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There's no use trying to surprise you by telling you that trees keep diaries, is there? Everybody knows that they carefully record, by the width of their annual rings, how much they grow from year to year, and how old they are -- things like that -- but did you know that they also tell in what years they had a long dry spell, or what years they suffered from fire or lightning-stroke or both in one; or from the attacks of insects, or other ills that trees are heirs to? They do. And some of the diaries of old trees reach back for centuries; are older, much older, than Franklin's autobiography or the famous diary of Mr. Pepys that you hear so much about in the history of English literature. I know of one tree diary kept by an old resident of California, who is still hale and hearty at the age of two thousand or so, reaching clear back to 245 A.D. In this diary he tells about one of the California forest-fires that occurred that year and caused him some loss of property. He belongs to the famous Sequoia family, who think nothing, you know, of living a thousand years; and often go far beyond that! The way in which a tree enters the record of a fire in its diary is this: when a living tree is injured, but not destroyed, by fire this fire may kill or burn away part of the outer bark, the inner bark, and the bole. When such scars are formed the tree at once tries to cover them with new wood, very much as new skin forms over an injury to your hand. The new wood grows from the living edges of the inner bark toward the centre of the wound until it completely covers it. The date of the fire can be told by counting the yearly rings that have formed in the wood growing over the scar. In the case of fire, the wood is charred. If the injury is due to lightning or to the breaking off of a limb by the wind or to insects or to fungous growths, this strange diary tells it; for all these kinds of injuries leave their characteristic marks. READS LIKE A DETECTIVE STORY! Not only that, but it can even be told whether the insects worked on the body of the tree, as the wood-beetles do, or, like the children of the winged Gypsies, ate away the leaves. Think of being able to tell this -- years, even centuries, after both the leaves and the Gypsies have mouldered back into the dust! In the years in which a tree's leaves are eaten away by the caterpillars the rings formed are unusually large on the trunk -- largest of all around the base -- and unusually small as you go up the tree, shrinking more rapidly toward the ends of the limbs and branches and most of all toward the ends of the top branches -- the bald-headedness and increased girth of advancing years, hurried on by illness. Some of these records tell of a broken heart. I call it the "mystery of the broken heart", not just to be talking -- for that wouldn't do at all in books that are intended to tell you the truth about the endless wonders of Nature -- but because the name of these sorrows of the woods is just that, "heart-break", and since the cause of heart-break is still a matter of dispute, I used the word "mystery". A heart-break is a crack in the heart of the wood. Some think that it occurs in the standing tree as the result of heavy wind-storms. Others are of the opinion that it takes place when the tree crashes to the ground at the time it is felled for lumber. Whatever the cause, the defect in the wood is very serious. And yet the crack is often so narrow that it may be overlooked until after the wood has been worked up into manufactured products. A contributor to American Forests and Forest Life, published by the American Forestry Association, from whose article on the subject I take this information, has in his possession a section of an airplane wing-beam of Sitka Spruce which shows two of these breaks. The defect is very common in African Mahogany, and, in the case of Mahogany, a break unnoticed in the lumber will show up badly when it has been finished, and filler and stain are applied. The danger of heart-break also grows, so it seems, with the growing years, for the trees in which it is found are always large. |
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