Distribution of Ectomycorrhizae in a Mature Douglas-fir/Larch Forest Soil in Western Montana

Abstract

Abstract The top 38 cm (15 inches) of a western Montana forest soil was 60 percent mineral, 23 percent humus, 15 percent decayed wood, and 2 percent charcoal. Most (to 95 percent) of the active ectomycorrhizae were associated with the organic fractions. Five percent of all active ectomycorrhizae occurred in the mineral soil fraction, 66 percent in the humus, 21 percent in the decayed wood, and 8 percent in the charcoal. Thus, the organic reserves in this forest soil were the most important substrates for ectomycorrhiza formation. Therefore, the parent materials (leaves, litter, and woody residues) for soil organic reserves may require management during timber harvesting and prescribed burning to prevent a subsequent loss in the capacity of soils of this type (limestone base) to support ectomycorrhizal associations in mature Douglas-fir/larch forests. Forest Sci. 22:393-398.