Forest soil plots (N=112) of the size 50x50 meter were sampled in 1989-90 (C1) and re-sampled in 2007-9 (C2) by soil auger, producing composite samples from the depths 0-25, 25-50, 50-75 and 75-100 cm. The soils were classified according to the carbon concentration in the uppermost mineral soil horizon (0-25 cm) at C1. Soils with less than 1.8% carbon gained carbon during the 18 yr period, while initially very carbon rich (4<C%<12) mineral soils and organic soils (C%>12) lost carbon. We hypothesize that the carbon losses reflect a very slow process of adaptation to the current more aerobic drainage regime of soils that were frequently water saturated in previous centuries. It was also hypothesized that carbon gains in soils with a low or intermediate carbon stock, typical of well-drained soils, reflected the favorable, high precipitation conditions during the monitoring period, allowing especially base rich loamy soils to take full advantage of the nitrogen deposition and CO2 fertilization effects.