Abstract
The occurrence of rhizomorphs in soil around dead trees was determined in stands of declining red spruce in hardwood, transition, and montane boreal forest types that differ in elevation. Rhizomorph incidence and population density were significantly lower in the higher elevation transition and montane boreal forest types. These data suggest that previously reported infrequent colonization of declining red spruce at high elevations is due to low levels of inoculum of Armillaria in forest soils. High lead concentration and low pH of the organic layer of soils in the higher elevation spruce-fir stands in the Northeast were correlated with low levels of inoculum, but these factors alone do not explain the variation in occurrence of the fungus.