Résumé
Ecosystem services are defined as the ecological and socio-economic value of goods and services provided by natural and semi-natural ecosystems. Ecosystem services are being impacted by many human induced stresses, one of them being nitrogen (N) deposition and its interactions with other pollutants and climate change. It is concluded that N directly or indirectly affects a wide range of provisioning, regulating, supporting and cultural ecosystem services, many of which are interrelated. When considering the effects of N on ecosystem services, it is important to distinguish between different types of ecosystems/species and the protection against N impacts should include other aspects related to N, in addition to biodiversity. The Working Group considered the following priorities of ecosystem services in relation to N: biodiversity; air quality/atmosphere; ecosystem changes; NO3 leaching; climate regulation and cultural issues. These are the services for which the best evidence is available in the literature. There is a conflicting interest between greenhouse gas ecosystem services and biodiversity protection; up to some point of increasing N inputs, net greenhouse gas uptake is improved, while biodiversity is already adversely affected.