How FATES simulates tropical ecosystems respiration

[suger-WU]

Dear model developer,

I have been using two different initialization methods in the FATES model — "cold start" with a spin-up of 500 model years and "cold start" with inventory initialization — to simulate ecosystem respiration in the Amazon dryland region. The parameter files for early and late successional broadleaf evergreen forests are being used in these simulations.

After comparing the simulation results with the observational data obtained from eddy covariance towers, I noticed that the ecosystem respiration results from both methods show a considerable discrepancy with the observations. Furthermore, neither of these methods seems to capture the seasonal trends in respiration, which is a key aspect I was hoping to observe.

Additionally, I am puzzled by the very low values of heterotrophic respiration obtained in both simulation methods, which seems unrealistic given the conditions. Could you please help me understand why this is happening and suggest appropriate methods or adjustments to improve the simulation of ecosystem respiration?

I would greatly appreciate your insights and advice on how to more accurately simulate ecosystem respiration.

Best,
Xiuyi