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

Abstract: 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 cen-ter 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. Key words: truffles, riparian, Sierra Nevada. Résumé: Les auteurs ont comparé l’abondance, la diversité et la composition des truffes, dans les portions ripariennes et plus élevées d’une forêt coniférienne mixte de la Sierra Nevada, en Californie. Pour localiser les truffes, les auteurs ont effectué les échantillonnages dans un seul bassin versant, au cours de deux saisons (printemps et été), pendant quatre ans, le but étant de déterminer si les truffes sont plus abondantes et plus diversifiées près des rives que sur le