Nordic Empetrum dominated ecosystems: Function and susceptibility to environmental changes

This paper reviews the knowledge on crowberry (Empetrum nigrum ssp. nigrum and ssp. hermaphroditum) dominated ecosystems in the Nordic region. Empetru m leaves and litter have high phenolic content resulting in slow decomposit ion, and with the formation of an organic top soil, nutrients are kept in a n organic nutrient bank in the soil mainly available for plants with ericoi d mycorrhiza. Empetrum nigrum ssp. hermaphroditum is a strong nutrient comp etitor and outcompetes most plants in late successional stages. This is due to chemical interference (allelopathy) and resource competition. Crowberry as an organism is resistant to atmospheric pollution and may even increase in vigor by high atmospheric N deposition in nemoral coastal heaths, but i s very sensitive to mechanical disturbances and fire. However, there are in dications that the closed nutrient cycle established when Empetrum is domin ant may be disturbed after airborne inputs of inorganic N.