Biomass Yield of 37 Different SRC Poplar Varieties Grown on a Typical Site in North Eastern Germany
Round 1
Reviewer 1 Report
Biomass yield of 37 different SRC poplar varieties 2 grown on a typical site in North Eastern Germany 3
Dirk Landgraf 1*, Christin Carl 1 and Markus Neupert 2
General Comments
This is not a groundbreakingly novel paper, however is of interest to the SRC community. The information contained is basic, but is nicely presented and clearly written. The figures need to be amended as they are misleading at present, and discussions should not contain new results or figures. Some additional context in the discussion would improve the MS to show broader application and understanding of wider context.
Specific comments
L32 – how are they ‘reducing hazardous emissions’? Do you mean via fossil field substitution or a biogenic process – please be specific with your language as this this a bit misleading
L33 – this is misleading. The EU are not supporting renewable energy policies because of SRC ability to reduce emissions, or bioenergy. But because of the need to reduce GHG emissions and avoid dangerous climate change. Rephrase.
L48 – acronym AFS hasn’t been defined
L87 – “shoots per stool WERE counted” – not ‘was’
Figure 1, 2, 3, 4 – the colours are not required in this graph, its clear from the x axis which varieties performed better – the colour coding key is just duplicating information unnecessarily.
192 – in this section you are now using 2 figures are the decimal, whereas previously you were using one. I don’t think two are needed In this section.
245-248 – This calculation is not appropriate for the discussion, neither is the figure 5. This should be in your results section. Then you discuss implications of this in the discussion section.
Figure 5 – must be moved to results section
Discussion – there is not any discussion about the influence of climate and possible impacts of future climate change or resource limitation. Where this study has taken place over a number of years, there has likely been annual fluctuations and extreme weather events (heat waves, droughts etc.). It would be good to see some discussion of the expected impact of this your results.
Discussion – I would also like to see how your varieties compare to other commercially used varieties of today – are they better or worse? What about pest resistance, or being hardy in different weathers?
Author Response
Please see the attachement.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Landgraf et al. described the performance of 37 poplar varieties in SRC evaluating the biomass, shoot number, plant height and diameter at breast height, and dry matter performing three sampling time after 1 year and in concomitance of the first and second harvest in 2015 and 2018.
Overall, the topic is interesting, the manuscript discusses an important issue and the experiment is properly conducted. Despite the current version is well prepared, some points in the manuscript must be improved. I report some specific comments as follows.
MAJOR COMMENTS
INTRODUCTION
The introduction is too fast, I suggest to further improve it. As example, a short description of poplar species and hybrid used in the experiment can be included also focusing on their strengths and differences. Moreover, since the importance of soil type in influencing poplar yield is widely discussed within the manuscript, an introduction regarding the soil influence in SRC must be inserted. Finally, the importance of SRC for biofuel production could be mentioned.
RESULTS
Even if the figures 2, 3, and 4 are attractive, after a first look they result little informative. They are perfect for an oral presentation, but I suggest to further detailed them for the manuscript. A) Using the median value, it is more informative a boxplot rather than a histogram. Alternatively, the average value can be reported. Readers do not have any information about the variance of measures (also in the manuscript standard errors or deviations are missing). B) The combination of results corresponding to 2015 and 2018 into the same bar using black arrows make the understanding difficult. I suggest using two joined boxplots. C) In the figure statistical results are completely lacking. Authors must include them directly in the figure (i.e. reporting letters next to bars) or adding a table. D) the color scale is not useful (also in figure 1). Otherwise, authors could transform the figures in tables.
Generally, statistics is lacking and, therefore, each sentence in result section is not supported by the statistical results. I recommend adding statistical results within the figures and to take into consideration that statistical analyses must have as factors both the poplar variety and the time of harvest. Moreover, the average values along the manuscript must be followed by standard errors or deviations (e.g. plant heights, diameters, dry matter biomass yield).
DISCUSSION
The discussion does not take into account possible differences in biomass yield related to the different poplar varieties used in the experiment. Please include some considerations about that point. Differences in biomass production among poplar species have been reported by manuscript reference [20] or by Verlinden et al. (2015, Biomass and bioenergy, 73, 174-185). Also, a sentence about tetraploid TI poplar performance could be inserted.
MINOR COMMENTS
Line 55 page 2:
Replace “was to be evaluated” with “was evaluated”.
Lines 73-74 page 2:
“The three TI 73 varieties came as rooted plants in pots and were planted after the removal of the pots”. Please rewrite this sentence.
Lines 245- 248 page 12:
“The latter means that the greater the average number of shoots, the greater is the dry matter biomass yield, which leads to the conclusion that the resprouting capacity of poplars does not only compensate the loss of individuals, but can also increase the yield”. This sentence is unclear, please rewrite it.
Line 258 page 12:
The comma after et al. must be deleted.
Along the manuscript:
Replace “an SRC” with “a SRC”.
Figure 1
Substitute “median” with “average” in the figure caption.
Figure 5
The description of results reported in figure 5 must be included in result section.
Author Response
Please see the attachement
Author Response File: Author Response.docx
Reviewer 3 Report
The manuscript (MS) has got interesting topic with very well defined aim. Its results could be convenient for the practical users of SRC or AFS.
I have got only two minor and one major remarks for the MS.
Minor remarks:
I suggest to change the keywords, because they are same with the title of the MS which is not convenient.
At line 214 is wrong DBY value for variety Esch 5 (-3.0 4.1). Correct it.
Major remark:
In the chapter 2.3 Data analysis is written that "differences between poplar varieties were analysed using the non-parametric Kruskal-Wallis test" (KW). But in the chapter Results are not any results for this type of the analysis. So it is not possible to find, which poplar varieties have got the statistically same growth parameters or which varieties have got the differences to each other. The multiple comparison tests after the KW tests are completely missing. So it is not possible to make (for example) groups of poplar varieties with the same growth parameters. Only one small trace after these statistical analyses is in the figure 1, where are standard errors of the parameters. So please add detailed results of KW tests and add multiple comparison test results - in the graphs or in the tables -for every of tested growth parameters. After this addition the MS will be much better.
Author Response
Please see the attachement.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
I really appreciate all efforts of authors to improve the manuscript following my advices.
I have only just a few further small suggestions. Since figures 1-4 refer to figure 5 I suggest moving this figure before the others and describe the biomass yield as the first results (that is also the most interesting). Also, I recommend reporting the letters about statistical comparisons directly in the figures 1 and 5 on the top of bars rather than in a table in the supplementary material (moreover, the table is mentioned only along the manuscript but it is not reported in the captions and its number is different within the main text and the supplementary material). Table 2 caption refers to the wrong figure.
Author Response
Please see attachement.
Author Response File: Author Response.docx
Reviewer 3 Report
Corrected version of the MS is better in all its parts. Thanks to authors to their effort to improve the MS quality. I have got only one small suggestion yet. In the main text is written, that supplementary file content Table 1. But directly in the supllementary content is only Table 3. Please check the number of the table.
After this minor revision I recommend the MS for publishing.
Author Response
Please see attachement.
Author Response File: Author Response.docx
