Forest ring

Such hypotheses include radially growing fungus, buried kimberlite pipes, trapped gas pockets, and meteorite impact craters.

[4] Because of their large scale, forest rings are not apparent from the ground, and it was not until aerial photography became a common surveying tool in the 1950s that geologists began to notice them.

and methanotrophs, such as Candidatus Methylomirabilis and Methylobacter, were highly abundant in samples from the 'Bean' and the 'Thorn North' ring, in Ontario, Canada.

[7] Forest rings were originally thought to be caused by the radial growth of fungi within the root system of black spruce (Picea mariana), possibly the fungus Armillaria ostoyae.

Observations of forest rings in the Abitibi region of Quebec have found no evidence of mass tree mortality by a pathogen.