PONE-D-21-20614

Impacts of pre-fire conifer density and wildfire severity on ecosystem structure and function at the forest-tundra ecotone

PLOS ONE

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This project was supported by funding awarded to MCM, JFJ and EAGS from the NASA Arctic Boreal and Vulnerability Experiment (ABoVE) Legacy Carbon grant NNX15AT71A and the Bonanza Creek Long-Term Ecological Research Program, which is funded by National Science Foundation grant # DEB1636476 and the USDA Forest Service Pacific Northwest Research Station. 

  

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Additional Editor Comments:

I now have one report from an expert reviewer who is general positive on the manuscript, but also raised some technique concerns that need to be addressed.

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Reviewers' comments:

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Comments to the Author

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Reviewer #1: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

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Reviewer #1: Yes

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Reviewer #1: Yes

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5. Review Comments to the Author

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Reviewer #1: This study examined the potential impacts of wildfire severity on understory vegetation composition, conifer recruitment and ALT across tundra-boreal forest ecotone based on field observations and experiments. The manuscript is well written and professionally presented. The sampling strategies and statistical analyses are carefully designed and sound. I recommend the publication of this manuscript with minor modifications and clarification. Yet both the page and row numbers are missing in the submitted manuscript, which makes the review process a bit inconvenient. So here I provide my comments based on page numbers of the PDF file generated by the journal system.

1) Page 10 of the generated pdf file: “Treeless tundra ecosystems are generally wetter with thicker SOL layers than forested ecosystems.” Not necessarily thicker SOL in tundra. Measurements from several previous studies reported thicker SOL in boreal forests than in tundra (a few examples below). Please justify and provide references for your statement.

Baughman, C.A., Mann, D.H., Verbyla, D.L., Kunz, M.L., 2015. Soil surface organic layers in Arctic Alaska: Spatial distribution, rates of formation, and microclimatic effects. J. Geophys. Res. G Biogeosciences 120, 1150–1164.

Harris, S.A., 1987. Influence of organic (Of) layer thickness on active-layer thickness at two sites in the western Canadian Arctic and Subarctic. Erdkunde 41, 275–285.

Jiang, Y., Rocha, A. V, O’Donnell, J. a, Drysdale, J. a, Rastetter, E.B., Shaver, G.R., Zhuang, Q., 2015. Contrasting soil thermal responses to fire in Alaska tundra and boreal forest. J. Geophys. Res. Earth Surf. 1–16.

Kasischke, E.S., Johnstone, J.F., 2005. Variation in postfire organic layer thickness in a black spruce forest complex in interior Alaska and its effects on soil temperature and moisture. Can. J. For. Res. 35, 2164–2177.

Lafleur, B., Cazal, A., Leduc, A., Bergeron, Y., 2015. Soil organic layer thickness influences the establishment and growth of trembling aspen (Populus tremuloides) in boreal forests. For. Ecol. Manage. 347, 209–216.

2) First paragraph on page 13 of the pdf file: The format of the references should be consistent throughout the manuscript. Here “(Roland et al., 2013)” should be changed to [41]. Some other references in this manuscript need to be modified as well, such as “(Roland et al., 2014)”.

3) Second paragraph on page 13: Though the text mentioned that the control plots were randomly selected, they do not seem to be randomly distributed in space according to Figure 1. How do you weight the cover types by their distribution?

4) Third paragraph on page 13: How do you determine the moisture categories for the plots? Here the text mentioned that there are four categories, while Figure 2 only shows three. Also, the two subplots were not properly labeled as a) or b) in Figure 2.

5) “Burn depth, carbon combustion, and active layer thickness” in “Data Analysis” (page 18) and “Discussion” (page 25) sections:

The authors modeled combusted soil C using LMMs to predict combusted C and calculate total belowground C for all sites. The manuscript only provides the coefficients and p-values for independent variables for the LMMs, while the overall performances of the model are missing. Can the LMMs predict the combusted soil C well? Since the belowground C contributes to the total C much more the aboveground C in these sites, the total C is largely affected by whether the LMMs can predict the combusted soil C accurately. And the findings regarding pre-fire conifer density impacts on total C will be questionable.

6) Data availability on page 8: The github link seems not working. Please double check.

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Reviewer #1: No

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Impacts of pre-fire conifer density and wildfire severity on ecosystem structure and function at the forest-tundra ecotone

PONE-D-21-20614R1

Dear Dr. Walker,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Kind regards,

Dafeng Hui, Ph.D.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

The authors have adequately address the reviewer's concerns.

Reviewers' comments: