Litter decomposition was studied in short-rotation forest stands on a low-humified peat bog using the litter-bag technique. Leaf and twig litters, mainly from willows and grey alder, were compared with regard to weight and nutrient losses. The study sites included untreated, limed and limed plus fertilized plots. The application of solid fertilizers, containing mainly phosphorus and potassium, once every second year (F treatment), was compared with daily irrigation-fertilization during the growing seasons. The application of liquid fertilizer (IL treatment) included all essential nutrients in balanced proportions. Leaves of Salix schwerinii differed from all other litter types studied in being more senesced and nutrient-poor at litter fall. They therefore contained lower initial amounts of leachable, water-soluble substances and also decomposed much more slowly than the others. Amounts of nitrogen released in “brown” leaves of this species did not fall below the initial level for at least 3 years, owing to large early increases. In all other litters initial nitrogen contents decreased by 19–75%. High initial concentrations of nitrogen and phosphorus were generally associated with rapid weight losses and releases of these elements. Potassium was rapidly lost in all litters, while loss rates for magnesium and calcium varied. Twig litter of basket willow, but not of alder, showed a net release of nitrogen during 3 years of decomposition. Most of the water-soluble substances were leached during the first few weeks, while the lignin fraction increased in the leaf litter of both basket willow and grey alder. Losses from the lignin fraction accounted for about 75% of the weight losses from the end of the first year onwards. Although similar in macronutrient composition, grey alder leaves, in general, were degraded much faster than basket willow leaves. Thus, species-specific differences seemed to be the major factor affecting decomposition rate and were superimposed upon other factors. However, soil treatments also affected degradation. Alder leaves, for example, were degraded and lost nitrogen and phosphorus faster in the IL plot than in the F plot. Both alder and willow leaves, produced some years after plant establishment, decomposed more rapidly than leaves from young plants. Nutrient turnover in short-rotation forest stands on sites with low productivity may thus increase rather quickly as site fertility builds up through intensive fertilization and repeated production of nutrient-rich litter.