Revealing the Impact of Understory Fires on Stem Survival in Palms (Arecaceae): An Experimental Approach Using Predictive Models

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Major comments:

 

This manuscript deals with a potentially interesting topic that could help managers knowing the post-fire responses of different palm species in Amazonian ecosystems. However, the work is missing important information and clarity. In my opinion the Methods section is not sufficiently clear and complete to allow understanding and replication. It also has some inconsistent/erroneous information. Additionally, the “individual mortality models” presented actually do not separate dead and alive individuals, as it would be expected; in fact, part of the individuals that survived were aggregated with the dead ones, while others were not. The “mortality” terminology is inconsistent and confusing throughout the manuscript. Moreover, the number of sampled individuals in several species is very small (between 9 and 14 individuals in three of the five studied species) to allow robust conclusions.

Below I include some other specific comments and suggestions that could be addressed by the authors in order to improve the manuscript.

 

 

Other comments:

 

Line 50: The meaning of “the first surface fire” is unclear and needs clarification.

 

L 55: Here the authors should say “fire severity” instead of “post-fire severity”.

 

L 68-70: This sentence is inaccurate and needs to be changed; the direct relation may exist in some cases but not in others, depending for example on plant species.

 

L 81-84; 93-94: Please explain why were these four species selected for this study. This is omitted.

 

L 85-88: The objectives 2 and 3 should be clarified; why the models would have these a priori selected variables? Why is plant size in a separate point?

 

L 88-92: More details are missing in these hypotheses; e.g. i) what type of relations (positive/negative)? iii) why larger stem reduces mortality?

 

L 97-100: Explain why was this area selected for the study.

L 112: Explain what is “terra firme”.

 

L 122-123: This reasoning is very strange; clarify.

 

L 130-140: More details are needed. Indicate how many trees from each species were sampled. Why the maximum height was 2.5m? How do you separate the juvenile stage of each species?

 

L 141-148; Table 1: Clarify if the measurements were effectively taken inside the buds; if so, explain how were the sensors introduced inside the buds without damaging the buds?

 

Table 1: Several variables need to be better explained to allow readers to clearly distinguish them. For example, what is exactly meant by burned leaves and what is the difference between PCF, FC and PQF. Moreover, the terminology seems inaccurate, as considering yellowish/brownish (dissected) leaves as “complete burned leaves” is incorrect (and they have not experienced the same level of heat/fire severity as black/carbonized leaves and associated stems/buds); and what about leaves with complete combustion?

“Mortality” is definitely not the same as “topkill” and this is very likely to induce readers in error (very often plants that are top-killed are alive and not dead). It is very important to use the correct terms (topkill or stem mortality). In the title the term “stem survival” is used, while “stip mortality” and “plant mortality” is also used in other places, making the text quite confusing.

 

Fig. 3 and Table 2: Inconsistent information about sensor location: “TK3 of the plant base: 10 cm above ground and 5 cm from the stipe surface” versus “10 cm above the ground and one centimeter from the surface of the plant stipe”.

 

Fig. 3: One square meter experimental fire seems too small to nearly replicate real wildfire conditions. The authors should justify their choice demonstrating that the conditions are similar.

 

L 208-213: The description of this Phase is very unclear, particularly in L 210-213.

 

L 229-242: According to the authors, the “individual mortality models” separate between “dead and regrowth individuals” (coded as 1) and “alive individuals” (coded as 1). The big problem here is that “regrowth individuals” are alive and not dead! The “mortality” terminology is confusing throughout the manuscript.

 

Table 4: The number of sampled individuals in several species is very small (between 9 and 14 individuals in three of the five species) to allow robust conclusions.

 

Fig. 4 and L199-200: Inconsistent information concerning the sampling months.

Comments on the Quality of English Language

A revision of the technical terms would improve the ms.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Review of the manuscript “Revealing the Impact of Understory Fires on Stem Survival in Five Palm Species (Arecaceae): An Experimental Approach Using Predictive Models”

It is a well-written article dealing with the impact of fire on five undercanopy palm species of an Amazonian forest. The experiment conducted to measure the impact of fire in terms of mortality is meticulously described. It sheds light on the role of stipe diameter in palm mortality- greater the diameter of stipe, lower the mortality due to fire. The study is about a system (Amazonian forests) for which fire studies are not many. Human ignited surface fires in these forests is different in severity and intensity.

The study is worth publishing in the journal with minor revisions as indicated below.

·         The paper needs to be tightened a bit, starting with title, which is long. At least the words ‘five’, ‘stem’ and ‘species’ are superfluous.

·         Please explain the extent to which palms are recognized at fire resistant. A reader would like to have some genus-specific information.

·         Line 80. “Based on these concepts”: which concepts?

·         Line 85. “Responses among each species”: the phrase needs to be replaced.

·         Lines 85-92. There is no reference to ‘stipe’ in the hypotheses.

·         Table 3. “Values” and “units” should be joined (use one column please).

·         Line 189. Vicinity of what?

·         Lines 266-267. Use of past tense would better.

·         Giving a picture of stipe and its description would be useful.

·         Lines 351-357. Please avoid repetitions.

·         Fig 8 (a). Is it individual post fire “probability” or “mortality” (on z scale)? If it is probability, then indicate probability of what?

·         Lines 572-577. The role of anatomical arrangements of palms in relation to fire needs to be discussed more. How the palms differ in anatomical features, and particular structure they have in place of bark? These points could be discussed with the support of relevant studies carried by others. In fact, it should be included in introduction too.

·         Lines 622-629. Regrowth of palm species is key to post-fire recovery, and a major adaptational feature. This calls for an elaborate analysis, based on existing literature. How palm species differ in regrowth needed to be considered adequately.

This is largely an applicational study, so one would like to have take home message in this regard.

To conclude, the study is very well conducted and presented. The points raised about may help improving the manuscript. The study is about a system about which not much is known, so the authors might need to think more about the justification of the research.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Interesting topic, excellent first sentence in Abstract.

Nice schematics of burning setup.

 Include common name of Euterpe precatoria (Acai) in Keywords because it is economically valuable species of broad interest.

Major comments.

Methods. Evidence is presented that the four resprouting palm species differ in mortality, so I do not understand why there was no attempt to account for species in the likelihood modeling. This could be done by estimating different parameters for each species, e.g., by estimating a different intercept for each species in the binary logistic mortality model. Then see if AIC improves.

Results section. The section titles are too much like conclusions. For example, instead of Temperatures measured at the apical bud vary, but does not explain mortality, it would be preferable to have a title like ‘Effect of apical bud temperatures on mortality’.

L266-274. Similarly, I don’t believe it is a good practice to state all your significant findings at the beginning of the Results section. It is more convincing to lead the reader through the results one by one.

There is a distracting variation in graph type. One kind of graph (3D wire mesh with datapoints) is used to show the AIC-best model for the 4 resprouting palms (Fig. 8a), and a different kind of graph (two panels, showing response to each predictor variable with confidence intervals) is used for the arboreal palm (Fig. 10). The same kind of graph should be used in both cases.

 There is redundancy in the graphs presented in the results section. Several graphs are just variations on preceding graphs, e.g., Fig. 9 shows the same model as Fig. 8a, and Fig. 11a seems to be a variation on Fig. 10. It is preferable to just show a graph once.

Several words are used incorrectly. First, stipe. The stipe is the part of the leaf blade that does not have leaf lamina attached. It seems that ‘stem’ is what is meant when ‘stipe’ is written. Second, canopy. The leafy part of a plant is its crown, not its canopy. A canopy is made up of multiple crowns.

L196. The sensitivity of the thermocouple is determined in part by thermocouple dimensions. Can you provide width of the thermocouple bead?

 

Editorial comments

L50-51. Unclear what ‘preserved temperature and moisture conditions’ means

L54. Energy release should be in kW m^-2. Not kW m^-1  - it’s an area-based measurement

L56. Insert ‘other’ before ‘understory’

L82. You state you are investigating four species, but provide five species names.

L101, 104. The circle indicating ‘degree’ is too low, it should be raised to superscript position.

L111. ‘More in species abundance than richness’ – what does it mean?

L114. Delete ‘and’, insert a comma

L117. Why should having many species and genera make this one of the ‘oldest plant  groups’?

L123. Explain what a ‘stiped palm’ is

L127. Why is ramet italicized?

Fig. 2. ‘Humidity’ would be a better word than ‘moisture’

L178-179. Part of the sentence is repeated

L179. Remove ‘s’ from ‘Temperatures’

L181-182. Insert a space between the number and the unit, e.g. ‘1 m’ not ‘1m’

L131, 141, 208. Delete the bullet symbol

L215 (Table 3). Use ‘Relative humidity’ instead of ‘Moisture’. Change commas to periods.

L227. There are a lot of variables here – was a linear regression done for every combination of variable?

Table 3, 4. Use a period instead of a comma to indicate a decimal point.

L266. Use past tense for Results because you are describing what happened. E.g., ‘Post-fire mortality varied among species’

L277. Do not use ALL CAPITAL LETTERS for family and subfamily, it is jarring.

Table 4. Units are incorrect, should be (cm) not (cm^-1).

L303. Instead of ‘TK3’, use ‘at 10 cm height 1 cm from palm stem’

L311-315. Why include these ALL-CAPS code names for variables if they are not used in Fig. 5?

L318-322. This explanatory/interpretive information should not be in results.

L324. ‘stipe flaring’ is unclear. Do you mean stem char?

Table 7. Why bother including ‘D.f.’ if it’s the same for every entry in the table? The 95% confidence interval. It is unclear what Exp(B) means. Why is there no entry for Intercept? The CI for DS does not encompass the DS estimate! It seems odd that the upper CI for CNSCAR is so high (6610). Are you sure this is correct?

L407. It should be ‘best model’ not ‘final model’

Figure 8a. The label for the Z axis should say ‘mortality’ somewhere.

Figure 8b. Is it possible to provide some further explanation of this figure, for those who do not understand ROC curves?

L426-441. All this is just a re-statement / re-interpretation of what has already been presented.

Comments on the Quality of English Language

The English is good although there are several words that seem to be misused (see comments)

Author Response

Please see the attachment.

Author Response File: Author Response.pdf