Its patchy , fragmented distribution makes it likely to experience isolation and extirpation of small populations .
The lichen is also vulnerable because it is slow - growing , slow to recover after mortality , inefficient in its dispersal , and already rare with unstable populations .
lichen 's patchy , fragmented distribution makes it likely to experience isolation and extirpation of small populations .
The lichen is also vulnerable because it is slow - growing , slow to recover after mortality , inefficient in its dispersal , and already rare with unstable populations .