As I recently wrote (10/30 Fall and Rise) nearly all the old ash trees of this forest are dying or dead, due to infestations of the Emerald ash borer. Pieces of them – from giant limbs to little crumbs, will be raining down onto the forest floor for at least another decade. Besides the obvious hazard to those of us who spend a lot of time in the forest, there are some unique opportunities…
…to see life forms that usually are happy to stay well above our heads. Several newly fallen chunks of ash lay on the trail yesterday, encrusted with foliose lichens in delicate shades of pale green. The very frilly Ruffle lichen was particularly interesting to see, since it doesn’t commonly grow near ground level. They all appeared to have been thriving prior to their fall, likely due to increased light levels as their tree declined. As you may know, lichens are actually a cohabitation of fungi and algae. They inhabit an amazing diversity of habitats, from barren rocky mountaintops to drippy rain forests to deserts.
To answer the question of how they manage to disperse themselves to such varied locales, lichens can reproduce asexually by shedding specialized specks of combined algal cells and fungal filaments. They can also just break into tiny bits when dried out – so either a windy day or a birds foot would suffice to get them into the treetops.
These fallen lichens are out of luck – stuck on the ground, they’re unlikely to travel anywhere but into a deer’s stomach. But who knows? If not annihilated by the powerful ruminant digestive system, perhaps they’ll be dispersed again throughout the forest.