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. Empetrum leaves and litter have high phenolic content resulting in slow decomposition, and with the formation of an organic top soil, nutrients are kept in an organic nutrient bank in the soil mainly available for plants with ericoid mycorrhiza. Empetrum nigrum ssp. hermaphroditum is a strong nutrient competitor 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 is very sensitive to mechanical disturbances and fire. However, there are indications that the closed nutrient cycle established when Empetrum is dominant may be disturbed after airborne inputs of inorganic N.