. Bulletin. Forests and forestry -- United States. 24 A PRIMER OF FORESTRY. is easy to kill trees with heartwood by girdling tbem, provided all the sapwood is cut through. But in those which liave no heartwood the tubes of the older layers of wood can still convey water to the crown, and when such trees are girdled it is often several years before they die. A great many theories have been proposed to account for the rise of water into tbe tops of tall trees, some of which, as in the big trees of California, may be over 300 feet from tlie ground. But none of these theories are quite satisfactor
. Bulletin. Forests and forestry -- United States. 24 A PRIMER OF FORESTRY. is easy to kill trees with heartwood by girdling tbem, provided all the sapwood is cut through. But in those which liave no heartwood the tubes of the older layers of wood can still convey water to the crown, and when such trees are girdled it is often several years before they die. A great many theories have been proposed to account for the rise of water into tbe tops of tall trees, some of which, as in the big trees of California, may be over 300 feet from tlie ground. But none of these theories are quite satisfactory, and it must be admitted that we do not yet know how the trees supply their lofty crowns with the water which keeps them Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States. Division of Forestry. Washington : G. P. O.
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