Notes from Windward: #70


Living with Lichens


     If you have the opportunity to walk around the forest in which Windward is settled, you may begin to gain an appreciation for an ancient association between two very distinct life forms‒an association that gives rise to the unique and diverse array of often peculiarly shaped and brightly colored lichens.

     I spend much of my day admiring the lichens that exist on this land, and often at the end of a day of working in the forest I will find that lichens have grown attached to me too‒I find them in my pockets, in my hair, in my shoes. Lichen is a prolific, diverse and beautiful part of this forest, and over a series of articles I hope to be introducing the lichens we share the forest with and how they contribute to this land we call home.

lichen growing on a large rock

     First, a little background about lichens. What we call lichens are an association between a fungus (mycobiont) and a photosynthetic partner (either an algae or a cyanobacteria referred to as the photobiont) that turns sunlight into sugar. There are an array of fungal species as well as algeas and cyanobacterias that can come together to form a lichen in an association that is commonly thought of as symbiotic, wherin both species benefit from the relationship--the fungus receives sugars (e.g. food) from the photobiont and the photobiont receives structure from the mycobiont. Its a partnership that enables both indiviudals to survive in an environmnet that neither would be able to survive in alone. Quite a metaphor.

lichen growing on a bolt

     However, lichenologists are finding that the association is not so simple; a lichen is not necessarily just an association between two species, but sometimes many species of algae can be found in a sinlge lichen, and sometimes the fungus behaves more as a parasite, simply taking the sugars that the photobiont works so hard to make, without giving anything back in return.

lichen growing on the side of a shipping container

     Lichens are an integral part of an ecosystem. While they often can be found on tree branches and trunks, lichens do not actively take nutrients from the structure they are growing on, rather they gain their nutrients from the sun. However they do facilitate chemical weathering and breakdown of whatever substrate they are growing on-- whether that be tree, soil, rock or metal. And as a result lichens can play an important role in colonizing new environments and making conditions suitable to more species. Despite their afinity towards harsh environmental conditions, lichens are very sensitive to air quality, and will not abound in regions plagued by air pollution.

lichens growing in our forest

     Introducing Oakmoss (aka Evernia prunastri). Oakmoss is the lichen that makes our decididous oaks evergreen, for as the oak leaves senesce and fall away every autum, the layer of oakmoss that densly covers the branches of the garry oaks is revealed. For 6 months of the year when the air is cool and moist, the oaks just stand as platforms for what is really a forest of oakmoss lichen.

oak moss

     Oakmoss is considered a foliose lichen (meaning it is "leafy" in structure and is only attached to its substrate at specific points) and can be found growing on trees of all kinds, but if the forest here can serve as a reference then it certainly thrives on its namesake. Interestingly, oakmoss is commonly used in various cosmetic items (soaps, lotions, perfumes) for its musky odor as well as for its ability to function as a fixative for other frangrances.

oak moss overlooking the canyon

     In North America, oakmoss lichen can be found primarily along the west coast, but it also grows abundantly in Europe. Apparently in Egypt, oakmoss lichen has even been added to bread, though for what purpose exactly I am not quite sure.

oak moss growing on a pine branch

Notes From Windward - Index - Vol. 70