Forest Gap Size Alters the Functional Diversity of Soil Nematode Communities in Alpine Forest Ecosystems

Round 1

Reviewer 1 Report

The paper “Forest Gap Size Alters the Functional Diversity of Soil Nematode Community in Alpine Forest Ecosystems” analyzed the effect of gap size on composition and structure of soil nematodes. The subject of this paper seems to be interesting to the readers of Forests. However, the results of the study are somewhat limited and the description of the methods should be improved. Overall, I think this is a decent paper with some potential to gain interest from nematode researchers as well as from other researchers working on canopy gaps.

In the introduction, the authors focused on describing how soil temperature and moisture can affect nematode community. However, in your MS you didn’t provide any information for a reader about temperature and moisture of soil samples you took to analyze nematode community structure. Please give some additional information or rewrite your introduction focusing on relating gap size to changes in soil nematode communities.

Methods,

Please specify how a gap center was estimated. Expanded gaps tend to have an irregular shape and this factor could affect your results. Was gap center always situated in canopy gap or in the case of small gaps also under tree crowns? This could vary even between gaps of the same category (i.e. small, medium, large). Moreover, did you check the gap age? The same goes for an expanded gap:canopy gap ratio which can be indirectly translated to the ratio of canopy closure. All of these limitations should be acknowledged somewhere in the discussion.

Was the aspect same for all plots?

Please provide a name and explain in details in methods or some additional materials about every indices you used in your paper, like J’, H’, SR, SI, EI, CI etc. In present version it is not understandable for researchers outside of your field.

L34 You described forest gaps as a natural disturbance type so please delete thinning cutting as this is a part of forest management.

L68 typo after year

L69 Picea is not a pine!

L146 Did you mean the differences between closed canopy and all gap sizes? Please be more specific.

L185 & 189 Please improve the grammar.

L261 What do you mean by degree of disturbance?

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

This is a very interesting manuscript, as the results appear to contradict a large body of literature in nematode ecology.  It clearly needs further analysis and interpretation to explain these results. 

The manuscript has numerous errors in word choice, grammar and sentence structure.  For example, in the Abstract, please consider the following changes:

line 16 and 17.  Insert "the" in front of "soil".

Line 17.  Insert "community" after "nematode".

Lines 18, 80, and throughout.  I recommend replacing the words "middle gap" with "medium gap" or "medium-sized gap", as these would infer the size relationship, rather than just position.. 

Line 21.  Replace "abundance" with "abundant".

Line 28, Change "nematode" to the plural "nematodes".  Also, replace "varying" with "changes".

Similar changes, too numerous to list here, are needed throughout the manuscript.

Line 68.  A number of references indicate the species name has been reclassified as Abies fargesii, var. faxoniana.  Please verify the correct taxonomic name for these trees.

Line 69.  Replace "pine" with "spruce".  Picea asperata is referred to (in English) by the common name "Dragon spruce".

Lines 76-81.  More information on gap formation is needed.  How old were the gaps?  Were they formed in the current season, or were they several years old?  Did the plant composition differ among different sizes of gaps.  From the viewpoint of the nematode, it is not clear that a closed canopy dominated by mature trees is significantly different from a closed canopy of shrubs or herbs (as suggested in lines 210-213).  If gap ages differed among plots, please discuss whether there is a correlation between time since disturbance and community structure.

Line 86-87.  Please provide more detail on how soil samples were collected.  For example, a high proportion of nematodes may occur in the surface litter layer, so samples that collect mineral soil only would miss this fraction of the community.  Did samples consist of a single core, or were multiple subsamples composited?  Did samples include rocks and coarse debris, or were large fragments screened out?  Were sedentary plant parasitic nematodes in roots observed?

Line 89.  Please indicate the duration and temperature at which soil samples were stored.  The term "freezer" implies the soil samples were frozen, which would almost certainly significantly impact nematode extraction.  Is that correct?  If so, the results may be very problematic.  Or did you mean "refrigerator"?

Line 153.  The meaning of the "spatial" composition is unclear.  Line 86-87 indicate that all soil samples for nematode extraction were collected from the center of gaps, so it is difficult to see what "spatial" composition could be determined. 

Lines 167-168.  This sentence is unclear.  Do you mean that fungivores were the "most "numerous" trophic group in the closed canopy..."

Lines 254-257.  If MI values increase along the gradient from closed canopy to large gaps, and the PPI does not (Table 2), then the PPI/MI ratio declines solely due to the increase in MI ratios.  Is there evidence that these statistics actually tell us something different.  The information appears to be redundant.  At a minimum, please explain why you think the change in the PPI/MI ratio reflects anything other than the increase in MI.

Lines 260-263.  The observation that the Maturity Index was lower and the Structure index was higher in the closed canopy than in gaps appears to contradict fundamental theory regarding these indices.  The gaps appear to represent a significant disturbance, yet had higher Maturity Indices.  This contradiction needs more discussion, and should be compared to other studies in the Literature.  Is there evidence that, for example, the assigned c-p values at the Family or Genus level are inappropriate for the nematode species at these sites? 

Author Response

Please see the attachment.

Author Response File: Author Response.docx