Solanum elaeagnifolium Invasiveness under Semi-Arid Environmental Conditions in Tunisia
Round 1
Reviewer 1 Report (Previous Reviewer 3)
I was already involved in the review process of this manuscript earlier and already back then found the topic interesting and well suitable for the MDPI journal Earth. In the first round of the review process, I had two major recommendations for improvement, first a more detailed description of the study site, and second, a more in-depth discussion about possibilities for control of the invasive species Solanum elaeagnifolium. While the authors adequately addressed the first issue, a serious discussion about possibilities for control beyond the application of chemicals is still basically missing, even though a short statement is added, that it is wise to prevent spread (what it is, for sure). Obviously the authors do not want or are not able to discuss this in more detail in this manuscript, which is their decision and which has to be respected. So, while still not fully convinced by the revision, from my point of view this manuscript can now be accepted for publication.
Author Response
Corresponding Author: thanks for these positive comments. As the reviewer very clearly states, there is not in the manuscript a deep discussion about possibilities for control beyond the application of chemicals. Actually this is not one of the aims of the research, and in general, in the whole invasive range of this species, there is little available information on this aspect. However, a sentence was add at the end of the conclusion section.
Reviewer 2 Report (New Reviewer)
The reviewed text addresses an important issue related to learning about the biology of invasive alien species in their new environment. This issue is particularly important in light of the growing problem of the negative impact of alien plant species on the environment and the human economy, as well as with the typical ability of invasive species to change their biology in newly colonized areas. The authors conducted an experimental study on the growth of Solanum elaegnifolium under the climatic conditions of North Africa in order to understand the biology of its growth and propose actions to control the population.
The text is written in a clear manner, allowing the reader to easily follow the reasoning. The way the field experiment was planned and the analysis of the results are not objectionable. Despite the local nature of the research, its results should be of interest to readers throughout the Mediterranean, South Africa and Australia. The text fully deserves to be published.
I hope that the authors continue their research to confirm the effectiveness of the proposed methods for the successful removal of this species.
The only objection to the reviewed text concerns the quality of the figures - in my copy they have low resolution and should be corrected.
Author Response
Corresponding Author: thanks for these positive comments. We will provide high resolution figures in the final editing steps, if the manuscript will be accepted for publication.
Reviewer 3 Report (Previous Reviewer 2)
In my previous review report, I recommended minor revision of the manuscript.
My new review report is still recommending the minor revision. The results are interesting, but they are presented poorly. What do I mean? See my comments below.
1. All illustrations are of the poorest quality. I cannot read words on the map in Fig.1. The low quality of illustrations is related to other figures in the manuscript.
2. In all graphs, bars should be added. It is strongly required to see standard errors of the presented mean values. In all graphs, you should add measurement units to the descriptions of X and Y axes.
3. In table 1, please, add measurement units for the precipitation.
4. In Fig. 3, you should designate what scale relates to columns, and what scale to lines. Now it is not obvious.
5. The main problem is still Conclusion. The main aim of this research was to identify possible management actions. This section doesn't provide any answers to this research questions. In addition, this section also doesn't answer the first question: What are the most important traits that make Solanum elaeagnifolium a successful invader? You should re-write completelt the Conclusion by answering all questions stated in the aim.
Author Response
Corresponding Author: thanks for these positive comments. The study is mostly an observational study, so that the data are analyzed with very basic statistics (e.g., error bars are not plotted in the graphs). The requested information on the graphs are actually (in some cases) included in the captions, and we will provide high resolution figures in the final editing steps, if the manuscript will be accepted for publication. We partially rephrased the conclusion section, according to reviewers’ comments.
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
Review earth-1878674
The paper entitled “Solanum elaeagnifolium invasiveness under semi-arid environmental
conditions in Tunisia” aimed to assess the plant traits, which are responsible for the invasiveness of this alien species. This study addressed a highly relevant ecological topic, but the journal Earth is not suitable for the publication of this topic. Overall, the present study has serious flaws concerning above all the design of the study (only one field site), the kind of the presentation of the results and the discussion.
In detail you can find my specific comments on the manuscript which I have broken dawn into the main sections of the manuscript.
Abstract:
Line 14: growing cycle? This is a phonological description of this plant species.
Lines 19–22: rephrase this section
Introduction:
Line 37: may replace? If available add some detail information about the influence of this invasive plant on native vegetation.
Line 40 ff: Add a short description of the distribution of this invasive plant in Tunisia
Line 42: invasiveness? Invasibility is the appropriate term.
Line 47: add some information about the role of animal husbandry practice for the dispersal of this invasive plant.
Material and methods:
Line 56: field experiment (you did not manipulate plants in the field)
Lines 56: Add an improved description of the field sites including soil and vegetation type. Only one field site; thus, the outcome of this study is restricted to this specific environmental conditions.
Lines 74–75: Flowering and fruiting are two phonological stages
Are seed production data recorded in this study?
Results:
Line 84: Therfore, …. Delete this sentence from the paper
Lines 85–150: In general, this section has to be re-organised. First, begin with a short description of the phenology of this plant species. Afterwards, all the recorded data has to be presented on the basis of plant individuals (n = 160) by calculation mean ± sd or se or probabilities (e.g. flowering and fruiting). The labelling of the Figures has to be improved (remove SOLEL, Fig.2 for example number of new shoots)
Line 97: … 2.2 times higher… Plant size effect
Discussion:
Here I missed a comparison of the findings with comparable native plant species.
Reviewer 2 Report
After reading the manuscript, I have found it very good in quality of the level, presentation and obtained results. I would like to add some comments below.
The Introduction is well written, as well. I recommend just state what research tasks were established to reach the aim.
In Materials and Methods, the research design has been described very well.
But, Fig. 1 has poor quality. I don't know why (maybe, it is caused by the PDF creation programme), but it would be better to improve the quality of this illustration.
In the section Results, figures 3-6 are recommended to merge in a composed illustration, where Fig. 6 would be in the bottom right corner (for illustration of the studied species). For each graph plot, please, add error bars. Is it possible? This will show the range of reliable values
Other parts of this section are well written.
The section Discussion is relatively well written, but in some cases, there is irrelevant material. For instance, lines 158-161 present the description of the obtained results, but it is not a discussion of results. The same is occurred for the whole paragraph in lines 182-191. This is the description of the obtained results. These and other parts should be moved to the section Results, while in the section Discussion, these results need to be discussed accordingly in light of the modern literature.
In the section Conclusions, please, add research implications and/or recommendations for counteracting the invasion of this alien Solanum species. In addition, it would be great, if the authors can compare these results with similar data obtained for other invasive Solanum species in this and other regions of the world.
Reviewer 3 Report
The manuscript entitled „Solanum elaeagnifolium invasiveness under semi-arid environmental conditions in Tunisia“ shows results of a three year plantation experiment conducted with this invasive weed, including vegetative propagation, flowering, fruiting and spread pattern under semi-arid environmental conditions. Results indicate the potential for rapid spread of Solanum elaeagnifolium and the high invasiveness of this species. This is an interesting study and well fitting the scope of the MDPI journal Earth. The study design, the analyses and the presentation of results are simple but adequate and sound. I have only two points I would like to ask the authors to address in a moderate revision (as this was not an available option I opted for major revision, which it is definitely not)
1 1) My first point is related to a study area description, which is basically missing. Please provide a map of Tunisia showing the location of Chott Mariem. And please also give some basic information on the study area, i.e. on climate (seasonal course of temperature and precipitation, chances for freezing events, which are mentioned in the ms), on natural vegetation Including some of the more common species and the vegetation structure (is it grassland or shrubland or semidesert???) and on land-use patterns (grazing???, which animals???).
2 2) My second point is related to the use of chemicals as management practice for Solanum elaeagnifolium infested areas. Application of chemicals is a fairly non-ecological measure for the control of alien plant species and from a nature conservancy point of view should not be the first choice. What about covering infested areas by blankets for a longer timeframe to prevent photosynthesis, a measure applied to other invasive neophytes in Europe. Are there other options? Please, also discuss in more detail possible collateral damage to the native flora and fauna when applying chemicals as control measure of this invasive weed.
