The Potential of Artificial Snags to Promote Endangered Saproxylic Beetle Species in Bavarian Forests

Round 1

Reviewer 1 Report

The paper is an interesting contribution of potential interest for conservationists and forest management. Rearing a rather large number of samples was certainly a very time consuming approach, on the other hand it made possible collecting exclusively insects emerging from the wood, and not attracted by snags, so the study design seems to be optimal. My only concern is whether 3 months of rearing is enough to obtain most of the species developing in the wood collected. Please be more precise when using terms referring to forest ecology, like "young forest", "highly preserved forest". Maybe explaining the meaning of these terms will be a good idea. In table 3 species are divided into ecological groups. I think that the term saproxylic has much broader meaning that remaining ones. Can't be a saproxylic species predaceous of fungivorous? This division should be critically re-analysed in my opinion. 

Comments for author File: Comments.pdf

Unclear English terms (e.g. "young forest", "highly preserved forest") were marked with yellow in the pdf file. 

Author Response

Reviewer 1:

The paper is an interesting contribution of potential interest for conservationists and forest management. Rearing a rather large number of samples was certainly a very time-consuming approach, on the other hand it made possible collecting exclusively insects emerging from the wood, and not attracted by snags, so the study design seems to be optimal.

– Thank you for the positive feedback on the study design.

My only concern is whether 3 months of rearing is enough to obtain most of the species developing in the wood collected.

– We agree that a longer rearing period would possibly have led to a higher number of hatched individuals and species. However, due to time and financial restrictions, it was not possible to wait longer. We added this point to the method section (lines 145-146).

Please be more precise when using terms referring to forest ecology, like "young forest", "highly preserved forest". Maybe explaining the meaning of these terms will be a good idea.

– We removed the term “young forest” from the introduction and replaced the term “highly preserved forest” with “near-natural beech forest”, according to Lachat et al. (2012).

In table 3 species are divided into ecological groups. I think that the term saproxylic has much broader meaning that remaining ones. Can't be a saproxylic species predaceous of fungivorous? This division should be critically re-analysed in my opinion.

– We agree that the category saproxylic does only provide very general information. We therefore revised Table 3 and Figure 3, now focusing exclusively on trophic groups. 

Comments of reviewer 1 within the diversity-2913574-review.pdf:

• Line 40: most numerous = most species-rich or most abundant? please by more precise

According to the comment we replaced "most numerous" by "most species-rich" (line 39).

• Line 47: strong deadwood?

We deleted the entire sentence to avoid confusion.

• Line 52 f.: "forests are young" do you mean forests composed of young trees or forests that are young in terms of forest continuity? Please be more precise.

We deleted the term "young" in the introduction section.

• Line 147: "liquid"

According to the comment we deleted the term "liquid".

• Line 200 ff.: This division is very superficial; if saproxylic means "dependent on dead wood at any stage of their development" it can be at the same time fungivorous, predaceous or saprophagous; saproxylophagous is a more precise term.

We agree that the category saproxylic does only provide very general information. We therefore revised Table 3 and Figure 3, now focusing exclusively on trophic groups. 

• Table 3: why families are ordered this way? this is neither alphabetical nor systematic order; moreover, one subfamily is also listed here.

We have organised the families alphabetically according to the commentary and removed the subfamily.

• Table 3: Coccinellidae

We have corrected this.

• Table 3: Latridiidae

We have corrected this.

• Table 3: Lymexyliidae

We have corrected this to Lymexylidae.

• Line 231: "highly preserved forest" unclear

We replaced the term “highly preserved forest” with “near-natural beech forest” (line 227) according to Lachat et al. (2012).

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper “The potential of artificial snags to promote endangered saproxylic beetle species in Bavarian forests” presents an interesting data on the role of dead wood in the form of human-made snags on saproxylic enotmofauna species compostion. The relations between biometric (height, diameter) and physiological (decay stage) characteristics of snags, the species, and the amount of dead wood in the vicinity, and the Coleoptera species diversity were analyzed. Due to the urgent need to protect biodiversity in European forests, emphasized by the European Union laws, the research undertaken on the benefits for commercial forests resulting from the artificial adaptation of snags, which has not been analyzed so far in southern Bavaria region, should be considered as absolutely valid.

Overall, the manuscript is interesting, well conducted and written in correct language, with single stylistic errors. In the introduction section, based on rich theoretical framework and literature review, authors explain the reasons for the research undertaken. Apart from the research goals specified in the paper, there are no hypotheses that the authors undertook to verify. In my opinion, they should be formulated in the introduction.

The methodology has been aptly chosen for the research objectives, although it requires in some areas of detail.  

It is not clear whether the authors identified the species of the collected material based only on the adult forms, or also on larvae stage. Moreover, as can be concluded from the description in the text, not all collected insects could be identified to the species level, therefore, it would be necessary to specify how many (% of the collected insects specimens) was identified to the species. It also seems appropriate to present the ecological characteristics of saproxylic beetles using indicators other than those used in the study (e.g. frequency, individual dominance of the species, Shannon Weaver's species diversity index, etc.). The authors can, of course, treat this as a suggestion and consider it in the future when publishing the results. However, in my opinion, the abundance of a given species may be important information indicating its preferences for the material and should be included in the results. The species richness index, in addition to the applicable Ivlev’s electivety index, should be explained in the methodology section of the manuscript.

The presentation of results (figures 6, 7) needs improvement by add important information about statistics. The captions of the figures lack an explanation of what the bars on the graph mean (standard deviation, standard error?). The results of the statistical analyzes described by the authors in the methodology are not provided anywhere. The results should be presented on a graph or in a separate table. Due to the multi-threaded aspect of the research and the collected data, I suggest also supplementing the presentation of results with multidimensional analyses, e.g. NMDS, PCA).

I have aslo some doubt aboyt terminology used by authors: line 47: „strong dead wood”. What did the authors mean when they used such a term? Not clear; line 351: instead of "man-made" I propose to use the term „human’made”.

Summarizing, due to high scientific value of the paper I suggest The Editor to minor revision of the manuscript after making appropriate corrections.

Author Response

Reviewer 2:

The paper “The potential of artificial snags to promote endangered saproxylic beetle species in Bavarian forests” presents an interesting data on the role of dead wood in the form of human-made snags on saproxylic entomofauna species composition. The relations between biometric (height, diameter) and physiological (decay stage) characteristics of snags, the species, and the amount of dead wood in the vicinity, and the Coleoptera species diversity were analysed. Due to the urgent need to protect biodiversity in European forests, emphasized by the European Union laws, the research undertaken on the benefits for commercial forests resulting from the artificial adaptation of snags, which has not been analysed so far in southern Bavaria region, should be considered as absolutely valid.

Overall, the manuscript is interesting, well conducted and written in correct language, with single stylistic errors. In the introduction section, based on rich theoretical framework and literature review, authors explain the reasons for the research undertaken.

– Thank you for the positive remarks on our manuscript.

Apart from the research goals specified in the paper, there are no hypotheses that the authors undertook to verify. In my opinion, they should be formulated in the introduction. 

– Thank you for this comment. Due to the explorative character of our study, we decided for open research questions instead of specific hypotheses.

The methodology has been aptly chosen for the research objectives, although it requires in some areas of detail.  It is not clear whether the authors identified the species of the collected material based only on the adult forms, or also on larvae stage.

– We considered adult forms only and added this information in line 149-150; since for larvae we would have to split the snags with axes and this would kill the forms that we awaited to emerge. Next, there were financial and time constraints for not doing this.

Moreover, as can be concluded from the description in the text, not all collected insects could be identified to the species level, therefore, it would be necessary to specify how many (% of the collected insects’ specimens) was identified to the species.

– Only ten species (16 specimens) were not identified to species level, which is a proportion of 14% of the collected specimens. We added this information in line 186.

It also seems appropriate to present the ecological characteristics of saproxylic beetles using indicators other than those used in the study (e.g. frequency, individual dominance of the species, Shannon Weaver's species diversity index, etc.). The authors can, of course, treat this as a suggestion and consider it in the future when publishing the results. However, in my opinion, the abundance of a given species may be important information indicating its preferences for the material and should be included in the results. The species richness index, in addition to the applicable Ivlev’s electivity index, should be explained in the methodology section of the manuscript.

– We agree that including abundance or abundance-based diversity measures would have provided additional insights on the ecological preferences of the observed species. However, beetle abundances in our dataset strongly depend on the species’ biology, in the sense that different species produce different amounts of eggs, which influences the number of hatched individuals. Therefore, we decided to focus our analyses on species richness, as abundances would not have been comparable across taxa. Furthermore, we added a sentence on how we calculated species richness in the method section (lines 148-150).

The presentation of results (figures 6, 7) needs improvement by adding important information about statistics. The captions of the figures lack an explanation of what the bars on the graph mean (standard deviation, standard error?). The results of the statistical analyses described by the authors in the methodology are not provided anywhere. The results should be presented on a graph or in a separate table. Due to the multi-threaded aspect of the research and the collected data, I suggest also supplementing the presentation of results with multidimensional analyses, e.g. NMDS, PCA).

– Thank you for your comment. We revised figures 6 and 7, including letters to all boxplots indicating significance values, and adding explanations to the figure captions. We agree that multidimensional analyses would have added interesting insights on the composition of beetle communities and its potential drivers. However, as this exceeds the scope of our paper, we intend to address this aspect in a follow-up manuscript.

I have also some doubt about terminology used by authors: line 47: „strong dead wood”. What did the authors mean when they used such a term? Not clear.

– We removed this sentence, as it had no context to the rest of the paragraph.

line 351: instead of "man-made" I propose to use the term „human’made”.

– We replaced the term accordingly (line 334).

Summarizing, due to high scientific value of the paper I suggest The Editor to minor revision of the manuscript after making appropriate corrections.

Reviewer 3 Report

Increasing saproxylic beetle communities can be achieved through various management practices aimed at promoting deadwood availability and habitat diversity. The authors of this paper

 have investigated the role of high stumps in enhancing the presence of species of ecological interest, such as endangered saproxylic species, within forest ecosystems. The emerged data of their study showed that integrating proactive high stump management during harvesting operations could significantly contribute to deadwood management and the protection of biodiversity in forest ecosystems. The results of this investigation are encouraging. Leaving standing dead trees (snags) and fallen logs in forests provides essential habitat for saproxylic beetles at different stages of decomposition. However, actively creating deadwood structures such as high stumps, log piles, and woody remains can supplement natural deadwood and enhance habitat availability for saproxylic beetles, playing a key role in their conservation.

The presentation of the paper is very good, and the analyses carried out are appropriate. The results are well presented and very clear. The nomenclature of the listed species is correct.

Few suggestions are here listed:

Table 4. Please add the authority and year for each listed species

Figs 3 and 4.  If possible, please change the colors of graphs because the categories are difficult to distinguish.

Line 324: please add the relevant reference: Mazzei A. , Bonacci T. , Contarini E. , Zetto T. , Brandmayr P. 2010. Rediscovering the “umbrella species” candidate Cucujus cinnaberinus (Scopoli, 1763) in southern Italy (Coleoptera Cucujidae), and notes on bionomy. Italian Journal of Zoology, 2011; 78(2): 264-270. DOI: 10.1080/11250003.2010.485210. ISSN: 1125-0003.

Author Response

Reviewer 3:

Increasing saproxylic beetle communities can be achieved through various management practices aimed at promoting deadwood availability and habitat diversity. The authors of this paper investigated the role of high stumps in enhancing the presence of species of ecological interest, such as endangered saproxylic species, within forest ecosystems. The emerged data of their study showed that integrating proactive high stump management during harvesting operations could significantly contribute to deadwood management and the protection of biodiversity in forest ecosystems. The results of this investigation are encouraging. Leaving standing dead trees (snags) and fallen logs in forests provides essential habitat for saproxylic beetles at different stages of decomposition. However, actively creating deadwood structures such as high stumps, log piles, and woody remains can supplement natural deadwood and enhance habitat availability for saproxylic beetles, playing a key role in their conservation.

The presentation of the paper is very good, and the analyses carried out are appropriate. The results are well presented and very clear. The nomenclature of the listed species is correct.

Few suggestions are here listed:

Table 4. Please add the authority and year for each listed species.

– We added the authority and year as suggested.

Figs 3 and 4.  If possible, please change the colours of graphs because the categories are difficult to distinguish.

– We changed the colours of the two graphs (Fig. 3 and 4) to improve readability.

Line 324: please add the relevant reference: Mazzei A., Bonacci T., Contarini E., Zetto T., Brandmayr P. 2010. Rediscovering the “umbrella species” candidate Cucujus cinnaberinus (Scopoli, 1763) in southern Italy (Coleoptera Cucujidae), and notes on bionomy. Italian Journal of Zoology, 2011; 78(2): 264-270. DOI: 10.1080/11250003.2010.485210. ISSN: 1125-0003.

– We added the relevant reference in our paper (line 310).

Author Response File: Author Response.pdf