I just finished reading Entangled Life (Merlin Sheldrek) and for anyone who has been following Ryan’s nutrition experiments this is worth reading. Actually it is a fantastic read regardless.
It will require a re-read from me but there are some studies cited about the relationship ( more diverse or robust ) between the fungal networks the directly related to annual tree growth.
Also something you never hear that not all mycorrhizal relationships are advantageous. It’s like probiotics , the ones that are manufactured are not the best matches for plants just the easiest to manufacture and blindly adding has potential drawback.
With that said the book made a case several times that all plants basically require some mycorrhizal relationship to be able to get Phosphorus in usable forms. This seems specially important the younger the plant.
Also if you ever heard Ryan say “trees don’t have credit cards” , this is probably true in a bonsai pot. But there are several chapters with an immense body of research showing that fungal networks allow for a “carbon/nutrient sharing network” that is cooperative and and top down