At present, the proportion of Norway spruce stands in the Czech Republic amounts to about 54%. Natural composition should amount to 11% and recommended proportion is 36.5%. Today, research is particularly focussed on defining the properties of forest sites unsuitable for growing spruce monocultures, changes in the cycle of elements (particularly nitrogen), processes of the organic residue decomposition and relationships between the condition of nutrition, soil properties and climatic conditions. A network of demonstration areas has been established for comparative studies of forest stands in the various degree of transformation. The meaning of transformation does not generally consist in the replacement of spruce monocultures by stands of other species but in assigning such a position to spruce where a multi-purpose forest will be in accordance with the forest site capacity. In experimental plots Hetlin, the process was studied of the accumulation of organic matter in the surface humus in spruce monocultures and in the course of their transformation to a mixed forest. Moreover, nutrient concentration was compared in L, F, H and A layers. In addition to this, condition of spruce nutrition was compared in a monoculture in relation to the amount of accumulated humus with optimum and deficit concentrations of main bioelements. Effects of spruce monocultures on the acidification of soil surface layers were compared with neutralization effects of beech stands.