Impact of European Beaver (Castor fiber L.) on Vegetation Diversity in Protected Area River Valleys
Round 1
Reviewer 1 Report
The manuscript describes a study that aims to test the relationship between beaver presence and species diversity and alien species presence. The topic is relevant and of great importance for conservation.
The manuscript has at least two important points to be improved:
- Scientific writing style should be used – a section for tables, figures and “schemes” in both methods and results is not acceptable.
- Statistical methods are either inappropriate or lack information and discussion. For example, Shannon index is not meant for cover description but species information (in the case of vegetation analysis), and its results cannot be compared directly as it is a logarithmic-based (needs to be transformed to have statistical and biological meaning). Factors tested are not described and therefore seemed to be tested using inappropriate statistical tests. Authors aim at establishing relationship between species diversity and beaver presence (and by position in the river, using plots that have different vegetation cover) although such a test was not carried out directly. The tests used at most can show that there are differences (or not) among factors (separately) but not the relationship in focus. Furthermore, there is not discussion about level of significance, the fact that the main factors (beaver presence) have only 4/6 repetitions. As such, a very careful rethinking of the statistical analysis should be carried out.
L9- Scientific names should be in italic – here and elsewhere.
L10- vegetation species diversity is a bit redundant. Vegetation diversity already implies its species.
L15-20 – It is essential to introduce information regarding how beavers influence species diversity - both native and exotic otherwise it is a loose statement. In reality, proving such causality is the essence of this study and therefore it should be in the abstract.
L28 – river embarkment erosion or where the highly reduced vegetation take place? Is this effect is that important?
L 34 – “with the river stream” – are authors referring to downstream flow/direction?
L39 – “Rivers” onwards is another paragraph.
L39-41 – “Rivers are natural corridors that facilitate the movement of invasive plants from urban areas to protected areas.” This sentence is lost here as the topic introduced here is not further explored and it is out of context. Amend or delete.
L47 – 67 – Paragraph starts discussing beaver and plant dispersion after which it suddenly moves to animal diversity (L55) and back to plants (L59). It is unclear to which type of diversity of species it is being discussed in L56-59. Clarify and amend.
L62 – the fact that beavers feed on native species is obvious which in turn does not cause per se the expansion of alien species. I would put it differently – beavers have a limited effect in controlling alien species because of current feeding preferences. Subtle but not less important.
L68 – plant species and taxa are redundant here.
L70 – plants do not “prefer”.
L74-76 – cite those studies.
L89 – more information about the park is necessary: how big, vegetation types and their cover (%) etc.
L93 – is instead if was.
L95- use gender neutral language.
L97-100 – “Majority of the study plots were set in forested areas…”. Why? What are the other types of vegetation that could be surveyed. What is their representativeness in the park? Details about method is necessary here.
L102 – “trees rarely occupied more than 75% of the experimental plots”. 75% of what? Canopy cover?
L103-104 – Include scientific names of those tree species.
L108-109 – Sentence construction is awkward – there is something missing here.
L110, below and above – transect and plots and overall method is very confusing. E.g., “In plots located where beaver were present, the first transect (D) was established”. I assume that the identification of beavers activity and dams was initially carried out, followed by the establishment of 3 transects, and each transect contains 3 plots. What was measured (in transects and plots within transects)? Revise the whole section.
L110 onwards – The number of plots per vegetation type (stratification, i.e. additional factors to be considered beyond river/beaver position) should be described and tested.
L120 – “degree of cover by individual plant species in three layers of the forest”. It is unclear what it means. The percentage of each plant within each layer? Or the percentage of ground cover by each species in each layer? If it is the latter, it does not make sense. Regardless of each one, information needs to be amended.
L113 – what was the method used to place a “random” plot? Random does not mean that a method to decide about their location was not used.
L134 – It does not exist in scientific literature a section “Figures, tables and schemes”. They are inserted and cited in the text. Delete.
L140 -141 – Delete “ is a figure” and “schemes follow the same formatting”. The latter might mean something actually but should be amended if it is the case.
L135 -Figure 1 – insert river network and vegetation cover in this figure.
L122-128 – Shannon is used to discusses species diversity and indicate on L123 but suddenly it is transformed to describe cover. That is a very unusual way of using this index and otherwise based on proper literature is not acceptable. Cover index is usually described through dominance which is based on basal area (in the case of trees), for example. Similar comment is applicable to Simpson.
L122-128 – Shannon is a ln index (as stated) and cannot be directly tested unless transformed to linear. More importantly, it has no biological meaning without transformation. Please refer to Lou’s work on effective number of species http://www.loujost.com/Statistics%20and%20Physics/Diversity%20and%20Similarity/EffectiveNumberOfSpecies.htm
L129-132 – What were the factor tested? Why non-parametric tests were used? What does it meand “the Mann-Whitney U test was used for two independent samples”? level of significance?
L154 “down trees”?
Table 2 – in methods is described the used of 3 vegetation layers but only 2 are shown.
L213, table 5 and other parts – authors discuss “cover area” but it is not clear how it was measured and tested. Again, Shannon for forest/vegetation cover is not the right index.
L271 owards- The information regarding the introduction of beavers should have been discussed in introduction/methods. It suddenly appears here to explain the results without proper consideration in methods (does it affects the sampling scheme? Does it matter?).
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript entitled „Impact of European beaver (Castor fiber L.) on vegetation species diversity in protected area river valleys” deals with an interesting and relevant research topic. The Eurasian beaver has been reintroduced to most European countries and has clearly become a conflict species in several countries. Nevertheless, there are few monitoring studies on the basis of which we could realistically judge the role of the beaver; the significance of the present research lies precisely in this. The objectives are clearly defined. The overall study is relatively straightforward, and the data and conclusions are valuable. However, to be publishable, I suggest the authors to apply some minor changes (minor revisions). With this revision, I feel the manuscript will represent a strong and valuable publication.
The introduction is well structured. The literature cited is relevant; nevertheless, there are still works related to the narrower topic of the manuscript (the impact of the Eurasian beaver on invasive plant species), which should be considered for citation here or in the discussion:
Juhász E et al 2020, A reintroduced ecosystem engineer species may exacerbate ongoing biological invasion: Selective foraging of the Eurasian beaver in floodplains, Global Ecology and Conservation 24, e01383, Doi:10.1016/j.gecco.2020.e01383
Juhász E et al 2022, Foraging decisions with conservation consequences: Interaction between beavers and invasive tree species. Ecology and Evolution Doi:10.1002/ece3.8899
The description of the study area and plots is detailed and informative. The survey methods are accurate.
Evaluation methods, including diversity measures, are well chosen. It is commendable that multiple approaches are used, as different indices are sensitive to different parameters.
Other minor comments:
- Italicize the scientific names throughout the manuscript
- the Shannon diversity index is given in two ways: both Shannon index and Shannon-Wiener index are acceptable, but better to choose and use one of them.
- Line 127: insert (C) after Simpson.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
In introduction it must talk a little more about the beaver, a few words about the species, habits, diet.
”In the taller-tree layer, the presence of beaver corresponded with the evening out of the ratio of species....” ( row 271) - it is not clear, it is something wrong in English language, I believe.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Authors have satisfactorily amended the manuscript as suggested.
