On constate que, sur un âge moyen des arbres variant entre 30 et 50 ans, en dehors d'un changement climatique, le rendement idéal serait obtenu au point zéro, c'est-à-dire à la même altitude.
If there had been no change in climate, given that the age of these trees may have been 30, 40, 50 years, then you would see that curve do its best at a zero elevational transfer.