XVI International Botanical Congess

This paper describes field and laboratory experiments designed to investigate the qualitative and quantitative impacts of anthropogenic N deposition upon the biology of ectomycorrhiza along a European gradient of increasing N deposition from North Sweden to Central Germany. A progressive decline in diversity was observed along the gradient. However, simulation of N deposition over 4 years onto mature Picea sitchensis at a 'clean' site in UK produced no shift in population structure. The extent to which the presence of mineral N, as NH4 or NO3, interfered with assimilation of amino-N was determined using excised mycorrhizal roots and intact plants. No inhibition of organic N uptake was detected. The results are discussed in relation to mycorrhizal community dynamics in particular and forest health in general.