Economic strategies of plant absorptive roots vary with root diameter

Kong, D. L.; Wang, J. J.; Kardol, P.; Wu, H. F.; Zeng, H.; Deng, X. B.; Deng, Y.

doi:https://doi.org/10.5194/bg-13-415-2016

Articles | Volume 13, issue 2

https://doi.org/10.5194/bg-13-415-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/bg-13-415-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 13, issue 2

Research article

|

21 Jan 2016

Research article |

| 21 Jan 2016

Economic strategies of plant absorptive roots vary with root diameter

D. L. Kong, J. J. Wang, P. Kardol, H. F. Wu, H. Zeng, X. B. Deng, and Y. Deng

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Final revised paper (published on 21 Jan 2016)
Supplement to the final revised paper
Preprint (discussion started on 13 Aug 2015)
Supplement to the preprint

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC C5782: 'Review', Anonymous Referee #1, 25 Sep 2015
- AC C6371: 'Responses to reviewer 1', deliang kong, 09 Oct 2015
RC C6896: 'Interactive comments on "The root economic spectrum: divergence of absorptive root strategies with root diameter", by Kong et al.', Anonymous Referee #2, 22 Oct 2015
- AC C7012: 'Response to reviewer 2', deliang kong, 25 Oct 2015

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (06 Nov 2015) by Michael Bahn

AR by deliang kong on behalf of the Authors (29 Nov 2015) Author's response Manuscript

ED: Referee Nomination & Report Request started (30 Nov 2015) by Michael Bahn

RR by Alexandra Weigelt (21 Dec 2015)

Suggestions for revision or reasons for rejection

In the revised version of their manuscript the authors present trait data on absorptive roots from seven mostly woody dicots to show that fine and thick absorptive roots differ in their root economic strategies. For five root orders of each species a limited amount of morphological traits was assessed together with total C and N content as well as their labile and recalcitrant fractions. One important morphological trait was root cortex diameter (EC). The data supports the conclusion that thin and thick absorptive roots differ in content of almost all C and N fractions and thus might also be differentiated along the acquisition-conservation trait-off from the root economics spectrum.
The paper presents valuable data on an important topic in trait ecology. Root traits and their differentiation and importance are currently very much debated and there is a strong need for data as presented in the current manuscript. Even though seven species is on the low side and the selection of species is from my point of view rather non-ideal (for such a low number I would have voted for either a more general spread e.g. including more conifers and other mycorrhiza types or for more specific thus excluding the fern and the one conifer). However, the morphological results are backed up by a much larger data base, which is convincing. The manuscript is well written and argues soundly. I think the concerns of previous reviewers (of which I am not one) are well met. I have only minor remarks on the manuscript which are listed below.

Minor remarks:
Check throughout for double and missing spaces e.g. L72 or L59 before as.
L31: ‘fractions ‘ At first I was not sure what to expect from this without reading the rest of the text. I would expect e.g. different C fractions such as sugar, other carbohydrates etc. from this description. This obviously is the case as these differentiations are the central point of the paper. I would make sure this is understood right away and denote the measured fractions in brackets already in the abstract.
L34: ‘more’ species. I would state 94 species here.
L42: ‘represents’ should be ‘represent’ as it relates to plant traits which is more than one either
L76: effects of
L79: in relation to
L 86ff: you say roots with less labile C and more labile N indicate acquisitive strategy and (89) roots with less labile C and N are conservative. Is this true like this, than only the CN ratio would be important or only N as C obviously would than not be decisive for a change in root mode.
L112: Is there any other justification as to why you chose exactly these species? They are a subset of the 96 you published on earlier, I presume, but to me it is a rather strange sub-selection with one fern and one conifer. I would recommend another sentence to justify this.
L122: ‘are mycorrhizas’ is not correct grammar. Either refer to are colonized with mycorrhiza or are mycorrhized.
L204: Why would you use thickness of 247 µm as a cut of? Just because it is the mean and thus you would split the data set in half? I have my problems with this rather arbitrary split as there is not clear ecological or physiological reasoning behind this size. I think this separation earns some justification as well.
L286-294: There should be no need to justify your study in the discussion. Shorten this part to one intro sentence without refs. Those have all been cited in the intro.
L 296: relatively
L352 strategy
L361 Notably
L391: including

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ED: Publish subject to minor revisions (Editor review) (21 Dec 2015) by Michael Bahn

AR by deliang kong on behalf of the Authors (27 Dec 2015) Author's response Manuscript

ED: Publish as is (08 Jan 2016) by Michael Bahn

AR by deliang kong on behalf of the Authors (09 Jan 2016)

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Short summary

Our study showed significant relationships among root traits indicating an acquisition-conservation tradeoff for thin absorptive roots while no such trait relationships were found for thick absorptive roots. The findings support our hypothesis that root economic strategies differ with increasing root diameter. The contrasting economic strategies between thin and thick absorptive roots, as revealed here, may provide a new perspective on our understanding of the root economics spectrum.