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Authors: Le T. Ho and Frank M. Thomas

## Abstract

Wood density constitutes an integrative trait of water relations and growth. We compared the recently developed blue intensity (BI) method, which has only rarely been applied to tropical conifers, for determining wood density with anatomical analyses in studying the three rarely investigated palaeotropical pine species Pinus kesiya, P. dalatensis and P. krempfii, which co-occur in South-Central Vietnam, but differ in their distribution areas. For species comparisons, we also calculated the hydraulic conductivity of the xylem with the Hagen-Poiseuille equation and the water potential causing 50% loss of hydraulic conductivity ($Ψ50$) based on the anatomical analyses. We hypothesized (i) that the BI values are correlated with the cell wall fractions, the calculated hydraulic conductivity and the $Ψ50$ values; and (ii) that the wider occurrence of P. kesiya, which also can grow at drier sites, is reflected by higher wood density, lower hydraulic conductivity, lower (more negative) $Ψ50$ values and a smaller variation in the wood anatomical features across the years compared to the other two species. In agreement to our hypotheses, the results of the BI and the anatomical method were closely correlated, especially for sapwood, and P. kesiya exhibited features that are related to the growth at drier sites and to a higher tolerance towards drought: higher wood density and cell wall:lumen area ratios of its smaller xylem conduits, lower calculated hydraulic conductivity and more negative $Ψ50$ values. The BI method is well suitable for determining the wood density in tropical conifers. As a fast and inexpensive method, it may be used for initial screening woody species for their water transport capacity and drought resistance.

In: IAWA Journal
In: IAWA Journal
Author: Alan Dickson

## Abstract

A conventional stereo light microscope was used to image polished wood surfaces at cellular resolution over size scales of the growth ring or larger. Bandpass filtering and local area contrast enhancement were used to aid automatic image thresholding and binarisation. An estimate for the location and proportion of cell collapse was introduced based on the distance between uncollapsed cell lumens. Additionally, spatial associations between vessels were determined using a Euclidean distance transform. The analysis of pith to bark cores provided sufficient detail to show significant intra and inter-annual trends in Pinus radiata tracheid dimensions (wall thickness, wall area, and radial widths). These trends were consistent with expectations and in agreement with the literature. Measured cell dimensions may be influenced by cell collapse and deformation as a result of drying. The analysis of air, kiln and oven-dried Eucalyptus nitens showed that cell collapse was highly variable but generally more prominent in the outer third of growth rings. There were significant changes in vessel shape across the growth rings and vessel area was significantly reduced by drying. The technique provides an intermediate step between detailed microscopy and macroscopic imaging that allows spatial analysis at the wood cell level.

In: IAWA Journal
Author: Pieter Baas
Open Access
In: IAWA Journal

## Abstract

The Hibiscus macrophyllus tree is widely planted in Indonesia especially on Java Island. It has several advantages to be developed commercially as a community or plantation forest compared to the famous introduced species Falcataria moluccana and Anthocephalus spp., including faster growth, higher wood density, and better stem morphology (straighter, more rounded, and lesser branches). However, information about the basic properties of this wood grown in plantations is limited. This study aimed to investigate the anatomical properties of H. macrophyllus and their variation at three ages (8, 12 and 16 years old), as well as to predict the mature wood development by using radial variation in fiber length, microfibril angle (MFA), and wood density from pith toward the bark as the indicators. The wood samples were obtained from a community forest area at Ciamis Regency, West Java Province. Furthermore, anatomical characteristics were examined through wood slides following the IAWA List, while fibre and vessel element dimensions were measured through macerated specimens prepared by modified Franklin’s method. The MFA was determined by X-Ray Diffraction, while wood density was measured in line with British Standard 373-57. The results showed that the anatomical structures were not influenced by tree age, except for wood porosity, and fibre and vessel element dimensions. The 16-year-old tree tended to be semi-ring-porous, the younger trees were diffuse-porous, while the fiber and vessel element length, as well as the diameter, were decreased. Meanwhile, the wall thickness was increased. The fibre length, MFA, and wood density were useful indicators for wood maturity that seemed to be developed at about 11 years of age.

In: IAWA Journal

## Abstract

Limited investigations have been carried out on the physiological and growth responses of bark to wounding, even though wound periderms play crucial roles in tree defenses. To understand the mechanisms of wound periderm formation, we studied the growth responses and structural changes of wounded bark of three Cryptomeria japonica individuals. We observed the developmental time frame and morphology of wound periderms around mechanically induced wounds in summer. The wound responses included discoloration, lignification, and suberization in tissues present at the time of wounding, followed by wound periderm formation and secondary metabolite deposition. The trees had developed wound periderms approximately 4 weeks after wounding. The wound periderms were within 3 mm in the axial directions and within 1 mm in the lateral directions from the wound surfaces. The distinct patterns of wound periderm formation in the axial and lateral regions resulted from the arrangement and anatomical features of the cells adjacent to the wounds. The wound phellem cells were tangentially narrower and axially shorter in the side and upper/lower regions, respectively, of the wounds. Therefore, the cell division frequencies in the planes parallel to the wound surface may be greater than those in the other directions. Wound reactions in bark might initially be triggered by microenvironmental changes, such as the spread of desiccation, which depends directly on the morphology of phloem cell complexes.

In: IAWA Journal
Author: Anat Elmann
Free access
In: Israel Journal of Plant Sciences

## Abstract

A taxonomic list of macro marine algae (seaweeds) described in the literature for the Red Sea during the years 1756–2020 is presented. The list was prepared using existing published studies, local monitoring reports, as well as “grey” or unpublished lists of seaweeds for the area. Altogether, we examined more than 300 publications and compiled more than 900 taxonomic names, of which 576 correspond to valid species, whilst 355 names were considered synonyms for these species. The phylum Chlorophyta (green seaweeds) was represented by 37 currently accepted genera and 133 species (including 74 species synonyms). The phylum Ochrophyta (Phaeophyceae only; brown seaweeds) was represented by 52 genera, 157 species and 99 synonyms; and the phylum Rhodophyta (red seaweeds) by 130 genera, 286 species and 182 synonyms. The brown seaweed Sargassum appears to be a particularly biodiverse genus in the area represented by 58 species and 26 synonyms. Our study shows the inconsistency and lack of long-term taxonomic studies and recent molecular investigations of seaweeds from nearly the whole Red Sea.

In: Israel Journal of Plant Sciences

## Abstract

A new species, Syzygium guipingensis sp. nov. (Myrtaceae), is described based on mummified fossil wood from the Miocene Erzitang Formation of Guiping Basin, Guangxi, South China. This species represents the most ancient reliable fossil record of the genus Syzygium in eastern Asia, showing the greatest similarity to the extant species S. buxifolium Hook. et Arnott. Its occurrence in the Miocene is consistent with the diversification age of the Asian lineage within Syzygium as estimated by molecular dating (11.4 Ma). The fossil record of Syzygium suggests that this genus migrated from Australia to eastern Asia in the Miocene, coincidently with the formation of island chains between these continents.

In: IAWA Journal

## Abstract

The bacterial decay of waterlogged archeological wood (WAW, hard pine spp.) taken from Daebudo shipwreck No. 2, which was buried in the intertidal zone in the mid-west coast (Yellow sea) of South Korea approximately 800 years ago, was investigated. The maximum moisture content of the outer parts (approx. 3 cm of depth) of WAW was approximately 4.2 times higher than that of undegraded reference pine wood. ATR-FTIR and solid-state 13C-NMR analysis indicated a relative increase of the lignin concentration in WAW caused by the degradation of cellulose and hemicelluloses across the board studied (31-cm-wide and 14.5-cm-thick board). Micromorphological studies also revealed that bacterial degradation was progressed to a depth of 15 cm (vertically 7.3 cm) from the surface, which is the innermost part of the board. Erosion bacteria (EB) were identified as the main degraders of WAW. Degradation by tunneling bacteria (TB) was occasionally detected. Decay resistance to bacterial attacks in WAW varied between cell types and between cell wall regions. Axial tracheids showed less resistance than ray tracheids, ray parenchyma cells, and axial intercellular canal cells, including strand tracheids, subsidiary parenchyma cells, and epithelial cells. Decay resistance was higher in ray tracheids and strand tracheids than in ray parenchyma cells and subsidiary parenchyma-/epithelial cells, respectively. Bordered- and cross-field pit membranes and the initial pit borders showed higher decay resistance than the tracheid cell walls. Overall, the S2 layer of the axial tracheids showed the weakest resistance to bacterial attacks.

In: IAWA Journal