Assessing Water-Saving Technologies and the Impact of Giant Tortoise Herbivory on the Restoration of Opuntia megasperma var. orientalis on Española Island—Galapagos

Round 1

Reviewer 1 Report

In the context of in the establishment of an endangered plant population the study demonstrated the value of water conserving devices and cages that protected seedlings from herbivory from giant tortoises. The work has value in documenting the restoration attempt and provides further evidence of the benefits of water conserving systems in these arid environments.

Because some birds eventually found their way into the cages and were trapped  the researchers decided to remove the cages and all the plants all died (as far as I can tell). Please state in the main document that no plants survived after the removal of cages if that is indeed true (as it appears in the supplement). The use of these water conserving devices for restoration had been tried elsewhere so the outcome was unsurprising, but you did demonstrate their use in the difficult conditions on Epanola. You did discuss the decline of the Opuntia population, but did not state for sure if any natural recruitment is now occurring on the island. If not, the situation looks bad, and its a bit mysterious how recruitment might have happened prior to the arrival of goats?  Would it have been worth it to kill a few birds for the sake of establishing the endangered cacti? The bird species you mentioned looked like common ones.

The study was very applied and the data collected in the context of an evolving restoration effort over several years. As an experiment it suffered some weaknesses but it seems forgivable in the circumstances.

Methods and results

The regression  data were not presented in full anywhere. 

I had strong suspicion that the data should have analysed so the three planting areas were a treatment and that the "batches" were also spatially restricted. Were the batches randomly spread between the three sites mentioned in Fig 1? If not you need to explain why you'd expect the conditions to be mostly similar, and that the rainfall/temperature to survival relationship  is more important than the site characteristics? Also it didn't look like you measured rainfall at the different planting sites directly?  So in the end I did not find the correlations Table 2 to be terribly convincing. Also I couldn't imagine how you really did this , and whether this should work for time series data. If all sites have mortality, how would their be a correlation between low mortality and high rain? You need to explain this in more detail if you decide to keep it at all.

Fig S3 should say what the red line and blue bars represent.

Table 3  you need to say what the F statistic and p-value are in the table caption. Shouldn't the regression be run as a single analysis with batches as a variable?

You might consider a title that includes tortoises

Seedlings of rare  Espanola Island (Galapagos) cactus successfully  established using water conserving technologies and giant tortoise exclosures.

Giant tortoise exclosures and water conserving technologies are essential elements in the effort establish endangered cacti on Espanola Island (Galapagos)

Comments for author File: Comments.pdf

Most of the changes I suggest are to improve the readability of the article. I made dozens of comments and edits in the document - I hope they help. Several short paragraphs on a single topic should be combined. Their was repetition often in the same paragraph.

Author Response

Please, see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

1- Does prickly pear as a vernacular name corresponds to Opuntia megasperma var. orientalis? The authors should clarify in Introduction section. If is that true please report a vernacular name in the abstract and scientific name between parentheses.

2- Groasis Waterboxx®: is not informative, therefore authors should clarify briefly the technology in the abstract and Introduction 

3- The authors reported that : O. megasperma var. orientalis is considered an endangered species. Why this meaning does not apperas clearly in the title of the manuscript ?

4- Introduction line 38: highlighting the impact of invasive species on fragile ecosystems. Authors are invited to include references and mention examples of invasive species and if possible a table summarizing  that point 

5- Figure 3 need amelioration (High resolution) especially for the text of histograms

6- Supplementary material is not available

Author Response

Please see the attachment

Author Response File: Author Response.pdf