Going back 15 years or so folks in Japan started reporting germinating and growing orchids from seed on a growing medium of corrugated cardboard.
So what is it about cardboard??
Let me post a couple of photos of cardboard on the surface of compost to which a blob of mycorrhizal fungus has been added.
It’s quite convincing that the fungus grows well over the cardboard and that superhighway seeds the surface of the compost.
The corrugated cardboard has moisture, air, celluloses, lignin ( and possibly glues).
If this whets the appetite - there is facebook site on growing orchids from seed on cardboard. look it up ‘Cardboard Orchids Sowing’