Boreal Forest Rings
April 26, 2007
Provided by: Ray Murphy
Summary authors & editors: Ray Murphy
In the boreal forests of Northern Ontario and Quebec, more than 2,000 large-scale forest ring features have been found during the course of aerial photographic surveys. What causes them has been the subject of speculation since they were observed in the very first aerial surveys conducted of the region decades ago. Since the 1990s, they have been the subject of detailed ground-based research investigations. Present research indicates that there are complex electrochemical reactions between underlying metallic ore bodies and the overlying limestone, creating shallow ring-shaped depressions at the surface.
The photograph shows one of these rings. It's located in a remote transitional forest-muskeg region almost exactly at latitude 50 degrees 30 minutes north and longitude 85 degrees 00 minutes west -- about 15 miles (24 km) north of the Kenogami River. This particular ring is approximately 1 kilometer in diameter. The trees are primarily black spruce, and in the ring area they have been observed to be more stunted and thin out, a characteristic of locally poorer drainage conditions. The yellowish color of the surface is sphagnum moss.
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