THE NUTRIENT CONTENT OF SCOTS AND CORSICAN PINES GROWING ON SAND DUNES

Abstract

A study has been made of the amounts of N, P, K, Ca, Mg, and Na in the needles, branches, bark, and wood of three age classes of Scots and Corsican pine ( Pinus silvestris L. and P. nigra var. calabrica Schneid) growing on sand dunes at Culbin Forest, Morayshire. Of the seasonal variations observed, the most significant was a rise in the N content of the bark in the autumn, especially in young trees. Dominant trees have lower levels of P, K, and Mg in the needles, branches, and bark than suppressed trees. Dead bark accumulation is much more uniform on Corsican pine than on Scots and the nutrient content of dead bark is small. Heartwood development is greater in Scots pine than in Corsican. In the heartwood of both species P and K contents are very low, but Ca, Mg, and Na accumulate. In the sapwood zone immediately surrounding the heartwood, high levels of all nutrients are found. The total amount of nutrients held in the crop has been calculated on a per acre basis for the three age classes of both species. At 48 years this value is still rising in Corsican pine, but at 64 years the total content of N, P, and K in Scots pine is beginning to fall, although the Ca content is continuing to rise due to heartwood formation. The bark and stem contain between one-third and one-half of the total nutrients in a tree, depending on age. Barking of stems before removal reduces nutrient losses from the site, but appreciable quantities are still removed in the wood.