Mary Gregory, botanist, editor and bibliographer and from 1980 Honorary Member of IAWA passed away unexpectedly on 20 August at the age of 85 at her home in Kew, England. Throughout her career Mary helped hundreds of plant anatomists with literature references on their subject of study, either in
Peter Gasson, Paula Rudall, David Cutler, Barry Tomlinson, Elisabeth Wheeler and Pieter Baas
Elisabeth A. Wheeler, Rashmi Srivastava, Steven R. Manchester and Pieter Baas
Associate-editor Michael Wiemann
forests, or mangroves subjected to strong seasonal fluctuations in salinity. Groenendijk et al. (2014) even found a significant proportion of tree species in a wet tropical forest from Central Africa to have distinct growth rings. The Deccan woods show a low percentage of taxa (19%) with distinct growth
Shu-Yin Zhang, Pieter Baas and Marinus Zandee
Twelve wood anatornical characters, together with broad parameters from ecology, habit and phenology were subjected to simple correlation analysis, path analysis and principal component analysis, in a total sampie of over 470 specimens belonging to 271 species of the Rosaceae from the entire distribution area of the farnily. The functional, developmental and systematic implications of the resulting relations are discussed. Based on the present analysis of ecological trends and previous phylogenetic analysis, a tentative scenario for the evolution of the Rosaceae is offered.
The intra-annual distribution of cell-wall lignin concentration was determined in Austrian pine tree rings and compared with tracheid diameter, lumen width, cell wall thickness and proportion of cell wall area. Lignin concentration was highly correlated with all tracheid dimensions, but only the proportion of cell wall area exhibited a direct statistically significant relationship. Since cell dimensions in Austrian pine are subjected to the indirect and direct influences of the water status of trees, the negative correlation between cellular lignin content and the proportion of cell wall area is attributed to an indirect effect of water stress on lignification in pine tracheids.
Geoffrey M. Downes, J. Gwinyai Nyakuengama, Robert Evans, Richard Northway, Philip Blakemore, Ross L. Dickson and Marco Lausberg
The relationships between wood anatomy in standing trees and the strength of boards were examined in Pinus radiata D. Don (thinned vs thinned and fertilized) at 2 contrasting sites. Fertilizer treatments were applied after mid-rotation thinning. Logs were taper sawn and boards, near the pre-treatment / post-treatment boundary, subjected to acoustic and strength assessment. Average wood property data from a 12-mm increment core obtained prior to harvest, was extracted from the relevant portion of the radius.
In general, fertilizer resulted in lower density, higher microfibril angle (MFA) and slightly lower stiffness. However, stiffness was still relatively high as the affected wood was from the more mature portion of the radius. SilviScan density and MFA data were good predictors of stiffness. Acoustic measurements on boards were strongly correlated with board stiffness. Path analyses explained up to 45% of the variance in stiffness, as a function of estimated MOE and log sweep.
Ilker Usta and Mike D. Hale
The anatomical structure of the cross-field pits in unsieriate rays of Sitka spruce has been examined by scanning electron microscopy. Microscopic images were subjected to image analysis to explain the differences in radial permeability (as assessed by fluid uptake) of dried wood from selected trees of two different seed origins (Queen Charlotte Islands, QCI grown in Rhondda, South Wales vs. South Oregon, SO grown in Dalby, North-East England). Different features of ray pitting were observed. The most radially permeable seed origin (QCI) had considerably larger cross-field pits in latewood than the least permeable (SO). Variation in pit size across the growth rings was minimal in QCI but an abrupt increase in size was noted in the latewood of SO. It is concluded that one of the important anatomical features influencing preservative uptake is the size and number of the cross-field pits.
Veronica De Micco, Enrica Zalloni, Angela Balzano and Giovanna Battipaglia
Tree rings provide information about environmental change through recording stress events, such as fires, that can affect their growth. The aim of this study was to investigate wood growth reactions in Pinus halepensis Mill. trees subjected to wildfires, by analysing anatomical traits and carbon and oxygen isotope composition. The study area was Southern France where two sites were selected: one subjected to fires in the last 50 years, the other characterised by comparable environmental conditions although not affected by fire events (control site). We analysed whether wood growth depends on the tangential distance between developing xylem cells and the limit where the cambium was directly damaged by fire. In the burnt site, thick wood sections, including fire-scar, were taken from surviving plants. Digital photo-micrographs were analysed to measure early- and latewood width, wood density, and tracheid size. Anatomical and isotopic traits were analysed in two series of tree rings (5 rings before and 5 after the fire) selected at different positions along the circumference (close or far from the scar). Anatomical and isotopic traits were quantified also on tree rings of the same years from cored trees growing at the control site. Results showed different wood reaction tendencies depending on the distance from the scar. The comparison between plants from the two sites allowed to exclude possible climate interference.
Our results are discussed in terms of two kinds of growth reactions: the local need to promptly compartmentalise the scarred cambial zone and sapwood after fire, and the general growth perturbations due to tree reaction to crown scorch during fire. Anatomical results, combined with dendrochronological and isotopic analysis, could provide an efficient way to distinguish between direct growth reactions due to heat-related damage on cambium and indirect outcomes related to defoliation.
Mark Riddell, Dave Cown, Jonathan Harrington, John Lee and John Moore
Spiral grain measurements are subject to a high degree of variation and interpretation, depending on the assessment method used. A new measurement approach was tested whereby light was directed through disc samples on a flatbed scanner and the deviation along the grain assessed by means of a template to allow the mapping of grain angle variation radially and tangentially within discs. Initial results showed that the approach was valid for green discs up to 35 mm thick and small enough to fit on an A4 scanner. Comparisons with traditional scribing and cleaving methods were favourable, indicating that the light transmission approach could allow much faster and more accurate data acquisition. The possibility of using larger discs would enhance the ability to assess spatial variation in grain angle and minimise the effects of sample reference geometry with respect to the tree axis (disc tilt and parallax). Further work may also be required to ensure that reliable spiral grain values are obtained from both sapwood and heartwood. The ultimate goal is to develop an automated system for reconstructing stem characteristics from measurements on large fresh green discs to enable the 3-dimensional mapping of individual stem variations in key wood properties and modelling the impacts of silviculture and genetics on wood products.
Linda C.Y. Hsu, John C.F. Walker, Brian G. Butterfield and Sandra L. Jackson
We investigated the potential for the roots of Pinus radiata D. Don to form compression wood. Compression wood was not observed in either the tap or any lateral roots further than 300 mm from the base of the stem. This suggests that either the roots do not experience the stresses required to induce compression wood formation, or that they lack the ability to form it. Roots artificially subjected to mechanical stress also failed to develop compression wood. It is therefore unlikely that an absence of a compressive load on buried roots can account for the lack of compression wood. Application of auxin to the cambia of lateral roots was similarly ineffective at inducing the formation of compression wood. These observations suggest that the buried roots of radiata pine lack the ability to develop compression wood. We also report the formation of an atypical S3 wall layer in the mechanically-stressed and auxin-treated tracheids and suggest that a reaction wood that is different to compression wood may well form in roots.
Frank M. Thomas, Christiane Bartels and Thomas Gieger
In the complex of natural factors responsible for damage to the Central European oak species Quercus robur and Q. petraea, repeated defoliation and drought are considered the most important ones. To investigate the impact of these factors on xylem anatomy and hydraulic conductance, saplings of both species were manually defoliated in the spring of two consecutive years, and equal fractions of defoliated and control saplings were subjected to drought stress in the third year of the study. Defoliation did not significantly reduce the annual ring width of the twigs, but in the twigs of Q. robur it resulted in a significant reduction of the cross-sectional area of early- and latewood vessels, and in a shift in the distribution of the earlywood vessel cross-sectional areas towards smaller size classes in the year after the first defoliation. In the earlywood of Q. petraea twigs, repeated defoliation led to a significant increase in the cross-sectional vessel areas and to a shift in their distribution towards larger size classes. No significant differences in the percentage loss of hydraulic conductance (PLC) occurred between trees that had been defoliated in two successive years prior to the drought experiment and control trees. However, PLC was significantly increased by drought. The different responses of the oak species are attributed to their different capability to recover from the applied stress factors.