STUDY ON THE LONGITUDINAL GAS PERMEABILITY OF JUVENILE WOOD AND MATURE WOOD

Abstract

The present study is aimed at longitudinal gas permeability measurement of juvenile wood and mature wood of the two most important poplar clones in Iran. Longitudinal gas permeability for juvenile wood of P.deltoides was 1.50 × 10−13, and for its mature wood was 28.18 × 10−13(m3 m−1). As for P.euroamericana, values were 0.16 × 10−13 and 13.74 × 10−13(m3 m−1) for juvenile and mature woods, respectively. The higher extractive content in juvenile wood in comparison with mature wood varies significantly among different clones; the maximum extractive content was measured to be 3.4% in juvenile wood of P.euroamericana, while the minimum (0.3%) was observed in mature wood of P.deltoides. A negative relationship is obvious between gas permeability values and extractive content. Vessel diameter in juvenile woods of both species tends to be lower than mature woods; maximum and minimum vessel diameters were observed in mature wood (67.3 μm) and juvenile wood (54.5 μm) of P.deltoides. Although vessel diameter has a great impact in gas permeability, in the present study no clear relationship was found between them. Therefore, the low permeability in the mature wood of P.euroamericana may be rooted in the intense settlement of extractives in the heartwood.