. Bulletin. Forests and forestry -- United States. li3G TIMBER PINES OF THE SOUTHERN UNITED STATES. distinguish the real chiiracter oC the tissues, as described later ou. A more serious difficulty arises in very old, slowly growing trees, where the ring sometimes is represented by only one to three cells (see fig. 18) and occasionally disappears, i. e., is entirely wanting in some parts of the cross section. Generally these eases, due to various causes, are too rare to seriously interfere in the establishment of the age of a tree. SPRING AND SUMMER WOOD. The difference between spring and summe
. Bulletin. Forests and forestry -- United States. li3G TIMBER PINES OF THE SOUTHERN UNITED STATES. distinguish the real chiiracter oC the tissues, as described later ou. A more serious difficulty arises in very old, slowly growing trees, where the ring sometimes is represented by only one to three cells (see fig. 18) and occasionally disappears, i. e., is entirely wanting in some parts of the cross section. Generally these eases, due to various causes, are too rare to seriously interfere in the establishment of the age of a tree. SPRING AND SUMMER WOOD. The difference between spring and summer wood is strongly marked iu these pines, the transition from the former to the latter being normally abrupt and giving to the annual ring the appearance of two sharply dertned bands. (See figs. i;5 and 18 ]i.) In wide rings the transition is sometimes gradual. The springwood is light colored, has a specific gravity of about , and thus weighs somewhat less tJian half as much as the darker summerwood, Avith a specific gravity of about to , so that the weight and with it the strength of the wood is greater, the larger the amount of summerwood. (See diagram, fig. 14.) t-LAST S0-^-2Np 50 ]f- 35P 50 RINGS.' f 4™ 50 RINGS. fcENTRAL 28 RINGS.!! irings or 50 Iyrs growth,' iSUMMER J2%. ' SUMMER WOOD 30%. SUMMER WOOD. 45%. SUMMER WOOD. 52%. SUMMER WOOD. 46% I. Fig. 13.—Variation of HiiiumiTwood per cent from jiitli to l):irk. The absolute width of tlie sumnierwood varies generally with the width of the ring (see diagram, fig. 15), i. e., the wider the ring the with'r tlie summcrwooil band. It decreases in a cross .section of an old log from near the pith to the periphery, and in tlie same layer, from the stump to the toj) of the tree. Where the growth of the stem is very eccentric, the wood along the greater radius has the greatest of summeiwood; thus, in a disk of Longleaf, for instance, there is on the north .side a radius of 15l2 mm. with 'J7
Size: 2286px × 1093px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookpublisherwashingtongpo, booksubjectforestsandforestryunited
