Why Do We Need to Document and Conserve Foundation Species in Freshwater Wetlands?

Round 1

Reviewer 1 Report

General comments to the authors:

I am in agreement with the authors that foundation species (simply by their definition) are critical to many aspects of wetland ecology.  I am a little surprised that the authors note that foundation species have been studied well in many marine and freshwater systems, but not for freshwater wetlands. Is this disparity strong enough to justify this extensive review of freshwater wetlands or is there another stronger justification for the focus on this one wetland system?  I also venture that systems such as coral reefs, salt marshes and mangrove swamps (to name a few) are experiencing similar anthropomorphic stress. So why is it so important to isolate and focus on freshwater wetlands per se?  I am not sure the authors have provided a strong enough case for their focus on freshwater wetlands. The results section is laborious to read because it strings together different systems and different life forms within each system. Figures 1, and 4 are not necessary and the insert photos for figure 2 and 3 are not needed at all.  In general this review lacks a clear synthesis and little is added to current theory about wetland ecology.

Specific comments to the authors:

Line 14 – 16. The word focus is used twice in this sentence leading to redundancy.  I recommend choosing a different word for one of them.

Paragraph 1.1, I think there must be stronger justification for the focus on freshwater wetlands other than because foundation species have been studied less in freshwater wetlands than other wetland types or that freshwater wetland are experiencing anthropomorphic stress ( so are all the other wetland systems and some much more so).

Line 54-56. I note that fires and droughts are included as both long-term and short-term effects.  You need to clarify the two references to fire and drought to separate their short-term and long-term effects.

Line 98 – 107.  I am a little concerned about the overemphasis on the term “foundation” species.  I think the authors are really considering the importance of the most dominant species in the ecosystem.  I think the authors need to clarify the difference between the term “Foundation species” and “Dominant species”.  If they are interchangeable in this review then I am not sure what this review is all about except to review wetlands ecosystem function.

Lines 140-`148.  There is an inappropriate font change here.  Perhaps the new font came from cutting and pasting.  It needs correction.

Figure 2, 3, 5 and 6. I presume, because there is no data on these slides, that the authors have simply drawn a line that represents the trend of the relationship.  If so then the legend should be modified to indicate that these are trend lines not lines developed by a statistical model of specific data or the output of a model.  Please be explicit about what these lines represent.

line 165.  “ from desiccation) from drought” seems inappropriate and redundant.  Please change to eliminate redundancy.

Line 172 – 173. Some thing is missing here because the sentence makes no sense.

Line 182.  Define TP.  Always define abbreviations when first used.

Line 190 – 192. This is a weak sentence, particularly the end where “functions” is added. Please strengthen this sentence. Also, I do not think the previous material provides a clear case.  I might suggest removing this sentence.

Line 197 – 198.  “also” is used twice in this sentence.  Please change the sentence it is weak and confusing.

Line 202. “The future of coastal wetlands” , what does that mean?  Do you mean the existence of the coastal wetlands as we now know them will likely decline to a new wetland system in the future?  Please rephrase this sentence because the term “future” is undefined.

Line 217 – 219.  Here is another case of font changes in mid sentence.  This makes me think that there has been cutting and pasting to produce this review article.  I hope that cutting is not from some other published article.  Reviewers always consider plagiarism when they see font changes in a document.  Be careful of font changes they are disturbing to reviewers.

Lines 262 – 281. This coverage of bald cypress stress tolerance is helter-skelter.  Please rearrange in an organized way.  Consider flooding tolerance separately from drought tolerance in the paragraph.

Lines 297 – 299.  This is very redundant to the previous paragraphs.  Perhaps this is another case of cutting and pasting from a couple of sources.  Remove this sentence on bald cypress because it is totally unnecessary.

Lines 310-312.  This is a very weakly constructed sentence.  Reword it to make it easier to read and less cumbersome.  Do not start the sentence with “Based on our literature review”.  It is obvious anything in this article is based on your literature review.

General about this “results section”. I find this results section very laborious to read.  The long and helter-skelter paragraphs on literature of one system and plant life form after the other makes it a grind to read.  I am sure there is another way to prepare this review, but I am not sure what it is.  Perhaps focusing on the functions of the fundamental species instead of the string of systems and life forms would work.

General about the figures.  Figures 1 and 4 are not necessary for a review article.  The insert photos in figure 2 and 3 are of little use.  Also, figures 2,3,5 and 6 are simply drawings of the response pattern for the various functional types.  This is appropriate for a talk, but they don’t provide much for a review article.  I was not really impressed by the types of literature analyses presented in the results section of this manuscript.

The first paragraph of the discussion is restating the results.  This is redundant and can be removed.  Focus the discussion of composing some novel theory from the results, not repeating the results.

Line 475 – 476.  This sentence is awkward.  I suggest rewriting it.

Most of section 3.1 is stating the obvious and has little value for the review.

The conservation section (3.2) is also relatively weak.  I do not see much synthesis coming from the review of literature and there is a too heavy emphasis on the sawgrass – cattail conservation system.  Surely there is some sort of conservation synthesis you can come up with that includes wetlands in general.

Lines 515 – 517.  This is a major conclusion from this review and the sentence is awkward and really difficult to understand.  What do you mean by giving “time” to foundation species? Do you mean that conservationist and managers should wait a long time as the foundation species adapts (by evolutionary processes?) or migrates to another location?

Lines 552 – 530.  The recommended new works are laudable; However, I am not sure that these new research plans came from this review of the literature.  In fact, I would say that the literature review had little to do with the research concepts.  Once again I am suggesting that the literature review in this manuscript was not designed to formulate new theory or come up with a new synthesis of ecological understanding about foundation species.

531-557. Yes I agree that there are many models that could be used to understand how climate change can influence wetland in the future.  However, I do not see how this particular review necessarily informed the need for modeling or the types of models that would be effective.  Again, I agree that modeling is important for prediction and conservation, but how did this review demonstrate that need?

Author Response

We would like to thank the reviewer for taking his/her time to swiftly provide comments and suggestions on our manuscript. Please find attached our detail response.

Author Response File: Author Response.pdf

Reviewer 2 Report

Thank you for the opportunity to review this paper. The manuscript for its major part is clearly written and easy to follow, and there is likely merit in the publishing of this piece of work and presenting its conclusions to the broad audience. I do feel, however, that some issues need to be addressed before its prospect publication. 

Authors claim to “provide justification for applying the foundation species concept more broadly to include invasive species”; however for the temperate/boreal wetlands they do not analyze vascular species that are going to replace native foundation species (excepting Molinia, which is not the best example of this process). For subtropical wetlands they show only Typha, or I miss something? In general, I have an impression that Authors have somewhat brushed boreal peatlands off and there has been an inequality between the presentation of Everglades and boreal/temperate oligotrophic wetlands. 

Figure 5.  I suggest to rebuild X-axis and put lower values close to the origin of the coordinate system, similar to the Fig. 2 or 3. 

Lines 349-350, please explain how diatoms could “create" a peat layer? 

2.2.2.2. Interactions with nutrients. Authors discuss a reaction of peatlands in the higher latitudes to high nitrogen deposition. What about increasing atmospheric deposition of P? Some researches suggest that atmospheric transport could bring about significant local redistribution of P among terrestrial ecosystems; total annual transfer of P to and from the atmosphere was estimated to 3.7 Tg (Tipping et al. 2014).  

Line 405  Should be Molinia instead of Molinea.

Lines 435-346 The claim that trees encroaching the oligotrophic peatlands (Pinus or Spruce) can produce a high-quality litter, which accelerates nutrient cycling is at the very least questionable. 

Discussion. I think the discussion needs some rearrangement. For the clarity of the text it should be better to evaluate potential stressors/ disturbances and their potential impact on foundation species and ecosystem services separately for various wetland ecosystems; otherwise, some sentences appear to be misleading or difficult to follow, e.g., about an increase of salinity in freshwater wetlands and its impact on tree species. 

The paper would benefit from a better graphical or tabular summary. Synthetic presentation of your key findings would assist readers a significant amount and would enable a simple comparison of your results with that obtained from other ecosystems. Provided figures, although informative are far too superficial. 

To sum up, I believe that the presented material needs some revision before publication.

Author Response

We would like to thank the reviewer for taking his/her time to swiftly provide comments and suggestions on our manuscript. Please find attached our detailed response.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The manuscript can be accepted in present form.  

Author Response

Thank you very much for your useful comments and for appreciating our work.

Best regards

Luca Marazzi