Trees witness history

1987/02/01 Arregi, Krexen Iturria: Elhuyar aldizkaria

• Botanika

Under the influence of sand storms, the stone pavement remains firm. In the White Mountains, located between California and Nevada, live the oldest living beings known on earth: Pines with beards ( Pinus aristata or pinus longaeva). These trees are about 4000 years old and the oldest of them has already turned 4900. The mark of these trees is really beautiful, especially if we consider that the living average of conifers ranges between 200-300 years.

Beard pines have been strongly nailed over the centuries. However, they have not grown too much in that long time, since the longer one only measures 7.50 meters. Apparently, beard pines grow every 100 years only 2.5 cm. Why less? That is the key to their aging. The wood of the barbed pine is half dead, but due to the dryness of the desert it does not rot. It preserves several living cells always under the target. This ensures sweat circulation.

In addition, the wounds and scars of the climatic and ecological conditions that have suffered the trunks have marked. They live isolated from the rest of the vegetation, from the 300 m in almost dry soil. Some of those on the road to the winds are parallel to the soil and erosion has also shown their roots. The old age of the Barbados pines and their admirable adaptability have captivated the botanist. Since 1958 these pines are protected and used for scientific research. Pines can be considered open books that tell a very old story.

The rings of the pines are marked by the climate changes they have suffered throughout their lives. The counting of the rings (it is known that every year the trees have a new ring), gives the age of the tree and the thickness of these rings shows us the climatic conditions that the tree has suffered. Therefore, analyzing the rings is possible to swim to the climate that has existed since prehistory. In addition, it is possible to study dead pines. The dry desert has kept the logs complete 9,000 years ago.

The study of the Barbados pines has produced a second revolution in prehistoric chronology. The first was radiocarbon dating. Beard pine, for example, has nullified the hypothesis that 14 carbon in the atmosphere has remained constant. The carbon isotope percentage of 14 atomic weights has remained constant only in the last 3500 years.

The study of pines has allowed the development of a calibration curve for carbon 14. With this curve it will be possible to adjust the age data obtained in radiocarbon. Therefore, we will proceed to a new dating of some ancient events and a new chronology, since it has been postulated that the proportion of carbon 14 in the atmosphere to reach those age data has remained constant over time.

The contemporaries of our ancestors of Ekain and Altxerri are present in the mountains of California as silent witnesses of history.