The effects of burning and grazing on soil carbon dynamics in managed Peruvian tropical montane grasslands

Oliver, Viktoria; Oliveras, Imma; Kala, Jose; Lever, Rebecca; Teh, Yit Arn

doi:https://doi.org/10.5194/bg-14-5633-2017

Articles | Volume 14, issue 24

https://doi.org/10.5194/bg-14-5633-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/bg-14-5633-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 14, issue 24

Research article

|

14 Dec 2017

Research article |

| 14 Dec 2017

The effects of burning and grazing on soil carbon dynamics in managed Peruvian tropical montane grasslands

Viktoria Oliver, Imma Oliveras, Jose Kala, Rebecca Lever, and Yit Arn Teh

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Final revised paper (published on 14 Dec 2017)
Preprint (discussion started on 06 Apr 2017)

Interactive discussion

Status: closed

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

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RC1: 'Discussion Paper', Anonymous Referee #1, 09 May 2017
RC2: 'comment on "No long-term effect of land-use activities on soil carbon dynamics in tropical montane grasslands"', Anonymous Referee #2, 16 May 2017
AC1: 'DETAILED RESPONSE TO REFEREES', Viktoria Oliver, 02 Jun 2017
AC2: 'Revised version of the original manuscript', Viktoria Oliver, 15 Jul 2017

Peer-review completion

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

ED: Reconsider after major revisions (07 Jun 2017) by Edzo Veldkamp

AR by Viktoria Oliver on behalf of the Authors (20 Jul 2017) Manuscript

ED: Referee Nomination & Report Request started (04 Aug 2017) by Edzo Veldkamp

RR by Anonymous Referee #2 (16 Aug 2017)

RR by Anonymous Referee #1 (05 Sep 2017)

Suggestions for revision or reasons for rejection

Revised revision of the original manuscript:
No long-term effect of land-use activities on soil carbon dynamics in tropical montane grasslands
Viktoria Oliver et al. Biogeosciences discussions : doi:10.5194/bg-2017-113

The Authors improved the manuscript considerably to an earlier version. However there are still some points, which were addressed in the first review, but not satisfactory implemented. There are some additional points which should be considered before publication.

Both referees suggest changing the manuscript title, which was not done.
The title is too unspecific concerning the land use activities. In addition in my view the study cannot evaluate the long-term effect of burning and grazing on soil dynamics. I agree with the authors stating that burning can have immediately effects on stable pools. However, that the stable pool is not immediately affected does not mean that there are no long-term effects: There were changes in the active and in the resistant pool (change in free LF and occluded LF). How these changes will affect the inert pool on long term is not clear. (In this meaning there were no short term effects on inert pool ……..). Please clarify the title. Please check also L446-448.

In addition, regarding the uppers 0-5 cm (Figure 5) there seem to be differences in the fraction of total soil C in the heavy fraction: The control site free LF as the most dominant soil C fraction, while in the grazed burnt plot most carbon is stored in the heavy fraction. The “inert” pool is altered. One explanation may be that the concept of stability of pools does not fit or that there are also effects of burning / grazing on the inert pool. However, differences in the soil C fraction in the first 5cm are not discussed at all. Although it could be assumed the changes due to land use are most pronounced in the upper part of the soil (highest temperature while burning, highest input of SOM). The same trend, less pronounced could be observed in 5-10 cm. Please make a concise interpretation of all the data included in the manuscript.

The authors provided more information about pool concept of different stability in soils. However, the wording is a bit confusing. The three different pools are introduced as active, recalcitrant, inert (L102). The recalcitrant pool is than named resistant pool (L109) or as “slow recalcitrant”. Please use stringent definitions.

I do not like the judgemental wording of negative or positive effects / finding throughout the manuscript, e.g. L 46 “ the free light fraction was negatively affected” . “the free light fraction was reduced” is much more specific without any subjective judgement. E.g. L 47-49; L347, L428. In addition the occluded LF increased, but it is stated that this fraction was not negatively impacted. According to the concept that would meant that the fraction of soil C in a resistant pool increased and thus in the authors sense would be positively affected.

L123-124. This sentence is not nicely embedded into paragraph.

L293: In the results section the unit of soil respiration is adapted to the measuring frame (express per seconds), while during discussion section the unit is still per year( L357) suggesting an annual database ( or even a yearly emission). I would prefer to use the measuring frame of seconds throughout the manuscript.

L 434: In the discussion of proportion of LF to total soil C, only one reference is given. For a comparison of the dataset, this is insufficient – especially there are reviews available (like Gregorich, E.G., Beare, M.H., Mckim, U.F. & Skjemstad, J.O. 2006. Chemical and biological characteristics of physically uncomplexed organic matter. Soil Science Society of America Journal, 70, 975–985) and more recent original papers. Please expand literature review.

Table 4 and Figure 5: It would be nice to have the same order if fraction of C and Mass recovery

Table 3 is missing

Figure 3: heading is missing. It would be nice to add the names of the sites to 2003 and 2005.

L656: The reference is not complete.

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ED: Publish subject to minor revisions (Editor review) (11 Sep 2017) by Edzo Veldkamp

AR by Viktoria Oliver on behalf of the Authors (25 Sep 2017) Author's response Manuscript

ED: Publish as is (28 Sep 2017) by Edzo Veldkamp

AR by Viktoria Oliver on behalf of the Authors (08 Oct 2017)

Short summary

Fire occurrence in the Peruvian montane grasslands has increased due to climate change and agricultural expansion. This study aimed to investigate how anthropogenic activities affect soil carbon stocks in this ecosystem. Burn history (burnt 10 years ago) and grazing appeared to cause no significant change in total soil carbon, but there were significant losses to the labile carbon, suggesting a change in the soil carbon dynamics – findings that are relevant for future environmental policymakers.