KOHLER, M. und HILDEBRAND, E. E. (2004): New aspects of element cycling and forest nutrition.
EFI-Proceedings of the Symposium “Towards the sustainable use of Europe`s Forests” 25.-27.06.2003 in Tours, France. No. 49, 171-180.
We need informative soil chemical parameters as indicators to assess the ecological and nutritional status of forest soils. The amount and bond strength of exchangeable magnesium are examples of such indicators. Mg is the most critical nutrient cation in forests of Central and Northern Europe due to its specific geochemical properties. It is very susceptible to leaching processes in acidifying forests. In the case of exchangeable potassium (K) extreme concentration gradients between aggregate surfaces and inner parts may control the K-uptake of trees and create K-deficiencies in South-West Germany. Apparently, the physical structure of forest soils affects the availability of chemicals for tree growth. A widely neglected fact is that the skeleton fraction of forest soils can contain a highly ecologically active nutrient ion pool. In skeleton-rich sites in the Black Forest Mountains, up to 80 % of the exchangeable Ca and Mg originate from the soil skeleton and not from fine earth. In light of these results, the traditional practice of only using homogenized fine earth for soil chemical analyses should be reconsidered.