Jinshi-Ben-Meeting 2021-08-25

[jinshijian]

SRDB

• Checked all data inputs from SH and HN.
• The editor of Ecosystem Health and Sustainability asked me to write a review paper about soil respiration. https://www.tandfonline.com/toc/tehs20/current

Soil Erosion Database

• Cobined data from 3 other review papers.
• Data from 400 more papers.
• Including only field measurements.
• Will have the manuscript updated soon.

Global C

• The deadline for the GLobal C manuscript resubmission is close, but the CIMIP6 data has some issues need to be resolved.
• It shows that RH:GPP ratio > than Rs:GPP ratio. For this two models (CESM2, CESM2-WACCM) have both Rs and RH, Rs:GPP = 0.27, but RH:GPP = 0.42 (please see also the attached figure).
• Possible reason: The previous Rs probably are root respiration rather than soil respiration; or the models developer updated their data (unlikely).
• To resolve this, we can (1) update the Rs data for those model have Rs data (The only models that have raRoot are CESM2-FV2, CESM2, CESM2-WACCM-FV2, and CESM2-WACCM), but Kalyn looks pretty busy, I dont know when she could provide me the updates.
• or (2) CMIP6 models also have ra data, we can using bootstrapping approch to estimate root respiration based on ra and (root:ra ratio from SRDB, similar as the method we used in the previous analysis), in this approach, we could have Rs:GPP ratio for all CMIP6 models (I actually like this approach more).
• but the proble for approach (2) is I am not 100% sure the ra outputs is totally ra or aboveground ra, I checked with Kalyn, but I got no sure answer from her either.
• Regarding the Ra column here is the description of the variable directly from the CMIP6 variable table Carbon mass flux per unit area into atmosphere due to autotrophic respiration on land (respiration by producers) [see rh for heterotrophic production] where as the description of Ra Root is Total autotrophic respiration from all belowground plant parts. This has benchmarking value because the sum of Rh and root respiration can be compared to observations of total soil respiration.
• , within that I see there is a Ra column, is this total autotrophic respiration or root respiration? If it is root respiration, that is great, I can directly get Rs = Rh + Ra.
• I did some caculation based on the CMIP6 outputs of GPP, Rh, and ra: residual = GPP - Rh - ra; and I found the residual is pretty big (~30% of GPP). If ra is total autotrophic respiration, then the residual should be close to 0. In this case, I assume ra from the CMIPS are above ground autotrophic respiration.
• Another question about CMIP6 data, there are few very small rh values, delete, or do some corrections?