Patterns of variation in the yeast florae of exudates in an oak community

Abstract

Yeasts associated with exudates of 16 red oak trees (Quercus rubra) were sampled repeatedly over a 2-year period. The 210 yeasts isolated were assigned to 28 species whose frequencies were characteristic of each habitat. Significant variation among the habitats was detected in the species diversity, composition, nutritional breadth, and physiological specificity of their yeasts. Some exudates were recognized as "typical" sap fluxes by their physical characteristics and their similar yeast florae. Others differed to various degrees in their yeast species composition, or in the physiological structure of their yeast communities. Among the factors linked to the observed variation were features of the adjacent vegetation, colonization by ants, or growth in open parts of the study area.