Impact of tree species on soil solutions in acidic conditions

Capillary solutions of two acidic forest topsoils were sampled for one year . On each of the two soils, there were three stands (Norway spruce, Douglas fir, Hardwood). Capillary solutions were extracted using the centrifugatio n method. Soil moisture under Hardwood stands was higher than under conifer ous stands. Soil solutions under the coniferous tree species were more acid ic and more concentrated in SO4-2-S and Na+ than under Hardwoods, showing t hat coniferous tree species intercept atmospheric depositions more efficien tly than hardwood tree species do. Soil solutions under hardwood stands wer e more concentrated in K+, Alt, Si and Fe3+ than those under coniferous sta nds. On the least desaturated site, soil solutions under the hardwood stand were less concentrated in NO3--N and C than under the coniferous stands. T he amount of rainfall significantly influenced results by diluting soil sol utions. When the amount of rainfall was high, there were little difference between tree species.