8 or 9 years ago my neighbor asked me to turn off a coniferous tree (pine) that blocked a lot of light.
I first sawed off the side branches and then shortened the bare trunk to about 2 meters above the ground. The intention was later to remove the entire tree with its root system, whereby the remaining trunk would help to pry things loose.
9 years later everything is still there as before. Only at the top of the trunk the bark has come loose. There is also no new branching, let alone needle formation.
I now wonder whether the root system of a felled or felled tree continues to grow, remains stable or dies. The latter seems the most logical to me: the tree should no longer be anchored in the ground and water, minerals and other nutrients should no longer be fed to the no longer existing leaves via the roots.
How does that actually work and is there a difference between coniferous and deciduous trees in this regard?
Answer
Dear Dirk,
An interesting question! Often people don’t really know exactly what the roots of trees are, precisely because it is so difficult to observe them.
In any case, the above-ground and underground parts of a tree are inseparably dependent on each other: a tree cannot grow without roots that absorb water and nutrients, but the roots cannot develop if above-ground photosynthesis comes to a complete standstill. Although they are visibly separated from each other, a lot of communication takes place between the roots and the above-ground part, mostly via hormones that are released in response to certain events (light, damage, …).
The lifespan of roots can vary greatly from species to species, and also depends on growing conditions (such as soil moisture and temperature). However, some general principles still apply:
– Although the stability of a tree is determined by its large, thick roots, the finest roots are the most important for growth: it is these roots that will absorb water and nutrients. And it is also those fine roots that die very quickly when they are no longer functional. That certainly happens within the first year. Even when a tree is still in good condition, it replaces its fine roots 2 to 3 times a year. In other words: if there is no longer any life to be found in the above-ground part (and you can also expect that a pine will absolutely not grow again after it has been cut down), then those fine roots have long since died.
– It is a completely different story with the large roots, and certainly with the central taproot: they will remain in the soil for a very long period (certainly decades), even if the tree is no longer living. What does change is the strength of those large roots. I suspect that the tensile strength must have been more than halved after 9 years.
– If it is an adult pine, you will be dealing with a meters deep central taproot. Even after nine years you will most likely not be able to just pry it loose… It can be quite a job to remove the tree with its root system, but maybe that is not necessary at all? Of course I don’t know what your garden looks like and how you would like it, but a tree sawn to the ground, where the root system remains, does not necessarily have to be disturbing. In this way you do not disturb the underground environment, and you give nature the opportunity to gradually recover all the raw materials from your tree…
Hopefully this provides an adequate answer to your question.
Answered by
dr. ir. Bert Reubens
Burg. van Gansberghelaan 96 box 1 9820 Merelbeke
http://www.ilvo.vlaanderen.be
.