Decomposição de agulhas de Pinus pinaster e de folhas de Eucalyptus globulus em regiões do interior e do litoral de Portugal

Abstract

Decomposition of needle litter of Pinus pinaster (PP) and leaf litter of Eucalyptus globulus (EG) was assessed using the litterbag methodology. Decomposition rate of these residues and release dynamics of nutrients with more relevance to the sustainability of forest systems were measured. The study was carried out in the litoral of Central Portugal (Furadouro,Obidos), using both PP and EG, in inland of North Portugal (Vila Pouca de Aguiar), using PP, and in an intermediate climate condition (Pegoes, Rio Maior), using EG. Decomposition rate of PP was lower than that observed for EG, differences being more pronounced in the initial stage of decomposition (first six months), when weight loss of the former was about one half of that observed for the latter. During the initial phase of decomposition of both PP and EG there was a remarkable release of P, K and Mg. N was rapidly released from EG with highest decomposition rate, and immobilized in PP with lowest decomposition rate. The pattern of Ca dynamics was dependent on species, with a general tendency of releasing from EG and, in contrast to be retained in PP. Green leaves corresponding to harvest residues decomposed and released nutrients faster than senescent leaves of EG.