Virtual Museum of Canada
Jardin botanique de Montrťal 
Centre for Forest Research

Transcription of video clip Light in the forest

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Battle of the pines

Five pine seeds germinate near each other.

Graphic representation of pine seedlings based upon a mathematical growth model

© Risto Siev√§nen, Jari Perttunen, Finnish Forest Research Institute (Metla)
The seedlings cohabit without problem.

During the first years of growth, the seedlings are small. Their modest foliage cohabits without any difficulty.

As they grow, the young trees touch and interfere with each other.



As the years go by, cohabitation becomes increasingly problematic. The foliage of each shades the other. The trees receive less light than before.

To avoid shade, the pines grow tall. They cease nourishment of their lower branches, which do not gather enough light.

The foliage is now completely intermingled. The situation has become unbearable.

At 13 years of age, the growth of the middle pines begins to slow. The position of the others casts shade on them.
These pines therefore grow more slowly than their neighbours, which leaves them even more in the shade.
It is a vicious circle, with a single, inevitable outcome.

One of the animation's pines has just disappeared: it is dead.
A second, centre pine follows soon after.

The survivors have a slender silhouette. It is the direct result of competition for light in the forest.
In a closed forest, pines stand tall, like this.

Pine graphic representation, plus some code lines from the mathemathical model used

© Risto Siev√§nen, Jari Perttunen, Finnish Forest Research Institute (Metla)
Theses pines are generated by a mathemathical model.

This simulation takes several factors into account: the general growth of pines, the quantity of light that reaches the different parts of the foliage and the quantity of light that is absorbed by the leaves.

These pines are very different, even though they are constructed according to the same mathematical model.




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