Above ground tree biomass and accumulation of nutrients in Pinus radiata plantations from northern Spain

Abstract

In this work the amount of nutrients accumulated in the above ground biomass of nine representative Pinus radiata plantations from NW Spain were studied. From the data of 54 trees, models to estimate the mass of the different tree fractions were developed. The logging residues accumulate the most part of N (60%), as well as substantial amounts of P, K, Ca and Mg (36 to 47%). The accumulations in tree biomass of P, Mg, K and, in some cases, Ca are considerably higher than the available amounts in the soil. The data confirm that the frequent deficiencies of these elements in this type of forest plantations are due to the low nutrient storage in the soils. They also suggest that the nutritional stability of these systems is dependent on the nutrient supply by the decomposition of logging residues. These results, along with those of previous studies, show the need to carry out an appropriate management of logging residues, as well as fertilisation programmes to compensate the nutrient extractions by the clear cutting, especially if whole-tree harvesting is carried out.