Exportação de nutrientes de povoamentos de Pinus taeda L. desbastados em diferentes idades

Abstract

Nutrient contents were estimated for each component from above-stamp parts of removed and remaining trees of three Pinus taeda L. plantations with 7, 10 and 14 years old, ready to be submitted to the first, second and third thinningv respectively. In the 7 years old plantation, before fírst thinning, were estimated the folowing nutrient contents in kg/ha: 355.0 of N, 21.3 of P, 114.8 of K, 88. 7 of Ca, 24.1 of Mg, 4.5 of Fe, 7.0 of Mn, 0.4 of Cu, 0. 7 of Zn and. 0.8 of H. In the 10 years old plantation, before second thinning, were estimated in kg/ha: 417.2 of 'N, 32.2 of P, 144.0 of K, 52.2 of Ca, 37. 7 of Mg, 8.9 of Fe, 7.9 of Mn, 0.6 of Cu, 1.0 of Zn and 1.3 of B. In the 14 years old plantations, “before third thinning, were estimated in kg/ha: 422.5 of N, 26.5 of P, 120. 7 of K I90.9 of Ca, 45.2 of Mg. 9.2 of Fe, 10.0 Mn, 0. 70 of Cu, 1.0 of 'Zn and 1.5 of B. The removings of stem wood with bark through thinnings of 38.4, 40. 7 and 39,3% trees exported 46, 124 and 139 kg/ha of evaluated nutrients in the first, second and third thinnings respectively. The branches and needlee, as slasch of thinning operations, contained 110, I32 and 134 kg/ha of evaluated nutrients in the 7, 10 and 14 years old plantations respectively.