Organic reserves: importance to ectomycorrhizae in forest soils of western Montana.

Abstract

The important attributes contributed to forest soils by organic matter make it im- perative to determine the quantity and type required to sustain good forest tree growth. Quan- titative measurement of soil humus, decayed wood, and charcoal as related to numbers of active ectomycorrhizal root tips (in random soil cores from old-growth sites in western Montana) showed both positive and negative relationships with organic matter. Increased quantities of organic material, to 45 percent by volume of the top 30 cm of soil, were associated with increased numbers of ectomycorrhizae. At 45 percent organic matter or above, numbers of ectomycorrhizae de- creased. Study results also showed association with soil organic matter had a relatively greater positive effect on ectomycorrhizae of the dry site than the moist sites. FOREST SCI. 27:442-445.