Abstracts

Soil Ecosystems

Carbon and nutrient cycling was investigated in undisturbed and disturbed fens in southern Finland. In a pristine state, these fens are characterized by the abundance of sedges, and have a sparse stand of pine (Pinus sylvestris) growing on low hummocks. Moss layer consists of a thick carpet of Sphagnum. Nutrient cycling is characterized by annual cycling of biomass and nutrients through the ground vegetation. The accumulating peat forms a longterm nutrient sink.

Following drainage, peat-forming plant species rapidly decline. After a stress period of 20-30 years, ground vegetation biomass reaches the original level, but the species composition, and thus litter quality, has changed. The growing tree stand is the main carbon binding body, and litter source, in the drained ecosystem, and forms a considerable nutrient sink. The N and P pools in tree stand biomass increase tenfold in 30 years. Simultaneously, the aboveground litterfall from the stand increases from 40 g m-2 to 300 g m-2 annually. The N and P pools in litterfall also increase tenfold. The composition of tree stand litterfall changes gradually: the proportions of slowly decomposing fine and coarse woody debris increase, which has an effect on the time scale of carbon and nutrient cycling in the soil.

Note. Abstracts are published in author's edition

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