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Species at Risk

Haller's apple moss

Bartramia halleriana

What's so special about Haller's apple moss?

Species at Risk - Who Knew?

Thomas Drummond first discovered Haller's apple moss in Canada in 1826, while studying the plants and animals of the Canadian Rockies.

Defining an individual moss plant can be difficult because one clump can consist of many shoots, which originated from a single spore and are genetically identical. We consider a single, separate clump of moss to be one individual.

Haller's apple moss is at risk because there are only three small populations in Canada . Recent surveys at two of the sites documented 130 individuals (clumps), covering a total of 116 sq. cm. The total Canadian population is estimated to be less than 250 individuals.

Why is the Haller's apple moss in danger?

Conservation biologists have found that species with small populations are particularly at risk of being wiped out locally. Haller's apple moss occurs at only three small locations. It seems that only a limited, suitable habitat is available.

A forest fire
A forest fire
© Parks Canada / R. Grey / 1973

These small populations and suitable habitats may be threatened by any small disturbance, including development, fire or trampling. Small populations are also at greater risk because the population size fluctuates due to weather, for example, and because of genetic problems related to a small breeding population.

Haller's apple moss may be rare because it competes with other species for light, water and nutrients. It is frequently found growing with the closely related common apple moss ( Bartramia pomiformis ), which is much more abundant and widespread. Competition with common apple moss may be limiting the Haller's apple moss population size and distribution, but further study will be needed to evaluate this.