The Circulation of Minerals in Plantations of Pinus sylvestris L.

The dry weights and amounts of sodium, potassium, calcium, magnesium,phosphorus, and nitrogen in the ground flora and organic layersformed over the mineral soil are recorded for an age seriesof plantations of Pinus sylvestris. From these data, the distributionof mineral nutrients within the plantations is deter-mined andcalculations are made of the annual circulation of nutrientsthrough the ecosystem. After 55 years of afforestation the amountof organic matter accumulated over the forest floor is onlyequivalent to the litter fall of the last 6 years. Thus, althoughafforestation results in a progressive accumulation of organicmatter, the woodland community is characterized by a large andrapid transfer of nutrients between the plants and mineral soil.