Fire and vegetation dynamics in northwest Siberia during the last 60 years based on high-resolution remote sensing

Sizov, Oleg; Ezhova, Ekaterina; Tsymbarovich, Petr; Soromotin, Andrey; Prihod'ko, Nikolay; Petäjä, Tuukka; Zilitinkevich, Sergej; Kulmala, Markku; Bäck, Jaana; Köster, Kajar

doi:https://doi.org/10.5194/bg-18-207-2021

Articles | Volume 18, issue 1

https://doi.org/10.5194/bg-18-207-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-18-207-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 18, issue 1

Research article

| Highlight paper

|

14 Jan 2021

Research article | Highlight paper |

| 14 Jan 2021

Fire and vegetation dynamics in northwest Siberia during the last 60 years based on high-resolution remote sensing

Oleg Sizov, Ekaterina Ezhova, Petr Tsymbarovich, Andrey Soromotin, Nikolay Prihod'ko, Tuukka Petäjä, Sergej Zilitinkevich, Markku Kulmala, Jaana Bäck, and Kajar Köster

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Final revised paper (published on 14 Jan 2021)
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Preprint (discussion started on 12 Jun 2020)
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Interactive discussion

Status: closed

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

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RC1: 'topic of high relevance, but major shortcomings in methods and overall presentation', Anonymous Referee #1, 22 Jul 2020
- AC1: 'Replies to the comments of referee 1', Ekaterina Ezhova, 13 Aug 2020
- AC3: 'Corrected version: Replies to the comments of referee 1 - updated, final version', Ekaterina Ezhova, 14 Aug 2020
  - AC4: 'Correction to last part of p.4 (Specific comments)', Ekaterina Ezhova, 06 Sep 2020
RC2: 'Highly relevant topic but major scientific and methodological flaws', Anonymous Referee #2, 24 Jul 2020
- AC2: 'Replies to the comments of referee 2', Ekaterina Ezhova, 14 Aug 2020

Peer-review completion

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

ED: Reconsider after major revisions (26 Aug 2020) by Kirsten Thonicke

AR by Ekaterina Ezhova on behalf of the Authors (06 Sep 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (28 Sep 2020) by Kirsten Thonicke

RR by Anonymous Referee #1 (05 Nov 2020)

Suggestions for revision or reasons for rejection

The authors have done a good job in addressing many of the previously raised concerns and the paper is much more easily accessible now. However, there are still a few remaining issues on the content, and many details to address. Also a thorough language check is needed.

Major points
- research question 1 and 3 are based on different vegetation definitions (section 1 on definitions as shown in table 5, section 3 uses the terms tundra, woodlands, and forests, without defining them further. Are these the same categories? For the consistency of the narrative of the paper, it is important that categories and definitions are precise and consistent across all sections. If the definitions in the 2 sections are not the same, then it is questionable how these two sections are related and part of the same paper.

Minor issues
--
- sort all sections logically, e.g. consistently from north to south when describing vegetation and climatic stations, and early to later dates (e.g. first Corona image description, then Landsat)
- for all satellite data: state source/reference of data (where downloaded), product level (DN, calibrated radiance, surface reflectance product). Also, you need to justify if no atmospheric correction was performed.

l2: replace plant species by vegetation types
L2: what kind of models are meant here? specify
L13: remove 'data set from'
L14: remove 'in the Arctic as a whole' - duplication
L22: Shrubification and afforestation in the boreal zone is not expected to provide a means for climate mitigation as the positive feedback to warming through albedo decrease is higher than the relatively low additional carbon sequestration and storage by trees. Revise.
L34: rephrase to 'that biotic factors interact with abiotic climatic factors...'
L35: what is meant by 'major species'? dominant species?
L 38: remove 'really'
L67: rephrase to 'the sites are covered by historical high-resolution satellite imagery (Corona archive)'
L68: what is meant by 'projective'? remove this term here
L79: 'in flat and hilly terrain' where is which vegetation type dominant? rephrase
L91 - entire section 2.1.2 move to vegetation dynamics - this section here is not well placed and interrupts the flow in the methods. These measurements are only used in the discussion, and sampling is very low (i.e. only 3 data points for e.g. ALT measurements in one place is really not enough to cover the spatial heterogeneity!), so maybe could be shifted to appendix.
L 93 - term 'background area' - either define when first used (area that was never burned?) or use 'control area' throughout the manuscript
L123: Introduce Corona imagery with a short description and reference.
L128: replace 'before' with 'at the start of' and remove 'started' at end of sentence
L129: indicate data portal used for Landsat data, reference, and what product was downloaded (surface reflectance? if DN, was data calibrated?)
L141: 'when necessary' - what was criteria here?
L151: time steps between fire and imagery differ a lot through time! what are the consequences on the vegetation succession?
L154: Section on vegetation dynamics: introduce change classes (original status -> status after transition, e.g. tundra -> woodlands). This will also help to improve understanding of related results figure!
L157: rephrase 'maps to satellite data of high spatial resolution'
Lines 155-179: This entire section is very confusion as it does not follow a clear logic - reorder by variable and describe data set, processing, and resulting variable one after the other (now all is repeated and mixed up in these 3 sections).
L181: NDVI represents vegetation 'greeness', not greening (greening only if positive trend of NDVI over time
L190: replace 'flight' by 'overpass' - but this sentence needs rephrasing in general
L204: burned tundra?
L209-211: introducing this section with temperature descriptions >0° is not useful. I advise to start with the general annual mean and monthly trends and then only refer to >5°C as this is what is addressed in this article (i.e. growth-related information).
L213: what is meant by '...' for temperature indications?
L217: add 'temperature of the growing season'
L235: what is meant by 'modelled'? expected based on table 5 classification? Projected by xxx?
L235-241: results are more accessible if in tabular format, i.e. where is vegetation expected to change based on table 5 and retrieved climate indices.
L248: 30% - how does this number relate to Fig 7b results?
L249: remove 'Table 5'
L274-L276: these 2 sentences are more appropriate for the discussion section as they are an interpretation of results.
L295: unclear what is meant here: largest part of burned tundra was in taiga zone?
L370-378: move this section to the discussion parts on fire.
L380: this is not a good fit to start the conclusions - this has not been discussed before and is not referenced here.
Fig 7b - change axis labelling
Fig 8b: convert y-axis and values to area (instead of pixels)
Fig 11: what are the change classes here in this figure? introduce definitions of vegetation stages and transitions in methods and also clarify in this figure.
Table1: sort vegetation distribution cell contents along N-S vegetation types or percentages
Table 2: move this table to appendix, as data are only used in discussion. Also, number of ALT measurements is too low to be representative (e.g. n=3 and n=5); this does not seem to be a full species list, but only dominant species? Also, if species level determination is not available, use sp (e.g. Ledum sp., Polytrichum sp.)
Table 4: reference for USGS is a sentinel website?
Table 7: move to appendix

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ED: Publish subject to minor revisions (review by editor) (09 Nov 2020) by Kirsten Thonicke

AR by Ekaterina Ezhova on behalf of the Authors (21 Nov 2020) Author's response Manuscript

ED: Publish subject to technical corrections (24 Nov 2020) by Kirsten Thonicke

AR by Ekaterina Ezhova on behalf of the Authors (27 Nov 2020) Author's response Manuscript

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Short summary

In changing climate, tundra is expected to turn into shrubs and trees, diminishing reindeer pasture and increasing risks of tick-borne diseases. However, this transition may require a disturbance. Fires in Siberia are increasingly widespread. We studied wildfire dynamics and tundra–forest transition over 60 years in northwest Siberia near the Arctic Circle. Based on satellite data analysis, we found that transition occurs in 40 %–85 % of burned tundra compared to 5 %–15 % in non-disturbed areas.