Portuguese researcher,
José Luis Penetra Cerveira Lousada (or the 'tree datador', as he likes
to be called), along with his research team at the University of
Tras-os-Montes e Alto Douro, has patented a formula that certifies the
age of olive and chestnut trees.
Meracei interviewed him to get to find out how they achieved it.
Portuguese
researcher, José Luis Penetra Cerveira Lousada, along with his research
team at the University of Tras-os-Montes e Alto Douro, has patented a
formula that certifies the age of olive and chestnut trees.
What are the methods and problems associated with dating the age of olive trees?
"One
of the most prominent feature of many trees, especially in those from
regions with very specific cyclic environmental alterations
(temperature, precipitation, photoperiod), is that the wood is formed by
concentric rings corresponding to successive annual increases in their
growth.
If its trunk is sectioned transversely, these rings
appear presenting a succession of bright and dark spots depending on
their anatomical structure. The first rings correspond to wood formed
during the first stage of the growing season (spring), while the darker
areas correspond to the wood produced in the final phase of this period
(summer / autumn). Evaluating the age of a tree is relatively easy, as
all you have to do is count the number of rings present in a cross
section of a trunk taken as close as possible to the base area.
This
method is well known and is frequently used in trees with relatively
young ages. However, in older trees, as in the case of olive and
chestnut trees, this methodology is very difficult, because with the
advancement of age the oldest part of the tree (located in the center)
enters in biodegradation, which leads to the total destruction of the
wood and leaves the tree hollow.
Therefore, dating the age of
these trees becomes an impossible task, either by counting the rings or
through radiocarbon techniques, because we don't have the certainty that
those rings will exist. In addition, to carry out these methods, we
must cut down the tree."
Your research team succeeded in guaranteeing the age of millennial olive trees - how did you achieve this?
"Unable
to apply traditional methods of dating trees to those which no longer
have rings inside, we developed a nondestructive method to estimate the
age of ancient trees. Using this methodology, we can calculate the age
of trees using a mathematical model relating age to the dendrometric
variables of the trunk, such as the diameter or the perimeter.
Although
the tree may no longer retain all of its growth rings, we know that the
most recent are located outside the trunk and that the ones being
destroyed are those on the inside, ie the tree always increases its
radius, diameter or circumference while growing. Therefore, the first
phase of the process involves the preparation and setting of an average
growth model of a tree, used to study the evolution of the perimeter,
the diameter and the average radius.
Once we develop this model,
we can use it to date any other tree of the same species and region,
based on its dendrometric characteristics.
So, through a
mathematical function specifically developed for this purpose, it is
possible to estimate the age of an olive tree depending on the size and
shape of the trunk, transforming the dating of hollow trees an extremely
fast process, which is non-destructive and affordable.
However, I
want to stress that the developed method is specific to each forest
species and region, so it cannot be extrapolated to other species or
regions with different soil and weather conditions.
What is the oldest olive tree that you have dated so far?
The
oldest olive tree that we have dated, which has a perimeter at the base
of over 9 meters, was estimated to be 2,854 years old. It is located in
downtown Santa Iria de Azoia (north of Lisbon, Portugal) and, despite being surrounded by concrete and asphalt, still exhibits an incredible vitality.