Muehleisen et al. synthesized changes in richness across 27 grasslands in response to experimental fertilization. This is an important study that sheds light on the mechanisms of species richness loss with nutrient addition. The manuscript is well-written and rich in details. However, some points need clarification or additional information to improve understanding, which I pointed out in my comments.

Introduction
Line 101: I recommend adding “of non-native and native species” after “new species” as native species can also be gained.

Methods
Lines 161-164: You mention that you collected cover species-specific cover but how explicitly did you use this data in this paper?
Line 169: Can you add a sentence about how you calculated this proportion? For example, was this a richness proportion in relation to the starting number of richness? Please clarify.
Line 174: Proportion in relation to what? Clarify.
Line 186: It is unclear whether an original species was still considered as lost if it was absent (i.e., lost) in a given year but recolonized in the following years. Can you clarify that?
Lines 188-189: I see now that the information about how proportion was calculated appears in these lines. I suggest moving this up once you mention proportion for the first time. This will be helpful to know right away.

Results
Lines 235-236: Do you mean that these original species lost were lost across all years of the study? Were new species entirely new and unique, meaning they were not the same as the original species?

Were there species of a particular functional group that was lost (e.g., perennials, species with N-fixing symbionts, N-fixers, etc.) and gained (e.g. invasive species)? You mention possible invasion of non-native species in the introduction and it would be important to report back in the results if this indeed happened. Reporting information on groups that were lost/gained would be key to report and inform future studies or even for management purposes.

Discussion
Lines 320: But also management that focuses on locally susceptible functional groups and generally susceptible rare species will be essential to maintain biodiversity.
Lines 328-320: How would you account for species reordering in this context? Species reordering (the change in species ranks based on their abundances) has been shown to be more strongly correlated with multivariate measures of community composition changes than changes in richness, evenness and species gains and losses (see Avolio et al. 2019).
Avolio, M., Carroll, I., Collins, S., Houseman, G.R., Hallett, L., Isbell, F., et al. (2019). A comprehensive approach to analyzing community dynamics using rank abundance curves. Ecosphere.

Conclusion
Line 387 – Unsure what you mean by “be in flux”? Do you mean that species composition may be changing throughout time?
Line 396 – It is unclear what is meant by “propagate” in “the impacts of fertilization may take longer to propagate”. Propagate in what way? Clarify.
Figures and tables

Figure 2. The letters a,b,c,d are not showing in each figure. Please add them.
It would be helpful to have a sentence in the figure caption saying briefly how you calculated proportional richness.

Supplement
Figure S1. Clarify what “Both” means in the figure legend.

Analyses and Models
Table S1. Try to orient the page formatted as landscape to fit the table horizontally. It was difficult to keep track of which row referred to which author.

Overall, I am satisfied with the changes made by the authors and believe this is a more improved and clear version of the manuscript.

Methods
Lines 161-164: You mention that you collected cover species-specific cover but how explicitly did you use this
data in this paper?
We included this information to be fully explicit about census measurements, but we do not use this data in
our analyses as we feel presence/absence fully captures the turnover dynamics of interest in our study. We
will happily remove this detail from the manuscript if the reviewer and editor feel it should not be included.

Reviewer's comment: My opinion is that if the data was not used - which here I understand why - there is no use in adding this information to the methods. It can also mislead the readers who think they will see this data presented in the results (as I thought I would).

Additional comment:
Editor permitting, add a sentence to the abstract reporting functional groups response.