In early April I observed what appears to be widespread disease of Arbutus trees (Arbutus menziesii) on the island. Leaf blight is a known factor affecting Arbutus trees; but I wonder if other factors such as climate change may also be contributing to what is perceived as a general decline of the species.
Arbutus trees are an iconic, evergreen, deciduous species on the Southwest coastline of BC. Many of the trees, which can live up to 400 years, are showing signs of stress or are dying.
I am a resident of Gabriola Island which lies off the East coast of Vancouver Island. In early April I observed what appears to be widespread disease of Arbutus trees (Arbutus menziesii) on the island. This tree species is relatively rare in Canada only occupying a small area of British Columbia’s Southwest coast and is the only native broadleaf evergreen tree in Canada. These trees prefer shaded roots with little soil overlay. Leaf blight is a known factor affecting Arbutus trees; there are 17 different fungal and bacterial entities that affect them according to a local expert, but I wonder if other factors such as climate change may also be contributing to what is perceived as a general decline of the species. Some of these trees, growing in protected areas with older, second growth timber, seem to be largely unaffected, healthy, and vibrant. Others, in areas close to roadways or other disturbed areas seem to be doing more poorly with considerable amounts of die off.
The horticulturist that I consulted with indicated a combination of factors that could be linked to Arbutus decline:
• A sharp decrease in rainfall over the winter, and summer drought in recent years.
• An unusually heavy snowfall in February 2021 with associated freezing affecting leaf tissue.
• Location of Gabriola Island near the edge of the Arbutus species growth zone.
• Anthropogenic disturbance breaking habitat connectivity.
• Changing water table.
Two main points were also made by the consult in summary:
1. The decline “may be the result of a physiological cycle that we don’t know about yet.”
2. Arbutus trees are resilient; their decline has been discussed frequently yet they continue
to recover from environmental stress.