FLORA + FAUNA OF THE NORTHWEST COAST A Look at Lichens

from COMPASS MAGAZINE VANCOUVER ISLAND | Issue 35 October / November 2021

by Compass Magazine Vancouver Island

WALKING IN THEIR FOOTSTEPS Harvesting on Vancouver Island

LUNA LOISEAU-TREMBLAY

With the change in season comes the rehydrating of

a group of special organisms often mistaken for fungi. Lichens are all around us when we step outside; on the forest floor, plastered on tree trunks, pouring from branches up in the tree canopy, forming designs on grave markers in a cemetery, clinging onto rock bluffs, even park benches!

Lichens are an example of a fascinating mutual symbiosis between fungi (the mycobiont) and a photosynthetic plant partner, namely green algae and/or cyanobacteria (the photobiont). In a lichen, the plant partner converts carbon dioxide into carbohydrates through photosynthesis, while the fungal partner provides the structure, allowing for greater surface area for the uptake of minerals and protection from too much light and drying up. Because of this incredible partnership, lichens are able to live in every environment, from dry coastal desert climates to freezing arctic temperatures, able to withstand an amazing spectrum between very wet and very dry conditions. Lichens are important because their presence is an indicator of healthy air quality, but they also contribute significantly to many processes such as nitrogen fixation and the biodiversity of plants and animals. With over 1000 species on the Pacific Northwest, lichens are a popular food, shelter and nesting source for many different kinds of animals from deer, elk and moose to mice, squirrels, birds and a multitude of insects and other arthropods. Lichens were traditionally used in many different ways by humans, and in this day and age are used as antibacterials in medicines, and in textiles such as wool dyes.

Growth of lichens comes in three main forms, defined by the terminology fruticose, foliose and crustose. Fruticose lichens are shrubby, an example common to our area is Reindeer lichens (Cladonia sp.), while foliose lichens are leafy and are often epiphytic, using trees as a support to grow and live on but without taking nutrients from the supporting structure. A common species of foliose lichen on the coast Lobaria pulmonaria (Tree

Lungwort) is often found hanging off the expansive branches of large maples. The third main form is crustose, in which the lichen cannot be separated from the substrate without taking it apart, such as in a powdery lichen on a rock or wood surface.

Often many different species of lichens will have colonized a small area, such as a small square of a tree trunk or branch surface. It is worth noting that lichens grow very slowly and it may take years to replace if their habitat is distrubed or destroyed. Although there is a great number of species in British Columbia and worldwide, lichens are poorly studied as qualified Lichenologists are few and far between.