Grazing Effects on Seedling Emergence in Contrasting Wet and Dry Year in a Semiarid Grassland
Round 1
Reviewer 1 Report
Reviewer Comments on Manuscript Agronomy-1884844
General Comments:
Interesting manuscript regarding the interaction between grazing and water availability for seedling germination and emergence in a semi-arid grassland.
The study contained in the manuscript seem rigorous, but the use of single observations (years) to generalize entire environmental conditions is questionable at best. This issue is enhanced in sections dealing with trends, which also is not investigated. These concerns cause disconnects between the study design and the interpretation of the observations. Therefore, the heavy emphasis on the wet and dry year must be removed and instead used as one of the comparative aspects. Perhaps the soil moisture observations could be incorporated further into the analyses as an alternative.
Another issue regarding the use of years as an indicator of precipitation is that other environmental and ecological conditions also vary with year, for example temperature and other cyclic events. Without further investigation or accounting for the variation there is no reason to suspect that the precipitation is the main effect contributing to these vegetation patterns, it might as well be something else weather-related. Therefore at least temperature variations need to be included as well.
The timing of the precipitation is probably more important than the overall amounts, especially in semi-arid ecosystems, with potential delays between the rains and germination not having been discussed in sufficient detail.
Further complicating the matter is the lack of experimental control in the study. The seed bank and species-specific responses have not been adequately described or accounted for. Perhaps the differential grazing treatment has altered the seed bank, or perhaps it has not, there is no way of accounting for this variation without investigating how much seeds are stored in the soil, and their relative likelihood of germinating based on how the grazing treatment is changing the species present. Although species richness is presented there is no information about the turnover or which species are present, perhaps it is a complete turnover between sites.
Finally, the study has incorporated observations happening after the cessation of grazing. The findings might be a one-time event happening after long-term grazing rather than continuous processes. Therefore, the discussion dealing with trends or restoration purposes are not applicable to the findings without a larger, more controlled and continuous observational and experimental study. The discussion needs to reflect these considerations as well.
All of these concerns needs to be addressed, which will require rewrite of multiple manuscript sections and optimally also include re-analysis of the data and refinement of the interpretations that can be drawn from the study.
Author Response
Response to Reviewer 1 Comments
We are grateful to you for giving us an opportunity to revise our manuscript. We appreciate you very much for your positive and constructive comments and suggestions on our manuscript. We have studied the comments carefully and tried our best to revise our manuscript according to the comments. The following are the responses and revisions. Thanks again to your hard work.
General Comments:
Interesting manuscript regarding the interaction between grazing and water availability for seedling germination and emergence in a semi-arid grassland.
Point 1: The study contained in the manuscript seem rigorous, but the use of single observations (years) to generalize entire environmental conditions is questionable at best. This issue is enhanced in sections dealing with trends, which also is not investigated. These concerns cause disconnects between the study design and the interpretation of the observations. Therefore, the heavy emphasis on the wet and dry year must be removed and instead used as one of the comparative aspects. Perhaps the soil moisture observations could be incorporated further into the analyses as an alternative.
Response 1: According to the above comments, we removed and rewrote those sentences of heavy emphasis on the wet and dry year in the text, instead of that, we compared the difference of the grazing effects in the two years. And also we added the analyses of soil moisture changes between the two experimental years under the different grazing intensities, as shown in Figure 7.
Point 2: Another issue regarding the use of years as an indicator of precipitation is that other environmental and ecological conditions also vary with year, for example temperature and other cyclic events. Without further investigation or accounting for the variation there is no reason to suspect that the precipitation is the main effect contributing to these vegetation patterns, it might as well be something else weather-related. Therefore at least temperature variations need to be included as well.
Response 2: For better understanding of the findings in this study, we added temperature data in the revision. The temperature data showed that the average temperatures during the growing season in the two experimental years were similar. It indicated that temperature might not be the main factor influencing the seedling emergence differences in the study. Perhaps other environmental and ecological conditions also vary with year, relatively speaking, rainfall is the key factor limiting the emergence and growth of plants in this area, which has been confirmed by many previous studies. We explained this aspect in the Discussion.
Point 3: The timing of the precipitation is probably more important than the overall amounts, especially in semi-arid ecosystems, with potential delays between the rains and germination not having been discussed in sufficient detail.
Response 3: Both the precipitation timing and the overall precipitation amounts affect the emergence of plants, but the timing of the precipitation may affect the emergence process more, we have further explained and discussed this issue in the revision.
Point 4: Further complicating the matter is the lack of experimental control in the study. The seed bank and species-specific responses have not been adequately described or accounted for. Perhaps the differential grazing treatment has altered the seed bank, or perhaps it has not, there is no way of accounting for this variation without investigating how much seeds are stored in the soil, and their relative likelihood of germinating based on how the grazing treatment is changing the species present. Although species richness is presented there is no information about the turnover or which species are present, perhaps it is a complete turnover between sites.
Response 4: For better illustrating this issue, we supplemented the species composition list under each grazing intensity in the two experimental years, and rewrote this section by further querying the relevant literatures.
Point 5: Finally, the study has incorporated observations happening after the cessation of grazing. The findings might be a one-time event happening after long-term grazing rather than continuous processes. Therefore, the discussion dealing with trends or restoration purposes are not applicable to the findings without a larger, more controlled and continuous observational and experimental study. The discussion needs to reflect these considerations as well.
Response 5: We explained this issue in the last paragraph in the Discussion in the revision.
Point 6: All of these concerns needs to be addressed, which will require rewrite of multiple manuscript sections and optimally also include re-analysis of the data and refinement of the interpretations that can be drawn from the study.
Response 6: We added some relevant data and rewrote those sections mentioned according to the above comments (as shown in the revised version with the “Track Changes” function).
Reviewer 2 Report
I think the article is interesting for a broad audience and suitable for publication in Agronomy pending minor revision.
Reading the title it is clear to the reader that the subject of the article is the emergence of seedlings of annual species. However, in the text, especially in the tables and figures, which should be self-explanatory, it is not always clear that annual species include grasses and forbs because you present them like they were three different plant groups. Tou may specify this aspect in the captions or in the legends.
I have some methodological remarks for the authors.
1) Explain why animals are led to these grasslands after the growing season, i.e. when productivity is low. It was for the experiment only or it is the traditional timing?
2) I guess that each group of 15 quadrats has a different location, posing potential problems related to spatial autocorrelation. Please explain if and how you accounted for this issue and how you can ensure that data within each group of plots are not autocorrelated.
3) Explain how you identified seedlings' species. Please, cite any text or dichotomous key used for identification.
4) Did you test the assumptions for ANOVA (i.e. data normality and homogeneity of variance)? If these conditions are not satisfied you can transform data properly or use non-parametric tests.
I made some linguistic corrections in the text; however, I suggest having the language checked by a native speaker.
You can find corrections and other comments in the appended PDF file.
Comments for author File: 
Comments.pdf
Author Response
Response to Reviewer 2 Comments
We are grateful to you for giving us an opportunity to revise our manuscript. We appreciate you very much for your positive and constructive comments and suggestions on our manuscript. We have studied the comments carefully and tried our best to revise our manuscript according to the comments. The following are the responses and revisions. Thanks again to your hard work.
Comments and Suggestions for Authors
I think the article is interesting for a broad audience and suitable for publication in Agronomy pending minor revision.
Point 1: Reading the title it is clear to the reader that the subject of the article is the emergence of seedlings of annual species. However, in the text, especially in the tables and figures, which should be self-explanatory, it is not always clear that annual species include grasses and forbs because you present them like they were three different plant groups. You may specify this aspect in the captions or in the legends.
Response 1: We specified this aspect in Introduction and Methods, and made further notes in the captions of tables and figures.
I have some methodological remarks for the authors.
Point 2: 1) Explain why animals are led to these grasslands after the growing season, i.e. when productivity is low. It was for the experiment only or it is the traditional timing?
Response 2: This was originally for the experimental design of previous study and now has become the traditional timing. To promote the restoration of degraded grassland, the local government implemented a seasonal grazing prohibition policy, which only allowed livestock entering those grasslands during the autumn and winter of each year. We added those information in the Materials and Methods.
Point 3: 2) I guess that each group of 15 quadrats has a different location, posing potential problems related to spatial autocorrelation. Please explain if and how you accounted for this issue and how you can ensure that data within each group of plots are not autocorrelated.
Response 3: Spatial autocorrelation in ecological investigation can be interpreted as the degree to which the target quadrat is affected by other quadrats within a specific range around. In this study, the spatial autocorrelation between quadrats is mainly avoided by selecting a suitable sampling range (covering the studied site as much as possible) and increasing the sampling interval.
Point 4: 3) Explain how you identified seedlings' species. Please, cite any text or dichotomous key used for identification.
Response 4: We identified seedling species by querying the online Flora of China. We cited the website address (www.cn-flora.ac.cn) in text.
Point 5: 4) Did you test the assumptions for ANOVA (i.e. data normality and homogeneity of variance)? If these conditions are not satisfied you can transform data properly or use non-parametric tests.
Response 5: We rechecked and analyzed the data. The data met the homogeneity test (except total seedling emergence in 2019). For these data, we conducted square-root-transformation to make it meet the assumption of normality and homogeneous variances. We added information in revision to indicate this issue. This led slightly change in the significance of figure 3c.
Point 6: I made some linguistic corrections in the text; however, I suggest having the language checked by a native speaker.
Response 6: We have made modifications according to your comments, and made some changes in English language and style by using MDPI English Editing Service.
Point 7: You can find corrections and other comments in the appended PDF file.
Response 7: We have made modifications according to the comments in FDF files, such as providing information of dominant species that characterize this grassland, adding a map with the location of the study area, adding a table for listing plant species of functional groups, and some other specific changes, as shown in the revised version with the “Track Changes” function.
Reviewer 3 Report
Comments to the paper manuscript, entitled „Grazing effects on seedling emergence of annuals in contrasting wet and dry year in a semiarid grassland”
In general, grazing is considered one of the important management practices for increasing grassland biodiversity. The impact of grazing on grassland biodiversity depends on several factors. On one hand, it increases species richness, and it is used for ecological restoration, on the other hand, overgrazing leads to the grassland degradation and the loss of biodiversity. So, it is crucial to understand, how can grazing management promote grassland biodiversity restoration.
General comments:
The paper presents valuable data on impact of grazing intensity on seedling emergency over the growing period. The introduction provides sufficient background with relevant references. The aim, the research design is clear. Results are clearly presented. The Conclusions are good.
Specific comments:
Title
The paper shows research results on seedlings of grass, forbs, and annuals, not only annuals seedlings. For this, I would consider the title and to cancel word “annuals”.
Methods and Results
I would recommend to list plant species of functional groups.It would be interesting to know better which plant species are supported by applied grazing management practices.
Author Response
Response to Reviewer 3 Comments
We are grateful to you for giving us an opportunity to revise our manuscript. We appreciate you very much for your positive and constructive comments and suggestions on our manuscript. We have studied the comments carefully and revised our manuscript according to your comments. The following are the responses and revisions. Thanks again to your hard work.
General comments:
The paper presents valuable data on impact of grazing intensity on seedling emergency over the growing period. The introduction provides sufficient background with relevant references. The aim, the research design is clear. Results are clearly presented. The Conclusions are good.
Specific comments:
Title
Point 1: The paper shows research results on seedlings of grass, forbs, and annuals, not only annuals seedlings. For this, I would consider the title and to cancel word “annuals”.
Response1: For better understanding, we removed word “annuals” in the Title, and explained the functional group classification in the text.
Methods and Results
Point 1: I would recommend to list plant species of functional groups.It would be interesting to know better which plant species are supported by applied grazing management practices.
Response 2: We list plant species of functional groups in Table S1 in the revision.
Round 2
Reviewer 1 Report
The reviewer comments were adequately responded to and the manuscript has been sufficiently improved in the scope of the study.
