Arbutus Decline in the Salish Sea – Past, Present, and Future
Crazy arbutus keeps its leaves and sheds its skin, who ever heard of such a contrary tree? This is the opening line to a song called “Sterner Stuff” written in 1975 by Gulf Islander Bob Bossin. I first heard the song when I was in my late teens, living in northern BC, at a point when I had no recollection of having encountered an arbutus. The words, however, stuck with me. I often think of them as I walk through my neighbourhood in awe of the natural beauty of our native madrone, Arbutus menziesii.
Arbutus Talk
On March 20th, International Day of Trees, the Mayne Island Conservancy hosted Priya Puri from the Raincoast Conservation Foundation for a presentation on arbutus. The presentation was well rounded and highly informative, giving many of us a new perspective on this regional treasure.
Arbutus is an ecologically and culturally important tree that has been on the decline in the Pacific North West for over 50 years due increases in herbivory resulting from loss of predators, as well as a variety of diseases, including root rot (Phytophthora cactorum), Arbutus canker (Natrassia mangiferae) and madrone canker (Fusicoccum aesculi).
Arbutus is not considered an economically valuable species. The curved, multi-stemmed morphology, along with a slow growth rate, contribute to it having no timber value. Historically, some timber managers treated arbutus like a weed, supressing its growth in favour of conifers. It is utilized by artisans and has been used by Coast Salish nations since time immemorial for numerous purposes including tools, clothing from the inner bark, and medicine.
For the W̱SÁNEĆ people, the ḰEḰEIȽĆ/arbutus is a sacred tree. In their story of the Great Flood, their people were saved by tying canoes to a ḰEḰEIȽĆ/arbutus at the top of LÁU,WELNEW/Mount Newton.
Arbutus is a key component of Garry oak and associated ecosystems, which are among the most endangered in Canada. It is an Ericaceous hardwood tree species and is one of 12 species of arbutus, which have a global distribution in arid, sub-Mediterranean and Mediterranean climates in coastal regions of the Americas and Europe. It goes by many names such as madrone, madrona, and madrono (meaning strawberry tree). A. menziesii is unique in that it is the only evergreen broadleaf tree native to Canada, and among the other Arbutus ssp. and Ericaceae species, it is the tallest and most tree-like. Interestingly, arbutus retain their leaves from June until August the next year, resulting in just 1-2 months of overlap when the previous years leaves are present with the new seasons growth. Some trees will lose their leaves a bit early in some years, making them leafless in April and May until the new leaves emerge in June. Arbutus are generally a long-lived species with some trees estimated to be over 500 years old.
Priya wrote her Masters thesis (Forestry) on the Influence of seed origin on Arbutus menziesii survival, health, and performance in two British Columbia provenance trials. The goal of the study was to understand if arbutus populations in BC might be more resistant to disease and pathogen if grown from seed collected in another growing region.
She gave us a summary of the research that was undertaken using seed from three different regions: British Columbia, Washington, and Oregon. All three provenances (seed sources) were grown in trial plots on Texada Island and in the Cowichan Valley. The results of the field trials suggested that a mixture of seed from British Columbia, Washington, and Oregon provenances may be a suitable option to mitigate arbutus decline and a develop more genetic diverse, resistant, and resilient population of arbutus in our region.
Arbutus Walk
The morning after Priya’s talk, a small group of islanders walked the trails at St John Point with her to put our observation skills to work. I think it is safe to say that we all saw Arbutus through a different lens that day. As soon as we walked on to the oceanside trail at the bottom of the field we were mesmerized by the sheer beauty of these woodland wonders. The walk along the trail took longer than intended because we would stop to talk about the anomalies we observed. Priya had never been to St. John Point, and was taken by the beauty of the place.
A couple of observations were made that are important to share with our readers.
- We observed that there are no seedlings in the natural forest. This is due to deer browse. The youngest trees observed are estimated to be 18 to 20 years old.
- A number of trees have been defaced, where names or initials have been carved into them. Carving into a living arbutus tree with initials or any other markings can increase its susceptibility to disease. The damage creates entry points for pathogens, making the tree more vulnerable to fungal and bacterial infections. These wounds, including carvings, can disrupt the tree’s natural defenses, allowing diseases like arbutus canker to take hold.
More Information
In a note I received from Priya after the presentation she asked that I share her email address for anyone who is interested in getting in touch with her, as well as a link to her thesis.
If you have suggestions for future Conservancy topics or speakers, or if you would like to volunteer for events, please email info@mayneconservancy.ca.
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