Answer:
I don't know exactly what the growth of lichens symbolizes in general, but I found the information about what does it mean for California state:
In 2016, according to The Mercury News (mercurynews dot com), Lace Lichen
becomes state symbol of California. The president of the California Lichen Society, Shelly Benson, said: " Lichens are widely overlooked. Our main mission was really to create more awarness about lichens and their role in the ecosystem."
As Lichen, widespread and may be long-lived, was chosen for a state symbol, its growth may symbolize the increase of state strength.
Explanation:
