Ring-porous

Powder-post beetle (Lyctus spp.) sapwood of ring-porous hardwoods. 

Figure 2.1 Light photomicrographs of wood cross-sections illustrating different anatomical features of softwood and hardwood (a) pine (softwood), (b) birch (diffuse porous hardwood), (c) oak (ring porous hardwood). Scale bar = 200 m.

Figure 5. Cross-sectional and longitudinal surfaces of a ring-porous hardwood. In the cross-sectional view (X) the largest diameter cells are springwood vessels whereas the smaller cells with obvious openings are sum-merwood vessels. Smaller diameter thick-walled fibers constitute most of the remaining volume. Transversely oriented food-storing cells can be seen on the radial surface (arrow). 40X (Courtesy of N. C. Brown Center for Ultrastructural Studies, S.U.N.Y. College of Environmental Science and Forestry)...

Figure 16. Types of vessel segments found in hardwoods. A and B springwood vessels from a ring-porous wood. Note the short length compared with the diameter. C and D typical vessel elements from diffuse-porous woods with simple perforation plates at each end. E typical diffuse-porous vessel element with scalariform perforation plates at each end. 140X...

Fig. 28.3. Photomicrograph of hardwood cross-sections depicting (a) ring-porous and (b) diffuse porous wood. (Courtesy U.S.D.A Forest Products Laboratory.)...

Such a low value indicates that no turbulence is expected. Even if d were fivefold larger and Jv were 10-fold greater, as can occur in a ring-porous tree, Re is still far less than the value of 2000 at which turbulence generally sets in. 

Figure 10. Light micrograph of the three types of pore patterns of growth increments in hardwoods as seen in cross section. Key A, ring-porous (red oak) B, semi-ring-porous (aspen) and C, diffuse-porous (yellow birch). (Reproduced with permission from Ref. 40. Copyright 1982, Technical Association of the Pulp and Paper Industry Press.)...

N. Guillou, Q. Gao, M. Nogues, R. Morris, M. Hervieu, G. Ferey, and A. Cheetham, Zeolitic and Magnetic Properties of a 24-membered Ring Porous Nickel(II) Phosphate, VSB-1. C. R. 

Figure 1.21. Vessels throughout the growth Figure 1.22. Large earl)fwood vessels in the ring in the diffuse porous wood of Populus ring porous wood of Quercus robur. x 40. robusta. x 60.

Vasicentric tracheids are found close to the vessels in some hardwoods, particularly in the earlywood of ring porous species. They are short tracheid-like cells with profuse sidewall pitting. They are often longitudinally bent and flattened transversely on account of the lateral expansion of the adjacent vessels. 

The ring-porous hardwoods tend to have a high density at the centre, which decreases and then increases to some extent toward the bark (Zobel and Buijtenen,... 

Sperry, J, S, Nichols, K, L., Sullivan, J, E, M., and Eastlack, S. E. (1994). Xylem embolism in ring-porous, diffuse-porous, and coniferous trees of Northern Utah and interior Alaska. F.cology 75, 1736- 1752. 

Several thousands of hardwood species exist, and each one has its own anatomical pattern. The density, for example, ranges from less than 100 kg m" (i.e., balsa wood) up to more than 1200 kg m" (i.e., ebony wood). They are usually divided into ring-porous and diffuse-porous types, though all intermediate types can be found ... 

A ring-porous species produces very large vessels (up to 500 pm in diameter) in earlywood. Simple perforation plates allow the vessel cells to communicate easily. 

FIGURE 40.5 Typical anatomical patterns encountered in temperate species (a) softwood, (b) ring-porous species, and (c) diffuse-porous species. The height of these images represents about 2 mm. (Microphotographs J.C. Mosnier, LERMAB-ENGREF, Nancy, France.)... 

The most permeable species in the longitudinal direction are among the ring-porous species (Quercus spp.) that have very large vessels (up to 500 xm in diameter). 

The situation is more complex with hardwoods. The growth rate has little effect on the wood properties of diffuse-porous hardwoods, but has a marked impact on the density of ring-porous hardwoods. Unlike softwoods, these produce denser wood when fast grown. 

Wood has a well-defined cellular structure. In softwoods and ring-porous hardwoods the cells produced in the early part of the growing season, the earlywood, are larger than those produced later in the season, the latewood. In diffuse-porous hardwoods the cells are more uniform in size. These differences in cell structure are responsible for the variation in density observed among wood of different species and even in wood of the same species, depending on local growth conditions." ... 

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