Soil Respiration and Related Abiotic and Remotely Sensed Variables in Different Overstories and Understories in a High-Elevation Southern Appalachian Forest
Round 1
Reviewer 1 Report
The paper is interesting and the consequence of a hard work to obtain the data. I have liked reading it and the paper could deserve publication in Forests if any other referee does not find serious flaws. My main concern is the final conclussion of the study, as temperature influence on soil respiration is well established here but I am not sure of the originality of this goal.
I wonder if authors can give arguments to defend the novelty and originality of their work.
Soil respiration, as a process of Paramount importance in the context of net carbon balance in ecology, has been studied in different forest hábitats, considering also the internal structure of the stand (composition of understory and overstory). The topic is of a high interest, due to an expected higher contribution of respired carbon from the soil with temperature rising. In this paper, authors aimed to predict soil respiration by means of proxies, mainly those defined by reflectance index. The paper is interesting and data of a high interest. However, although reflectance indexes could, in fact, indicate the degree of vegetation activity, how this fact could infuence soil respiration is not intuitive. Such indexes are only a proxy of tree canopy activity and soil respiration could be mostly affected by the metabolismo f many other biological activity without infuencing PRI (related to PSII status) or NDVI (related to chlorophyll amount…). So, authors should better explain why this proxies could be useful in the study of Rs. The finding that Rs and temperature are closely linked is interesting, but not very surprising. Can the authors highlight in a better way the real significance of their results? I miss this fact throughout the paper. The overall peresntation of the paper is of the highest quality, with no flaws in term of references and so on. My opinión is that the results are interesting, of interest for a global interpretation of the terrestrial ecosystems metabolism and I would like t osee the paper published. However, I also consider that a certain lack of novelty can be atributable. So, I encourage the authors to reconsider the paper in order to transmit the originality of their results in a more evidente way.
Author Response
Response to Reviewer 1
No specific edits were noted by reviewer one. They do, however, point out a significant flaw in the paper. They indicate that we do not emphasize the novelty of the research and over emphasize the relationship of temperature and respiration. We agree with this comment. The novel portions are 1) to determine if the relationship with temperature and moisture differs at a fine scale (vegetation types) and 2) does soil respiration have any significant relationship between remotely sensed vegetation indices for the on-ground vegetation types. To address this, we made many changes to the objectives, discussion and the conclusion section.
Reviewer 2 Report
See attached document
Comments for author File: 
Comments.docx
Author Response
Response to Reviewer 2
We agree that separating heterotrophic and autotrophic Rs would be an excellent study. We in fact allude to this in our discussion (345 -348) and conclusion section (lines 401-402).
“In the future, we should focus on developing models that try to isolate vegetation effects and partition the Rs into its autotrophic and heterotrophic components in order to get a better picture of species influence on Rs. “
“Future studies may want to gather more data on litter differences, partition the Rs into its
autotrophic and heterotrophic components, and take the LAI under each vegetation type. “
However, this was not the intent of this study which in itself was a large undertaking. Now that we have established a small but significant effect of changes in vegetation and at a relatively small scale, the next step would in fact establish a study to look at soil/plant (biotic) factors in more detailed.
Latin names were changed to italics
L.232 was reworded. Different transformations were used for temperature and moisture because we picked the transformation that best fixed the statistical issue (e.g. non-constant variance).
Reviewer 3 Report
Overall, the text is very informative and important.
There are some minor comments
l. 120: a comma is missing
l 124 and elsewhere : the authors chose the temperature unit to be 'Celsius deg' instead of 'deg Celsius'. I am not sure why this would help.
l. 138 and elsewhere: maybe 200m2 is easier understood than 1/50 of a hectare.
l. 158 'soil push method' : I am not sure what it is and wonder whether it is important to convey the information. 0 to 10 cm would do the job.
Table 1: the accuracy of numbers is too high. e.g. Temp 12.2 +/- 0.3 would suffice.
Columns should be aligned to +/-
Figure 1: is there a reason why the y-axis is not drawn?
Fig 3: the size of symbols is large and may over-print many other symbols
Chapt 3.3.1: it may be better to avoid abbreviations in subchapter titles.
The Discussion section is a bit colloquial. I suggest to follow a (more boring) scheme of
- we interpret xy as <your discussion>
- this deviates from REFx because <your opinion> and agrees with REFy.
Overall, the limitations of remote sensing data could be stronger elaborated, in case the authors agree on that. It is appealing to use readily available proxies for target variables by means of remote sensing. But the limitations need to be explicetly stated.
Author Response
Response to Reviewer 3
Several minor edits were indicated and these have all been corrected.
Symbols on figures have been resized and we agree they look much clearer.
Y-axis has been added to figure 1
Number of significant digits has been fixed in Table 1
Thank you for the suggestion regarding the writing style of the discussion. However, we did not rewrite the style of the discussion. We did however emphasize the limitation of the remotely sensed data both in the discussion and conclusion.
Round 2
Reviewer 2 Report
Accept in present form
