Heterogeneity in Decomposition Rates and Nutrient Release in Fine-Root Architecture of Pinus massoniana in the Three Gorges Reservoir Area
Round 1
Reviewer 1 Report
The manuscript is interesting and undoubtedly meets the interest of Forests readers. Its main drawback is the poor quality of presentation, particularly in the Results and Discussion sections. I read it several times and every time I missed the logical sequence of the presented items. The experimental design is not adequately described. The statistical test adopted is wrong; as there are three levels/items to be compared, it becomes a multiple comparison test. Given the low number of items, I suggest using the post hoc Bonferroni test. Several comments are reported below but the manuscript needs a broad revised editing which I did not highlight their all in detail waiting for an improved version. In conclusion, I cannot recommend its publication in the present form, but I strongly encourage the authors to resubmit an improved version of this manuscript.
L17. high turnover rates of what?
L61. Move references from line 62 to 61 so that “… of tree species [25-28].”
L75. Also for the not specialized readers, provide a brief description of what kind/category of compounds do the AUR refer to: aliphatics (i.e. suberin), lignin and secondary metabolites (i.e. alkaloids, phenylpropanoids and tannins).
L101. the sites…
L104-105. move “(mean ± SE)” to the previous line after 2.22%. You do not need to write it again after first mentioning
L112. “hm” is uncommon. Please substitute with “ha” i.e. hectare.
The experimental design is not adequately described. “Three plots, each 20 × 20 m, were randomly chosen in each plantation.” How many plantations?
L124 and L128. It is not clear what is inside the mesh-bag: one orders-class, e.g. 1-2? Considering the other two 3-4 orders-class and 5-6 orders-class, it totals three mesh-bag per subplot? If this is the case, it is better at L120 to label these three classes as: 1-2 orders-class, 3-4 orders-class and 5-6 orders-class. Moreover, how much mesh bags are in total? 3 order-class x 3 subplots x 3 plots x ?plantations?
L159-160. It is a repetition. Remove it
L195-196. It sounds a repetition of the previous sentence. Remove it.
L199-200. It sounds a repetition of the subsequent sentence. Remove it.
L233-234. There are grammar, editing and root-orders errors. Rephrase.
L237. During decomposition, in lower-order roots (orders 1–2 and 3–4) with lower C:N ratio, root residual N was released, immobilized, and then released whereas in higher-order roots (orders 5–6) with higher C:N ratio, root residual N was immobilized, released, and then immobilized (Figure 3,4).
L254. What does it mean “… was obvious…”
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper is a worthwhile contribution to the recent growth in the number of publications regarding the role and nature of fine root decomposition in forested ecosystems.
Although limited to a single species in a single site over a single year it does serve to challenge some of the earlier conceptions of fine root decay and reaffirm some of the more recent observations and conclusions.
One larger concern is that it does not mention the possible role of mycorrhizal fungi in the behavior of the lowest order of fine roots. Pines are often symbiotic with ecto-mycorrhizae and the fungal sheath may have an impact on the findings, yet this possibility was not mentioned.
Also, many of the literature references were marked [Error bookmark not defined] which was frustrating.
I have some specific comments on short sections that I found confusing or poorly worded:
line 17 the dependent clause beginning with "which.." seems to refer to the plant productivity and metabolism Suggest restructuring the sentence.
lines 25-26 the sentence is awkward and confusing; it appears to say that releasing N resulted in immobilisation of N??
line 42 clarify the comparison that you are making "promotes changes compared with..." greater ,lesser, how?
lines 51 and following This is quite true that the move to analyzing root processes on the basis of order is an improvement in many respects, but it still does completely address heterogeneity within the branching order groups (degree and type of mycorrhizae, suberization, local effect of soil environment, etc.)
lines 72 and following the role of herbivores and herbivore defense seems logical but what about pathogens and pathogen defense??
line 101 "the sits" ??
line 129 indentation
line 132 I like having a map but this map could tell us more if it showed additional info such as forested areas of three gorges region or areas of this species of pine or perhaps a clearer look at the particular county It seems to have a lot of extra information when more local information would be more helpful to the reader
line 154 why did you use the paired-sample t-test to test differences among three classes?
line 166 You define AUR but not AHR (both are defined i the main text)
Figures 2 and 3 could be combined into a Figure 2a and 2b and reduced in size given the relatively few points
Figure 5 and 6 I assume that the points are values are from the individual subplots
I hope these comments are helpful.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The manuscript is improved but it still needs an effort to be ready for publication. Below are other comments which must be addressed for its improvement and clarity. Please, take your time to correct the text. There are still several grammars and editing mistakes.
L92. This new sentence is disconnected form the previous one. Rephrase
L150. … plantation…
L155. Within each plot, to minimize the influence of slope, three subplots (3 × 3 m) were set… Delete “in each plot” at the end
L185. … litterbags were laid within the topsoil (1-10 cm depth).
L186. … collected from one subplot for each root order class (27 litterbags in total at harvest)…
L188. A total of 135 litterbags per root order class were collected, 405 in total (three order class).
L198-199. “forest products serial digestion technique”. For the number and importance of the compounds analysed, more details in brief should be provided.
L208. … using the Bonferroni multiple comparison test with a 5% rejection level.
L213-220-. General comment from this point throughout the rest of the text: the variables investigated (N concentration, AUR, AHR etc.) are always in the singular when treatments are compared (e.g. N concentration was higher in A than in B…). Plural is used when more treatments are presented/discussed together.
L220. The initial AUR concentration in order 1–2 was almost 1.19- and 1.31-fold higher than in order 3–4 and 5–6, respectively.
Table 1. first column: Order class
L293. Effect of Fine Root order class on Decomposition and N Release Pattern
L298. Delete “for example” and the time you are referring to is not so initial, so that it is better to write: On day 120, the remaining mass was 73.78%...
L300. Delete “For example”
Figure 3 and 4. “Error bars represent mean ± standard error (n = 3)”. You cannot write these kinds of errors; they constitute the basic statistic writing. In Figure 2 you write “standard error”, in Figure 3 “SE”. Moreover, error bars are not visible for several means, so that: “Data represent means ± SE (n = 3) (SE not shown if smaller than symbol)”
Figure 4. Why do you show three points per order class (maybe one per plot), whereas k values in table 2 are one per order class (all three plots combined?)? I suggest a detailed explanation of the number of these k values in the Statistical analysis section or in the Results section
L447. N-rich defensive chemicals may include alkaloids, but this category of secondary metabolites is not as diffuse as phenols and terpenoids. Alkaloids are more abundant in Angiosperm Dicotyledones like Papaveraceae, Ranunculaceae, Solanaceae, Amaryllidaceae, less abundant in Monocotyledones, and sporadic in Gymnosperms. The reference 55 is very old, and the occurrence of alkaloids in Pinus massoniana is too much speculative. As you did not measure secondary metabolites, please remove this sentence. The high N concentration is because of the absorptive function (NO3-) of lower order roots and their higher metabolism which include higher proteins and enzymes concentrations. Mycorrhiza cannot be ruled out as you correctly mentioned at L477-481. As you consider the carbon quality the main actor for the explanation of your results, may you provide a simple definition of “quality” when first mentioned, for example at L56 or L93?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
