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

We compared the ectomycorrhizal community structure of oak forest stands lo cated in either an urban or a rural area. Urban stands had higher N deposit ion 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 gla sshouse. Twenty-six ectomycorrhizal types were distinguished on mature oak in rural soils versus 16 in urban soils. Nine ectomycorrhizal types were di stinguished on Q. rubra seedlings grown in rural soils versus seven in urba n soils. Despite fewer ectomycorrhizal types in urban soils, richness of ec tomycorrhizal types per centimetre fine root of mature oak or Q. rubra seed lings did not differ between urban and rural soils. Ectomycorrhizal coloniz ation (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 commu nity structure between the urban and rural stands are likely due to anthrop ogenic impacts.