Truffle abundance in riparian and upland mixed-conifer forest of California's southern Sierra Nevada

We compared the abundance, diversity, and composition of truffles in riparian and upland areas within a mixed-conifer forest of the Sierra Nevada of California. We sampled for truffles in a single watershed over two seasons (spring and summer) and 4 years to determine whether truffles were more abundant and diverse in riparian than upland sites in old-growth, mixed-conifer forest. Truffle frequency, biomass, and species richness were greater in riparian sites than in upland sites in both spring and summer samples. Species composition of truffles also was different between sites, with nine and one species found exclusively in riparian and upland sites, respectively. Distance between the center of truffle plots to logs and trees was lower and soil moisture was greater in riparian sites compared with upland sites, suggesting that log density, tree proximity, and soil moisture may influence truffle production in these habitats. Our study underscores the importance of riparian areas for truffles, a primary food source for northern flying squirrels (Glaucomys sabrinus) in the Sierra Nevada of California.