Plant species richness and the exceedances of critical loads for N deposition: an overview



Roland Bobbink
Landscape Ecology, Institute of Environmental Biology,
Utrecht University
r.bobbink@bio.uu.nl


Abstract

The emissions of ammonia (NH3) and nitrogen oxides (NOx) have strongly increased in the second half of the 20th century. Because of short- and longe-range transport of these nitrogenous compounds, atmospheric nitrogen (N) deposition clearly increased in many natural and semi-natural ecosystems. N deposition is now a major threat to biodiversity. Empirical N critical loads are effect tresholds for the environmetal impacts of N deposition. After a short introduction of the ecological consequences of N enrichment and the empirical critical load approach, an overview will be given on the relationship between the exceedances of N critical loads and plant species richness in several groups of ecosystems (grasslands, arctic/alpine communities and forests). Finally, the use of the empirical load approach will be discussed.