Some Ecological Characteristics of a Neophyte of the Canary Islands: Pluchea ovalis (Asteraceae)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript of Pestano et al. addresses an importante topic in the field of biological invasions. Its main aim is to understand the ecological factors that drive the invasion of the invasive Pluchea ovalis the Canary Island. Overall, the manuscript is well written and easy to read.

My impression is that the manuscript should be more detailed, particularly in the Materials and Methods and Results sections. In the Material and Methods section, I recommend a clear justification about selection of treatments. For example, why this study focuses on light and dark conditions? Or the selection of “flooding, darkness, drought, heat, nutrient deficiency“ for the greenhouse experiment?

The discussion of the manuscript is not sufficiently deep and, in some parts, only repeat the results. The manuscript lacks a clear interpreation of the results by comparing them with existing literature. The lack of robust evidence of the impacts of Pluchea ovalis limits the generalizability of results.

Based on my comments and those provided in the attached file, I suggest that the authors do the necessary revisions to enhance its overall clarity and quality.

Comments for author File: Comments.pdf

Author Response

We would like to thank the refereee for his time and dedication to improve the manuscript... we notices the improvements after implementing his comments. We proceed answering point by point:

 

Comments 1: My impression is that the manuscript should be more detailed, particularly in the Materials and Methods and Results sections. In the Material and Methods section, I recommend a clear justification about selection of treatments. For example, why this study focuses on light and dark conditions? Or the selection of “flooding, darkness, drought, heat, nutrient deficiency“ for the greenhouse experiment?

Response 1: We agree with this comment. Therefore, on page 3 (paragraph 3) between lines 124 and 128 we have changed the text explaining why we choose this temperature ranges and photoperiods. Referring to greenhouse experiment treatments, on page 4, paragraph 2, lines 175 and 177, we have changed the text explaining that those treatments are selected as possible environmental conditions where the species can be involved.

Comments 2: Why these photoperiods? Why both? What is the objective of this analysis?

Response 2:This photoperiods are selected in order analyze possible effects of total darkness conditions on the same temperature range compared to a 12h light – 12h darkness that can be considered as the default circadian rhythm. We have made some changes to explain this on page 3 (paragraph 3) line 128.

Comments 3: under controlled conditions?

Response 3: this experiment was carried out under controlled conditions because we have data of irrigation, relative humidity and temperature. We have changed the text on page 4 (paragraph 1) line 169 to mention that the experiment was made under controlled conditions.

Comments 4: This treatment should be detailed as occurred in the others.

Response 4: thank you for highlighting this. Control treatment is the only one with no changes with regard to the original composition previously described. Changes have been made on page 4 (paragraph 2) lines 179 – 180.

Comments 5: Why this treatment?

Response 5: since the species settles on waterlogged soils with external water sources and a high nutrient input it is expected to have a lower germination rate under this treatment.

Comments 6: Collection of these variables occured in both dates/seasons? I think that is necessary to reformulate the previous sentence.

Response 6: Collection of all data was made of both seasons. In relation, we have changed the text on page 5 (paragraph 3) line 245.

Comments 7: Why?

Response 7: Data from both photo – periods was analyzed separately to check posible differences between temperature ranges under the effect of the same light conditions.

Comments 8: The y-axis should be identical in both graphs; the meaning of bars, circles and lines should be explained, as well as the meaning of "10_17_N and D".

Response 8: thank you for pointing this out. We have changed the y – axis for the 24h darkness photo – period graph and explain the meaning of circles, bars and lines on page 7 lines 330 – 332.

Comments 9: The values are means? The SD or SE should be presented.

Response 9: Mean germination time (MGT) are the only mean values. SD has been placed for each value in MGT column on page 7.

Comments 10: Here, it would be important to present the distribution of plant species by both situations: control and invaded.

Response 10: We agree with this comment. We have created a new list (Table S2) including species present in both types of plots. This new table can be found in page 1 of the Supplementary materials. Also, we have clarified this on page 9 (paragraph 2) lines 424 – 425.

Comments 11: But the values are statiscally different between plots? In both seasons? The results only indicate "higher" or "loer" wich seems insufficient.

Response 11:Thank you for pointing this out. In relation, we have performed ANOVA and Kruskal – Wallis (depending on the case) to check for differences on soil properties between plot types. Also we have changed the text on page 6 (paragraph 2) lines 264 – 266 to explain this part of the data analysis and on page 9 (paragarph 3) lines 426 – 428 to explain results.

Comments 12: Please indicate the meaning of all abbreviatures (%MO or %OM).

Response 12: It was a mistake written in spanish. It has now been corrected in the graph on page 8.

Comments 13: The S1 and S2 figures are quite difficult to understand. The meaning of each abbreviature is lack. It would be better to present a figure with % of native and invasive plants in both situation: control and invaded.

Response 13: We agree with this comment. To support the information, we have made two new graphics of the percentage of native and invasive species on both types of plots. This new figures can be found at page 2 of the Supplementary materials. Also, related changes in the text have been made on page 9 lines 424 – 425.

Comments 14: This result is based on Figure 3? The comparison between photoperiods is not available.

Response 14: Yes, this result is based on figure 3. With this sentence we mean that germination is cleary different depending on light and temperature conditions.

Comments 15: Based on the results (Figure 3), there is no differences between the highest temperatures. Please revise.

Response 15: With this comment we mean that at higher temperatures germination is lower compared to the apparently better temperature range for the seeds to germinate (17 – 24ºC).

Comments 16: This fact is not strange. Previously, it is referred that the species prefers "waterlogged soil" (lines 61-62. So, it is necessary to discuss it.

Response 16: What do you mean with “this fact is not strange”? We interpret the lack of germination in the hot substrate and drought treatments as the preference of the species for soils with a higher content of moist and water availability.

Comments 17: Across the text there is no information about the allelopathic potential of P. ovalis. If this information exists, it should be referred

Response 17: We have no found any information on the possible allelophatical effect of P. ovalis. Nevertheless, our results indicate that species richness is higher on invaded plots, so Pluchea ovalis could be facilitating the presence of all these species.

Comments 18: Both species are drought tolerant. How can you explain the presence their presence in the same area of P. ovalis, that is not drought tolerant?

Response 18: Probably because both species were settled in that place before the arrival of P. ovalis. Furthermore, we believe the presence of P. ovalis in this location is consequence of water leaking from a nearby pipe.

Comments 19: P. ovalis is present in Tenerife since 2000. In my opinion, it is a short time to cause dramatic alterations in soil to justify the presence of other invasive plant species.

Response 19: Yes, but its expansion is happening really fast. Anyway, we are not confirming this process to be happening. More studies on this should be made to confirm this theory.

Comments 20: Are you sure that P. ovalis is responsible for soil alterations that facilitate the invasion of Opuntia and Cenchrus or the oposite? It would be important to have historical data to confirm your hypothesis. Its lack and robust evidence of the impacts caused by P. ovalis, make your suggestion (inclusion in the Spanish catalogue of IAPS).

Response 20: We can not confirm that P. ovalis is responsible of soil alterations and facilitation of invasion. Anyway, the fast expansion of the species over the territory makes necessary its inclusion in the spanish catalogue of IAPS, especially if we take into acount the special carachteristics of island ecosystems.

Comments 21: Please see my previous comment.

Response 21: This has been answered in the previous comment.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript addresses a topical issue and is an important piece of scholarship. Despite its strengths, there are some weaknesses that I would like to point out.

1. I recommend revising the title of the article. It is now too general and does not convey the full content of the article. I also recommend removing the authors of the taxon and instead mentioning the family in the abstract and text.
2. The introduction needs to be significantly expanded. Much of the information is now concerned with the object of the study and the location of the research rather than an overview of the issues under consideration. It is necessary to give an overview of the issues related to the study (ecology and biology of seed germination, the impact of invasive species on species diversity and soils, etc.).
3. Avoid working slang in the text. There is a lot of it, but I cannot point out all cases. One example: 'Pluchea ovalis is an African - Arabian shrub species'. Do not call the species "African-Arabian", but instead say that it is native to Africa and the Arabian Peninsula. 
4. The captions of almost all figures need to be corrected. They must be clear and fully explain the content of the figure (e.g. Figure 1).
5. Many technical errors. Intervals should be given without spaces (300-800 mm instead of 300-800 mm). The names of the plant communities should be spelled Artemisio thusculae-Rumicetum lunariae Rivas-Martínez instead of Artemisio thusculae-Rumicetum lunariae Rivas-Martínez etc.
6. I strongly recommend that the graphs in Figure 3, Figure 4 be arranged one per column and that the entries be enlarged considerably so that all the information is clearly visible.
7. The caption of Table 1 should appear before the table, not after it.
8. The discussion section is too weak. The discussion needs to be expanded and all the hypotheses tested (the issues addressed) need to be discussed in a broader context: what are the effects on the species, on the soil of the species under study and on other species studied by other scientists. How the effects are similar and how they differ. 
9. I recommend that the conclusions be restructured and clearly state whether or not the hypotheses put forward have been confirmed. There should also be a clear summary of all the results and a takaway message.

Author Response

We thanks the referee for his time and dedication to improve the manuscript... we have answered all his comments and explain some of them. Thanks again.

Comments 1: I recommend revising the title of the article. It is now too general and does not convey the full content of the article. I also recommend removing the authors of the taxon and instead mentioning the family in the abstract and text.

Response 1: Thank you for your comments. Regarding the title, previously we made some chagnes to make it more specific, but it was difficult due to the lack of references. Also, regarding your comments about the species authors we have made changed it on the abstract (page 1 line 9) and in the text (page 2 line 59).

Comments 2: The introduction needs to be significantly expanded. Much of the information is now concerned with the object of the study and the location of the research rather than an overview of the issues under consideration. It is necessary to give an overview of the issues related to the study (ecology and biology of seed germination, the impact of invasive species on species diversity and soils, etc.).

Response 2: We agree with this comment. The introduction has been expanded with new text about invasive species effects on soil properties and plant communities and germination ecology on page 1 (paragraphs 2-3) lines 34-44.

Comments 3: Avoid working slang in the text. There is a lot of it, but I cannot point out all cases. One example: 'Pluchea ovalis is an African - Arabian shrub species'. Do not call the species "African-Arabian", but instead say that it is native to Africa and the Arabian Peninsula.

Response 3: Thank you for highlighting this. The respective changes have been made in the text.

Comments 4: The captions of almost all figures need to be corrected. They must be clear and fully explain the content of the figure (e.g. Figure 1).

Response 4: We agree. Most of figures caption have been changed in adition to the other reviewer comments.

Comments 5: Many technical errors. Intervals should be given without spaces (300-800 mm instead of 300-800 mm). The names of the plant communities should be spelled Artemisio thusculae-Rumicetum lunariae Rivas-Martínez instead of Artemisio thusculae-Rumicetum lunariae Rivas-Martínez etc.

Response 5: All intervals have been changed. The name of the plant communities have been changed on page 3 line 105 – 107.

Comments 6: I strongly recommend that the graphs in Figure 3, Figure 4 be arranged one per column and that the entries be enlarged considerably so that all the information is clearly visible.

Response 6:  We agree this comment. All graphs are now arranged one per column and captions have been expanded due to the comments of the other reviewer.

Comments 7: The caption of Table 1 should appear before the table, not after it.

Response 7: The caption now appears before the table.

Comments 8: The discussion section is too weak. The discussion needs to be expanded and all the hypotheses tested (the issues addressed) need to be discussed in a broader context: what are the effects on the species, on the soil of the species under study and on other species studied by other scientists. How the effects are similar and how they differ.

Response 8: Thanks for pointing this out. We have expanded the discussion with a new text on invasive species germination in native and invaded territory on page 11 lines 503 – 507.. However, due to the lack of studies about this species it has been so hard for us to gather sufficent information.

Comments 9: I recommend that the conclusions be restructured and clearly state whether or not the hypotheses put forward have been confirmed. There should also be a clear summary of all the results and a takaway message.

Response 9: The conclussion has been changed and a new text has been added linked to the new one in the discussion and a final takeaway message has been added too.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors,

I revised this new version, and I am satisfied with the modifications implemented by yours. I only have a minor issue in the Introsuction section. The addition of the two paragraphs (lines 34-44) seems to be out of place. In my opinion, they should be placed after line 62. As such, I suggest that the manuscript can be considered for publication.

 

Author Response

We would like to thank the refereee for his time and dedication to improve the manuscript... we notices the improvements after implementing his comments. We proceed answering point:

Comments 1: I revised this new version, and I am satisfied with the modifications implemented by yours. I only have a minor issue in the Introsuction section. The addition of the two paragraphs (lines 34-44) seems to be out of place. In my opinion, they should be placed after line 62. As such, I suggest that the manuscript can be considered for publication.

Response 1: We agree whith this comment. Changes have been made on the text. Thank you for your Comments.

Reviewer 2 Report

Comments and Suggestions for Authors

After the reviews, the article has been revised, but some of the comments and suggestions have been taken into account in a very formal way, or not at all, although the reply states the opposite. I would therefore like to draw the authors' attention to the fact that, when replying to comments, one should carefully examine what the comment is about. I will therefore simply repeat some of the comments and state the newly identified shortcomings.

1. I recommend revising the title of the article. It is now too general and does not convey the full content of the article. I also recommend removing the authors of the taxon and instead mentioning the family in the abstract and text. If the article deals with seed germination, seedling development and the like, then perhaps the title should be about these issues rather than the very broad concept of ecology, which is barely covered. And you should not do the opposite of what is being suggested - remove the authors of the taxon from the title of the article, and add them in the text.
2. The authors should note the use of the terms altitude and elevation. They are not identical: elevation refers to orographic features, while altitude defines the specific position of a site above sea level. 
3. The newly added text (lines 264-266) is not at all clear. On the contrary, it confuses things even more. And it is incorrect to use two methods to analyse data from one group. If at least some of the data is non-normally distributed, then one non-parametric method of analysis should be used.
4. Box-plots must show any differences between the experimental options. Why is only one listed?  Instead of using an asterisk, I recommend using letters to indicate differences. All graphs of this type need to be corrected and revised.
5. What do the abbreviations in the title row of Table 1 mean? Please explain or provide a clear reference where they can be found quickly. In general, I recommend that some abbreviations that are used only two or three times in the text be dropped. This does not save space, but only makes the text harder to read.
6. If you have used the Dunn post-hoc test, the values are given in the low z rather than the high z (chapter 3.2). What does the 3 next to H in the sub-script mean? I have not found an explanation anywhere. Is it a df value? 
7. Despite the authors' claim to have added to the discussion, the addition is not significant. After all, the discussion could be extended to other invasive species of Asteraceae, say Baccaris halimifolia. 

 

 

Author Response

We would like to thank the refereee for his time and dedication to improve the manuscript... we notices the improvements after implementing his comments. We proceed answering point by point:

Comments 1: I recommend revising the title of the article. It is now too general and does not convey the full content of the article. I also recommend removing the authors of the taxon and instead mentioning the family in the abstract and text. If the article deals with seed germination, seedling development and the like, then perhaps the title should be about these issues rather than the very broad concept of ecology, which is barely covered. And you should not do the opposite of what is being suggested - remove the authors of the taxon from the title of the article, and add them in the text.

Response 1: We have changed the tittle of the article indicating it does not deal with all posible ecological caracteristics. Also, the authors of the taxon have been removed from the title and added in the text. We apologyze for the misunderstanding.

Comments 2: The authors should note the use of the terms altitude and elevation. They are not identical: elevation refers to orographic features, while altitude defines the specific position of a site above sea level.

Response 2: Thank you for pointing this out. Respective changes on the text have been made on page 3 lines 105 and 108.

Comments 3: The newly added text (lines 264-266) is not at all clear. On the contrary, it confuses things even more. And it is incorrect to use two methods to analyse data from one group. If at least some of the data is non-normally distributed, then one non-parametric method of analysis should be used.

Response 3: What do you mean with this? Two methods of analysis (ANOVA and Kruskal – Wallis) were used because we have non – normally distributed data and normally distributed data.

Comments 4: Box-plots must show any differences between the experimental options. Why is only one listed?  Instead of using an asterisk, I recommend using letters to indicate differences. All graphs of this type need to be corrected and revised.

Response 4: Thanks for this comment. Graphics and their changes have been changed-

Comments 5: What do the abbreviations in the title row of Table 1 mean? Please explain or provide a clear reference where they can be found quickly. In general, I recommend that some abbreviations that are used only two or three times in the text be dropped. This does not save space, but only makes the text harder to read.

Response 5: This abbreviations are for germination indices calculated before. They are named and explained in chapter 2.3 on page 4 lines 148 – 156. Should I explain them in the table caption? Also the non abreviated name of the indices inside the table would be too long.

Comments 6: If you have used the Dunn post-hoc test, the values are given in the low z rather than the high z (chapter 3.2). What does the 3 next to H in the sub-script mean? I have not found an explanation anywhere. Is it a df value?

Response 6: the package give the H value and the post – hoc test gives us the probability associated to the statistical of comparison that they are equal. On the other hand, the sub index next to H is a df value.

Comments 7: Despite the authors' claim to have added to the discussion, the addition is not significant. After all, the discussion could be extended to other invasive species of Asteraceae, say Baccaris halimifolia.

Response 7: Changes on the discusión have been made taking into account previous studies with other asteraceae species, due to the lack of information about Pluchea species.

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

Much of the content of the manuscript, technical shortcomings aside, is already well drafted, but there are still shortcomings in the description of the statistical methods and the presentation of results. 

It is regrettable that the authors do not read the comments carefully and ignore some points, even though they say in their replies that corrections have been made. I will therefore now try to explain the essence of the shortcomings in more detail. 

Section 2.7 requires: 
(a) Indicate which data sets were normally distributed, which were non-normally distributed and which methods were used to test it. 

b) justify why you chose Dunn post-hoc. Why did you give it priority (there must be a basis for the structure of the data) over the Mann-Whitney post-hoc test?

(c) It is unacceptable that the effects of agrochemical indicators have been analysed using two methods. If at least one of the datasets has a non-normal distribution, one (non-parametric) method of analysis should be used to analyse all the datasets in that dataset, but without mixing parametric and non-parametric methods (lines 349-351). 

(d) it is necessary to clearly state how you present the results (a comment was already made on this but you ignored it). If you specify df values next to the H value, you need to write both df values in a different format. The two possible formats are H _{3; 26} or H (3; 26). Dunn post-hoc z is lowercase, not uppercase. 

Despite the fact that the authors claim to have shown the differences between the treatments in the graphs, no changes have been made in the version of the manuscript I got for assessment. For example, Fig. 3 shows differences (no difference) only between 17_24_N and 24_31_N, and the authors do not indicate the significance of the difference between the other treatment variants. The same applies to the other box-plots. By the way, the graph covers almost the entire caption of Fig. 3.

Instead of adding the missing information to the Table 1 caption, the authors deleted the explanations of all abbreviations. I wrote a note earlier and made it clear that the abbreviations in the header row of the table (the first row of the table) should be explained in the table caption. If you still have questions, I recommend that you read carefully the journal's instructions to authors and the requirements for figures and tables.

I strongly recommend that the authors carefully edit the manuscript and remove the numerous technical shortcomings (uneven formats, unnecessary gaps between words, characters, etc.). 

 

Author Response

We would like to thank the refereee for his time and dedication to improve the manuscript... we notices the improvements after implementing his comments. We proceed answering point by point:

Comments 1: Indicate which data sets were normally distributed, which were non-normally distributed and which methods were used to test it.

Response 1: Thak you for this comment. Regarding this, the first paragraph of the 2.7 section (page 6 lines 279-285) has been changed.

Comments 2: justify why you chose Dunn post-hoc. Why did you give it priority (there must be a basis for the structure of the data) over the Mann-Whitney post-hoc test?

Response 2: We chose Dunn test because is adequate for non-parametric data, with control of error, I considered robust and precise.

“Dunn, O. J. (1964). Multiple Comparisons Using Rank Sums. Technometrics, 6(3), 241-252.”

Comments 3: It is unacceptable that the effects of agrochemical indicators have been analysed using two methods. If at least one of the datasets has a non-normal distribution, one (non-parametric) method of analysis should be used to analyse all the datasets in that dataset, but without mixing parametric and non-parametric methods (lines 349-351).

Response 3: Thank you for pointing this out. Now all soil properties data has been analyzed with Kruskal-Wallis test.

Comments 4: it is necessary to clearly state how you present the results (a comment was already made on this but you ignored it). If you specify df values next to the H value, you need to write both df values in a different format. The two possible formats are H 3; 26 or H (3; 26). Dunn post-hoc z is lowercase, not uppercase.

Response 4: Format has been changed on all cases. Finally we have decided to use H_{x; y} format.

Comments 5: Despite the fact that the authors claim to have shown the differences between the treatments in the graphs, no changes have been made in the version of the manuscript I got for assessment. For example, Fig. 3 shows differences (no difference) only between 17_24_N and 24_31_N, and the authors do not indicate the significance of the difference between the other treatment variants. The same applies to the other box-plots. By the way, the graph covers almost the entire caption of Fig. 3.

Response 5: In figure 3 differences are only indicated between 17_24_N and 24_31_N because there are no differences between any other groups. Also we have changed the * for letter a and indicate in the caption the meaning of letter a. The same for both plots on figure 4. Caption of figure 3 has been move down so that it is naot covered by the figure.

Comments 6: Instead of adding the missing information to the Table 1 caption, the authors deleted the explanations of all abbreviations. I wrote a note earlier and made it clear that the abbreviations in the header row of the table (the first row of the table) should be explained in the table caption. If you still have questions, I recommend that you read carefully the journal's instructions to authors and the requirements for figures and tables.

Response 6: Sorry for the misunderstanding. The meaning of abbreviations in the header row of the table have been added again in the table caption. Anyway, the complete description of all indices is located and referenced in the 2.3 section on page 4 lines 150-158.

Round 4

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript has been corrected satisfactorily, with only technical shortcomings remaining, which can easily be resolved in the final stages of editing.