SPATIAL-DISTRIBUTION OF FINE ROOTS, RHIZOSPHERE AND BULK-SOIL CHEMISTRY IN AN ACIDIFIED PICEA-ABIES STAND

Soil and fine-root sampling were carried out in a Norway spruce (Picea abies (L.) Karst.) stand with high levels of atmospheric deposition of sulphur and nitrogen in south-western Sweden. Living and dead fine roots in both LFH- and mineral horizons were excavated from soil cores. The bulk and rhizoshpere soil concentrations of Al, Ca, Mg, Fe, K and pH were measured in water extracts. The magnesium concentration was significantly higher in the rhizosphere than in the bulk soil except for in the deepest horizon. The Ca/Al-ratio increased with depth in both the rhizosphere and bulk soils while it decreased with depth in fine roots. The ratio was lower in dead than in living fine roots. The amount of both living and dead fine roots decreased with depth. The necromass/biomass ratio was highest in the 10 to 20 cm mineral soil horizon.