Dear authors,
many thanks for your comments. Please resubmit a revised version, providing a point by point explanation on how you have changed the manuscript to respond to the criticisms raised.
Best wishes,
Sönke Zaehle

Dear authors,

many thanks for the thorough revisions, which have addressed the reviewer concerns. I find that the manuscript has been significantly improved. However, I have a couple of minor items that need to be addressed before the manuscript can be accepted for publication.

Best wishes,
Sönke

Comments:

- title: can you think of a more telling / concrete title (e.g. mentioning CO2 and N2O, the land cover types, and/or the geograhic region)? While your study a generally applicable concept of a case-study, the results are specific to the study location.

- I'm confused with the inclusion of G2: I've search the document several times for G2 to find a reason why it was not modelled. If I've missed this in the text, it may lead better highlighting. However, given that the title of the paper is constraining a model (and not on GHG fluxes in a Hessian landscape), I don't see why these data need to be included at all, if these data are not used for the model fusion, or highlighted in discussion and conclusion as an important area for model development?

- I think the conclusion section (or an additional Discussion section) needs to be extended to briefly explain what this study has contributed in terms of novel understanding of GHG fluxes at the study location (at least in terms of potential for new knowledge now that the system works). Currently, the conclusion section is a good summary of the manuscript, but ...

Minor comments:

- p3 L11: Light beech or European/common beech?

- p3 L 18-19: Please check these numbers. Is wet deposition really that low? What about dry deposition? Note the unit still needs to be kg N / ha / yr.

- Section 2.3.1 - given the tiered model-data-fusion later, briefly explain already.
here whether or not CO2/N2O losses feedback (and if so how) on water cycle and plant physiology

- Section 2.3.2 - please introduce the meaning of tier 1 and 2 already at the beginning. Otherwise, this is still hard to follow (ie. tier 1 = water and plants, tier 2, GHG given tier 1).

page 7 L 25: define "major effect"

page 10 L13 (and possibly similar instances): four numbers are given, but associated with three treatments, which does not work out. Please clarify text (here, and possibly at similar occasions)

in general: avoid the use of "quite" low etc. thorughout the manuscript. Please use exact language.

Please revise figure axis label to be larger and thus easier to decipher.