not clear to me why you provide these relationships if you measured the sap flow rates of the trees as you mention in the abstract. Could you show data with the fitted relationships?

248-250 As stated above, when integrating water use by trees and crops in mm, we need to know for each landscape which proportion of the landscape you assign to trees, and which proportion to crops. What width do you assume for the tree rows?

Table 6 The response of total water use to grid size is different for different systems/locations. Could you please describe the differences, e.g. lowest ET at 100 x 100 in single row, Chek, and increasing ET with greater grids, whereas the trend with multiple row systems in Temen is completely different. Which mechanism is behind it? Can you discuss this a bit more?

273-275 Delete instructions

276-293 This part is not so interesting. It would be helpful to give a summary of your main findings here. Then, in subsequent pararaphs, you can explain the novelty of your work in comparison to existing literature.

276 “further studies” is not appropriate here.

 

 

 

 

 

Author Response

Revision of manuscript Thevs et al. Tree wind breaks in Central Asia and their effects on agricultural water consumption

Response to reviewer #2

Comment by reviewer	Response
General comment	The second last paragraph of the introduction was changed as follow, in order to better justify this research here: Literature findings were based on tree wind breaks of multiple rows of trees often combined with shrubs as undergrowth, i.e. the type which was propagated during Soviet Union times. Such type was studied in [20] as well. Today, small stretches of this wind break type still remain, but if people plant new tree wind breaks they opt for single rows largely from poplars without any undergrowth. Therefore, this paper will include these single row tree wind breaks and thus partly builds on [20]. The literature cited above mainly focusses on the effects of tree wind breaks on crops, but do not address the trees as a water consumer or source of income.   English was further edited.
Specific comments
Line 23 Tree water consumption was determined through sap flow measurements. There is no information on this in the Materials and Methods and Results.	Sentences which indicate sapflow method were added to the method and result section (cf. highlighted text).
Line 23 Water consumption by trees is expressed in mm, but it remains unclear how this information is integrated with crop water use, accounting for the area of the crops and the ground area covered by the trees. This aspect needs to be made explicit in the materials and methods.	This information was added at the end of the method section, see highlighted text.
Line 58	“and” was deleted.
Line 65	Yes. This sentence was changed into “…wind speed was only reduced to 90% compared to open field conditions.”
Line 67	Test was changed accordingly.
Line 96-113. I found the text on the locations of the study sites hard to follow. Ferghana valley is mentioned in the text but not shown on the map. Please try to shorten and clarify this section. Start by stating the number of sites (four according to Table 6), their names and what is in them.	This part of the text was shortened as suggested (first paragraph of materials and methods section).
Line 125	Was changed according to review.
Line 130. the location of the meteorological stations should be stated. Were they at one of the locations or spread over locations? Were they mobile and moved in the landscape? More information is needed.	This information was added: The climate stations were placed along lines perpendicular to the tree wind break. Thereby, the climate stations had to be relocated every two to three weeks and their distances to the tree wind breaks had to be changed, in order not to disturb farm operations. In total, the climate stations were used during the whole growing seasons.
Line 132 “expressed as”, not “used in”	Text was changed accordingly.
Line 136. It would be helpful to include formulas for ET0 and ETc, and explain which input variables in these equations were entered as measured, and which were derived from literature. Evaporation as calculated represents the potential evaporation, I presume? It is worthwhile to clarify this. You probably want to indicate that by using windbreaks, crops would be able to produce (almost) the same yield, but using less water. Still, this is a point that the current analysis does not prove, but you can sketch a likely scenario in the discussion.	The formulae for ETo and ETc were included. Though, many more calculations are needed to calculate ETo than suggested by just the ETo formula. It would be well beyond the scope of this paper to write down all these calculations here, as the source [20] presents these formulae much better than it could be done here.
Line 138. “obtained”, not “inherited”	Text was changed accordingly.
Line 140-142. Here it looks as if you compare calculation results to empirical data, but I did not see that in results. I have the impression that you use GIS only to integrate information on measured water use by trees with calculated water use by crops to generate landscape level water use. Please clarify.	This paragraph was included to clarify: In a second step, a local GIS model was developed for each site and tree wind break type, in order to calculate ETc impacted by tree wind breaks and tree water consumption together. In this model, daily climate data layers were used, which were adjusted according to the micro climate profiles mentioned above. This GIS model was implemented in GRASS GIS (https://grass.osgeo.org/).
Line 160. Drop “on”	Text was changed accordingly.
Table 3. Would it make sense to include Kc values in the table?	Kc values were added to table 3.
Line 207. Drop “underneath in”	Text was changed accordingly.
Line 210. It would be nice to see more data on climate data at different distances from trees. You mention that the GIS framework takes into account air temperature, aie humidity, wind speed and solar radiation (147). But we do not see the data on measured climate variables. We do see fitted relationships in Table 4, but it would be far preferable to see the data with the fitted relationships.	Scatterplots on climate data were included.
Line 218-231. It is not clear to me why you provide these relationships if you measured the sap flow rates of the trees as you mention in the abstract. Could you show data with the fitted relationships?	Scatterplots of these relationships were added.
Line 248-250. As stated above, when integrating water use by trees and crops in mm, we need to know for each landscape which proportion of the landscape you assign to trees, and which proportion to crops. What width do you assume for the tree rows?	These information were added in the last two paragraphs of the method section.
Table 6. The response of total water use to grid size is different for different systems/locations. Could you please describe the differences, e.g. lowest ET at 100 x 100 in single row, Chek, and increasing ET with greater grids, whereas the trend with multiple row systems in Temen is completely different. Which mechanism is behind it? Can you discuss this a bit more?	The four paragraphs before Table 6 were rewritten, in order to explain the differences of tree wind break systems more clearly. The last two paragraphs of the discussion were rewritten accordingly.
Line 273-275. Delete instructions	Was deleted.
Line 276-293 This part is not so interesting. It would be helpful to give a summary of your main findings here. Then, in subsequent pararaphs, you can explain the novelty of your work in comparison to existing literature.	We would rather like to leave this paragraph as a validation, in order to show to readers that our findings are not out of range. Eventually we would leave the decision to the editor, if such validation is wanted by the journal.
Line 276 “further studies” is not appropriate here.	This sentence was changed into: ETc values in this study are in the range of [27], who measured water consumption of corn with values between 741 mm and 841 mm measured in Texas with a lysimeter under sprinkler irrigation.

 

 

Reviewer 3 Report

This is interesting work that uses a combination of measurement and modeling to quantify the effect of tree shelterbelts in reducing agricultural water demand. I think it can be published after some revisions and editing.

line 65: "was only reduced 90%" - write "was only reduced to 90%" or "was only reduced by 10%"
Introduction: Explain more clearly how this work extends earlier publications such as Ref. 23
Table 4: state the units used for T
line 253: give the table number
line 266: "was reduced from 1035 mm" --> "was reduced from 1035 mm without any tree wind break"
Table 6 needs an informative caption
lines 273-275: delete

Author Response

Revision of manuscript Thevs et al. Tree wind breaks in Central Asia and their effects on agricultural water consumption

Response to reviewer #3

Comment by reviewer	Response
Line 65	^text was changed to “wind speed was only reduced to 90%...”
Table 4	Units were added.
Line 253	The table number was added.
Line 266 "was reduced from 1035 mm" --> "was reduced from 1035 mm without any tree wind break"	Text was changed accordingly.
Table 6	The following caption was added: Water consumption – evapotranspiration (ET) of crops without tree wind breaks (ETc) and with tree wind breaks of different grid sizes
Lines 273-275	These lines were deleted.