The Effects of Nitrogen Fertilisation on Plant Species Richness in European Permanent Grasslands: A Systematic Review and Meta-Analysis

Round 1

Reviewer 1 Report

The review concerned the review article: The effects of nitrogen fertilization on plant species richness in European permanent grasslands: a systematic review and meta analysis.

Abstract captures the content of the article.

The introduction is well written, but there is not enough information about nitrogen fertilization, the need for such a treatment, advantages, disadvantages, etc. Here, please expand this issue in the introduction.

The separation of material and methods is described and explained clearly and completely. In line 120 and others, the unit kg N / ha / yr appears. Throughout the work, please correct the lines between the dots and add -1 to the notation.

Chapter research results, in my opinion, is described extensively, but it results from the amount of data analyzed. Correlation charts readable.

Moving on to the discussion, I think that this chapter should also be extended with additional citations. I justify this by the fact that the article concerns a review of nitrogen fertilization and the literature used is very, very extensive.

I accept it for printing, but with minor changes.

Author Response

We thank the reviewer for their helpful comments.

In response, we have greatly expanded on nitrogen fertilisation in the introduction and broadened the literature cited.

We have also corrected the notation used for nitrogen addition levels throughout, including in the figures.

We have also greatly expanded the discussion with additional and important citations, both to new and to existing text. 

Thanks again to the reviewer - their suggestions have improved the text considerably.

Reviewer 2 Report

For a better understanding of the relationship between the number of species lost or gained in meadows/pastures in relation to the amount of N applied per ha in the analyzed researches, it would be advisable to explicitly indicate the values ​​used for the conversion of manure doses.

  A more precise specification of the research directions (type of experiment, experimental network) to clarify some of the conclusions presented would be welcome, considering the multifunctionality of grasslands and the importance given to them in PILLAR II of the COMMON AGRICULTURAL POLICY.

Author Response

Thanks to the reviewer for their helpful suggestions. 

In response to providing specific conversion factors for Kg N ha-1 from manure, we felt that providing all conversion factors may take too much space and be too much detail, since these depend on livestock type and manure state (i.e. dry or slurry) as well as obviously application rate. Instead, we have altered the text and sign posted the reader to the specific conversions used so these can be more easily found.

We have also expanded on our research directions and clarified the conclusions and expanded the discussion greatly.

We thank the reviewer again for these helpful suggestions

Reviewer 3 Report

This manuscript aims at examining how nitrogen fertilisation affects plant species diversity, using a systematic review and meta-analysis of nitrogen fertilisation studies in European per-manent grasslands. This study demonstrates fertilisation induced reductions in plant species richness were greater when defoliation rates were lower. Further I think the research topic will be interesting for the readers of the Journal. The paper is well written and easy to understand, and the statistics used are appropriate.

 

 

1.     Introduction

This section is an insufficient background review of studies on the effect of nitrogen fertilisation on species diversity.

 

2.     The discussion generally needs improvement.

Soil development involving mineral weathering and pedogenic development effect plant productivity and diversity in grasslands. For example this article “Soil development mediates precipitation control on plant productivity and diversity in alpine grasslands”

Author Response

We thank the reviewer for their helpful comments.

In response, we have greatly expanded our background review of studies of nitrogen effects on plant diversity. We have also greatly extended and improved the discussion as suggested, but due to the editors request to only include very relevant and important literature, we felt the one suggested didn’t meet this criterion as it was not about fertilisation. Instead we included several other relevant studies instead.

We thank the reviewer again for their suggestions which have improved the manuscript.