The Grassland Fragmentation Experiment in the Swiss Jura Mountains: A Synthesis
Round 1
Reviewer 1 Report
General comments
Long-term fragmentation studies are very rare in ecological research. In the present manuscript the authors summarized the findings of the 7-year grassland fragmentation experiment in the Swiss Jura Mountains. Altogether 15 publications were analysed for this synthesis. Overall, the manuscript provides an excellent overview of the main findings of the experiment and the implications for conservation. The results are well presented and the text is also superb. Even typos are completely missing.
Specific comments
Line 63. ‘Habitat type of the EU Habitats Directive’ instead of ‘FFH habitat’
Author Response
Long-term fragmentation studies are very rare in ecological research. In the present manuscript the authors summarized the findings of the 7-year grassland fragmentation experiment in the Swiss Jura Mountains. Altogether 15 publications were analysed for this synthesis. Overall, the manuscript provides an excellent overview of the main findings of the experiment and the implications for conservation. The results are well presented and the text is also superb. Even typos are completely missing.
Specific comments
Line 63. ‘Habitat type of the EU Habitats Directive’ instead of ‘FFH habitat’
A: Done
Reviewer 2 Report
This interesting paper brings together results from a seven-year experimental fragmentation experiment carried out across three calcareous grassland sites within the Jura mountains, Switzerland. The experiment consisted of 48 grassland fragments, ranging in size from 0.25–20.25 m2, isolated by mowing.
The experiment is impressively comprehensive in focus, including long-term monitoring across a wide range of different taxonomic groups, as well as work on species interactions and ecosystem functions. Key findings include clear impacts of isolation on the matrix, higher above ground and root biomass in fragments than controls, but variable impacts of fragmentation across different groups, with some groups showing higher biodiversity and abundance in fragments and others lower. Species interactions also changed with fragmentation - for example, there was a higher proportion of ant-attended aphid colonies in fragments than control plots, and the number of Bromus erectus infected by fungus was higher in smaller fragments. Pollination rates and foraging behaviour also varied with fragmentation, potentially explaining the lower genetic diversity observed in Stachys officinalis in fragments. Some differences in responses across taxa were related to species traits. For example, large invertebrate species were commonly found at higher densities in fragments, but small species at lower densities.
Overall this paper is well-written and the findings clearly-presented. This represents an impressive body of work and it is very useful to have this brought together into a single publication. However, I do have some suggested changes to the structure and approach, which will, I hope, make this more accessible. My overarching suggestion is that the paper mostly lays out the results from each study in turn, rather than synthesising findings to give consensus results. I would recommend going through the paper to try to do this a bit more, as I think it would aid interpretation and also reduce words.
I also found the order of the different findings sections a bit confusing in places. I think this should follow the likely impacts of fragmentation through the ecosystem – so whether the experiment affected the matrix, the impacts of fragmentation on colonisation and extinction, the impacts on abundance, richness and diversity, the impacts on species interactions and functions, the impacts on genetic diversity, and the confounding influence of species traits. I think this would also mean some explanatory sections could be reduced.
Across findings sections, I would also suggest amalgamating all methods into section 2.4 – I think this would be clearer and again reduce repetition. Similarly, I think it might be clearer to have the known impacts of fragmentation from the literature included in more detail in the main introduction, so that the individual findings sections don’t need to include these – I think this would save quite a lot of words and again improve clarity.
Finally and perhaps related to the overall order of the findings sections, there were several places where results appeared in sections that didn’t seem to be specifically related to the section heading - e.g. several sections included information on effects of fragmentation on abundance. I think it would be good to go through and check for this and move any sections like this.
I include more specific details below:
Abstract – this was very clearly written, but it would be good to include a few more specific details of findings in here, if possible within the word limit.
Introduction
41-44 – perhaps not impossible, but extremely difficult. I think it would also be worth flagging more clearly here that this point relates to comparative studies of existing fragments, rather than experiments.
Table 2 – It is very useful to have this overview, but I wonder whether structuring this by overall topics (e.g. abundance and diversity, behaviour, ecosystem functioning etc. or mirroring the sections identified in Section 3), rather than papers would make the scale of the experiment and focus clearer? I would suggest restructuring in this way.
Section 3.1 - 209-214 – I think it would be clearer to have the methods all together in section 2.4 to reduce repetition (as stated above)
Section 3.2 – This is partly about the effectiveness of the study in changing conditions in the matrix, so I would recommend moving this to above the current section 3.1. I suggest moving sections related to collection methods, e.g. 243-245, to section 2.4, as I think it would be clearer to have all this in one section (as above).
Figure 3 – “air temperature” next to the red and blue dots in the figure itself isn’t very clear – could these be relabelled as mean and minimum air temperature. I think it would also be useful to include maximum temperature in this plot for completeness.
Section 3.3 - I expected to see accumulation curves or non-parametric indices of total species number by fragment size in this section. I think this would help to clarify the overarching impacts of fragmentation on total species number.
Section 3.3.1 – It would be helpful to have a figure summarising these findings all together and I suggest adding this.
Section 3.4 – 366-367 – I am not sure what this means, as the previous section gave results from composition analyses? Please reword to clarify.
Table 4 – Please clarify the analytical approach used here – I think you used seven separate tests? It might therefore be prudent to control for the number of separate tests used with something like a Bonferroni correction, and interpret significance following this.
Section 3.6 – This section felt like it came too early, given that this is about changes in genetic diversity as a result of changes to pollination. I think it would make more sense to move this towards the end of the findings, after impacts on pollinators have been introduced. Also consider changing the title of this section, as the link with pollinator behaviour has not been formally assessed here.
Section 3.7 – 461-463 – This text is about comparing to the matrix, so suggest moving this to section 3.2.
Section 3.8 - 546-547 – This section is about impacts on population size, so suggest moving to section 3.7.
Section 3.9.1. 599-608 – this is about the consequences of changing pollination and would be clearer combined with section 3.6, with Figure 6 complementing Figure 4.
Figure 7 Legend “The stromata of E. bromicola prevent in an early stage the development of inflorescences” is not clear – please reword for clarity.
Section 5.3 – I am not sure what you mean by “success controls” please could you reword and clarify?
I hope that these comments help improve this valuable paper.
Ed Turner, Insect Ecology Group, University Museum of Zoology, Cambridge.
Author Response
Reviewer 2
Comments and Suggestions for Authors
This interesting paper brings together results from a seven-year experimental fragmentation experiment carried out across three calcareous grassland sites within the Jura mountains, Switzerland. The experiment consisted of 48 grassland fragments, ranging in size from 0.25–20.25 m2, isolated by mowing.
The experiment is impressively comprehensive in focus, including long-term monitoring across a wide range of different taxonomic groups, as well as work on species interactions and ecosystem functions. Key findings include clear impacts of isolation on the matrix, higher above ground and root biomass in fragments than controls, but variable impacts of fragmentation across different groups, with some groups showing higher biodiversity and abundance in fragments and others lower. Species interactions also changed with fragmentation - for example, there was a higher proportion of ant-attended aphid colonies in fragments than control plots, and the number of Bromus erectus infected by fungus was higher in smaller fragments. Pollination rates and foraging behaviour also varied with fragmentation, potentially explaining the lower genetic diversity observed in Stachys officinalis in fragments. Some differences in responses across taxa were related to species traits. For example, large invertebrate species were commonly found at higher densities in fragments, but small species at lower densities.
Overall this paper is well-written and the findings clearly-presented. This represents an impressive body of work and it is very useful to have this brought together into a single publication. However, I do have some suggested changes to the structure and approach, which will, I hope, make this more accessible. My overarching suggestion is that the paper mostly lays out the results from each study in turn, rather than synthesising findings to give consensus results. I would recommend going through the paper to try to do this a bit more, as I think it would aid interpretation and also reduce words.
Following the suggestion of the reviewer we made several changes in the structure of the text by moving sections or paragraphs to more appropriate places (for details see the separate replies below). Please note that due to the shifting of individual chapters or sub-chapters, the numbering of the chapters has changed.
I also found the order of the different findings sections a bit confusing in places. I think this should follow the likely impacts of fragmentation through the ecosystem – so whether the experiment affected the matrix, the impacts of fragmentation on colonisation and extinction, the impacts on abundance, richness and diversity, the impacts on species interactions and functions, the impacts on genetic diversity, and the confounding influence of species traits. I think this would also mean some explanatory sections could be reduced.
We changed the order of the findings sections as suggested by the reviewer. We also deleted some explanatory sentences to avoid redundancy.
Across findings sections, I would also suggest amalgamating all methods into section 2.4 – I think this would be clearer and again reduce repetition. Similarly, I think it might be clearer to have the known impacts of fragmentation from the literature included in more detail in the main introduction, so that the individual findings sections don’t need to include these – I think this would save quite a lot of words and again improve clarity.
Following the suggestion of the reviewer, we amalgated all main methods into section 2.4. In this way we improved the manuscript. However, we decided to present the most important theory and some key findings from the literature in the Introduction, and more specialised theory and findings from the literature to individual topics in the findings section for the following reason. Most readers will not read a 30-page review or synthesis from the first to the last page. They are rather interested in a specific topic, e.g. fragmentation effects on functional diversity or on the extinction rate. It is important for these readers that within their topic of interest the effects to be expected from the specific theory are presented shortly before our findings in the individual sections. We have tried to avoid possible redundancy. We are convinced that this approach will make our article attractive to a broad readership.
Finally and perhaps related to the overall order of the findings sections, there were several places where results appeared in sections that didn’t seem to be specifically related to the section heading - e.g. several sections included information on effects of fragmentation on abundance. I think it would be good to go through and check for this and move any sections like this.
Following this advice, we checked the findings section and move several parts to more appropriate places (details see below).
I include more specific details below:
Abstract – this was very clearly written, but it would be good to include a few more specific details of findings in here, if possible within the word limit.
We agree with the reviewer. However, the length of the Abstract is limited to 200 words. The extremely short Abstract does not allow any extension.
41-44 – perhaps not impossible, but extremely difficult. I think it would also be worth flagging more clearly here that this point relates to comparative studies of existing fragments, rather than experiments.
We improved this sentence following the advice of the reviewer.
Table 2 – It is very useful to have this overview, but I wonder whether structuring this by overall topics (e.g. abundance and diversity, behaviour, ecosystem functioning etc. or mirroring the sections identified in Section 3), rather than papers would make the scale of the experiment and focus clearer? I would suggest restructuring in this way.
We understand the argument of the reviewer. However, it is not as easy as the reviewer makes it out to be. Several articles deal with different topics, e.g. abundance and ecosystem functioning, or behaviour and genetic diversity. To which overall topic do these articles belong to? We would need to define at least 10 overall topics, and more important, some articles need to be listed under two or even more topics. That would create little clarity but more redundancy. We give these arguments a higher weight than the reviewer’s argument. Therefore, we did not change Table 2.
Section 3.1 - 209-214 – I think it would be clearer to have the methods all together in section 2.4 to reduce repetition (as stated above)
Following the suggestion of the reviewer, we amalgated all main methods into section 2.4.
Section 3.2 – This is partly about the effectiveness of the study in changing conditions in the matrix, so I would recommend moving this to above the current section 3.1. I suggest moving sections related to collection methods, e.g. 243-245, to section 2.4, as I think it would be clearer to have all this in one section (as above).
As suggested, we moved the descriptions of the collection methods to section 2.4. A part of the section (changing conditions in the matrix) was moved to the matrix section. However, we have kept the paragraph relating to the species’ response in its original place for the following reason. From the perspective of taxa (species or groups of related species) a particular matrix is perceived in a different way, resulting in taxa-specific responses. Here individual taxa have a greater weight than the matrix.
Figure 3 – “air temperature” next to the red and blue dots in the figure itself isn’t very clear – could these be relabelled as mean and minimum air temperature. I think it would also be useful to include maximum temperature in this plot for completeness.
We improved this figure to improve clarity following the suggestion of the reviewer.
Section 3.3 - I expected to see accumulation curves or non-parametric indices of total species number by fragment size in this section. I think this would help to clarify the overarching impacts of fragmentation on total species number.
This is a misunderstanding. The title and the following text were not precise enough in the earlier version of the manuscript. We did not examine fragmentation effects on total species richness. Total species richness is related to site (not to fragments or control plots) and combines data obtained with several methods. Accumulation curves and non-parametric indices cannot be presented because of the different methods used in different papers. Total species richness is only presented to illustrate the generally high diversity of these grasslands. To clarify this point, we changed the partitioning of the sections, inserted a new subtitle (new section 3.1.) and improved the text.
Section 3.3.1 – It would be helpful to have a figure summarising these findings all together and I suggest adding this.
Following the advice of the reviewer we inserted a new figure summarising these findings (new Figure 4).
Section 3.4 – 366-367 – I am not sure what this means, as the previous section gave results from composition analyses? Please reword to clarify.
We rephrased this sentence.
Table 4 – Please clarify the analytical approach used here – I think you used seven separate tests? It might therefore be prudent to control for the number of separate tests used with something like a Bonferroni correction, and interpret significance following this.
We decided to omit this table, because no significant difference remained after the Bonferroni correction. Furthermore, we shortened the text.
Section 3.6 – This section felt like it came too early, given that this is about changes in genetic diversity as a result of changes to pollination. I think it would make more sense to move this towards the end of the findings, after impacts on pollinators have been introduced. Also consider changing the title of this section, as the link with pollinator behaviour has not been formally assessed here.
Following the suggestion of the reviewer, we changed the order of these two subchapters so that they now follow one after the other (as sections 3.9.4. and 3.10.). We also made small adjustments in the text. The numbering of the figures has been changed as a result.
Section 3.7 – 461-463 – This text is about comparing to the matrix, so suggest moving this to section 3.2.
The context of this text is intended to explain why the density was higher in the edge zone of fragments. Therefore, this short part that mentions the matrix should not be moved.
Section 3.8 - 546-547 – This section is about impacts on population size, so suggest moving to section 3.7.
Population size is not the same as abundance (former section 3.7.). Extinction and recolonization are major topics in habitat fragmentation, attracting a considerable number of readers. Placing „extinction and recolonization“ to the topic „Abundance“ would greatly diminish the value of this section. Therefore, we prefer not to move this section.
Section 3.9.1. 599-608 – this is about the consequences of changing pollination and would be clearer combined with section 3.6, with Figure 6 complementing Figure 4.
Following the suggestion of the reviewer, we changed the order of these two subchapters so that they now follow one after the other. The numbering of the sections and figures has been changed as a result.
Figure 7 Legend “The stromata of E. bromicola prevent in an early stage the development of inflorescences” is not clear – please reword for clarity.
We rephrased the legend to this figure.
Section 5.3 – I am not sure what you mean by “success controls” please could you reword and clarify?
We improved the text to clarify this point.
I hope that these comments help improve this valuable paper.
We thank Prof. Ed Turner for his valuable comments. They helped to improve the manuscript.
Round 2
Reviewer 2 Report
Thank you to the authors for their detailed changes and clear replies to my comments, which all make sense. I’m very happy to endorse this extremely useful paper for publication. In looking through again, I found a few minor typos, if of help:
200 – cut “the”
201 – “end of vegetation period” isn’t quite clear, suggest “end of the growing season”?
208 – “nests” not “nest”
213 – “fragment” not “fragments”
838 – is “and orthopteran.ch” a typo? I think this can be cut?
1110 – add “the” before “case”
1197 – add “in” before “pollinator”
With all best wishes
Ed
Author Response
Line numbers cited by the reviewer are those of the pdf version of manuscript from the previous round.
Reviewer 2
General comments
Thank you to the authors for their detailed changes and clear replies to my comments, which all make sense. I’m very happy to endorse this extremely useful paper for publication. In looking through again, I found a few minor typos, if of help:
Specific comments
200 – cut “the”
Done
201 – “end of vegetation period” isn’t quite clear, suggest “end of the growing season”?
Done
208 – “nests” not “nest”
Done
213 – “fragment” not “fragments”
We rephrased to by omitting the “the” before “fragments”
838 – is “and orthopteran.ch” a typo? I think this can be cut?
This is not a typo but the name of a website. This was now clarified to avoid confusion.
1110 – add “the” before “case”
Done
1197 – add “in” before “pollinator”
Done
