Growth Responses of Eucalyptus pellita F. Muell Plantations in South Sumatra to Macronutrient Fertilisers Following Several Rotations of Acacia mangium Willd.
Round 1
Reviewer 1 Report
The authors have addressed most of my concerns on the original manuscript. I do not have any reservations other than a couple of clarifications and typos.
The authors should clear the confusion present in discussion section L265-267 of revised manuscript where they state "The volume gain per unit P applied was higher than for A. mangium suggesting that E. pellita has a lower efficiency of P fertilizer use (ie wood volume productivity per unit of P fertiliser applied". However, in the response to the reviewers comments they state "Our finding confirmed that the P fertiliser applied to E. pellita resulted in lower volume than that of A. mangium of the same rate of P, indicating that E. pellita had lower P use efficiency than that of A. mangium (Figure 5 a and b).". The Figure 5b clearly shows that volume response to P was significantly higher for E. pellita.
A paper by Santana et al. (2000) New Zeal. J. For. Sci., 30 (2000), pp. 225-236 would be a good reference for estimating nutrient use efficiency from nutrient content and concentrations.
L136. change metsufuron to metsulfuron
L200. Change ',' to '.' after (Table 4).
L266. Change ie. to i.e.,
Author Response
Dear Editor,
Ref: Manuscript 640211-revision2
Title: Growth responses of Eucalyptus pellita plantations in South Sumatra to macronutrient fertilisers following several rotations of Acacia mangium
Once again, we thank you for the two reviewers for providing constructive suggestions for revision. As you can see, we have responded to all of them and have revised the manuscript to accommodate most comments. Our response to the comments from both reviewers is noted below as annotations in parenthesis (red) for easy validation.
If there is any more points to be clarified, please let us know. We look forward to the final decision.
Best regards
Alen Inail
Eko B. Hardiyanto
Daniel S.Mendham
Author Response File: 
Author Response.doc
Reviewer 2 Report
Thank you so much for your sincere revision and I carefully read the revised manuscript.
Now I understood the design of statistical tests of this study. Generally, posthoc tests
are applied for the comparison of more than three groups.
In Figures 1 and 5, judging from the alphabetical letters, the statistical tests seemed to be applied within inner groups. For example, in figure 1a, the statistical comparison was applied non-fertilization (0kg) and fertilization (30 kg) on each plantation age, independently. In this case, generally, there is no need to apply multiple comparison tests.
Therefore, I think the current manuscript needs some minor revision in the description of statistical test. Namely, Tukey HSD should be deleted in whole through the manuscript,
and the below suggested sentences should be changed to
line154; ...ANOVA. Statistical differences treatments or species were tested by t-test.
line 221: having the same letter did not differ significantly.
as same in
line 280: having the same letter did not differ significantly.
That's all.
Author Response
Dear Editor,
Ref: Manuscript 640211-revision2
Title: Growth responses of Eucalyptus pellita plantations in South Sumatra to macronutrient fertilisers following several rotations of Acacia mangium
Once again, we thank you for the two reviewers for providing constructive suggestions for revision. As you can see, we have responded to all of them and have revised the manuscript to accommodate most comments. Our response to the comments from both reviewers is noted below as annotations in parenthesis (red) for easy validation.
If there is any more points to be clarified, please let us know. We look forward to the final decision.
Best regards
Alen Inail
Eko B. Hardiyanto
Daniel S.Mendham
Author Response File: Author Response.doc
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
This manuscript is an interesting paper that looks at growth responses of E. pellita plantations to nutrient additions in sites with a long history of A. mangium plantation in South Asia. This study is a well-designed replicated trial spanning different sites in South Sumatra. There are some interesting results; however, modifications are still necessary to improve the paper. Below are some of the comments that need to be addressed.
General Comments:
The study design should be presented more clearly. There are multiple study designs (e.g., factorial design with levels of N and P vs. randomized complete block design with four treatments (K at three levels and Ca)). From what I understand, the Core experiment has a factorial experiment (N and P) and additional K and Ca treatments. Also, there is another RCBD experiment comparing two plantation species' responses to P addition. The method, as it reads, is somewhat confusing because of many experiments not described clearly. Including either a table showing treatments or an ANOVA model for each experiment would be beneficial to avoid this confusion. One of the significant components of the paper is the nutrient content in plant components. The authors need to elaborate more on how nutrients were analyzed (e.g., ICP). The authors also refer to efficiency in many instances in the paper. However, this has not been fully elaborated. For example, how was efficiency estimated? Is the efficiency uptake efficiency, or reuse efficiency, or physiological efficiency? Also, how was a proportional response to P estimated is not clear in the paper. Looking at Figures 3 and 4, I did not understand why a nutrient content for Mg would be lower at age four than at age three years. The annual nutrient uptake rate at age 4 is well above zero (See Figures 3 and 4). There should be some error in the calculation. If not, this needs explanation (e.g., why the Mg content at age 4 (in Figure 3) was lower than at age 3, even though Figure 4 annual Mg uptake suggests a positive uptake at age 4). In the discussion, the authors discuss a lot about P use efficiency. However, the lack of efficiency estimation procedure in the methods in the current manuscript makes it too difficult to follow. From what I understand, higher nutrient use efficiency in plants suggests that smaller nutrient uptake would yield higher biomass, so less fertilization is necessary. The authors, here, frame this differently. For example, volume gain per unit P applied was higher, so a lower efficiency of P use. (see lines 243-245). In lines 289-290, the authors suggest that the probable cause for no response to K and Ca could be supplementation from harvest residue. This statement is important. However, authors could use results from previous research on A. mangium harvest residue decomposition (Bich et al. 2018, Forests 9, 577 paper) to estimate net nutrient release via decomposition. I also do not fully agree on the author’s statement that “soil demands may be low because of harvest residue”. Turnover rates of these residues (bark, branches, and leaves) vary a lot. In general, 99% mass loss for A. mangium leaves occur in 3.4 yrs, branch ~ 9 years, and bark ~ 22 years. Conclusions on the lower internal efficiency of P use in E. pellita should be removed. Otherwise, clarifications on the estimation of nutrient use efficiency should be made in the methods and results section.
Line comments:
L37: Is crown damage by monkeys an observational statement? If not, cite it. Table 1: Were soil analyses not done on Satellite IV and V experiments? L133: Was herbicide application spot application? Table 2: Include 'Standard Error' and ‘n’ in the allometric equation table. L156: Does ‘…across all experiments…’ suggest average with treatments pooled together for the experiment? May need rewording. L158: Please include the ANOVA table with main effects and interaction effects. It could be added as a supplementary table. L166-171: Italicize H, D, V. Figure 1 c. How was volume response to P estimated? Please include in the figure caption. Figure 1d. How was a proportional response to P estimated? Include in the caption. Figure 3 and Figure 4. Year 4 value for Mg may be incorrect in one of these. L213. Instead of p-values only, include F values as well. L214-223. Italicize latin binomial names. L323-325. The sentence is not clear. Rewording may be necessary. Some bar graphs show mean separation. Some do not. Does this mean that the bars with no mean separation are not statistically different? (e.g., Figure 5d has a mean separation, but Figure 5b does not).
Author Response
Dear Editor,
Ref: Manuscript
Title: Growth responses of Eucalyptus pellita plantations in South Sumatra to macronutrient fertilisers following several rotations of Acacia mangium
We thank you and the two reviewers for providing many constructive suggestions for revision. As you can see that we have responded to all of them and have revised the manuscript to accommodate most comments. Our response to the comments from both reviewers is noted below as annotations in parenthesis (red) for easy validation, and the revised manuscript sections have been highlighted in yellow. In cases where we do not agree with the suggestions, explanations are provided.
This paper has improved because of the quality of the two reviews. It is much appreciated.
If there is any more points to be clarified, please let us know. We look forward to the final decision.
Best regards
Alen Inail
Eko B. Hardiyanto
Daniel S.Mendham
Author Response File: Author Response.doc
Reviewer 2 Report
I carefully read the submitted manuscript. This study evaluated growth responses of non-nitrogen fixing tree Eucalyptus pellita to the various nutrient managements after harvesting of nitrogen fixing tree Acasia mangium.
I think topic is interesting and suitable for forests and this study provide important information for the managements of plantation in Indonesia.
Introduction section was clearly written and well constructed. However, I think the application of statistical tests were not adequate. Therefore, major revision should be needed in this point. Then, following the results of re-application of adequate statistical tests, results and discussion section should also be revised. The applied Duncan test induces type-I error. Therefore, another post-hoc multiple comparison test, for example Tukey HSD should be applied, or instead of multiple comparison test, the application of linear contrast is also acceptable.
Minor comments
#1: 2.2 treatment design
I think a figure of study design is helpful for clearly understanding of readers.
#2:Tables and figures
It is helpful for readers that the results of statistical tests also presented in tables and figures.
That's all.
Author Response
Dear Editor,
Ref: Manuscript
Title: Growth responses of Eucalyptus pellita plantations in South Sumatra to macronutrient fertilisers following several rotations of Acacia mangium
We thank you and the two reviewers for providing many constructive suggestions for revision. As you can see that we have responded to all of them and have revised the manuscript to accommodate most comments. Our response to the comments from both reviewers is noted below as annotations in parenthesis (red) for easy validation, and the revised manuscript sections have been highlighted in yellow. In cases where we do not agree with the suggestions, explanations are provided.
This paper has improved because of the quality of the two reviews. It is much appreciated.
If there is any more points to be clarified, please let us know. We look forward to the final decision.
Best regards
Alen Inail
Eko B. Hardiyanto
Daniel S.Mendham
Author Response File: Author Response.doc
