The spatial distribution of clones in the ectomycorrhizal fungus Suillus bovinus (L. ex Fr.) O. Kuntze was studied from somatic incompatibility pairings of isolates in four Scots pine (Pinus sylvestris L.) stands with different forest history. A pattern of increasing clonal size, decreasing clonal number, and decreasing fruiting per unit area, was found with increased forest age and relatively little disturbance. Establishment by spores was important on disturbed sites, while mycelial spread increased in importance with decreased disturbance. The number of clones was found to be 800 ha-1 in younger forest stands and decreased to between 25-130 ha-1 in mature stands. At the same time the diameter of the area occupied by a single clone increased from 1-3 m to 30 m. Implications of the observations are discussed in terms of ecological strategies and population dynamics.
Keywords: Suillus bovinus; clonal size; somatic incompatibility; spreading strategy.