Spruce bark beetles (<i>Ips typographus</i>) cause up to 700 times higher bark BVOC emission rates compared to healthy Norway spruce (<i>Picea abies</i>)

Jaakkola, Erica; Gärtner, Antje; Jönsson, Anna Maria; Ljung, Karl; Olsson, Per-Ola; Holst, Thomas

doi:https://doi.org/10.5194/bg-20-803-2023

Articles | Volume 20, issue 4

https://doi.org/10.5194/bg-20-803-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-20-803-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 20, issue 4

Research article

|

20 Feb 2023

Research article |

| 20 Feb 2023

Spruce bark beetles (Ips typographus) cause up to 700 times higher bark BVOC emission rates compared to healthy Norway spruce (Picea abies)

Erica Jaakkola, Antje Gärtner, Anna Maria Jönsson, Karl Ljung, Per-Ola Olsson, and Thomas Holst

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Final revised paper (published on 20 Feb 2023)
Supplement to the final revised paper
Preprint (discussion started on 07 Jun 2022)

Interactive discussion

Status: closed

RC1:
'Comment on bg-2022-125', Anonymous Referee #1, 20 Jun 2022

This study investigates the effect of bark beetle attack on Norway spruce biogenic volatie organic compounds. While I think it is a interesting study subject, I found the manuscript difficult to evaluate because I could follow the experimental design: what was the n for all the different treatments, plots, sites, ect.? when was sampling performed i.e dates and time? I think it would be very helpful to make an experimental design figure.

My other major comment is about the statistics. I saw that there was a statistics paragraph in the methods, but I would like to have more details about how the statistics were perform. Also, no statistic were included in the result or figures.

Finally, in the first sentence of the last paragraph of the introduction it is stated "The defense mechanism of Norway spruce is poorly understood." I don't think this is a fair assessment of the field. We know quite a bit about the induction of terpenes, phenolics, and traumatic resin ducts (e.g Krokene, 2015 Conifer Defense and Resistance to Bark Beetles in Bark Beetles: Biology and Ecology of Native and Invasive Species ; Celedon and Bohlmann, 2019 Oleoresin defenses in conifers: chemical diversity, terpene synthases and limitations of oleoresin defense under climate change, New Phytologist). Although, I agree that we still have a lot to learn.

Citation: https://doi.org/10.5194/bg-2022-125-RC1
- AC1: 'Reply on RC1', Erica Jaakkola, 10 Aug 2022
  
  We appreacate the remarks and comments by referee #1, and we have responded to each of these in the attached pdf.
  
  Citation: https://doi.org/10.5194/bg-2022-125-AC1
RC2:
'Comment on bg-2022-125', Anonymous Referee #2, 08 Jul 2022

This study is interesting and has its own important value to supplement what has been done previously and giving new information about bark beetle infestation effect to BVOC emission from Norway spruce bark. A lot of confusing information and weak Discussion is not helping to reveal this experiment value. Important part is also the new emerging volatiles, but these get so little attention or no attention in Discussion part. Discussion part is weak and needs more improving, more references and discussion that is connected with results and putting the results in bigger picture. I suggest leaving out the comparison with leaf emission; this does not give an extra value to the study. This has opposite effect: to diminish your efforts.

Citation: https://doi.org/10.5194/bg-2022-125-RC2
- AC2: 'Reply on RC2', Erica Jaakkola, 10 Aug 2022
  
  We appreciate the remarks and comments by referee #2, and we have responded to each of these in the attached pdf.
  
  Citation: https://doi.org/10.5194/bg-2022-125-AC2

Peer review completion

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

ED: Reconsider after major revisions (26 Aug 2022) by Nicolas Brüggemann

AR by Erica Jaakkola on behalf of the Authors (28 Sep 2022) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (12 Oct 2022) by Nicolas Brüggemann

RR by Anonymous Referee #1 (21 Oct 2022)

Suggestions for revision or reasons for rejection

The manuscript is improved, but still requires revision. The writing needs to be improved for grammar, word usage and flow. I still find it difficult to follow the methods and the reference list is not complete (e.g. Ortega & Helmig, 2008 is not included). I think the sub-study with two trees should be removed from the manuscript as it is not possible to statistically compare two individuals. See more specific comments below:
The use of the word “campaign” is not correct. This needs to be changes in all instances.
The paragraph beginning after line 55 needs more connection between the thoughts.
In the concluding paragraph of the introduction, I think it would be better to list all four aims in one sentence. It is confusing that aim (IV) is at the end of the paragraph.
“Four Norway spruce trees were selected at each plot in HTM, and three trees at each plot in NOR. A total of 18 trees were measured, whereof 12 were measured repeatedly during the growing season in HTM.» I can’t figure out how these statements fit with Tables 1 and 2. How many total trees were included in the experiment? From table 1 it seems that there were 31 infected trees, but table 2 indicates only 14. Were repeated measures performed only on some trees?
Why were measurements at NOR only performed once and included only infected trees? Are the tree genetics between these two sites the same? How could genetics effect the BVOC results?
Can you be sure that entry and exit holes were correctly designated without excavating the bark?
Were any post-hoc test performed after the Kruskall-Wallis test?
Figure 6 I think early and late BVOCs in infected trees should be compared to early and late BVOCs in healthy trees rather than the full season.

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ED: Reconsider after major revisions (06 Nov 2022) by Nicolas Brüggemann

AR by Erica Jaakkola on behalf of the Authors (10 Dec 2022) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (22 Dec 2022) by Nicolas Brüggemann

RR by Anonymous Referee #1 (12 Jan 2023)

ED: Publish subject to technical corrections (29 Jan 2023) by Nicolas Brüggemann

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Short summary

Increased spruce bark beetle outbreaks were recently seen in Sweden. When Norway spruce trees are attacked, they increase their production of VOCs, attempting to kill the beetles. We provide new insights into how the Norway spruce act when infested and found the emitted volatiles to increase up to 700 times and saw a change in compound blend. We estimate that the 2020 bark beetle outbreak in Sweden could have increased the total monoterpene emissions from the forest by more than 10 %.