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Ed C. February, W.D. Stock, W.J. Bond and D.J. Le Roux

The primary objective of this study was to determine the relationships between water availability, plant growth and selected vessel characteristics for Eucalyptus grandis and two hybrids, so as to ascertain whether these xylem characteristics predict water use efficiency. Cuttings of Eucalyptus grandis, E. grandis × camaldulensis and E. grandis × nitens were planted in 220 litre drums from which rainfall was excluded. One half of the individuals received a low watering treatment; one half received a higher watering treatment. Soil moisture depletion through root uptake was monitored weekly and the removed water replaced to maintain 60 and 80 litres in the pots of the low and high watering treatments respectively. Mean values for tangential vessel diameter, vessel frequency and vessel element length were compared for the two treatments. In E. grandis and the hybrid E. grandis × camaldulensis vessel diameter (P < 0.01 ' P < 0.05 respectively) and vessel element length (P < 0.05 for both) increased from the dry to the wet treatment as water uptake through transpiration increased. There is no significant correlation between available water and vessel frequency. For E. grandis × nitens, on the other hand, only vessel frequency was significantly (P < 0.01) correlated with water uptake. In all three species/hybrids water availability also had a significant influence on stem diameter (P < 0.0001) and transverse sectional stem area (P < 0.0001) which increased with increased water consumption. These results suggest that E. grandis × nitens may be more water use efficient than E. grandis, which is commonly grown for timber and thus could potentially be used as a replacement species that is more water conservative in this water limited region.

Teresa Quilhó1, Isabel Miranda and Helena Pereira

Within-tree variations in fibre length, width, wall thickness and wood basic density of Eucalyptus grandis × E. urophylla (urograndis) were studied in five 6.8-yr-old seedling trees and five 5.6-yr-old trees from one clone from Brazil. Samples were taken at 5%, 25%, 35%, 55%, 65% and 90% of stem height and five radial positions (10%, 30%, 50%, 70% and 90% of radius). The tree average fibre length, width and wall thickness were in seed and clone trees: 0.955 mm and 1.064 mm, 18 μm and 20 μm, 3.6 μm and 4.4 μm respectively. The axial variation of fibre dimensions was very low, while there was a consistent but small increasing trend from pith to periphery. The basic density ranged from 397–464 kg/m3 to 486–495 kg/m3 respectively in seedling and clone trees with a low variation along the stem. In comparison with other eucalypt pulpwood, e.g. E. globulus, the urograndis hybrid showed similar fibre dimensions and lower basic density. Overall the within-tree variation of these wood properties was low and age had a small impact on the variation of density and fibre dimensions.

Robin Adey-Johnson, J. Paul Mclean, Jan Van den Bulcke, Joris Van Acker and Peter J. McDonald

resolution down to sub-micron levels (Bucur 2003). This technique has been used to study vessel size in oak ( Quercus robur L.) and beech ( Fagus sylvatica L.) (Steppe et al . 2004); bordered pits in mature Norway spruce heartwood (Trtik et al . 2007) and the micro-structure of hybrid Aspen ( Populus

Adam Miodek, Aldona Gizińska, Marcin Klisz, Tomasz Wojda, Krzysztof Ukalski and Paweł Kojs

& Wareing 1981; Barnett & Miller 1994; Oribe et al . 2003; Gričar et al . 2006; Begum et al . 2012; Rahman et al . 2016, 2018), the diffuse-porous hardwood hybrid Populus kitakamiensis ( P. sieboldii  × P. grandidentata ) (Begum et al . 2007), and the ring-porous hardwood Quercus serrata (Kudo et

Ilona Peszlen

Anatomieal properties of three Euramerican hybrid poplar [Populus × euramericana (Dode) Guinier] clones, the Italian 'I-214' and the Hungarian 'Kopecky' and 'Koltay', were investigated. Six trees from each clone were sampled from plantations (aged 15 and 10 years) at two sites in Hungary. Disks were removed at breast height from each tree to study the effect of age on variation of anatomical properties. Along the eastern radius, vesscl and fibre parameters were measured for each growth ring using an image analyser.

Rudolf Schmid and Pieter Baas

The occurrence of multiple perforation plates and helical wall thickenings in vessel elements of 144 species (plus 12 varieties and 2 hybrids) in 53 genera of Myrtaceae was extensively explored. Scalariform perforation plates occur in 40 species (plus 1 hybrid), in Luma, Myrceugenia, Myrteola, Ugni, and in the monotypic Myrtastrum rujo-punctatum, Neomyrtus pedunculata, and Tepualia stipularis. Ugni candollei also has foraminate (i.e., sieve-like) perforation plates. Helical wall thickenings occur in 33 species (plus 1 hybrid), in Acmena, Austromyrtus, Myrceugenia, Myrcia, Myrcianthes Psidium, Xanthomyrtus, and in Myrtus communis. Most of these records are new. The speeies with exclusively scalariform perforation plates (in Luma, Myrteola, Neomyrtus, and Ugni) are from cool mesic habitats; those with mixed simple and multiple perforation plates are also largely cool mesic but show a somewhat greater diversity of habitats. Myrtaceae with exclusively simple perforation plates predominate in all habitat types. Helical wall thickenings occur sporadically throughout the distributional range ofthe family. However, tropical species tend to have weaker helical thickenings than the subtropical and temperate species exhibiting them. The possible functional significance of these ecological tendeneies is discussed. It is hypothesised that multiple perforation plates were retained in some cool mesic Myrtaceae because of a lack of strong selective pressure to eliminate them from this type of environment, rather than that they were retained because of adaptive significance in trapping embolisms. The systematic and diagnostic value of multiple perforation plates and helical wall thickenings is also discussed. Scalariform plates are largely confined to related genera in Myrtoideae; Tepualia is the only representative from Leptospermoideae. Helical wall thickenings are only of limited diagnostic and systematic value above the species level.

J.E. Phelps, J.G. Isebrands and R.M. Teclaw

The coppicing ability of Populus hybrid clones after dormant season harvesting is weil suited to a short-rotation, intensively cultured (SRIC) growth system. stems formed from coppice exhibit a greater amount of growth than first-rotation trees during the juvenile stage. This research examines and compares properties, including specific gravity and fibre length of the wood and bark, of 3-year-old firstrotation stems (from cuttings) and 3-year-old coppiced stems of three hybrid Populus clones grown und er SRIC. Trees produced from coppiced stumps were 1.5 to 2.5 times larger (in height and diameter at the base) than first-rotation trees after 3 years of growth. Some of the wood properties of the first-rotation trees differed from those of the coppiced trees. For example, wood specific gravity was higher and wood fibres were longer in the sampies removed from the basal portion of the first-rotation trees. Although significant, these differences were small and not important from an industrial standpoint. The increase in woody biom ass after coppicing is likely to be more important to industry than any decreases in wood properties expected during short-rotation, intensive culture of Populus trees.

Michael Grabner, Ulrich Müller, Notburga Gierlinger and Rupert Wimmer

The genus Larix is exceptional for its high content of extractives in the heartwood, with the dominant component arabinogalactan found abundantly in cell lumens of tracheids. On parallel samples prepared from 20 European, Japanese and hybrid larch trees (Larix decidua Mill., L. kaempferi Carr., and L. decidua × L. kaempferi, respectively) extractive contents and mechanical parameters were measured. The hot-water extractives in the heartwood had a significant effect on transversal compression strength and Young's Modulus. In heartwood, increasing extractive content went hand-in-hand with better mechanical properties in the transverse direction. The extraction procedure led to negligible changes in the sapwood. Anatomically the extractive-filled tracheids showed a tendency of being arranged radially, closely to wood rays. The extractive arabinogalactan in larch heartwood has multiple effects on different aspects of wood quality, among which is lateral mechanical enforcement.

Silvia Monteoliva, Gabriela Senisterra and Raúl Marlats

The variability of wood basic density and fibre length was determined in six 13-year-old willow clones growing under two different site conditions in Argentina. Values of basic density and wood fibre length were obtained and variance analyses were performed considering site and clone as sources of variation. Components of genetic and phenotypic variations were determined to calculate heritability in the broad sense. Site influence was significant for basic density, which ranged from 0.364 kg/dm3 and 0.455 kg/dm3. Clones “americano” and hybrid cv “A 13-44” showed the highest density values in both sites. For fibre length, values of the continental site were significantly higher. For each clone, mean values vary between 837.1 μm and 1142.1 μm. Heritability values show that the genetic control is stronger for density (h2 = 0.65) than for fibre length (h2 = 0.32). The clones “americano” and “13-44” stand out because of their high density and long fibres.

Isabel Carrillo, Sofía Valenzuela and Juan Pedro Elissetche

An evaluation of 100 Eucalyptus globulus and 100 E. nitens trees (six years old) was made using the Pilodyn micro-drilling tool as an indicator of wood density. Thirty E. globulus and thirty E. nitens trees with high, medium and low density were selected and sampled with an increment borer at breast height for anatomical analysis using fibre tester equipment and the Resistograph device to generate detailed information about fibre biometry and anatomical wood properties of both species for hybrid development. Eucalyptus globulus trees had a basic wood density average of 478 kg/m3, while E. nitens had a density of 490 kg/m3. Both micro-drilling tools showed significant correlation coefficients with basic wood density. Correlation coefficients between basic wood density and Pilodyn values were negative, being -0.53 (p = 0.01) and -0.68 (p < 0.001) for E. globulus and E. nitens, respectively. For both species a positive correlation was observed between basic density and Resistograph mean amplitude; the correlation coefficient was 0.84 (p < 0.001) for E. globulus, and 0.85 (p < 0.001) for E. nitens. Eucalyptus nitens trees had a higher density and amplitude average and smaller Pilodyn values than E. globulus trees, while the latter had higher coarseness, fibre length and diameter at breast height than E. nitens trees. However, E. nitens showed larger differences between features of earlywood and latewood in a growth ring than E. globulus trees.