Dear authors:

Thank you for sending your replies to referee comments. Your manuscript received four reports, which suggest controversial decisions from reject to minor revision. I read carefully all comments and your responses and conclude that this manuscript has a couple of shortcomings claimed by multiple referees. First, referees claimed about the fact you developed a conceptual approach but applied to a real forest (i.e. Harvard Forest). In most cases, readers expect that a new approach may explain the reality (observation) better than previous works and deepen our understanding. However, you declared that this is a conceptual paper and theoretical exercise and that accuracy is not requited for the specific site. This is, indeed, disappointing for many readers. Second, referees claim that the manuscript is insufficient (i.e., too concise) in the model description, leading to some confusion and misunderstanding.

Referees in general agree that this work has good scientific significance, and for most of the minor points, your responses look appropriate. Finally, I conclude that the manuscript needs major revision considering all comments (including above ones) especially in terms of presentation, and the revised manuscript should be re-examined by (same or other) referees. I appreciate your efforts and am looking forward to receiving the revised manuscript.

Dear Authors:
Thank you for providing your responses to referee comments and a provisional revised manuscript. For many points, you agreed to modify the manuscript as suggested, including a major modification of Method section. Although it is still arguable that this manuscript lacks quantitative comparison (in addition to qualitative one, such as statistical metrics), I confirmed that it was fairly improved. I have one reservation. In response to referee #3, you agreed that the spike of root C in Figure 4 could be caused by a wrong initial value. If so, give a revised simulation result using a better initial value. Please do your best, even though this is a conceptual study. Without this, I cannot accept this manuscript. Also note that I may ask the referees to examine the revised manuscript.

Dear Authors:
Thank you for sending the revised manuscript.
I shared it with referees and asked them whether they have additional comments. No additional question and recommendation was provided from them. Based on my examination of the revised manuscript, I conclude that it would be acceptable for publication from Biogeosciences.