Human activities have dramatically increased atmospheric nitrogen (N) deposition within large regions of the world. Arbuscular mycorrhizal (AM) fungi can be sensitive to increased N availability and are important belowground carbon (C) sinks. Our previous results have shown a significant decrease in the abundance of AM fungi in maple (Acer spp.) fine roots following more than a decade of experimental additions of N designed to simulate chronic atmospheric N deposition. This decrease may affect AM fungal community composition and ultimately ecosystem processes. In order to understand the function of AM fungi under chronic N addition in more detail, we applied molecular techniques to characterize community composition. DNA was extracted and amplified by polymerase chain reaction (PCR) using AM fungal specific primers. The PCR products were cloned and identified using restriction fragment length polymorphism (RFLP) and sequencing.

Results/Conclusions

No significant effect on AMF species diversity was found. However, N addition did affect the AMF community composition significantly. The observed effect on community composition implies that AM fungal species associated with maples differ in their response to elevated nitrogen.