by Andrea Williams
Some years ago, a lichenologist gave me a sage piece of advice: there’s no better lichen viewing than in an oak woodland after a rain. And I tend to agree, especially after a storm like we’ve just had. The normally gray spots on dark branches and trunks pop vibrant gray-green, pale gray, blue-green, and yellow-green against wet bark, and the many small branches with lichens—or even the lichens themselves—have fallen to the ground for easy examination.
Lichens are fascinating for so many reasons: the mutualistic relationship between fungus and algae that allows them to live almost anywhere on the planet; the fabulous variety of shapes and colors; their role as ecosystem pioneers, indicators, and engineers. Many of us know so little about them, it can be difficult to appreciate them. But even realizing that lichens are beneficial to the trees they grow on, not harmful, can aid in improving one’s outlook on lichens. Lichens growing on trees are only using the branch as a platform; they don’t tap into the tree’s nutrients or water like a parasite. Instead, because lichens are “leaky,” they often add water and nutrients harvested from fog or rain—especially nitrogen—back to the soil through dripping or dropping to the ground, as has happened during this storm. It’s true, you do tend to see more lichens on dead or dying trees, but that’s not because the lichen killed the tree. Rather, the lichens grow better with more light and also are easier to see with fewer leaves on the tree.
To learn more about lichens, the California Lichen Society is a great resource. They produce a mini-guide to Northern California lichens and hold ID workshops at the College of Marin a couple of Fridays a month. And this Friday, October 16, from 11-2 they’re leading a hike from Rock Spring parking area (at the intersection of Pantoll Road and Ridgecrest Boulevard outside of Mill Valley). Calling it a “hike” may be an exaggeration—there is such lichen diversity here they won’t get far!