The authors received two detail expert reviews that raise major criticisms of many key aspects of the paper. I agree with this criticisms which makes the paper borderline for publication. However, as the authors outline an extensive and detail plan for major revisions that that could bring it above the threshold I recommend re submission that will be reviewed again.

Nevertheless, it should be noted that there are some issues that will be difficult to overcome without actually taking the time and extending the work. The revisions outline mainly suggests to 'admit' the shortcomings, such as the limitations of the model, the disconnection of the model and data, the limited data, missing soil and environmental data, and more. It seems strenuous to justify publication listing so many limitations with the narrow aim of, in the authors words: "...show the need for caution with applying isotopic methodology in multiple situations...".

The report from expert reviewer confirms that the author indeed made a major effort in addressing many of the serious concerns raised in the first review cycle and I concur.

The extensive revisions include additional data, and authors, more attention to the model together with the added simulations, and the expanded and more careful discussion (as well as the useful diagrams). This will make the paper a useful addition to the discussion of the important issue (and dogma) of xylem water isotopic composition, even if it may not provide the 'final word' on the issue. I therefore recommend publication after the minor corrections pointed out by the reviewers are taken care of.

In this additional revisions cycle the authors have now taken care of the remaining, technical, comments of the Rev-1 in a satisfactory way and I recommend the publication of this paper in its present form.