Habitat Significantly Affect CWD Decomposition but No Home-Field Advantage of the Decomposition Found in a Subtropical Forest, China

Round 1

Reviewer 1 Report

The manuscript shows the results of very interesting work on an important topic, which has diverse and sometimes contrasting backgrounds. The "home field advantage" effect has not been extensively studied in coarse debris, so this type of work is of interest.

The work is generally well planned and correct. However, there are some aspects that should be reviewed. Comments and suggestions about the manuscript are presented below.

Introduction.

Correct, clear and concise. The most relevant aspects are presented with respect to the questions posed by the work. The hypotheses are correctly stated although, as usual, the predictions that emerge from them are not presented. It is very useful to leave the predictions as they allow to quickly understand the logic of the research design. The predictions are what is actually going to be tested in the work, they express the results that the researchers would expect to obtain if the hypotheses are correct. Unfortunately, inclusion of predictions in scientific papers is unusual. This is just a suggestion, in case the authors want to include them they would complete the presentation of the hypotheses and facilitate the understanding of the work.

Materials and Methods

Correct but some addition or clarifications are needed.

Study area

How far apart are the two study areas (CF and DBF)?

Sampling design

Lines 109-110. Was the selected coarse woody debris of each species on the forest floor or was it specially cut from a living tree? If they were in the soil, could there be an effect of the community of microorganisms that originally inhabited the detritus? In the case of fungi, the presence of fungi in the substrate conditions the possibility of other fungi to colonize that substrate. Therefore, it seems important to make clear the origin of the detritus, and if they were kept with their original community of microorganisms or were sterilized before be transferred to the "visiting field".

Line 117: The initial chemical composition is in table 1, not in table 2 as it appears in the text.

Line 128: It is Table 1 not table A1.

Line 133: I imagine the authors mean that the twigs, roots, and stones were discarded, not selected.

Line 135: This information is in Table 2 not in table 1 as it appears in the text.

Results

 A lot of information is presented, generally in a clear manner. However, there are some aspects that can be improved and some errors that need to be corrected.

 

Line 194: Table 1 appears in the materials and methods section and I think it should go in the results section since it presents the results of the quality of the debris at the end of the study.

Why is a comparative statistical analysis of the initial values of each debris not presented? It is important to know if the initial differences were significant or not. In lines 207-209 it is mentioned that the initial quality of the two types of debris differed significantly but that information is not presented in the table. Nor in the case of soil in table 2.

Why the P content of CWD are not presented in Table 1?

Table 2: the initial content of P does not seem to be correct. Is it possible that it is expressed in mg instead of g? On the other hand, it does not coincide with the value of the C/P, N/P rate either. I suggest reviewing all the values in Table 2.

Lines 208-209 and 275-278 mention significant differences both in the initial quality of the substrate of the two types of debris and in the nutrients of the soil, however, these significance are not indicated in the table (with different letters). The magnitude of that significance is also not presented.

Line 216-217 total PLFAs of P. strobilacea were significantly higher only in CF.

Lines 272-273: Consider changing “…CWD decomposed faster in P. strobilacea than in C. japonica CWD…” by “…P. strobilacea CWD decomposed faster than C. japonica CWD” because the former be misunderstood as referring to CF and DBH

Lines 306-308. This sentence needs to be revised. The data do not allow that assertion to be made. It cannot be affirmed that the reduction of C is what causes the observed pattern because it inhibits growth. On the other hand, it is not clear what the relationship is with table 5.

Line 336, the figure is 4c not 4a

The results present information that could be used more widely. For example the comparison between the initial and post incubation nutrient content. In any case, the objective of the work is fulfilled and the initial questions and hypotheses are answered; I understand that deepening the analysis of other aspects exceeds the objectives of the work.

Conclusions.

Correct. Clear and concise.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper is an interesting study and what most important quite novel. Authors studied CWD decomposition of two subtropical forest trees but they took into account contribution of Phospholipid Fatty Acid Analysis (PLFA) of microbial community. The results may be interesting for other researchers who study problem of deadwood in forests and in general for specialists in forest ecology.

I miss some more detailed information. Not all methodological aspects are clear. Below I present minor issues that should be addresse:

Line 25: DBF and CF give full name instead of abbreviations

Line 88: instead of “hypothesized” write “hypotheses”

Lines 107-108 “The six sample plots were similar in elevation, slope, and slope position” I suggest to provide table with more detailed information about study design or incorporate it to the text. Please write ranges of elevation (altitude a.s.l.), slope in degrees, slope position (aspect).  

Lines 122 – 135. Sample collection. There are no information about coarse woody debris (CWD). I guess that CWD were represented by lying logs but CWD also include stumps, snags (dead standing trees). Were all logs lying on the forest floor and touch the soil? Or were they suspended logs? This is important for the rate of decomposition. Another significant problem is advancement of decay of CWD. Although authors mention about decay of CWD but in the text there are no mentions about decomposition of the studied CWD. During the decay of CWD various chemical substances and elements are released and it enhances colonization by fungi, lichens and vascular plants. The decomposition degree of CWD also might have an impact on PLFA. Therefore, this information is required in material and methods. Since McCullogh (1948) many attempts to form classification of decay were made. There are from 4 to 8 classes of decomposition (Holeksa 2001). So, what was decay class of the studied logs?

McCullough, H.A., 1948. Plant succession on fallen logs in a virgin spruce-fir forest. Ecology 29 (4), 508–513.

Holeksa, J. 2001. Coarse woody debris in a Carpathian subalpine spruce forest. Forstwiss Centralblatt 120: 256-270. doi: 10.1007/BF02796097.

Petrillo, M. et al. 2015. Decomposition of Norway spruce and European larch coarse woody debris (CWD) in relation to different elevation and exposure in an Alpine setting. iForest-Biogeosciences and Forestry, 9(1), iForest 9: 154-164. - doi: 10.3832/ifor1591-008

Lines 182-184. This description is too scarce. Write more methodological assumptions of principal components analysis (PCA) and redundancy analysis (RDA).

The figures 2A and 2B present samples based on PLFA in CWD and soil respectively. Two groups of microbial community composition for C. japonica and P. strobilacea are distinct according to the first axes of PCA. However, you can try to perform passive projection of grouping variable or PERMANOVA to conform statistical significance between two microbial communities.

How many iterations of Monte-Carlo test were used? Did you calculate variance inflation factor (VIF) in RDA? Looking at figure 2C it seems that variables C and C/N are correlated. They are situated very close on the ordination diagram. Probably one of the is redundant. The values of VIF can show which of the used variables are inter-correlated.

Line 190: Why White’s nonparametric t test was used? It is not popular statistical test for examining significance of differences. Write why this test was chosen.

Line 230: “STAMP analysis” you referred to the name of statistical software but you should use the name of statistical analysis.

Line 314. The same: “STAMP analysis” …

Author Response

Please see the attachment

Author Response File: Author Response.pdf