What affects the determination of the age of an olive tree?
An olive tree is often described as centenarian or even ancient, but is this literal or just a figure of speech?
Like all living organisms, the olive tree has a life expectancy. This time, however, is studied more than any other tree in the Mediterranean flora, as it is the longest and most admired. Of course, not all olives have the same age, as various parameters are involved that affect it. Some of them are:
– The climate
– The annual climatic conditions at any given time
– The variety of the olive tree
– The type and quality of the soil
– The pruning
– The fertilization
– The diseases attacked during its life
Ancient olive trees in Greece
However, an average life span of an olive tree is considered to be 400-600 years. A much longer period than fruit trees for example, which live 30-150 years. However, in areas of the Mediterranean, as in our country, olive trees over 800 years old can be found. The most typical example of this is the olive groves in the olive groves of the region:
- The olive tree in Vouves, Chania, where today it is considered the oldest olive tree in the world, with 5.000 years! This impressive olive tree is a wild olive tree (olea oleaster), inoculated with the Tsunati variety.
The olive tree in Kavousi, Heraklion, which is estimated to be 3.250 years old. The variety of the olive tree is mastoid (mulberry), inoculated with wild olive (olea oleaster).
The olive tree in Adissarou, Naxos, estimated at 4.500 years old.
Methods of age measurement
At this point, the question of how to measure the age of such a large tree arises. This measurement is very complicated and of course not very accurate. This is because the trunk is almost never symmetrical and its sections do not have concentric circles, but are often polycentric. But let’s go over some of the measurement methods that exist:
- The method of annual rings.
This is the most classic method of determining the age of an olive tree, based on the number of concentric rings and the maximum radius of the last ring. In particular, every year the olive tree forms a ring. This activity is carried out by the cambium of the wood and is not always the same. When the year has extreme weather conditions (very cold or very hot, extreme rainfall), the ring is thin and poorly formed. On the contrary, in years with mild weather conditions, the shape of the ring is uniform. Furthermore, the rings are not concentric, as they are subject to external factors such as fires, frost cracks or other changes and pollution effects. However, an average growth rate of 0,5-1,5 mm per year is considered to be an average of 0,5-1,5 mm per annum.
Example: A trunk with a maximum radius R=150cm (or 1500mm) and an annual radial growth rate averaging r=1mm will have an age of T=R/r=1500/1=1500 years. That’s a lot to say! But what does a 1.500-year-old olive tree look like?
Like this! The impressive cavities are perhaps the most characteristic sign of time.
- Measuring the circumference of the trunk
But if we do not have visual contact with the torso rings, what do we do? This is where the second method comes in. In this, we measure the circumference of the trunk at a height of 1.5 meters from the ground and divide it by 2,5. Care must be taken to convert the circumference of the olive tree into centimeters. This will give an approximate age.
What must always be remembered is that in most cases the larger the circumference of the trunk, the older the tree is in age.
- The radioactive carbon isotope (14C) method
According to the science of dendrochronology (yes, there is such a science!), radiocarbon isotope dating, where it is the measurement of the 14C/12C ratio in organic matter. This method is considered to be the most effective method for determining the age of the olive tree and can estimate ages of up to 60,000 years. According to this method, the objects of study are determined chronologically on the basis of the amount of carbon they carry, using special instruments called spectrometers. But let’s see what this carbon has to do with age, without going into scientific detail.
The radioisotope carbon is an essential element of the biosphere and therefore of organisms, since carbon dioxide (CO2) is formed through it and atmospheric oxygen. As is well known, in the process of photosynthesis trees break down CO2 and take the carbon from the environment. This amount of carbon is in fact constant or otherwise predictable in each organism and in this case in each tree. Taking into account that the half-life of the radioisotope of carbon is about 5,700 years and with the help of special equations (don’t worry we won’t analyze them here), appropriate conclusions can be drawn. As far as olives are concerned, it is true that the older the olive tree is, the more accurate will be the finding of its age.
Instead of an epilogue
In conclusion, to the initial question of how many years an olive tree lives, the answer is many, many years. If we consider the number of years such trees are old, we will realize that they are indeed monuments of nature. Thousands of years ago, such trees were the first temples, with their hollows housing, according to murals, the first idols. They witness to events that modern man cannot see, but can only read about in historical texts. For this reason, we ought to love them and they will reward us with their long-term presence. It is no accident that they are a symbol of divinity according to the ancient Greeks.
The olive tree is a sacred expression of nature, synonymous with above-ground life. The umbilical cord that connects earth and God vertically.
