The New Year brings not only a new word that I didn’t know before but also an interesting phenomenon (Ha spelt right first time!).
Allelopathy is a biological phenomenon by which an organism produces one or more bio-chemicals that influence the growth, survival, and reproduction of other organisms.
So basically this Lichen is using chemical warfare against the Moss. Yes Lichen. That boring grey, thin, seemingly inactive, crust produces chemicals that directly affect its competition ensuring its survival against the much quicker growing and more invasive Moss which has colonised the whole of the rest of the boulder.
I suppose it shouldn’t be that surprising that lichen, being partly if not mostly fungus, could be capable of producing toxins but this maybe one of the best examples I’ve seen of why they do it.