KOHLER, M., WOLSFELD, N. und HILDEBRAND, E.E. (2003): Stones in Forest Soils: "Hot Spots" of the nutrient uptake?
Biologie in unserer Zeit, 33/4: 252-256 (in German language).
Stones in forest soils are much more involved in geo-/biochemical ion cycles than usually assumed. Hairline cracks of the stones are filled with weathered fine material containing high amounts of plant available nutrient cations. This nutritional potential is settled by fungal hyphae. For a growing hypha, there is a fine earth continuum which stretches weblike through the stones. In mineral soil horizons which do not contain humic substances, heterotrophic fungi can only survive as mycorrhiza. That means these fungi live in symbiosis with tree roots which provide carbohydrates and receive nutrients. The presence of hyphae in stones is therefore an indicator of a bypass flux of nutrients directly from stones into trees. This may explain the deficit of plausibility that healthy trees grow on forest soils with a dramatic depletion of nutrient cations in the fine earth. Moreover, we found hyphae in stones which had no hairline cracks. Hyphae apparently penetrate actively the stones. These findings are in accordance with north-european studies, which report about “rock-eating-fungi”.