THE IMPORTANCE OF SOIL ACIDITY, MOISTURE, EXCHANGEABLE CATION POOLS AND ORGANIC-MATTER SOLUBILITY TO THE CATIONIC COMPOSITION OF BEECH FOREST (FAGUS-SYLVATICA L) SOIL SOLUTION

Humus horizons of dystric cambisols were sampled si, times during 1990-1992 at 66 points along a beech forest transect in Scania, s. Sweden. Cation concentrations of soil solutions obtained by centrifugation of sifted samples at field moisture were related to pH, DOC, exchangeable pools of the cations and soil moisture. Soil solution Al was speciated in free ionic (easily reacting) Al(r) and organically complexed Al(org). Two or three variables accounted for a large share (70-90 %) of the cation variability between sampling points. Exchangeable soil pools were the most important variables for K, Mg, Ca, and Mn and contributed more when calculated on C.E.C. than on soil dry weight. Some function of pH was also of importance to most cation concentrations. Al(r) correlated well with both Al(org)(+) and pH(-). Soil moisture was positively related to DOC and K, negatively to H-ion concentration. pH measured by different methods were closely correlated (r = 0.93-0.97), pH(KCl) and pH(BaCl2) being ca. 0.5 unit lower, pH(H2O) ca. 0.3 unit higher than soil solution pH, which varied between 3.5 and 5.6.