Peer review of: Soil fungal networks maintain local dominance of ectomycorrhizal trees (2020)



 
 
Reviewers' Comments: 
 
Reviewer #3: 
Remarks to the Author: 
4.5.20 Nature communications review 
 
This study is a massive effort to examine the effects of common mycorrhizal 
networks in promoting ectomycorrhizal tree monodominance in the tropics. This is a 
really interesting question, that I think has puzzled many mycologists over the 
decades, and this paper does a great job showing data that EMF support positive 
density dependent growth and monodominance whereas AMF support negative 
density dependent growth. The effort involved in this paper is behemoth – at risk of 
offending the editors…. I can’t see why it shouldn’t go in Nature rather than Nature 
Communications. Usually I’m a pretty harsh reviewer but honestly I really enjoyed 
reading this paper. 
Clearly I am not an original reviewer of the paper. However, reading through the 
responses to reviewer comments it appears that the authors took reviewer 
comments seriously and addressed all of them adequately. For the most part I 
agree with reviewer comments except for a few (Q5, Q7, Q30). For Q5 – I don’t see 
what is wrong with backward model selection and I took several multivariate 
statistics classes as a graduate student. I also disagree with Q7. ITS works 
adequately for mycorrhizal fungi and any AMF it finds you can certainly infer are 
there. I would have no issue with you using ITS data to infer AMF presence and 
indeed would like to see that data in a supplemental table or figure. ITS might not 
get as many lineages as AMF specific primers, but if you see Lekberg and Opik 
“More bang for the buck? Can arbuscular mycorrhizal fungal communities be 
characterized adequately alongside other fungi using general fungal primers?” New 
Phyt 2019 they clearly show that ITS primers can assess many AM fungi although 
not quite the diversity that AMF specific primers do. I also disagree with Q30 – 4 
weeks is ample time for many microbial communities to restore – certainly bacteria 
would recover in this time period. So I agree with reviewer response to this 
question. In general I liked this paper but just have a few minor comments below: 
 
My own line comments: 
Line 31: I believe the correct grammar here would be investigating mechanisms is 
critical 
 

Lines 46-48: agree, this is a very interesting question! 
 
Line 64-65: not that you need more citations, but a recent review paper Tedersoo 
et al Science 2020 “How mycorrhizal associations drive plant population and 
community biology” also talks about this very point at length and suggests that 
positive density dependence enhances EMF monodominance whereas negative 
density dependence causes diversity in AMF forests 
 
Lies 68-69: I disagree with previous reviewer comments. I think common 
mycorrhizal networks is fine – just say CMNS proxied by access to root-associated 
fungal networks from different mesh sizes – because how else would you measure 
this?? 
 
Line 74: 1,200 1 m2 seedling quadrats! What an amazing effort! 
 
Line 77: >17k individuals!! That’s very impressive. You must have had a lot of 
technicians/undergrad labor for this – I hope you acknowledge them in the 
acknowledgements 
 
Lines 78-80: very interesting! 
 
Line 86: and the speculations in Tedersoo et al Science 2020 
 
Figure 2: legends are too small to read. I suggest you increase font size. 
 
Lines 102-105: also that in general EMF trees tend to be more dependent on EMF 
and obligate on the symbioses than AMF plants. 
 
Figure 3: font size should also be increased in legends/axes here. 
 
Line 139: moisture content 
 
Line 148: it would be interesting to at least include a supplementary table of the 
EMF and AMF species assessed here since I think ITS primers are valid and many 
readers would appreciate it as long as you have the data. Not everyone hates ITS 
primers like Reviewer 1 (clearly, seeing as ITS is the universal barcode of fungi – 
Schoch et al PNAS 2012) 
 
line 186-187: Yes, the idea that EMF mantle better protects plant roots against 
pathogens than AMF was posited in the Tedersoo et al Science 2020 paper – I am 
not an author on that paper but I just read it last week and it discussed CMNs 
extensively so it is quite relevant here. 

 
Line 195: also Gao et al Molecular Ecology 2013 
 
Lines 372-374: this isn’t really acceptable to me. I need to see accession numbers 
here. You can always set them to release upon publication but without an accession 
number it’s not believable that you will do the work of uploading the data 
otherwise. 
 
 
 
Reviewer #4: 
Remarks to the Author: 
This is a resubmission and I believe that Liang et al. satisfactorily addressed the 
reviewer’s comments. While this is an observational study and doesn’t provide 
direct causation, it does provide very compelling evidence that mycorrhizal 
networks are likely a possible mechanism in explaining forest species diversity. This 
is by no means the last study of this emerging paradigm and I hope this study will 
spur the scientific community to help advance this hypothesis into a possible 
theory. 
 
Overall, this was a well-polished article and easily understandable. All my 
comments are minor, but I believe they will improve the readability. 
 
Throughout the manuscript it is stated that high biodiversity is expected with AM-
associated tree species due to a negative PSF (e.g. ln 44 & 203). While references 
are provided, the mechanism is never really explained. Why would a high pathogen 
load can cause high diversity – what’s the paradigm? You state “…which maintain 
high diversity by reducing the survivorship of conspecific seedlings in high density 
patches...” Based on this explanation, it still doesn’t exclude the possibility of 
monodominance or a few genera taking over. It is just not obvious in the 
manuscript and I think 1-2 sentences can provide a fully-formed explanation. 
 
Figures 2,3,4 & Sup 1: Please change the bar graphs into box plots to provide data 
transparency and it is more informative. Overall, bar graphs basically hide most of 
the results by just showing average and SE, at least with a box plot the reader can 
get a sense of how the data was distributed within the treatment.