Physical, chemical and mechanical wood properties of Pinus nigra growing in Portugal

Abstract

The wood of Pinus nigra populations planted in Portugal, comparatively to Pinus pinaster , has higher total extractive content, lower Klason lignin and H/G ratio, and similar mechanical properties, presenting advantages for industrial purposes. P. nigra was used in the reforestation of mountainous areas in Portugal, but its wood chemical and mechanical properties were never studied. This work intends to evaluate the chemical and mechanical wood properties of the P. nigra populations planted in Portugal, to relate these properties with previously characterised physical features and to compare these data with other European P. nigra stands and species, namely, P. pinaster. Wood chemical and mechanical properties were analysed in 90 trees from six Portuguese sites, using near-infrared (NIR) spectrometry and the three-point bending test. The wood of the P. nigra populations planted in Portugal presented average values of total extractive content = 9.4%, Klason lignin = 26.69%, MORRad = 14.93 MPa and MOERad = 1200.98 MPa. Ring density showed no significant correlation with ring width. The P. nigra populations planted in Portugal presented qualitative and quantitative properties similar to P. pinaster wood, the main resinous species in Portugal. Facing the lack of raw material for wood industry due to frequent forest fires in the Mediterranean region, P. nigra could be used to reforest mountainous areas of those regions.