What are the tree rings?

The research results of using tree rings began at the beginning of this century. This scholar is Douglas. 1867 was born in Vermont, USA, and later came to Arizona to set up a new weather station. 190 1 year, he began to visit some logging camps near Stafford, Frug, to investigate the tree ring patterns of newly cut trees there, and wanted to find evidence that sunspot activities with a period of 1 1 were recorded in these tree rings. He didn't find evidence immediately, but he noticed that the pattern of annual rings in one area and another seemed to be the same. For example, a newly cut tree in a logging camp has two thin rings inside and three thick rings outside, and so do the newly cut trees in other camps. It can be inferred that this pattern shows that two years is bad weather and three years is good weather. Douglas noticed that this type of halo he found seemed to be everywhere in northern Arizona.

In the first 20 years of this century, Douglas continued to study the pattern of tree rings. In fact, it is Douglas's initiative to determine the age of ancient buildings by identifying tree rings. The ruins of Indian villages in the southwestern United States have long attracted the interest of archaeologists. Those villages were first carefully built by craftsmen, and many of them have obviously been used for centuries, but then they were abandoned somehow. It is estimated that these villages existed as early as 2000 BC. Douglas began to investigate the residual wood in the ruins of Indian villages from 19 16, and studied its annual rings to determine its age. By 1929, he finally made a "floating" chronology.

Where there is a civilized tradition, the use of tree rings may be unexpected and surprising. For example, in Novgorod, Russia in the Middle Ages, the streets were muddy, and citizens paved roads with logs. When one layer sinks into the mud, spread another layer. Up to now, at least 28 streets have been filled with layers of logs. These logs date from 953 A.D. to 1462 A.D., which is really an Expo around the world. Another example is the oil paintings of masters such as Rembrandt and Rubens. By analyzing the annual ring patterns on their oak oil paintings, we can know the age of the paintings.

Generally speaking, the application of tree rings mentioned above belongs to the category of tree ring science. At present, the hot topic of this subject is to measure the past meteorology and major meteorological changes from tree rings.

This work is much more complicated than dating, because it depends on the different widths between rings grown in different years. Because of the inherent variability between trees and between tree rings, we can say that this tree is five years older than another tree, but it is difficult to determine the exact number of different widths between tree rings.

Modern dendrology can be said to have originated from the research work of biologist Fritz of the University of Arizona in the 1960s. Fritz and his colleagues carefully investigated the growth process of some trees near Tucson. They cover branches and even the whole tree with plastic film to determine how many gases a tree actually ingests and releases. After 10 years of work, they finally got a detailed understanding of the whole process of the growth of an annual ring.

The growth of tree rings is not as simple as it seems at first glance. For example, if last year was a good year for trees to grow, then the extension of roots will exceed that of previous years, and the growth of the whole tree will also exceed that of previous years. Similarly, no matter what the climate is like in the next few years, a bad year will slow down the growth rate in the next few years. It is an arduous task to analyze the effects on trees, but once this task is completed, the results will be widely used like chronology.

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