Predicting the Stiffness of Sawn Products by X-ray Scanning of Norway Spruce Saw Logs

AbstractThe connection between branch and trunk in a tree must be strong enough to transfer all loads acting on the branch, and it is well known that such branch-stem connections are indeed very strong. In this paper, X-ray computer tomography is employed to investigate the local fibre orientation in the close surrounding of a knot in a Norway spruce specimen to better understand the origins of the mechanical strength of the branch-trunk connection. First, a wood specimen containing an entire knot from pith to bark was imaged with a voxel size of 52 µm. Subsequently, smaller specimens were cut from this original specimen and imaged again with increasingly higher resolution over four levels. With the highest resolution level (2.6 µm voxel size), the tracheids with smallest lumen were successfully traced. The results revealed how the direction of the fibre paths that start below the knot curve around it as the paths progress upwards to the region just above the knot, where the paths divide into two: one set of paths integrating with the knot on its top side and the other set continuing up along the trunk. Fibres that integrate with the knot at its top follow paths just before they continue into the knot, with a radius of curvature of only about 1 mm in both vertical and horizontal directions. No abrupt change of fibre pattern between latewood and earlywood is observed; rather, a continuous change of fibre direction across annual layers can be seen. The detailed characterisation of the local fibre structure around the knot provides new data that can explain the remarkable strength of the branch-trunk connection.

Download Full-text

Simultaneous X-ray diffraction and X-ray fluorescence microanalysis on secondary xylem of Norway spruce

Wood Science and Technology ◽

10.1007/s00226-012-0474-y ◽

2012 ◽

Vol 46 (6) ◽

pp. 1113-1125 ◽

Cited By ~ 5

Author(s):

Kari Pirkkalainen ◽

Marko Peura ◽

Kirsi Leppänen ◽

Ari Salmi ◽

Antti Meriläinen ◽

...

Keyword(s):

Norway Spruce ◽

Secondary Xylem ◽

X Ray Diffraction ◽

X Ray

Download Full-text

Alteration of element contents in guard cells of Norway spruce (Picea abies) subjected to ozone fumigation and (or) water stress: X-ray microanalysis study

Canadian Journal of Botany ◽

10.1139/b94-012 ◽

1994 ◽

Vol 72 (1) ◽

pp. 86-92 ◽

Cited By ~ 9

Author(s):

D. Le Thiec ◽

C. Rose ◽

J. P. Garrec ◽

D. Laffray ◽

P. Louguet ◽

...

Keyword(s):

Drought Stress ◽

Picea Abies ◽

Norway Spruce ◽

Manganese Content ◽

Stomatal Closure ◽

Calcium Content ◽

Guard Cells ◽

Potassium Content ◽

X Ray ◽

Simultaneous Implementation

Two clones of Norway spruce Picea abies (L.) Karst. (Gerardmer clone and Istebna clone) were subjected to an ozone-enriched atmosphere. The X-ray microanalysis of elements present in the guard cells showed a decrease in potassium for the Gerardmer clone along with a larger closing of guard cells and an increase in calcium contents; for the Istebna clone, ozone did not affect these contents. When a drought stress was applied, an increase in calcium content of guard cells of the Istebna clone was also found. However, the potassium content was smaller in this case for the two clones and could well be due to stomatal closure. When ozone and drought stress were applied together, the potassium content in the Istebna clone was not affected, but for the Gerardmer clone, ozone reduced the decrease in potassium content that occurred as drought stress developed. However, calcium (and manganese) content increased significantly when the Gerardmer clone was exposed to ozone. It seems likely that the Gerardmer clone is sensitive to ozone and when subjected to a drought stress this sensitivity is increased. For the Istebna clone, the resistance to ozone is unaffected by the drought stress treatment. The Istebna clone, however, seems sensitive to drought. These characteristic responses in the two different Norway spruce clones are probably due to genetic differences and may explain the contradictory observations in the response of the stomata during the simultaneous implementation of the complex stresses. Key words: Picea abies, guard cells, ozone, drought stress, X-ray microanalysis, elements.

Download Full-text

Microfibril Angles Inside and Outside Crossfields of Norway Spruce Tracheids

Holzforschung ◽

10.1515/hf.2003.003 ◽

2003 ◽

Vol 57 (1) ◽

pp. 13-20 ◽

Cited By ~ 17

Author(s):

H. C. Lichtenegger ◽

M. Müller ◽

R. Wimmer ◽

P. Fratzl

Keyword(s):

Norway Spruce ◽

Cell Walls ◽

Mechanical Stability ◽

Microfibril Angle ◽

Adjacent Cell ◽

Cell Axis ◽

X Ray ◽

Cellulose Fibrils ◽

Weak Points ◽

Ray Parenchyma Cells

Summary The major part of the wood cell wall consists of parallel-aligned cellulose fibrils. Locally, pits connecting adjacent cell walls disturb the fibril arrangement. The local fibril orientation around these mechanically weak points is crucial for the mechanical stability of the cell. In some softwood species like spruce, the pit apertures at junctions of tracheids and cross-running ray parenchyma cells are elongated and slit-like. The pit orientation has often been assumed to directly reflect the fibril orientation. In this paper we use X-ray microdiffraction to determine the local microfibril angle (tilt angle versus the cell axis, MFA) in single tracheid walls of Norway spruce in the vicinity of pit apertures. The results from microdiffraction are compared with the pit orientation observed under the light microscope.Whereas a good correlation was found in thick-walled latewood cells from the stem and compression wood, large discrepancies occurred for thin-walled earlywood cells. A simple mechanical model that could explain the different situation in earlywood and latewood is presented.

Download Full-text

Lignans in Knotwood of Norway Spruce: Localisation with Soft X-ray Microscopy and Scanning Transmission Electron Microscopy with Energy Dispersive X-ray Spectroscopy

Molecules ◽

10.3390/molecules25132997 ◽

2020 ◽

Vol 25 (13) ◽

pp. 2997

Author(s):

Tuomas Mansikkala ◽

Minna Patanen ◽

Anna Kärkönen ◽

Risto Korpinen ◽

Andrey Pranovich ◽

...

Keyword(s):

Norway Spruce ◽

Imaging Techniques ◽

Dry Weight ◽

Mass Spectrometry Analysis ◽

Gas Chromatography Mass Spectrometry ◽

X Ray ◽

Spectrometry Analysis ◽

Cell Lumina ◽

Transmission Electron ◽

Scanning Transmission

Lignans are bioactive compounds that are especially abundant in the Norway spruce (Picea abies L. Karst.) knotwood. By combining a variety of chromatographic, spectroscopic and imaging techniques, we were able to quantify, qualify and localise the easily extractable lignans in the xylem tissue. The knotwood samples contained 15 different lignans according to the gas chromatography-mass spectrometry analysis. They comprised 16% of the knotwood dry weight and 82% of the acetone extract. The main lignans were found to be hydroxymatairesinols HMR1 and HMR2. Cryosectioned and resin-embedded ultrathin sections of the knotwood were analysed with scanning transmission X-ray microscopy (STXM). Cryosectioning was found to retain only lignan residues inside the cell lumina. In the resin-embedded samples, lignan was interpreted to be unevenly distributed inside the cell lumina, and partially confined in deposits which were either readily present in the lumina or formed when OsO4 used in staining reacted with the lignans. Furthermore, the multi-technique characterisation enabled us to obtain information on the chemical composition of the structural components of knotwood. A simple spectral analysis of the STXM data gave consistent results with the gas chromatographic methods about the relative amounts of cell wall components (lignin and polysaccharides). The STXM analysis also indicated that a torus of a bordered pit contained aromatic compounds, possibly lignin.

Download Full-text

X-ray Densitometry of Norway Spruce Subfossil Wood From the Austrian Alps

Tree-Ring Research ◽

10.3959/1536-1098-72.01.23 ◽

2016 ◽

Vol 72 (1) ◽

pp. 23-34 ◽

Cited By ~ 3

Author(s):

Marzena Kłusek ◽

Michael Grabner

Keyword(s):

Norway Spruce ◽

X Ray ◽

Austrian Alps ◽

Subfossil Wood

Download Full-text