RADIAL AND AXIAL VARIATION OF NON-POLAR EXTRACTIVES IN EUCALYPTUS GLOBULUS Jorge Gominho 1* , Ana Lourenço 1 , Isabel Miranda 1 , António Velez Marques 1,2 and Helena Pereira 1 1 Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal; 2 Superior Institute of Engineering of Lisbon, Polytechnic Institute of Lisbon, Rua Conselheiro Emídio Navarro 1, 1959-007 Lisboa, Portugal (*Jgominho@isa.ulisboa.pt) ABSTRACT In order to evaluate the radial and axial variations of the extractives in E. globulus, one mature tree with 32 m was harvested and six discs were taken at different height levels: 0%, 5%, 10%, 35%, 50%, and 60%, of height. The heartwood was present at all levels and contained more extractives than sapwood. The bole section from stump to 60% height level represented 81.8 kg (o.d.) with 36.9 kg sapwood and 44.9 kg heartwood. Extractives amounted to 2.94 kg of which 1.83 kg in heartwood. The extractives content decreased with height and with radial position. The main contribution for the total content was done by ethanol extracts (1.3 – 8.9 %). Non-polar compounds represented respectively in sapwood, outer heartwood and inner heartwood 0.30 %, 0.50 % and 0.43 % at base level and 0.25 %, 0.30 % and 0.32% at 60 % of total height. In non-polar extractives the major compounds identified were fatty acids and sterols. I. INTRODUCTION Extractives are important non-structural components of wood that show a high chemical diversity e.g. hydrophilic and lipophilic compounds, and have a large impact on wood properties and processing. They are responsible for wood colour, odour and they protect the tree from microbial and insect attacks, [2]. Their occurrence, composition and distribution depend of species, growing site, position within the tree and genetic factors, [1]. The extractives content varies axially and radially within the tree: they decrease to the tree top and from the inner to the outer part [3]. The heartwood is the preferential region where the tree accumulates extractives, [4]. In pulping, the effect of both non-polar and polar extractives is highly negative as regards yield and product quality as well as process and equipment, [5]. Therefore wood extractives are one of the main concerns for pulping engineers. This problem is significant even in pulp industries using E. globulus wood which is a raw-material known to have a low content of total extractives (2.9-5.7 %), [6]. The lipophilic fraction of wood extractives plays an important role in pulp and paper production, since it induces formation of pitch and stickies, even if present in the wood in only small amounts as in e.g. E. globulus where the dichloromethane extractives range between 0.4-0.8 %, [7]. The objective of this work is to study the radial and axial variations of non-polar compounds in E. globulus trees using as a case study mature trees for which a higher content in extractives is expected. II. EXPERIMENTAL One mature tree with 40 years of age was chosen and stem disks with 20 cm thickness were taken at different height levels: 0%, 5%, 10%, 15%, 20%, 25%, 35%, 45%, 50%, 60%, 75% of total tree height and top (< 6 cm of diameter). The wood samples were air-dried, and the regions of sapwood and heartwood were marked and the respective area measured using an image analysis system, [8]. The tree volume, and the sapwood and heartwood volumes were calculated by sections corresponding to the different height levels of sampling according to Gominho and Pereira [8]. For basic density and chemical analysis the heartwood was divided in outer heartwood and inner heartwood (at 1/2 of the heartwood radius). In this study, only six height levels were analyzed: at 0%, 5%, 10%, 35%, 50% and 60% (Figure 1). The basic density was calculated using the oven-dry weight and the green volume determined by water immersion. For extractives analysis the samples were grinded and sieved. The 40-60 mesh fractions (5 g) were Sohxlet-extracted successively with dichloromethane, ethanol and water until the completed extraction (16 h with each solvent) and the extractives content was determined gravimetrically. All the analyses were done in duplicate. The dichloromethane extracts were dried under N2, derivatized with BSTFA and