Date of Award

Spring 2019

Project Type


Program or Major

Natural Resources

Degree Name

Master of Science

First Advisor

Heidi Asbjornsen

Second Advisor

Isabel Munck

Third Advisor

Jeffrey Garnas


Inonotus obliquus is a fungal infection of birch trees that produces a large sterile conk, known colloquially as Chaga. When dried, Chaga has medicinal value as an anti-mutagen and for gastro-peptic relief. With the growth of the natural remedies market over the last decade, Chaga has increasingly become the target of harvest in the White Mountain National Forest (WMNF). Forest managers of the WMNF have asked USFS Forest Health Protection staff whether special use permitting for Chaga as a Non-Timber Forest Product (NTFP) should be allowed. However, it is difficult to make management recommendations or best management practices for harvesting Chaga because the abundance and ecology of the Chaga resource in the WMNF is currently unknown. This project sought to quantify the Chaga resource in the WMNF and determine incidence of Chaga by tree species, habitat type, and other variables. Two surveys were conducted in the 2017 and 2018 field seasons, with a total of 66 sites and 2,611 birch trees sampled across the WMNF. These surveys found positive correlations between Chaga presence and birch tree age, diameter at breast height, and site elevation. Chaga was also disproportionately associated with yellow birch. Chaga frequency in WMNF birch trees was low: only 2% of trees sampled had a visible Chaga conk. However, Chaga was present in 56% of stands surveyed.

In addition, Chaga infections were seen to cluster together in four separate areas surveyed. There was no clear correlation between Chaga presence and either stand-level species composition or annual basal area increment. Additional damages to infected trees only associated with Chaga presence insofar as said damages resulted from Chaga presence. In summation, Chaga, while comparatively rare, is widely distributed across the WMNF and tends to prefer older, large-diameter yellow birches at higher elevations as hosts. These results will ultimately be used to craft a series of Best Management Practices (BMPs) for Chaga harvest with a better understanding of the fungus’ preferred habitat and potential for cultivation.

Chaga BA 3d Graph best.gif (796 kB)
3D animated GIF rendering of Non-Metric Multi-Dimensional Scaling ordination performed on species basal area dataset