Floristic Composition Mediates Change in Forage Nutritive Quality of Atlantic Mountain Grasslands after Experimental Grazing Exclusion
Round 1
Reviewer 1 Report
In my opinion, the paper deals with a relevant topic for this journal, such as assessment of effects (directly or mediated by botanical composition) of management through grazing on some grassland features. The novelty of the outputs is not so high but I found the proposed approach useful to investigate effects of grazing on herbaceous plant communities. However, I think it should be remarkably improved before considering it for publication. Moreover, a deep revision by a native English speaker is advisable. Specific issues to be addressed are the following.
Lines 18-19: in the abstract this sentence is not so clear, as forge quality is repeated twice. I advise authors to check and rewrite it.
Line 35: independently should be followed by “on”.
Line 37 and following: in presenting ecosystem services provided by grasslands, I think authors should add some important topics (and relevant citations about them) such as conservation of landscape heterogeneity and of habitats useful for wild animals (such as deer or similar).
Line 43: authors report the growing season from May to October-November, but this is true in the specific area under investigation. Here it seems that this issue is referred to all semi-natural grasslands, so I advise them to be more general.
Line 55: are forbs (intending in this way species not grasses or legumes) considered highly palatable? Maybe they are rich in mineral elements but generally with a reduced palatability. Or palatable is referred to legumes only? please rearrange the text accordingly.
Lines 63-65: the sentence is really repetitive. Please rearrange the text avoiding repetitions.
Line 71: I think that “any” should be followed by the singular noun “effect”, so the verb should be “is”. Please check it.
Line 77 and following: authors introduce the concept of physical properties of the soil as Z variable but a lot of soil characteristics then measured concern a lot of chemical features (pH, chemical elements content, and so on). I think authors should here present Z variable as “physical and chemical properties of the topsoil”.
In point 2.1 (materials and methods), in the presentation of studied areas, authors should report altitudinal range of the experimental sites here, as they refer (line 109) to upland and lowland farms in the same point.
Line 107: Tn is ton (=1,000 kg)? use an international standard symbol, t or kg.
Line 110: authors use the term “stocking rate” but here they refer (I argue) to number of individuals of animals grazing in the whole area. Stocking rate is, correctly, the ratio between the number of animals (as Livestock Units, LU) and the surface (in ha) in which they graze for a given time. Please, change the whole test in a correct manner.
In point 2.2 a lot of names of studied sites are reported. I think that maybe a little map of presentation and localization (encompassing part of the Spain) of the sites would help readers worldwide to better individuate them.
Line 126: “were” should be “was” as it refers to potential biomass.
Line 131: I think authors should specific in a better way the factor Time. Does it refer to different cuts along the same grazing season? In the relevant figures (see later) legend can’t help to understand this point.
Line 143 and following: how many quadrats were performed along the grazing season?
Line 145 and following: was reported methodology for botanical surveys applied firstly along this study or is it commonly and widely used? Please address this issue and add an appropriate reference if needed.
Line 156: the carbon nitrogen ratio (C/N) is here presented as a variable interested by the study but afterward in the text no results was displayed about it. Authors should present some results concerning C/N or, if not, please delete it from analysed parameters inside materials and methods section.
Line 179: authors selected Simson index as a parameter to describe diversity inside grasslands. Why? The most used parameter in this domain is Shannon index (H’) that could be calculated as well with the same data collected. Authors should properly justify their choice. Moreover, I think that authors should add the formula for the calculation of Simpson index in the text.
Figures 2 and 3: which is the unit of measure of x-axis? Months?
Lines 243-244: where we can see a possible mediation of species diversity on potassium content in forage? Are data not shown? Please specify.
Line 258: I don’t think the parenthesis “(randomized)” is necessary as also a fixed factor can cause effect on a response variable.
Line 277: what is ANPP? I guess Aboveground Net Primary Production, as we can argue from title of reference number 37. Maybe authors should add it in the text (with ANPP among parentheses) as this acronym is the first time that is cited in this paper.
Line 284: I advise authors to add some example (references) of effects of stocking rate on vegetation forage quality in longer period.
Line 287: effect of animal impact on herbage height is remarkably due to level of stocking rate. Please circumstantiate this aspect.
Line 290 and following: I found this part of discussion a bit obvious. I think authors should improve this part.
Please revise carefully also the references list, I noticed some errors in format and names. For instance, in number 21 and 23 (Lasanta et al. and Strauus et al.) the years are not bold (line 439 and 443), and in 52 (Fisher et al.) Oxford is written Oxfor (line 507). Moreover, reference 17 (Gerber et al.) seems highly incomplete.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Thank you for the opportunity to review this interesting manuscript. In this study the authors aimed to determine to what extent reductions in pasture quality in abandoned extensive pasture are due directly to the lack of grazing or to concurrent changes that occur in plant species diversity. Although not the first to consider pasture quality changes due to abandonment, the manuscript introduces a novel approach - mediation analysis - to untangle these confounding effects over a long time period. The paper is well written and concise and I recommend it for publication after a few concerns have been addressed.
General Comments:
- In general the grammar in the paper is very good but in a few places the author uses sentences that are over-complex which reduces readability. In particular line 36-39 in the introduction and lines 259 - 267 in the discussion. Please can you reword these and check the manuscript for similar ones. I have included some specific comments too on this.
- Is it possible to report the least square treatment means for each variable in each year somewhere either in main or supplementary material. Knowing the least square means in addition to the reported contrasts between them is useful for comparing nutritional values of the forage in the study and in other studies.
Specific comments:
L37. please replace maintain with 'the maintenance of'
L44. remove decisively
L107. please check the unit, the SI unit for tonne is 't'
L111. It might be helpful for comparison purposes to also give the stocking rates as a unit/ha, perhaps in parentheses, so the reader does not have to check the total land area to calculate this themselves
L117. please tell us how the field sites were selected? were there any criteria that led you to choose these or was it random?
L120. is flat terrain predominant in this grazing region? If not please explain why did you choose only flat terrain? Could slope also be a confounding factor on species prevalence?
L125. Not sure if the word "sequential" is correct. In what way was their use sequential? Did you go to each one in turn to take measurements through the season?
L131. Please confirm for your effect of 'time' in the mixed models analysis - was this the year (so n=5) or some other smaller denomination of time e.g. sampling timepoint (n = ?)
L145-146. When you estimated species cover did the operator separate the sward to get an idea of species volume or estimate only by what can be seen from a top-down view? Also did you check how consistent estimates were between operators?
L151. To what level was it clipped? To the ground or grazing height? Was the entire biomass in the 1m2 clipped or just a subsample taken.
L158. The topsoil physical properties were measured only at the end of the experiment - Why not also at the beginning to see whether change has occurred due to the study treatments?
L169. You mention previously that you included a repeated effect in your model - did you choose a covariance structure for the repeated effect e.g. compound symmetry/unstructured/etc.?
L179. Could you please add one sentence to describe what is the Simpsons index of diversity for those who do not know?
L196. There are two values within parentheses separated by a comma, please confirm what is each value - only one can be the degrees of freedom.
Figures 2 and 3. What is the unit of time in these graphs?
L259. I suggest replacing "standard linear modelling" with "linear mixed modelling" because standard linear modelling could also apply to simple linear regression and other techniques that you did not use here.
L260-263. This sentence is an example of being over-complex as per my general comment. Suggestion for improving it could be e.g.: "By means of a linear mixed modelling approach, we found that experimental fencing to recreate exclusion of ungulate grazers in an atlantic grassland system reduced forage nutrient quality indicators after just six years of experimental manipulation."
L263 - 267. Similar to previous sentence, this is difficult to read, please can you rephrase?
L263. Please change to "neutral" detergent fibre not "neutro"
L271. Add "a' before long
L277. Please spell out the abbreviation (ANPP) on the first use (unless I missed it)
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I think authors improved their paper accordingly to my previous issues. I think it can be accepted in the present form, I just found some minor issues to be addressed as follow (line numbering is referred to the new version of the manuscript):
- line 169 and line 193: here the soil properties are called “physical” and is not reported also “chemical” as previously pointed out. Maybe also in figures/legends they can named them only “soil properties”;
- line 172: cmolc/kg should be replaced using exponential notation (cmolc kg-1);
- lines 346-348: I would suggest authors to stress the concept of preserving legumes by means of extensive grazing is of remarkable importance for forage quality of pastures not only in this area but for almost all grassland. I think they could generalize this concept to enhance importance of their findings, here and also in the last paragraph (lines 358 and following).
Author Response
Our responses to Reviewer's comments can be found in the uploaded file.
Author Response File: Author Response.pdf
