General comments

This is an excellent article on a very timely issue. In fact, effects of climate change on alpine vegetation have so far almost exclusively been analysed with respect to the impact or warmer temperatures. The parallel effect of drought, triggered by higher demand at higher temperatures even with stable precipitation sums, has largely been neglected. In his paper, Choler convincingly shows that this might become a major driver of plant productivity, especially when warm and dry years / years with little snow fall coincide – a coincidence that will likely occur more frequently in the future. I think the article can and will contribute to re-focusing the interesting of alpine ecologists on these interactions between warming and drought, not only in terms of productivity, but also in terms of species distribution and diversity.

Specific comments

I found the analysis very well done and the paper very well written. The discussion is thoughtful and does not overstretch the findings. I have just one minor comment

1. Other than stated on line 37, there are reports of decreasing plant cover at high elevations over the last decade also in the more humid north-eastern parts of the Alps (cf. Lamprecht et al. 2018, New Phytologist).

Some typos

• Line 27: effect instead of effects
• Line 42: mountain ranges instead of mountain range
• Line 99: seasonally snow covered instead of seasonally snow covered
• Line 277: such as woody instead of such woody
• Line 314: Remove ‘D’

Review of

Above-treeline ecosystems facing drought: lessons from the European 2022 summer heatwave

by Philippe Choler

General comments:

This is an interesting statistical analysis focusing on the response of alpine vegetation to climate conditions. Several datasets are used, including a remote sensing product. The paper is short and well written, but could be improved.

Recommendation: minor revisions.

Particular comments:

- L. 6 (“Europe”): replace by “a large part of Europe”

- L. 136-137 (noise of MODIS NDVI): the choice of the MODIS NDVI should be better justified. Why not using the CGLS LAI or NDVI products? They are much less noisy that the MODIS products.

- L. 240: The Discussion section is good but a difficult to read. Readability could be improved by reorganizing Section 4 into subsections corresponding to questions to be addressed.

- L. 336: Of course, higher spatial resolution atmospheric reanalyses are needed, especially over mountainous areas. You may also mention that high spatial resolution products are now available (Sentinel-1, Sentinel-2 for example).

Editorial comments:

- L. 27: negative effect

- L. 29: occur

- L. 99: seasonally snow-covered