Ectomycorrhizal fungi grow symbiotically on the roots of trees and provide them with nutrients and protection in exchange for carbon from photosynthesis. Many of these fungi form underground fruiting bodies; it is thought that ectomycorrhizal fungi gain long distance dispersal when small mammals eat these truffles and deposit their spores elsewhere in their feces. This study examined the role of small mammals in transporting spores from mature forests into disturbed areas. Twelve sites were chosen in the Interior Cedar Hemlock biogeoclimatic zone, based on the time (from 7 to over 100 years) since their last disturbance (either clearcutting or forest fire). In each case, small mammals (chipmunks (Tamias amoenus), flying squirrels (Glaucomys sabrinus), red squirrel (Tamiasciurus hudsonicus), red-backed vole (Clethrionomys grapperi), and deer mice (Peromyscus maniculatus)) were trapped and their feces were collected in both disturbed and adjacent mature areas, in both the early summer and fall of 2008. Truffles were collected on the same plots. Fungal DNA was extracted, amplified, and processed for t-RFLP from both truffles and feces for identification and comparison purposes. Fecal pellets were also observed microscopically for the presence, identification, and quantification of truffle spores.
Results/Conclusions
Chipmunks were the most frequently trapped spore-carriers on the sites followed by red-backed voles then flying squirrels. The percentage of fecal samples that were positive for fungal spores was 95.5% for flying squirrel (n=17), 83% for red squirrels (n=8), 78% for red-back voles (n=20), 71.5% for chipmunks (n=136), and negligible for deer mice (n=418). Thus, of the small mammals sampled in this biogeoclimatic zone, chipmunks appear to be the most important dispersers of fungal spores. Deer mice have been known to be opportunistic mycophagists in many areas; this study demonstrated that although they are abundant in the Interior Cedar Hemlock zone, they are not important dispersers of fungal spores in this area. The dominant mycorrhizal fungi forming truffles on these sites were Hysterangium separabile, Rhizopogon vesiculosus, and R. vinicolor; preliminary results indicate that Rhizopogon spp. spores were dominant in chipmunk feces. Implications of these results on forest management will be discussed.
