Publications

Tree mortality is becoming more common in wild forests, plantations, and orchards. Remedial or preventative counteracting measures are limited because, before the onset of overt dying, reliable methods to distinguish intrinsically healthy trees from unhealthy trees are lacking. Survivotypes within dead populations can nevertheless be identified and conserved in support of achieving suitably adapted future forests.

Abstract The determination of phenols based upon coupling with 4-aminophenazone in the presence of an alkaline oxidising agent has been examined. The importance of pH has been studied and a suitable buffering agent has been recommended. The reactivity of many phenols of pharmaceutical interest has been investigated and the application of the method to a number of pharmaceutical preparations is described.

Several new developments are noted since publication of “Porsild spruce in Canada” in The Forestry Chronicle in January 2013. Firstly, Porsild spruce has been found in northeastern Quebec. Secondly, although researchers were unaware of the fact until now, the Porsild spruce phenotype has been found to be a common component in the New Brunswick tree improvement program’s second-generation seed orchard in support of reforestation. Thirdly, a wild tree discovered in New Brunswick displays morphological features of Engelmann spruce and, based on observed similarities between Yukon Beringia Porsild spruce phenotypes and the accepted Engelmann spruce phenotype, it is possible that the New Brunswick Engelmann spruce tree was derived from the local Porsild spruce population.

A critique is provided of the physical and chemical control of primary and secondary xylem development in terms of mechanics, genetics, phylogenetics, and the larger field of plant physiology. Strengths and weaknesses of the phytohormone theory of vascular development are analyzed. Homeobox genes, sub-cellular phytohormone localization, anatomical responses to varied phytohormone ratios and dosages, polar auxin transport, second messengers, radial fluxes in water potential, intercellular signalling, lignin biochemistry, and the phylogenetic position of bryophytes in relation to xylogenesis are identified as some areas for future research. Homeodomain proteins are addressed in terms of cambial initials and cell-fate determination, and other genetic and environmental factors controlling differentiation of diverse cellular phenotypes are reviewed. As a 'continuum hypothesis', it is proposed that the extent of secondary wall sculpturing during tracheary element differentiation is a function of the duration of homeotic gene expression.

Direct differentiation of ‘dormant’ fusiform cambial cells (fees) into tracheids in stem cuttings of Pinus contorta Dougl. was investigated by light and transmission electron microscopy. In cuttings from which all but one pair of needles had been removed, differentiation occurred close to the needle trace without prior cell division or expansion. The highly osmiophillic, granular cytoplasm of differentiating fees exhibited numerous mitochondria, dictyosomes and endoplasmic reticulum (ER) cisternae and was enriched with vesicles and polyribosomes. The protoplasm did not become highly vacuolated, as it normally does, until differentiating tracheids were approaching maturation. During differentiation, secondary walls were deposited in fees as ribs of annular and spiralled thickenings and also as borderedpit-like structures devoid of margo and torus and lacking the typical lamellar structure of secondary-xylem tracheids. The fee plasma membrane at sites of secondary-wall growth was in dynamic flux, dilated vesicles derived from both ER and dictyosomes apparently fusing with it at these locations. In addition, electron-dense blebs were invariably plasma membrane-associated and appeared to be exocytotic; these blebs became rare during autolysis and they were never seen in non-differentiating cells. Deposition of oriented nascent cellulose microfibrils appeared to occur in the absence of associated cortical microtubules. As secondary-wall deposition neared completion, vacuoles derived from rough ER grew and fused; concomitantly, the protoplasm disappeared resulting in fully autolysed tracheids. Auxin (indol-3-ylacetic acid, IAA) promoted the gel-like protoplasm of dormant fees to became highly vacuolated, and cell division and expansion followed; however, tracheid differentiation did not occur. Polyribosomes, rough ER, and dictysomes were less abundant than in differentiating fees and the cytoplasm of auxin-treated fees was fine grained and less densely stained. The electron-dense exocytotic blebs found at the plasmalemma in differentiating fees were not induced by IAA treatment. Fees of control cuttings enlarged somewhat and became more vacuolated but otherwise remained dormant.

The defining feature of each forest is the organism that humanity generically designates as ‘tree’ [...]

This study investigated the carbon (C) content in b oles of twenty western hemlock ( Tsuga heterophylla (Raf.) Sarg.) trees. Bole samples were obtained from southern Vancouver Island in British Columbia (Conuma River, south of Muchalat Lake, Apple River, and Harris Creek) from a Western Forest Products Inc. management area, during the summer of 2003. Disks (10 centimeters thick) were o btained from the top of live crown (TLC), the base of live crown (BLC), and at breast height (BH) of each tree . By elemental analysis, C content of 20 genotypes had a mean of ~53.5% (w/w), standard error of the mean [SEM] 0.1). Since the variation in each tree was so small, and the SEM for each of the positions within the bole was 0.1 a nd 0.2, we conclude that there was only slight vari ation among genotypes at the 99% level of confidence in the thr ee positions within the bole. Considerable addition al research is needed in order to have accurate estimates of total C content in any tree, and given that there is var iation in C content within tree species, and in order to accoun t for C in any forest stand, total C content should be estimated by integrating each individual tree component.

Using one purification procedure, endogenous indol-3-ylacetic acid (IAA), a known regulator of vascular development in woody plants, was characterized by capillary gas chromatography–mass spectrometry in developing secondary xylem of 6 conifers, 16 hardwoods, and 4 additional species of woody plants indigenous to the northern temperate zone. The results suggest IAA may be ubiquitous throughout the Tracheophyta.

Quiescent 6-year-old lodgepole pine (Pinus contorta Dougl. var. latifolia) were transferred in midwinter from outdoors to warm, long-day greenhouse conditions. Vascular cambia from these trees were harvested on the day of transfer and weekly thereafter until xylem development became apparent. The stage of cambial reactivation in each tree was assessed by microscopy. Cambial extracts were then analyzed quantitatively by high-performance liquid chromatography (HPLC) at four ultraviolet wavelengths. A major HPLC peak, at 254 nm, was associated with radial expansion of cambial derivatives and increased markedly with secondary-wall formation and lignification in differentiating tracheids. The presence of this peak suggests a facile means for assessing commitment to tracheid differentiation in lodgepole pine.

At present, a carbon (C) content of 50% (w/w) in dry wood is widely accepted as a generic value; however, few wood C measurements have been reported. We used elemental analysis to investigate C content per unit of dry matter and observed that it varied both radially and vertically in boles of two old-growth tree species: sugar maple (Acer saccharum Marsh.) and giant sequoia (Sequoiadendron giganteum (Lindl.) Bucholz). In sugar maple there was considerable variation in tree ring widths among four radii for particular annual layers of xylem, revealing that the annual rate of C assimilation differs around the circumference and from the base of each tree to its top, but the observed variation in C content was unrelated to diameter growth rate and strongly related to the calendar year when the wood was formed. Carbon content in sugar maple wood increased in an approximately linear fashion, from < 50 to 51% from pith to cambium, at both the base and top of the boles. In giant sequoia, C was essentially constant at > 55% across many hundreds of years of heartwood, but it declined abruptly at the sapwood-heartwood boundary and remained lower in all sapwood samples, an indication that heartwood formation involves anabolic metabolism. Factors that may be responsible for the different C contents and trends with age between sugar maple and sequoia trees are considered. Tree-ring data from this study do not support some of the key assumptions made by dendrochronology.