Ectomycorrhizal diversity and community structure in oak forest stands exposed to contrasting anthropogenic impacts

We compared the ectomycorrhizal community structure of oak forest stands located in either an urban or a rural area. Urban stands had higher N deposition rates, soil heavy metal levels, and earthworm counts than rural stands. Ectomycorrhizal types were quantified on roots of mature oak (Quercus) in soil cores and on Quercus rubra L. seedlings grown in soil cores in the glasshouse. Twenty-six ectomycorrhizal types were distinguished on mature oak in rural soils versus 16 in urban soils. Nine ectomycorrhizal types were distinguished on Q. rubra seedlings grown in rural soils versus seven in urban soils. Despite fewer ectomycorrhizal types in urban soils, richness of ectomycorrhizal types per centimetre fine root of mature oak or Q. rubra seedlings did not differ between urban and rural soils. Ectomycorrhizal colonization (ectomycorrhizal tips/m fine root) was lower in urban than rural soil cores but higher on Q. rubra seedlings grown in urban versus rural soils. Fine root length per unit soil volume was higher in urban than rural stands. No difference in fine root length was observed between Q. rubra seedlings grown in urban and rural soils. These differences in ectomycorrhizal community structure between the urban and rural stands are likely due to anthropogenic impacts.Key words: air pollution, anthropogenic impacts, community structure, diversity, ectomycorrhiza, Quercus rubra.