CHAPTER XIII. 

 THE CURVE OF THE BIG TREES. 



The curves of tree growth thus far exaniiued all belong to relatively recent times. Yet 

 their length of 200 to 300 years suffices to indicate the existence of climatic cycles longer 

 than any which are deducible from actual meteorological records; hence we are led to 

 expect that longer curves would indicate still longer cycles. The tree which gives most 

 promise of furnishing a long curve is obviously the Sequoia washingtoniana* of California. 

 This tree is not only the largest species existing at present, but also the longest-lived, so 

 far as we have certain knowledge. A few other species, such as the baobab, are known to 

 live to great age, but as they are denizens of tropical countries where seasonal variations 

 are slight, they do not produce marked annual rings which can easily and accurately be 

 measured. The cedar of Lebanon is another old tree. A branch of this which broke off a 

 few years ago is said to have been 2,000 years old, according to a count of the rings made 

 by an American member of the faculty of the Syrian Protestant College at Beirut. Un- 

 fortunately, however, the number of really old cedars is limited to a few score, and it is 

 to be hoped that these will be available for measurement for many years to come. In 

 India, among the Hima ayas, certain species of great age and size may eventually give 

 valuable records, but they are not likely to carry us back half as far as does the Sequoia 

 washingtoniana. The same is true in Australia, although it, also, has some old trees of great 

 size. Thus there is reason to think that the sequoia will always be the most important 

 tree in this respect, not only because of its extraordinary age and size, but because a large 

 number of the trees are readily accessible and are being cut year by year, a few at a time, 

 in a way to render them easily available for study. It may seem a pity that trees thousands 

 of years of age should be cut for fence posts and "shakes," but it is fortunate for our 

 present investigation. Nor is it a matter of much regret from the point of view of future 

 generations, for the United States Forest Service has wisely reserved most of the areas 

 where the trees abound, and only the most conservative cutting will there be permitted. 

 Moreover, the areas which are owned privately, and of which the Government can not 

 afford to take possession, revert to the public domain as soon as the lumber is cut, so that 

 as new trees grow they will be preserved for the future. 



A curve of growth such as that of the Sequoia washingtoniana is important not merely 

 or chiefly as a record of local climatic conditions, but as a standard from which may be 

 deduced the climate of any part of the world during the past 2,000 or 3,000 years. Ac- 

 cording to the growing consensus of opinion among meteorologists, the more marked 

 cUmatic variations of different parts of the world are intimately coordinated; and this 

 conclusion, as we have seen, is confirmed by the studies of the present volume. As yet 

 the relation between various factors in different parts of the world, such as rainfall in 

 tropical Africa and winds in the Sahara, or storms in central Asia and the monsoons in 

 India, has not been determined with precision, but this is gradually being accomplished. 

 The great difficulty lies in the fact that exact meteorological records are nowhere available 

 for a period of much over a century, and in most places for less than half that time. They 



* The California Big Tree has often been known as Sequoia giganlea Endl. That name, however, is synonymous wil h 

 Sequoia semperim-eiis, the redwood. Tlie earhest name applied to the Big Tree is Taxodium washinglotuanum 

 Winslow, published ui 1854. The combination Sequoia washingtoniana was made by Sudwortli in 1S9S, and 

 this is the name that must stand for the species. Jepson, in his Silva of California, uses for this tree the 

 name Sequoia giganlea Decaisne, dating from 1S.54, but since this is obviously a homonym of Endlicher s name, 

 it is untenable. 



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