Mycorrhizal community structure of Scots pine trees influenced by emissions from aluminum smelter

Abstract Ectomycorrhizas of Scots pine were studied in three forest stands in the vicinity of an aluminum smelter: one young stand (0.4 km from the smelter) and two mature stands (2.5–3.0 km from the smelter). The aim of the study was to evaluate a possible influence of pollutants emitted from the smelter on the abundance and diversity of mycorrhizas in the upper soil layer (0–5 cm). Seventeen mycorrhizal morphotypes were distinguished in the root samples from the three study sites (10–13 at one site). The same dominant morphotype was observed at each of the sites. Biomass of fine roots and total number of mycorrhizas were significantly higher at the young forest stand than at the two mature stands, however the fungal biomass in the fine roots, measured as ergosterol content, was lowest at the young stand. The results suggest a negative, indirect effect of pollution on fine root production, and thus fewer short roots available for mycorrhizal colonization in mature forest stands, rather than a direct effect through the soil.