MPSC Rajyaseva 2025 CSAT — Question 46

Carpenters from time immemorial must have known that tree trunks have rings, which give rise to the grain in a piece of wood. We find them mentioned by associates of Aristotle, but Leonardo da Vinci was the first person to suggest that as trees grow, they add a new ring every year. Today, we understand that when spring arrives and Vegetation comes alive after the dormancy of winter, the cells just inside the bark of a tree start to be divided. They produce large, thin - walled cells that we see as the light - coloured material scientists call early wood. Later in the season, the growth slows down and the cells get smaller and thicker walled. This so - called latewood looks darker and is what makes up the dark rings in a tree trunk. After the latewood forms, the tree becomes dormant again for the winter and the whole cycle repeats. The result is that many species carry in their trunks a series of alternating dark and light bands, each pair corresponding to a year's growth. These contrasting bands are most evident in conifers; distinctions between rings are not as pronounced in most temperate deciduous species and are absent in many tropical trees. Trees are living archives, carrying within their structure a record not only of their age but also of precipitation and temperature for each year in which a ring was formed. The record might also include the marks of forest fires, early frosts and, incorporated into the wood itself, chemical elements the tree removed from its environment. Thus, if we only knew how to unlock its secrets, a tree could tell us a great deal about what was happening in its neighbourhood from the time of its beginning. Trees can tell us what was happening before written records became available. They also have a great deal to tell us about our future. The records of past climate that they contain can help us to understand the natural forces that produce our weather and this, in turn can help us plan.