I made a chart and in the process learned that as a rule of thumb mulch C:N more or less follows an exponential time decomposition rate for carbon. Your decomposition time will vary depending on location temperature, latitude etc.
I based it on carbon decomposition rate data I could find, and Australian Native Forests and Plantations.
My conclusion is;
- build soil with with grass/legumes/compost/green leaves in the first year.
- add leaf litter in the second year.
- add twig & bark in the third year.
- add branch in the fourth year.
- add sapwood in the fifth.
- add heartwood in the sixth.
Basically; grow to chop and drop and by year 7 your soil will be awesome.