摘要 : The long-term dynamics were analysed of the decomposition of different fractions of forest litters by using models derived from a theory on decomposition and element cycling in organic matter. The analysis of decomposition was don... 展开 The long-term dynamics were analysed of the decomposition of different fractions of forest litters by using models derived from a theory on decomposition and element cycling in organic matter. The analysis of decomposition was done (i) by measuringdecomposition rates of, and nutrient changes in, needles, twigs, and branches in field experiments at 4 coniferous forest sites in Sweden (3 clear felled sites - 2 dominated by Norway spruce, Picea abies, and one by Scots pine, Pinus sylvestris, before clear felling; and one thinned Norway spruce monoculture), and (ii) by estimating parameters used in the models with information derived from these experiments. The analysis showed that variability in decomposition rate decreases with increasing substratediameter. The models were also used to predict the long-term dynamics of carbon, nitrogen, and phosphorus in logging residues. The predictions made suggest that from a short-term perspective, the nutrient-rich needles and twigs are a more important nutrient source for the subsequent forest generation than branches. However, in the long run the nutrient concentration of the coarse litter fractions will also be important. The predicted amounts of carbon and nitrogen in logging residues were compared withmeasured amounts in the humus layer. On a productive Norway spruce site 16 years after clear-felling, the remaining logging residues were predicted to increase carbon amounts in the forest floor by 50%; on a low productive Scots pine site this figure was 100%. The corresponding nitrogen amounts in the forest floor should have been 30% higher at the spruce site and 70-80% higher at the pine site. 收起