X-ray diffraction was used to study variations in the crystallinity of wood and the average thickness and length of the crystallites of cellulose as a function of the number of the year ring in Norway spruce [Picea abies (L.) Karst.]. The crystallinity increased from ring 4 to ring 10 from the pith and was constant after ring 10. The crystallinity of mature wood was about 30% Ϯ 5%. The average thickness and average length of the crystallites were 3.2 Ϯ 0.1 nm and 28 Ϯ 2 nm, respectively; and no systematic variation of these values with the number of the year ring was observed. The mean microfibril angle decreased near the pith but was constant in the mature wood.

The aim of this study was to examine the effects of elevated carbon dioxide [CO 2 ] and ozone [O 3 ] and their interaction on wood chemistry and anatomy of five clones of 3-yearold trembling aspen (Populus tremuloides Michx.). Wood chemistry was studied also on paper birch (Betula papyrifera Marsh.) and sugar maple (Acer saccharum Marsh.) seedling-origin saplings of the same age. Material for the study was collected from the Aspen Free-Air CO 2 Enrichment (FACE) experiment in Rhinelander, WI, USA, where the saplings had been exposed to four treatments: control (C; ambient CO 2 , ambient O 3 ), elevated CO 2 (560 ppm during daylight hours), elevated O 3 (1.5 Â ambient during daylight hours) and their combination (CO 2 1 O 3 ) for three growing seasons (1998)(1999)(2000). Wood chemistry responses to the elevated CO 2 and O 3 treatments differed between species. Aspen was most responsive, while maple was the least responsive of the three tree species. Aspen genotype affected the responses of wood chemistry and, to some extent, wood structure to the treatments. The lignin concentration increased under elevated O 3 in four clones of aspen and in birch. However, elevated CO 2 ameliorated the effect. In two aspen clones, nitrogen in wood samples decreased under combined exposure to CO 2 and O 3 . Soluble sugar concentration in one aspen clone and starch concentration in two clones were increased by elevated CO 2 . In aspen wood, a-cellulose concentration changed under elevated CO 2 , decreasing under ambient O 3 and slightly increasing under elevated O 3 . Hemicellulose concentration in birch was decreased by elevated CO 2 and increased by elevated O 3 . In aspen, elevated O 3 induced statistically significant reductions in distance from the pith to the bark and vessel lumen diameter, as well as increased wall thickness and wall percentage, and in one clone, decreased fibre lumen diameter. Our results show that juvenile wood properties of broadleaves, depending on species and genotype, were altered by atmospheric gas concentrations predicted for the year 2050 and that CO 2 ameliorates some adverse effects of elevated O 3 on wood chemistry.

Non-structural carbohydrates in silver birch (Betula pendula Roth) wood were analysed in a 7-yearold clone and in five mature stems. The analysis was conducted to obtain more detailed information on seasonal fluctuation of these components and of the tree-totree variation and within stem variation. The sugars were analysed by GLC-MS. The smallest total soluble sugar amounts (consisting of sucrose, fructose, glucose, raffinose and myo-inositol) in young trees were measured during mid-summer (ca. 0.3%) and the largest while in dormancy (ca. 1.6% on wood dry weight basis). Raffinose was detected in autumn as a minor component. The proportion of monosaccharides and the amount of myoinositol were largest during growth. Compared to other studies silver birch showed more evident seasonal fluctuation in soluble sugars than evergreen tree species. The sugar amount in mature stems was approximately at the same level as in young trees that had the same felling time. Tree-to-tree variation in the non-structural carbohydrates in the mature wood was fairly large. However, the amount of total soluble sugars, sucrose and glucose showed significant variation within the stem. The amount of these sugars was largest in samples that were taken close to the cambium. Starch was also detected close to pith. According to the heartwood definition and starch measurement results in this paper, it could be stated that silver birch does not form heartwood.

To study the effect of growth rate on fibre characteristics and their variations in Norway spruce, trees were sampled in a nutrient optimisation experiment in northern Sweden. Data was collected from 24 trees (40 years old) from fertilised and control plots after 12 years of annual nutrient application, as well as from older trees outside the experimental area. Fibre length, fibre diameter, cell wall thickness, lumen diameter and cell wall percentage were measured from every third annual ring at breast height and at a height of 4 m. Fibre properties, as well as their standard deviation, were closely related to ring number and distance from the pith. Intra-ring variation of fibre characteristics was high compared to their variation between trees. Fertilisation reduced fibre length and cell wall thickness, but increased fibre and lumen diameter in rings of the same age. The difference in fibre width, cell wall thickness and lumen diameter between fertilised and control trees was less apparent, but a greater difference in fibre length was found between the treatments with regard to distance from the pith. There was a similar effect of fertilisation on fibre properties in early-and latewood. The effect of enhanced growth rate was less pronounced at a height of 4 m (near the pith) than at breast height (in older rings). It was demonstrated that it is possible to model intra-tree variability of fibre characteristics using ring width and cambial age as independent variables. Models presented are, however, limited by the relatively young age of the sample trees used. KeywordsFertilisation Fibre length Fibre width Cell wall thickness Brought to you by | Tokyo Daigaku Authenticated Download Date | 6/12/15 1:45 AM

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