AbstractEctomycorrhizal fungi are mutualistic symbionts of many forest trees and play a major role in nutrient uptake. They form diverse communities in boreal forest soils but functional differences within this group of fungi remain largely unknown. We study ectomycorrhzal fungi in mineral soil to determine how abiotic preferences influence their spatial distribution in stratified soil profiles. This is achieved by correlative field studies of species distribution and soil characteristics at a spatial resolution relevant to soil heterogeneity and mycelial size. Field sampling strategies are being evaluated to establish a protocol for simultaneous small-sample analysis of ectomycorrhizal community and soil chemical variables. Species-specific substrate preferences are examined by studies of regulation of enzymatic and biogeochemical activity in response to relevant organic and inorganic sources of phosphorus. Studies of four species in the genus Piloderma have demonstrated that different strategies to obtain phosphorus are reflected by their spatial distribution in a podzol soil profile.