Northern flying squirrel mycophagy and truffle production in fir forests in northeastern California

Abstract

In this paper we summarize the results of four studies in which we either examined the feeding habits of the northern flying squirrel (Glaucomys sabrinus), a mycophagous (consuming fungi) small mammal, or compared the abundance of truffles (sporocarps of hypogeous mycorrhizal fungi) among different types of fir (Abies) forest. The studies were conducted within the Lassen National Forest in northeastern California between 1990 and 1994. In the first study, we found that abundance of northern flying squirrels was significantly less in old-growth fir stands that had been shelterwood-logged 6 to 7 years previously than in nearby, unlogged old-growth and mature fir stands. Truffles were common in the diet of flying squirrels, truffle frequency was low in the shelterwood-logged stands compared to the unlogged old-growth and mature stands, and abundance of flying squirrels was correlated with truffle frequency across the 12 stands in which we estimated both. In the second study, we found no significant effects on total truffle frequency and biomass of truffles from commercial thinning or broadcast burning that had occurred about 10 years previously, but there were significant effects of thinning on frequencies of individual truffle genera. In the