WHY TREES DIE.
" The days of our years are three score years and ten." What a trifle seems the span of human life when we compare it with the age of trees ! We have seen in the east remnants of our primeval forests—trees that measure one hundred feet and more in height, with a circumference to correspond. Several species of oak, the tulip tree and the sycamore reach a hundred and fifty feet. lint when we have seen the "Big Trees" of California towering to a height of three hundred feet and more, we get a larger conception of what trees may attain to in size and age. Stumps of these giant trees record from two to four thousand years of growth, and the estimated age of some living specimens is live thousand years. On the slopes of the sierras the Douglas spruce and Lambert pine often reach a height of three hundred feet. The highest known tree is an Australian species of Euca lyptus, which occasionally comes close to five hundred feet high.
In the old world there, stands to-day many a tree of gigantic stature whose age probably exceeds two thousand years—cedars of Lebanon, and giant plane trees, and oaks, and yews, and chestnuts. Imagine a tree whose trunk is thick enough to touch the curbstone on either side, if it were planted in an average city street. Then you will have some idea, of the size which trees may attain to. The rings of growth, counted when one of these patriarchs dies, prove that its age has not been over estimated.
Why, indeed, should a tree die at all ? Each successive year renews the organs by which life is maintained. The division of each cambium cell renews the youth of that cell. Each year multiplies the number of new feeding roots and extends new shouts, which are clothed with fresh leaves. Why, then, should not z.t, tree live forever? "A tree, weer dies of old age! This declaration of Professor B. E. Fernow, formerly Chief of the Division of Forestry, U. S. Depart ment of Agriculture, authoritatively answers on r question. Theoretically, a tree may taste immortality. Practically, it accumulates infirmities with years, and death sooner or later overtakes it. A tree is a depend ent creature. it may starve or die of thirst if the soil is hard or dry or impoverished under it. Caterpillars may eat its foliage. Plant lice and scale bugs may suck its juices. Beetles may tunnel under the hark and into the wood. Under these attacks the tree is helpless.
Moreover, the air is laden with the genus of tree diseases. Their name is legion, — scab, rot. blight, rust, mildew, — these are some of them. The leaves, fruit, branches, roots and wood itself—each part has a Bost of such enemies whirl lodge wherever the tree pre sents it vulnerable point. These germs of fungous diseases grow, and their rapid development means the destruction of the tissues of the tree.
The wind. too, is an enemy of the tree because every broken limb offers a lodging place for spores of fungi which may work down into the main stem and by slow degrees reduce it to a hollow shell. I\ lany it large tree shattered by a storm and strewn a wreck upon the ground owes its death to the development of a wood-destroying fungus whose germ entered by way of a broken branch. It behooves us, therefore, to keep the insects and fungi from getting into onr favorite trees. A few practical suggestions will be found in the chapter entitled, insects. Diseases and Spraying." If one wishes to kill ? I, large tree. the easiest way is to girdle it.
A belt of the hark a foot wide or more is usually stripped from the base of the trunk all around. This exposes the living layer, whose cells lose their moisture through evaporation, and very soon die. The ascending sap is not necessarily disturbed, as its course lies through the newest wood. llut the returning current, which habitually desctuids through the inner bark and cambium, is unable to bridge the girdled place. The roots, which depend upon this food sent them by the leaves, soon die of The leaves die and fall, because the disabled roots cease to send up sap from below.
Trees differ widely in tenacity of life. Some promptly die if the bark is but badly bruised. Others live, though girdled, if the inner bark adheres in places. 11 a tree by any such chance survives girdling. it thickens its trunk above the wound. This thickening is caused by the excess of food that accumulates from above while the wound is healing, and the means of conveying it below are yet inadequate.
This fact is turned to practical account, especially in fancy fruit culture. The spurs of grapes. for instance, are girdled when fruit is well gar exam to hasten and to make perfect the ripening of the cluster.