Trees lose their leaves in winter because otherwise they could freeze. But why do you find high in the mountains and in the far north, where it is much colder than here, trees that do not lose their leaves? Won’t they freeze?
Apparently there are evergreen trees that do not suffer from freezing. But why then do we have so few native evergreen trees?
Asker: William, 47 years old
Answer
Dear Wim,
A difficult and therefore interesting question. Probably not everyone shares my opinion, but I work with forest models and we can predict that behavior with it, so somehow that shows that we understand it.
A coniferous tree (or other evergreen tree) has the advantage of not having to produce all the leaves/needles again every year. On the other hand, such a needle that can hibernate ‘costs’ more energy to make. And to be able to hibernate it is a tougher leaf, but with lower photosynthesis rates, so less efficient
A deciduous tree loses a lot of energy in leaf formation every spring, but with sufficient sun and water, that tree makes up for that very quickly because of the high photosynthesis.
In the end, under good conditions (not too cold or too dry and a sufficiently long summer), the balance turns out in favor of the deciduous tree, but if the winter lasts too long, it remains too cold or too dry in the summer (southern Spain) then the tough conifer wins.
Of course, a coniferous tree can normally survive in the places where a deciduous tree grows, but it is overshadowed by the faster deciduous tree.
Answered by
DR. Gaby Deckmyn
Ecology of forests and mixed landscapes Simulation of forestry Simulation of global change effects on plants
University of Antwerp
Prinsstraat 13 2000 Antwerp
http://www.uantwerpen.be
Prinsstraat 13 2000 Antwerp
http://www.uantwerpen.be
.