Dear authors,

Thank you for your patience with the review process of this manuscript. We have received comments from two domain experts. Both think the manuscript holds merit, but have several comments.

Both reviewers comment on the issue of generality of results due to the study of a few sites, which should be addressed.

Reviewer 1 also raises concerns about the clarity with the discussion of timescales. I also agree with them that the manuscript could go further to links to prior findings about sap flow-VPD hysteresis.

Reviewer 2 points out potentially unclear objectives. On this point, I do wonder if sufficient motivation and/or investigation of alternatives was provided about the chosen slope and area metrics to address the stated questions. Are there other metrics that should be considered? If not, are these sufficient to understand stress?

Additionally, one could understand water stress from space at daily and longer timescales with plant functioning-soil moisture relationships, making it easier for remote sensing to capture lower frequency sampling needs. More motivation should be provided about additional information held within diurnal sap flow-VPD relationships.

Figure 6 is an interesting contribution and the acronyms should be provided in the caption for clarity.

Please provide a revised manuscript that responds to these reviewer comments. Thank you for submitting your work to Biogeosciences.

Sincerely,
Andrew Feldman

Dear authors,

Based on the reviewer's second review and my own evaluation, the manuscript is now publishable within Biogeosciences. Congratulations!

Sincerely,
Andrew Feldman