Partitioning of canopy and soil CO<sub>2</sub> fluxes in a pine forest at the dry timberline across a 13-year observation period

Qubaja, Rafat; Tatarinov, Fyodor; Rotenberg, Eyal; Yakir, Dan

doi:https://doi.org/10.5194/bg-17-699-2020

Articles | Volume 17, issue 3

https://doi.org/10.5194/bg-17-699-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-17-699-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 17, issue 3

Research article

|

11 Feb 2020

Research article |

| 11 Feb 2020

Partitioning of canopy and soil CO₂ fluxes in a pine forest at the dry timberline across a 13-year observation period

Rafat Qubaja, Fyodor Tatarinov, Eyal Rotenberg, and Dan Yakir

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Final revised paper (published on 11 Feb 2020)
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Preprint (discussion started on 31 Jul 2019)
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Status: closed

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

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RC1: 'Partitioning of canopy and soil CO2 fluxes in a pine forests at the dry timberline', Anonymous Referee #1, 26 Aug 2019
- AC1: 'Response to two Reviwers comments', Dan Yakir, 30 Sep 2019
RC2: 'Partitioning of canopy and soil CO2 fluxes in a pine forests at the dry timberline', Anonymous Referee #2, 27 Aug 2019
- AC1: 'Response to two Reviwers comments', Dan Yakir, 30 Sep 2019

Peer-review completion

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

ED: Reconsider after major revisions (30 Sep 2019) by Frank Hagedorn

AR by Rafat Qubaja on behalf of the Authors (12 Nov 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (15 Nov 2019) by Frank Hagedorn

RR by Anonymous Referee #2 (29 Nov 2019)

Suggestions for revision or reasons for rejection

The quality of manuscript is significantly improved by authors, and is now close to the publication in the journal. Before the accept, I feel there is a little bit more of needs of revision and/or re-consideration for some specific points in the manuscript. Some of them are very confusing for readers to understand the manuscript easily.
Those specific points are as follow:
L13: “measured” should be “were”
L121: “An instrumented eddy covariance tower” should be “An instrumented eddy covariance (EC) tower”
L224: In order to secure reliability of the Keeling plot approach in the present study site, add a sentence, which is similar to the sentence in L166-L167 of Author’s response (i.e. “We must conclude of course that....”), after the sentence ended with “....to avoid this caveat”.
L256: “The analytical precision was 0.1%” should be “The analytical precision was 0.1‰”?
L269: “The precision was 0.1%” should be “The precision was 0.1‰”?
L271-L286: Because “Rl” in Eq.12 is very confusing with “Rl” in Table 3 (Rl means foliage respiration here), “Rl” in Eq.12 should be “ALP” or something else which makes it to be easier to imagine the aboveground litter production.
L305: “r = 0.62“ should be “r = -0.62”.
L306: “r = 0.45” should be “r = -0.45”.
L337: The sentence “daily Rs values could reach 6.1 μmol m-2 s-1” is true? There is no Rs data over the value of 5 μmol m-2 s-1 in Figure S1-6 nor Figure 2.
L340: Delete “(Fig. S1-6)”.
L349: Add “(no data in any of figures nor tables)” after “(r = 0.2 and 348 0.1, respectively; p < 0.01)”.
L351: Add “(no data in any of figures nor tables)” after “(CV~40%)”.
L359: “Refluxes” should be “Re fluxes”.
L373: “being highest” should be “being the highest”.
L377: “Repartitioning” should be “Re partitioning”.
L382: Add “(Fig. 2)” after “limited water loss”.
L409: What does “Despite relatively high rates of respiration fluxes” mean? According to Table 3, the magnitude of Re is only 75% of GPP. Add clear description for “relatively high rates of respiration fluxes”.
L417-L418: “presented n Table 3” should be “presented in Table 3”.
L418-L419: “the belowground allocation” should be “the TBCA”.
L419-L423: This sentence is very confusing. Does this sentence mean that “While there is little change in the ratio of the respiration components to Re or to GPP, the shift from the autotrophic components (i.e. Rsa, Rl, and Rw) to the heterotrophic component (i.e. Rh) has occurred as indicated by increasing ratio of Rh to Rsa + Rl + Rw from 0.27 in 2003 to 0.37 in 2015.” ?
L467: “the remarkable increase” may be prefer than “the marked increase”.
L468-L472: This sentence would be better to be changed as “Here, because comparing the non-continuous data from the present (2016) and earlier (2001–2006) studies is sensitive to the large interannual variations in the ecosystem activities and fluxes (Qubaja et al., in press), we focused on the more robust changes in the ratio of the respiration components to the overall fluxes (Re) (Table 3)”.
Figure 3: Caption should be “a) The seasonal variations in the relative contribution of soil autotrophic (Rsa), heterotrophic (Rh), and abiotic (Ri) components to Rs, and b) seasonal variations in the relative contribution of soil autotrophic (Rsa), heterotrophic (Rh), abiotic (Ri), and foliage and stem respiration (Rf is obtained from the Re-Rs) components to ecosystem respiration (Re) during eight campaigns (Jan–Sep) in 2016. The contributions were determined with linear mixing models using isotope signature analysis (δ13C and Δ14C) of soil CO2 profile from 0 to 120 cm soil depth. These results confirmed earlier estimates of Grünzweig et al. (2009) and Maseyk et al. (2008a)”.
Figures 2, 3, SI-6: Please consider to add vertical lines representing the periods of spring, summer, autumn, and winters. In the manuscript, seasonal characteristic of fluxes is one of the mainly focused topics; however, it is difficult to identify those from figures without the visually representing period of individual season.

Finally, please run careful refining of every sentences in the manuscript again, in order to avoid unnecessary confusion.

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ED: Reconsider after major revisions (03 Dec 2019) by Frank Hagedorn

AR by Rafat Qubaja on behalf of the Authors (12 Dec 2019) Author's response Manuscript

ED: Publish as is (06 Jan 2020) by Frank Hagedorn

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Short summary

This paper presents a study of the CO₂ fluxes in a pine forest plantation at the dry timberline in the Negev, combining the present time with the long-term perspective. Two key issues that limit our understanding are the need to know the sources of CO₂ fluxes and the need for long-term perspectives. We provide evidence that helps explain the forest plantation productivity under stressful conditions, which can assist in predicting the response of forest to future drying climate.

Partitioning of canopy and soil CO2 fluxes in a pine forest at the dry timberline across a 13-year observation period

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Peer-review completion

Partitioning of canopy and soil CO₂ fluxes in a pine forest at the dry timberline across a 13-year observation period