Are European Trees Prepared for Being Limited by Other Nutrients than Nitrogen?

Abstract

The growth of forest trees in the relatively young soils of Europe has historically been limited by nitrogen (N). The high anthropogenic N deposition and intense forest management during the last century, however, have caused forest trees in large areas to show signs of being limited by phosphorus (P) or base cations. This indicates that the current situation is not sustainable. The net addition of N to forests here stems from deposition and N fixation, both processes that add N to the topsoil. Phosphorus and cations are released by weathering in the mineral soil. Do European trees have what it takes to efficiently take up P and cation nutrients when they become scarce? Important factors influencing their capacity to take up P and cations are their roots’ distribution and function, mycorrhizal distribution and type, and the response of their root and mycorrhizal growth and function to N depositions and nutrient deficiencies. The literature shows that the ability to be limited by something other than nitrogen will be hardest for shallow-rooted conifer trees, followed by ectomycorrhizal deciduous trees; arbuscular mycorrhizal trees will handle the shift best. This knowledge should be incorporated into forest growth models to promote sustainable management decisions.