Dear authors,

thank you for submitting the revised manuscript, which has been evaluated again by on of the initial reviewers. While the reviewer appreciates your conceptual approach, it remains unclear in how far the new benchmark methodology is applicable. I agree that more information and a clear presentation is required to show this. For example, the optimizations and model parameter adjustments are challenging to interpret in the context of applying and benchmarking LSMs. E.g. L375 states that ORCHIDEE parameters were adjusted to ITRDB sites while L426 states that also the default parameterization was used. Table 2 shows an improvement or deterioration of benchmark metrics if optimization parameters are applied - with mixed results and for few sites -, but from the discussion of these results it remains largely unclear what this really implies for being able to use ITRDB for the proposed purpose, including information on how representative the experiments in this study are for ITRDB. This renders it challenging to conclude in how far the methodology is applicable in practice. Please consider the reviewer's comments and my additional suggestions in preparing a revised manuscript.

Sincerely,
Christian Folberth

Further suggestions:

- Section 4.1: The counts and corresponding percentages of improved metrics with optimization appear not to agree with the bold boxes in Table 2. Please check and/or clarify.
- Discussion: Subheadings may aide in better following the presentation.
- Please check captions of supplementary figures, i.e. Fig. S2-S4 show diameter.
- Regarding the clarity of the manuscript, i.e. the modelling, data processing and optimizations, it may be helpful to include a diagram of the study design and workflows
- I recommend updating the code repository, especially if this may aide in reproducing your experiments during further review.

Dear authors,

your manuscript has now been assessed by a new reviewer. While the reviewer in principle acknowledges the scientific approach of the study, he/she still has substantial issues following the presentation, which may impair full judgement. There are also major concerns regarding parts of the presented concepts. Please consider these comments when preparing a revised manuscript and thoroughly elaborate on the study presentation, structure and intelligibility.

Sincerely,
Chris Folberth

Additional comments:

1) One obstacle to the intelligibility may be the enumerations in sections 2.1-2.3 (and beyond), all of which have 3-5 bullets that partly relate but are not fully consistent, which also raised questions by reviewer 3. Condensing and/or restructuring section 2 would certainly improve comprehensibility. The new Fig. 2 connects these elements to some extent but foremost serves as a visual TOC. An option may be to extend Fig. 3 with the corresponding virtual trees, metrics, processing, etc. if feasible without overloading. In addition, section 2.3 (iv) contains two metrics, amplitude and timing, which further complicates connecting the descriptions with display items and results. Please consider these as exemplary notes and suggestions.

2) Due to the importance of the virtual tree concept in the study, introducing a separate sub-section would aid in highlighting this.

3) As this study should be considered a proof of concept and presents comprehensive conceptual elaborations, mentioning this in the abstract would aide in guiding readers' expectations. Also mentioning the number of sites used for testing would be helpful in this respect.

4) Legends would improve accessibility of figures. Also check use of "dotted" or "dashed" when describing line types.

Dear authors,

thank you for submitting a revised version of the manuscript. While I appreciate that you have addressed the reviewer's and my own comments to some extent and streamlined the manuscript, issues in the accessibility and presentation of the research still persist, such as the lagged introduction of the central concept of virtual trees in figures and text as well as the use of inconsistent and imprecise wording. A few non-exhaustive examples are provided in the attachment.

Prior to proceeding with this manuscript, these issues will need to be addressed. As all reviewers so far have acknowledged the scientific approach and merits of the study, albeit noting that not all details were clear to them, I hope the authors can sort this out.

In addition, there are changes - although minor - in the main results table that are not indicated anywhere or adopted in the text. This is not best practice. Thoroughly check your evaluations and the manuscript for consistency, and track and explain any corrections you may have to make.

Best regards,
Chris Folberth

Based on my assessment, the authors have addressed the reviewers' comments raised throughout the discussion, and substantially improved the clarity and structure of the manuscript eventually. Therefore, I am happy to recommend acceptance of this manuscript subject to technical corrections as detailed in the attachment.

Best regards,
Chris Folberth

Dear authors,

based on the revisions, I am happy to accept the manuscript for publication. Attached are few editorial comments to be considered when preparing the final manuscript.

Sincerely,
Christian Folberth