Annual rings

Fig. 1. Schematic section, where AR = annual ring, BP = bordered pits, F = wood fiber, FWR = fusiform wood ray, HRD = horizontal resin ducts,...

Kreis-s e, /. circular saw. -schicht, /. circular layer, (of a tree) annual ring, -umfang, m. circumference, periphery, -umlauf, m. circulation, cycle. 

Bischoff JL, Fitzpatrick JA (1991) U-series dating of impure carbonates An isochron technique using total-sample dissolution. Geochim Cosmochim Acta 55 543-554 Broecker WS, Olson EA, Orr PC (1960) Radiocarbon measurements and annual rings in cave formations. Nature 185 93-94... 

Martin RR, Zanin JP, Bensette M J, Lee M, Furimsky E. Metals in the annual rings of eastern white pine (Pinus strobus) in southwestern Ontario by secondary ion mass spectroscopy (SIMS). Can J For Res 1997 27 16-19. 

LA-ICP-MS is well suited for monitoring element distribution in annual rings of trees. Annual ring profiles in pine and birch from the Norwegian-Russian border and from northwest Russia measured by LA-ICP-MS as a rapid and sensitive method show the pollution history (especially of the heavy metal content) of the area. No correlation was found between the pollution levels of the soils and the observed metal content in the annual rings by Garbe-Schoenberg et al.20... 

Other data were obtained by sawing parallel to the annual rings so that a saw cut included only summer wood or spring wood, collecting all the sawdust and using the cut volume and wood weight to determine density and extractive content (Table I). 

Banding is most intense in the early stage annual rings and becomes less pronounced as the fish grows older. 

When collecting evidence from a burial environment, caution must be exercised to ensure that the botanist knows exactly where the plant material was found. The presence of roots and stems in a burial may have preceded the remains or may have been replaced into the grave during back-filling of the soil. Both types of evidence could potentially lead to an inaccurate estimate of PBI if the surrounding conditions are not considered (Willey and Heilman 1987). It must also be stressed that the number of annual rings represents the minimum time since deposition as it is possible that the roots and stems did not invade the grave at the exact time the body was buried. 

The width of the annual rings varies greatly depending on tree species and growth conditions. The variation limits for Scots pine in Scandinavia may be 0.1 -10 mm (Fig. 1-4). For similar reasons the proportion of latewood may vary greatly. Typical percentages for the latewood in Scandinavia are 15-50% for pine and 10-40% for spruce the values are higher in the northern than in the southern parts of these countries. 

Fig. 5-2. Resin canals in Norway spruce (Picea abies) (Back, 1969). (A) Horizontal resin canal in a ray (tangential section) originating from the inner annual rings. The canal is surrounded by epithelial cells which secrete resin into the canal cavities. (B) Horizontal resin canal in a ray (tangential section) originating from the outer annual rings. The canal is filled with epithelial cells because of their swelling during sample preparation. (C) Vertical resin canal (cross section).

The rings in trees are not always annual. In many desert species a ring forms when large xylem cells are produced after a suitable rainy period followed by smaller cells, and this can occur more than once or sometimes not at all in a particular year. Moreover, trees from the wet tropics can have no annual rings. 

The original sand grinder used a central shaft with a series of annual rings which spin between 1220 and 2k00 rpm to achieve a peripheral disc velocity of about 2000 ft./min. or 10 meters/ sec. (Figure k) Unlike the ball mill or Attritor, this media is accelerated 200 - 300 Q s by this centrifugal force as compared to 1 G in the ball mill. 

Archaeologists can test the assumption that the ratio of to was the same in ancient times as it is now by dating a sample of wood of known age. The age of a particular sample of wood from the cross section of a tree (Figure 21.4) can be determined by counting the annual rings, and then testing a portion of the wood from an inner ring. 

The growth of trees is accelerated during sunspot maxima thus the eleven-year sunspot cycle is reflected in the increasing and decreasing width of the annual rings of trees. This effect is so reliable that archaeologists use it to date the establishment of ancient settlements. (Knoll, in Campbell 1967, p. 291)... 

Fig. 74.—Part o a transverse section of a twig of the linden, four years old. m. Pith ms, medullary sheath x, secondary wood Ph, phloem 2, 3, 4, annual rings c, cambium pa, dilated outer ends of medullary rays b, bast pr, primary cortex k, cork. (From Sayre after Vines.)...

Fig. 75.—Part of a cross-section through branch of Cytisus laburnum. (The branch was cut from the tree at the end of October.) Prom A to E the last annual ring of wood from A to B the spring growth with large tracheal tubes T, T, T) between B and C and D and D are wood-fibers between C and D and D and E, wood parenchyma from E to F, cambium F to G, phloem portion C to H, cortical parenchyma M, medullary ray. Below A the last woodrfibers and wood parenchyma formed the previous year. From Sayre after Haberlandt.)...

Growth increments reach their most advanced form in temperate-zone trees where the norm is a single, generally distinct, and circumferential band of wood production each year (Figure 6). The appearance of these so-called annual rings varies between hardwoods and softwoods with species, tree age, and growing conditions. These factors, together with certain other environmental effects, can also... 

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