Pennisetum Hydridum’s Potential for Controlling Invasive Chromolaena Odorata

Round 1

Reviewer 1 Report

The manuscript of Xu et al. “Pennisetum hybridum potential for of control…”  deals with an interesting aspect of plant ecology as it is plant invasion ecology and tools and procedures to control the invasion of certain number of species very damaging for the environment as it is considered Chromolaena odorata. The manuscript is clear, easy to follow, well related results with discussion and figures and tables are appropriate in general. I have some minor concerns about the manuscript related with the ecological insight of the study (and the sustainability relationship of the study), the requirement of some statistical correction and as well as the local interest of the manuscript. Also the English sounds good along the text, I found some weird expression that can be correct but not appropriated for a scientific manuscript, because of that I will recommend the edition of the manuscript by a native technical professional editor.

More specific changes

Introduction.- One of my main concerns in the justification of using an exotic (and hybrid?) species in order to control the dispersion of an invasive species. So, you are not doing any ecological restoration at all, you are switching from one species considered very negative to another with not ecological value from the ecological point of view, but of interest for forage in some areas. Can you develop this idea in the introduction? This aspect can go against the scope of the journal “sustainability”, but can be defended if the eradication of another more pernicious species is possible.

Line 70: What do you mean with “destructive plant”? is it modifying the ecosystem at any level? i.e. Myrica faya modifies the nitrogen cycle in some island, favoring a complete change at ecosystem level, while Bromus tectorum modifies the cycle of the disturbances (fire), favoring the colonization of more and faster areas… why is so destructive C. odorata? Maybe the colonization of C. odorata is related with habitat changes induced by humans; in that case, C. odarata is not a cause of disturbance, just a symptom.

Figures: You have a great number of analyses, in these cases are necessary to apply a correction; I will recommend a multiple test comparison (Bonferroni or Holm).

Fugure 5a,b,c: If you do not have statistical differences in all the groups analyzed, then you do not have to located letters over the columns.

Discussion: Discussion can be reduced in a 30% base in the obtained results.

In general, the paper is of interest, although long for the restricted results obtained and with results obtained at a local level. In spite of these aspects, I consider that manuscript can be of interest if it is published a “study case”, “note” or “short communication”.

Author Response

The manuscript of Xu et al. “Pennisetum hybridum potential for of control…”  deals with an interesting aspect of plant ecology as it is plant invasion ecology and tools and procedures to control the invasion of certain number of species very damaging for the environment as it is considered Chromolaena odorata. The manuscript is clear, easy to follow, well related results with discussion and figures and tables are appropriate in general. I have some minor concerns about the manuscript related with the ecological insight of the study (and the sustainability relationship of the study), the requirement of some statistical correction and as well as the local interest of the manuscript. Also the English sounds good along the text, I found some weird expression that can be correct but not appropriated for a scientific manuscript, because of that I will recommend the edition of the manuscript by a native technical professional editor.


 

Point 1: Introduction.- One of my main concerns in the justification of using an exotic (and hybrid?) species in order to control the dispersion of an invasive species. So, you are not doing any ecological restoration at all, you are switching from one species considered very negative to another with not ecological value from the ecological point of view, but of interest for forage in some areas. Can you develop this idea in the introduction? This aspect can go against the scope of the journal “sustainability”, but can be defended if the eradication of another more pernicious species is possible.

 

Response 1: Thank you for your suggestions!

An exotic species which is not capable to regenerate in particular habitats or competitively subordinate to native species will achieve natural eradication of it and promote restoration of native communities after excluding the target invasive plant. We have listed examples and added explanations at the first and second paragraphs of section ‘Introduction’ (Lines 45 – 50 and Lines 57 – 60).

 

Point 2: Line 70: What do you mean with “destructive plant”? is it modifying the ecosystem at any level? i.e. Myrica faya modifies the nitrogen cycle in some island, favoring a complete change at ecosystem level, while Bromus tectorum modifies the cycle of the disturbances (fire), favoring the colonization of more and faster areas… why is so destructive C. odorata? Maybe the colonization of C. odorata is related with habitat changes induced by humans; in that case, C. odarata is not a cause of disturbance, just a symptom.

 

Response 2: Thank you for pointing out this problem.

In its invaded range, C. odorata can inhibit soil biota, decrease the richness of almost all native plants and form mono-dominant stands, suppress regeneration in native communities, and alter the fire regime in savannas. We have added this information at the section ‘Introduction’ (Lines 76-78).

 

Point 3: Figures: You have a great number of analyses, in these cases are necessary to apply a correction; I will recommend a multiple test comparison (Bonferroni or Holm).

 

Response 3: We have applied the Holm method across all the LSD tests, and adjusted the results in Figure 2, 3, 4 & 5. According to the latest analyses, the results have been slightly changed (Lines 198, 213 and 215), but major results and conclusion have not been changed.

 

Point 4: Fugure 5a,b,c: If you do not have statistical differences in all the groups analyzed, then you do not have to located letters over the columns.

 

Response 4: Thank you for pointing out this problem. We have erased the letters over the columns in Figure 5a, b, c & d (Line 249)

 

Point 5: Discussion: Discussion can be reduced in a 30% base in the obtained results.

 

Response 5: We have rewritten part of Discussion (Lines 313 -321).

 

Point 6: In general, the paper is of interest, although long for the restricted results obtained and with results obtained at a local level. In spite of these aspects, I consider that manuscript can be of interest if it is published a “study case”, “note” or “short communication”.

 

Response 6: Thank you for your suggestion! But we still hope the manuscript published as “article”.

Reviewer 2 Report

The paper is of high scientific value.

I have one big concern. I could not find more precise information about Pennisetum hydridum apart from very short:

Hybrid giant napier 78 (Pennisetum hydridum) is a tall, exotic, multipurpose crop with high photosynthetic efficiency 79 (Ma et al. 2011)

I have only access to the abstract of the paper:

Ma C-j, Liu F-g, Chen J-c, He J-m (2011) Correlation analysis between yield and morphological traits of 385 hybrid giant napier of different growth years. Pratacultural Science 28.

I strongly recommend to describe it very clearly and in a detailed way the origin of the plant. My experience is, that the Replacement control is a method of invasive species make sense only when the native wild plant is applied.

 

Author Response

Thank you very much for your suggestions!

Pennisetum hydridum is a tall multipurpose crop with high photosynthetic efficiency, and is a perennial, tussock- forming plant, and formed as a hybrid of elephant grass and African Pennisetum (P. purpureum × P. typhoideum). It is recorded and conserved by International Center for Tropical Agriculture (CIAT), coded as CIAT6263. This information have been displayed the first paragraph of section ‘Materials and site’ (Lines 102 – 104).

An exotic species which is not capable to regenerate in particular habitats or competitively subordinate to native species will achieve natural eradication of it and promote restoration of native communities after excluding the target invasive plant. We have listed examples and added explanations at the first and second paragraphs of section ‘Introduction’ (Lines 45 – 50 and Lines 57 – 60).

Pennisetum hydridum is a strong competitor, has little invasion risk, does not produce allelochemicals, and can be easily removed (Lines 87 – 88). Its properties suggest that it is a potential candidate for replacement control.

 

Round 2

Reviewer 1 Report

Dear Editor,

The manuscript improved in many aspects, but I still consider that the scientific soundness of the subject is very limited, and I still will consider to be published as a short note...

Other specific comments and clarification that still remain:

Line 168: should say "P values were corrected with a multiple testing Holm´s procedure" Again line 218 Title graph 3,4,5 Reduction of a 40% of the discussion is still needed

Author Response

 

Point 1: The manuscript improved in many aspects, but I still consider that the scientific soundness of the subject is very limited, and I still will consider to be published as a short note...

 

Other specific comments and clarification that still remain:

 

Line 168: should say "P values were corrected with a multiple testing Holm´s procedure" Again line 218 Title graph 3,4,5 Reduction of a 40% of the discussion is still needed

 

Response 1: Thank you for your suggestions! We made revisions as follow:

We have corrected the mistakes in section “Data analysis” (Line 165) and in the captions of Figures 2, 3, 4 & 5 (Lines 214, 229, 246 & 262). We have lightly reduced the “Discussion” (Lines 313 – 315). However, to fully discuss our results, most content of “Discussion” was remained.

Author Response File: Author Response.docx