Regulation of nitrogen nutrition at the whole tree level: biotic interactions in the rhizosphere of European beech forests
Despite high N requirements for growth and development, many forest trees have developed at sites with low N availability that are characterized by a largely closed ecosystem N cycle. Under such conditions trees have to compete with other organisms for the limited amount of N present. The competitors include the soil microflora, the natural regeneration, other understorey species, as well as competing tree species. In this contribution mechanisms of these competitive interactions are discussed in beech-dominated, deciduous forests that constitute the potential natural vegetation of Central Europe.