Reply on RC1

Reviewer 1 This is an interesting and useful combination of field work observation, sampling and lab experimentation to examine modern plant communities and charcoalized plant parts at different roasting temperatures for the purpose of improving the development and interpretation of palaeoenvironmental records of charcoal (a proxy for fire) in boreal forests. The results should be of interest to a wide variety of researchers in EGU fields and interested in biogeosciences related to fire at local to large spatial scales, palaeovegetation research, and archaeology.


SPECIFIC COMMENTS:
L36 -This might be semantic, or a question of (spatial and time) scale and thus the need for clarity. The word impact is a bit ambiguous without further clarity on the context and use of this term. What is meant here '[a] fire impacts boreal forest''. Over the long duree, is it the changing attributes of fires and the fire regime that impact the boreal forests? Does this mean one fire is impactful? Boreal forests have a lot of spatial heterogeneity in vegetation structure that is in part caused by fire and in part also influences fire itself. A changing fire regime has significant outcomes on the land cover. But if fire is a process in boreal forests itself, it seems more of a feature than of the biome rather than something that just impacts it. Throughout the paper the framing of the disturbance regimes needs to be balanced with how these disturbance regimes (mostly fire explored here) are a part of the system, and not something that just happens to the boreal forest and changes (impacts) it.
R: Thank you. I have rephrased this to acknowledge the role of disturbance by fire in the functioning of boreal forests, but also the concerns on the impact of changes in fire frequency or intensity. It reads: ''Disturbance by wildfires is among the most common disturbance types in boreal forests, triggering gap dynamics or stand-scale forest replacement depending on intensity and frequency (Goldammer, 2015). Ongoing and anticipating increase in the frequency and severity of wildfire in boreal forests is raising concerns on its impact on the composition of these forests as well as climate (Jones et al., 2020). R: Thank you for pointing this out. Indeed, a wildfire burns at much higher temperatures than 500 degrees, but with this sentence, I highlight the temperature range that leads to the charcoal formation. In the revised paper I introduce an additional sentence clarify the range of fire temperatures and those resulting in charcoal formation (Rein, 2014).

L40 -Fire intensities in
L49 -worth stating somewhere that the Courtney-Mustaphi and Pisaric, 2014 study discussed potential for not just focusing on known-fuel morphotypes for charcoal analysis but for categorising all morphologies found in a local-scale study to examine the variability; as this would be useful to explore relationships to not just the known-fuelsources of charcoal but taphonomic processes and possibly fire types (or another variable). R: Added: ''Courtney-Mustaphi and Pisaric (2014) also discussed the potential for categorising of charcoal morphologies to explore relationships to taphonomic processes and possibly fire types.
L60 -It would be useful to make distinctions between studies using ovens, flames, and other pyrolysis and combustion methods.
R: I am working to distinguish between results originating from studies that have used muffle over, open flame, or calorimetric methods.

L68 -spp? Or taxa? What was the minimal taxonomic resolution?
R: Genus is the minimum taxonomic resolution used here, however, most plants have been identified at the species level.
L69 -was there any testing in this study? It appears to be mostly a characterization study, which has merit. The purpose, objective, aims are not congruent with the content R: I have replaced the word test with evaluating. The three main objectives presented in the introduction are then detailed in the Results /Discussion. R: Rounder, intended as circular, as in 2-Dimensional scale. I have not quantified the degrees of angels. I am working to point out clearly the differences and the potential usefulness of additional measurements on roundedness.
L264 -Add a caveat about the need to do detailed comparative studies on graminoid versus conifer needle fuels and subsequent charcoal. And perhaps among Graminoid growth forms themselves: Poaceae subfamilies, Cyperaceae, and others. R: Added. Comparative studies on graminoid charcoal originating from Poaceae (grass) versus Cyperaceae (sedge) family will further improve the identification of fuel types given the ecological differences of the two groups i.e., Cyperaceae growing on wetlands, and Poaceae often on dry habitats. Misidentification of charcoal morphotypes from graminoid and conifer needle and subsequently of fuel types is another caveat that could be improved through detailed comparative studies of these fuel types. Levesque et al 1988. Lévesque, P. E. M., Dinel, H., Larouche, A. 1988

L315 -intensity, as in heat/energy given off by fire?
R: The sentence adjusted to denote intensity as high-energy release

General comments: Introduction in general:
I think there needs to be a distinction between flame combustion, roasting by hot air (ovens), pyrolysis. This needs to come out more obvious to the read beginning in the abstract, methods, and discussions. It needs to be stated that dry roasting in an oven is a proxy for one type of heating of vegetation in a natural fire, different to flame burning, etc. This is evident in the statement by the authors on L124 that 'All plant tissue was reduced to ash at 450 °C (Fig. S1).' In natural fires, flame and air temperatures do reach higher. I think the main items that need to be acknowledged is that the oven approximates some aspects of the heating conditions of natural fuels and that a crucial variable that is not explored is time at a (burning) temperature.With roasting in an oven the influence of flame dynamics and turbulent air flow is missing to the same degree as fires outdoors. This needs to be acknowledged as part of the experimental design and open the need for additional research.
R: Many thanks for pointing out the inconsistent use of burning types i.e, roasting by hot air (ovens), and pyrolysis, which is in the current form of the paper were sometimes used interchangeably. In the revised version I will make it clear that all combustions were in the oven thus roasting by hot air. I will additionally acknowledge the limitation of the experimental design to some aspects of the heating conditions of natural fuels, especially on the relation between time and the burning temperature.

It would be useful throughout and within this paper (if anything was combusted in a different method) to add the categorical naming of how the material was 'burned'. See
Table1 in the following publication: https://doi.org/10.1016/S0031-0182(00)00174-7 R: All plant material used for burning experiments was dried before and burning conditions (muffle oven, preheating) were the same for all measurements. The only difference is the use of different temperatures. This information was added in the caption of Table 1. List of plant materials burned. All plants are from Siberia, Russia, except Picea abies, originating from Taunus, Germany. All plant material was dried before the combustion in the muffle oven.
I have some broad suggestions on how certain details are communicated.-The plant anatomy of bryophytes is treated rather colloquially and requires refinement. -Are the species names known for the bryophytes? Many burn differently at low temperature because they hold water droplets differently, making some taxa more difficult to ignite even under the same fire weather conditions. R: I have used Sphagnum spp. (likely S. medium/S. divinum) and brown moss (Polytrichum commune). Their names are visible in all graphs and Table 1. I acknowledged that moss burned differently but have not discussed the reasons for this. I am working to find anatomical differences between them, however, the fact that different moss species hold water droplets differently, making some taxa more difficult to ignite under the same fire weather conditions, holds in nature but not in laboratory burning experiments, where all plants were dried prior combustion.
-The use of the word 'twig' needs some level of description here as twigs are different in deciduous, coniferous, herbaceous? and colloquial terms. Can this be more explicit throughout the paper as it may vary by plant types.