Habitat Associations of Hypogeous Fungi in the Southern Appalachians: Implications for the Endangered Northern d Flying Squirrel (Glaucomys sabrinus coloratus)

-gporocarps of hypogeous mycorrhizal fungi (truffles) are the major food of northern flying squirrels (Gluucomys satinus). The two subspecies of northern flying squirrels that occur in the southern Appalachians, G. s. colmatus and G. s. fuscus, are endangered species which are primarily found in the ecotone between high-elevation spruce-fir and northern hardwood forests. Our objective was to determine the microhabitat and macrohabitat characteristics associated with the presence and abundance of truffles in suitable habitat for northern flying squirrels. We sampled for truffles in 24-26, l-m* plots on each of 10 northern flying squirrel sites in North Carolina and measured microand macrohabitat characteristics associated with sample plots and sites. Elaphomyces granulatus was the most common species of truffle found (78.7%). Re s d pruce (picea rubra) was significantly more likely to be one of the three closest trees to plots with truffles. Further, spruce was the most important species in plots with truffles, followed by beech (Fag-us grandr@lia), red oak (@ercus r&-a) and yellow birch (Bet& lutea), whereas the most important species in plots with no truffles were beech, followed by yellow birch, spruce and red oak. At the macrohabitat (site) level, spruce was the most important species in sites with high truffle production followed by beech and red oak, whereas the most important species in sites with low truffle production were beech, yellow birch, spruce and rhododendron (Rhododendron spp.). Significant variables entered into a linear regression model predicting the number of truffles in a site were the importance values of fir (A&es &zxri), spruce and silverbell (Ha&a carol&a). Our data suggest that spruce-fir or mixed spruce-fir/hardwood stands are important foraging sites for northern flying squirrels in the southern Appalachians. The northern flying squirrel (Gluucomys satinus) is relatively common in conifer and hardwood forests throughout much of northern and western U.S. and Canada (Wells-Gos ling and Heaney, 1984). However, northern flying squirrels found in the southern Appalachians predominantly inhabit high-elevation spruce-fir/northern hardwood forests (Weigl Q et aZ., 1992), which are among the rarest and most threatened forest types in the South (White et aZ., 1993). Because these forests mostly occur at elevations > 1350 m, the habitat . is naturally fragmented and island-like. Logging, road-building, pollution and the intro, duced balsam woolly adelgid (Ad&es piceue) have caused further habitat loss, degradation and fragmentation (white, 1983). Because squirrel populations declined with the continual loss of habitat, the two southern Appalachian subspecies Gluucomys s. fuscus and G. s.