Specific gravity, fibre length and cell wall thickness of various hybrid Salix clones were compared. The densest clone was 1.47 times denser than the least dense clone. The highest specific gravity was 0.5, found in Salix viminalis L.whereas the lowest was 0.372, found in Salix dasvclados L. The clone with longest fibre was 1.34 times that of the clone with shortest fibre. Clones with long fibre also showed high specific gravity such as Salix viminalis L. The cell wall thickness in Salix clones varies from 0.0025 mm to 0.0037 mm or 1.48 times from minimum to maximum cell wall thickness. Since the above fibre properties indicate various paper strength characteristics such as flexibility coefficient and felting index, it is possible to select clones with superior characteristics for propagation as suitable source for pulp and paper industry.

The objectives of this research were to investigate the proportion of decayed wood in mature aspen stems, its chemical composition and its potential utility as a fuel or as a substrate for conversion to fine chemicals as part of an integrated utilization scheme. Three sound and ten decayed aspen stems were sampled from a boreal forest site. Stem analysis indicate that on average, 20% of the merchantable stem volume was in advanced decay and that considerable sound wood recovery was possible. Wood specific gravity and chemical composition were determined. The holocellulose content (volumetric basis) in advanced decayed wood was reduced by 67%. Thermal analysis of the wood using a differential scanning calorimeter provided graphical evidence of a different sequence of events occurring during the combustion of decayed wood and a resulting heat content per unit weight that was 40% higher than that of sound aspen wood. A higher degree of enzymatic hydrolysis was attainable with white-rotted aspen wood. Approximately 62% of the theoretical glucose yield was obtained from decayed aspen wood after alkali-peroxide pretreatment followed by a 12 hour hydrolysis using technical grade enzymes. The above information is used to elucidate future opportunities for wood recovery and energy production from decayed wood resources.

The energy characteristics of hybrid willow (Salix spp.) were evaluated to improve the selection and breeding program of this short-rotation species. The differential scanning calorimeter (DSC) has proven to be a valuable tool over the conventional adiabatic oxygen bomb calorimeter (AOB) based on its accounting for losses due to dissipated heat, incomplete combustion of pyrolysis and the loss of the heat of vaporization. The average heat content of the four unextracted hybrid willow determined by AOB and DSC was 4635 cal/g and 1609 cal/g respectively. Clone SP-3 is the superior tree based on its energy content per volume of biomass and energy content per square meter of land. Chemical composition of the wood was determined to elucidate its effects on the pyrolysis and combustion. Fuels with high extractive and lignin contents will not necessarily liberate the highest energy when burned. The ash, although representing only a minor proportion by weight, appears to be a major determinant in the combustion behaviour of a material.

Hybrid willow (Salix spp.) is a potential source of pulp as demonstrated by its fibre morphology, chemical composition and pulping kinetics. Fibre length and cell wall thickness measurements on one and two years old clones ranged from 0.49 mm to 0.70 mm and 2.5 /jm to 3.6 pm respectively. Fibre length variation by annual growth layer varied from 0.5 mm in the first growth layer to about 1.1 mm in the last growth layer and the maximum growth rate occurred in the first two to three years for fourteen years old clones. The clones were producing more fibre fraction as indicated by volumetric composition. The UV absorptfvities of milled wood lignin was found in the range of 12.17 -14.31 Lg"'cm" 1 at 278 nm and the presence of syringyl and guaiacyl lignin was observed. "C-NMR results of acetylated milled wood lignin showed clonal structural variations during lignification process and the Klason lignin content of one and two years old clones ranged from 20.8% to 26.1%. Bulk kraft delignification of mature wood resulted in 5-6% higher yield than juvenile wood from the same clone and the pulping activation energy ranged from 98 kJ.moP 1 to 120 kJ.mor".'7b whom correspondences should be addressed 197

Pulping kinetics of extractive-free wood from jack pine trees sampled from the Fort Frances, the Atikokan and the Thunder Bay districts of Ontario, Canada, were investigated. Wood samples were cooked at three different temperatures: 140 ~ 155 ~ and 170 ~ with a white liquor concentration of 32 g/L sodium hydroxide and 10.4 g/L sodium sulphide (25% sulphidity). The results indicated that the average activation energy for pulping of trees from the Fort Frances, the Atikokan and the Thunder Bay districts were 91.0, 81.0 and 81.4 kJ/mol, respectively. The differences of activation energy for pulping between sapwood and heartwood were insignificant. Activation energy for pulping of wood increased from top to bottom of the tree.