Forest Tent Caterpillar Outbreaks Drive Change in Ant Communities in Boreal Forests

Round 1

Reviewer 1 Report

This paper explores the impact of short-term canopy openings resulting from outbreaks of the forest tent caterpillar on ant communities in a temperate and a boreal forest. The Introduction is comprehensive and provides adequate depth of all the areas of science that bear on the paper’s clearly defined hypotheses. The study is well-designed but somewhat limited by the small number of focal trees at each site, the proportion of traps without ants, and the incidence of defoliation in the control sites in the temperate forest. Nevertheless, the paper reports significant findings on changes in ant communities and a connection between ants and predators in the boreal forest sites. That the authors were unable to establish a link between disturbance and ant diversity was probably due to the limited duration of the study. The findings are of considerable interest to forest ecologists and entomologists. The authors chose to use the Sørensen dissimilarity index to compare species diversity between sites. Although many other community dissimilarity indices occur in the literature, including the Avalanche index of Hao et al. (2019), this was a suitable approach for the data sets that were to hand.

The paper is well-written and needs only minor edits (see below) before publication.

1.     Methods: the statement at Lines 137-139 does not completely agree with Lines 146 -148. Are both necessary? What about the situation for the sugar maple/beech forest?

2.     Did the control and defoliated stands have similar tree densities?

3.     A brief statement on tree canopy heights would be useful. Were there many saplings 1-3 m tall and few mature trees? It is hard for the reader to visualize the scenes of the study and why saplings were chosen for confirming folivore activity? Also, please state how canopy openness (Table 2) was assessed?

4.     English expression

Line 17 forests (in Québec, Canada)

Line 87 from to canopy

Line 115 on soils microorganisms

Line 178 list. since the

Spacing between numeral and unit is inconsistent, e.g. 0-5cm and two samples from 5-10 cm

Line 206 Collembolas were prepared from identification and identified

Line 437 Resource pulses

Figure 2 caption: the caption does not match the figure arrangement

Figure 3 caption: please add a noun after “in a) boreal and b) temperate”

the manuscript is very well written

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The paper "Forest tent caterpillar outbreaks drive change in ant community in boreal forests", in terms of the subject matter, set goals, conducted research and a very broad analysis of the obtained results, is very significant, since it is about economically very harmful species of defoliators and their very useful natural enemies - predatory species of ants. The work is properly scientifically conceived, all the rules of good practice have been followed, and the choice of statistical analysis is adequate.

In the text, it is necessary to observe some of the basic rules:

The international codes of botanical and zoological nomenclature oblige the authors of scientific works to include the name of the first author of the first publication and the first year of the first publication in addition to the Latin name.

Malacosoma disstria author, year (99)

Malacosoma. dystria (121)

Populus tremuloides Michx, year (142)

Acer saccharum Marsh, year (150)

Fagus grandifolia Ehrh, year (151)

Camponotus novaeboracensis author, year; Myrmica alaskensis author, year; Formica subanescens author, year; Aphaenogaster picea author, year; Lasius americanus author, year; Stenamma diecki author, year (263-266).

It is necessary to apply this in the work.

Also, in biological scientific papers, abbreviations for species names are not used, as was done in this paper. If you want to avoid unnecessary repetitions, then the Latin name is only given for the first time according to the binomial system. Further in the text, instead of the full name of the genus, its initial letter is given followed by a species. native names are given in full.

M. disstria (FTC) outbreak - first time in the text (138)

Author Response

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Reviewer 3 Report

Natural disturbances, including insect outbreaks, are critical external effectors that change the structures and functions of forest ecosystems. In this manuscript, the author examined the effects of forest tent caterpillar outbreaks on ant communities and other anthropoid groups between boreal and temperate forests in Canada. it is a fascinating subject.  The manuscript is clearly structured. However, some problems need to be answered.

 Q1: L13-15, there may be a bit of omittance since the aim is not only involved in the ant communities but contained the cascading effects of defoliator outbreaks, just like the description in the following lines.

 Q2: L45, what is the brown or underground food web? What is different between them? Please explain it.

 Q3:L76, which soil microarthropods are prey for ants? The author can give some examples, such as orders that belonged to the Arthropoda. 

 Q4: L88, forest management? What kind of management belongs to the low, moderate, or high? The explanations in this bracket are inconsistent with the above description (L86).

 Q5: L91 & L 96, shade-intolerant and less shade-tolerant ant species need to give a definite concept. The behavioral habits and characteristics of ants did non include the ecological roles in the above description (L64-65). It is a meaningful way to discuss it in the following sections.

 Q6 L 153: what is a mix of insect pests (defoliator, borer, or piercing-sucking insect)？ How to keep consistent with the previous sites? More importantly, which species were present in the trophic webs for these two sites before FTC outbreaks?

 Q7: L158, how to classify the outbreak and control sites? 

Q8: L 163, what kind of experiment devise? What role is in this experiment design?

 Q9: L171, Did you measure the canopy openness in 2017? Because of the FTC outbreak in 2016-2017, it is expected to renew the previous condition of the forest canopy next year. If it is true, what role is in this section? 

Q10: L182-183, what kind of ant species (functional groups) can be collected through pitfall traps? Predator, leaf-chewing herbivores, or all? Do you use other methods to catch ants? 

Q11: L211, how to define the predators? Some examples, such as wasps, are not considered as predators. 

Q12: L 247-249, Did you present the table of the key species in this manuscript? Or provide supplemental data listing all the ant species, sites, functional groups, etc., which is crucial to this manuscript. 

Q13: L287, L293, where is Figure 2a and 2b? 

Q14: L288-289, showing your data in this sentence. 

Q15: L324, Table 3 in the last line, 0.447 S? 

Q16: L331-333, the author needs to check the obtained data from the survey based on functional groups of ant or underground species since different feeding habitats can have other cascading effects on the FTC outbreaks. 

Q17: L353, how to define the intensity of disturbance? 

Q18: L364, how to classify the canopy openness? What value is high, moderate, and low?

Q 19: L376-424, it is essential to distinguish the functional groups and their habitat, including predator or herbivores, shade-tolerant or shade-intolerant, which is directly related to food, canopy openness, or others. These may be further analyzed and discussed here. 

Q20: L 449, the last section should focus on the main result in this manuscript but not include some discussion or unpublished data. This section needs to change. 

Author Response

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Author Response File: Author Response.docx

Reviewer 4 Report

The article is a detailed study of the Forest tent caterpillar outbreaks drive change in insects. The results could potentially have a practical significance, found that forest tent caterpillar outbreaks caused decreases in species richness and increases in the evenness of ant communities in defoliated sites. However, at this stage, there are some issues with this manuscript that would need to be addressed in a major revision. Some important details from the Material and Methods and Results sections of the MS are missing (see Major Remarks). I divide my comments into major and minor remarks below: 

Major remarks

1. The MS lacks data support related to the outbreak level of the forest tent caterpillar, we think that different outbreak levels may have different impacts on arthropod diversity. We suggest adding the data or other evidence that can prove the outbreak level. 

2. We suggest presenting the species and quantity of all captured insects in a Supp Table. Because the manuscript involves a lot of discussion about the frequency of insect occurrence. 

Minor issues.

Line 15 Delete “, we”

Line 24 “This pattern was driven by the presence of other predators.” Is there any corresponding data to support the conclusion？

Line 36 This sentence is difficult to understand, please revise.

Line 37 Defoliation?

Line 62: “northern forests” change to “forests”

We suggest combine the fifth and sixth paragraphs together. 

We suggest using Latin scientific names to replace FTC. 

We did not see Table 1 throughout the MS. 

Line 120 delete “at the ecosystem level”.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Ant communities have an indispensable role in ecologically complex ecosystems. The author examined forest defoliator outbreaks' direct and indirect effects on ant communities in Canada's temperate and boreal forests. The quality of receiving manuscript showed a critical improvement, and I suggest an acceptance in the present form. 

Reviewer 4 Report

I have carefully reviewed the revised paper entitled " Forest tent caterpillar outbreaks drive change in ant community in boreal forests" and their revision notes to the comments specified by the reviewers. 

The current work is is a detailed study of the Forest tent caterpillar outbreaks drive change in insects. The results could potentially have a practical significance, found that forest tent caterpillar outbreaks caused decreases in species richness and increases in the evenness of ant communities in defoliated sites.